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A new sauropodomorph ichnogenus from the Lower Jurassic of Sichuan, China fills a gap in the track record
Historical Biology
Abstract
A dinosaur tracksite in the Lower Jurassic Ziliujing Formation of Sichuan Province, China consists of a spectacular sub-vertical exposure, with multiple track-bearing levels and trackways showing parallel and bimodal orientations. Based on well-preserved material, the new ichnogenus and ichnospecies, Liujianpus shunan ichnogen. nov. ichnosp. nov. is erected to accommodate distinctive sauropodomorph trackways occurring in this assemblage. Liujianpus has a unique combination of features, some relating to the early Jurassic basal sauropodomorph (prosauropod in traditional usage) ichnogenus Otozoum, others to the sauropod ichnogenus Brontopodus. Despite such a mix of basal sauropodomorph- and sauropod-like features, the trackmaker of Liujianpus is likely a basal sauropodomorph. This identification is consistent with the occurrence of basal sauropodomorph skeletons from geographically and chronologically close localities. The other distinct morphotype from the tracksite is linked to a sauropod trackmaker. As such, the ichnofauna consisting of two distinct foot morphotypes reflects the diversity of sauropodomorph dinosaurs in the Early Jurassic of Asia.
... The only reported tracks similar to those of Liujianpus are unnamed tracks from the Early Jurassic of Morocco illustrated, but not described in detail, by Ishigaki (1988). Liujianpus differs from Otozoum by having larger manus prints, by lacking segmented (by digital pads) digit imprints and shorter digit imprints (25%e30% vs. 40%e50% track length), and by having greater outward rotation (Xing et al., 2016d). Similar differences differentiate Liujianpus from Lavinipes. ...
... Similar differences differentiate Liujianpus from Lavinipes. Liujianpus tracks are similar to Brontopodus tracks in broad, general, nondiagnostic ways, such as having outwardly rotated manus prints and the "elephantine,""fleshy," and outwardly rotated pes prints with large, anterior claw imprints (Xing et al., 2016d). The pace angulation of Liujianpus is similar to those of sauropod trackways as well, but Liujianpus manus prints differ 6. Jurassic vertebrate tracks and traces in often exhibiting distinct traces of five digits; pes prints differ from those of sauropod tracks in having Digit I the shortest and Digit III the longest, as well as having a welldeveloped Digit IV imprint; typical sauropod tracks have a digit length formula I > II > III > IV > V. ...
The Jurassic period was crucial for continental ecosystems, with dinosaurs rising to dominance and many key vertebrate groups emerging. In the Early Jurassic, theropod tracks were dominant, alongside those of crocodylomorphs, synapsids, ornithischians, and sauropodomorphs. The Middle Jurassic saw a shift to more diverse ichnofaunas, with new tracks from saurischian dinosaurs, thyreophorans, and possible ornithopods, while non-dinosaurian tracks became rarer. The Late Jurassic marked the peak of this diversity, with abundant tracks from theropods, sauropods, ornithopods, and thyreophorans, along with some non-dinosaurian tracks from pterosaurs, crocodylomorphs, turtles, and lepidosaurs.
... Small Jurassic Brontopodus-type tracks are unusual. However, a similar Brontopodus-type trackway JYS11 is known from the Lower Jurassic Ziliujing Formation of the Jiaoyuan tracksite, Sichuan Province, China (Xing et al. 2016b). The JYS11 tracks have a mean pes length and width of 26.4 and 18.7 cm, respectively, and are roughly contemporaneous with the much larger sauropodomorph track Liujianpus shunan. ...
... The JYS11 tracks have a mean pes length and width of 26.4 and 18.7 cm, respectively, and are roughly contemporaneous with the much larger sauropodomorph track Liujianpus shunan. Such assemblages indicate that small and large sauropodomorphs may have co-existed (Xing et al. 2016b). Xing et al. (2021d) described a diverse size range of sauropod trackways from the Middle Jurassic Chaya Group of Eastern Tibet, China. ...
A newly discovered dinosaur tracksite in the Middle Jurassic Xietan Formation of the Zigui Basin, is the first reported from Hubei Province, China. Access to the site is difficult due to the steep inclination (~60°) of the track-bearing beds. The tracks are poorly preserved and occur in a fragmented mudstone substrate. However, it is possible to identify a sauropod trackway and isolated tridactyl (theropod) tracks, suggesting a saurischian dominated ichnofauna. The preserved sauropod trackway falls into the range of a typical wide gauge sequence and, together with the overall shape of the imprints and low heteropody, points to the ichnogenus Brontopodus. The tracks are of relatively small size and can possibly be attributed to juveniles of a large species or, alternatively, to adults of a small species of eusauropods. The tridactyl tracks are incomplete and cannot be assigned to a distinct ichnotaxon with certainty.
... Small Jurassic Brontopodus-type tracks are unusual. However, a similar Brontopodus-type trackway JYS11 is known from the Lower Jurassic Ziliujing Formation of the Jiaoyuan tracksite, Sichuan Province, China (Xing et al. 2016b). The JYS11 tracks have a mean pes length and width of 26.4 and 18.7 cm, respectively, and are roughly contemporaneous with the much larger sauropodomorph track Liujianpus shunan. ...
... The JYS11 tracks have a mean pes length and width of 26.4 and 18.7 cm, respectively, and are roughly contemporaneous with the much larger sauropodomorph track Liujianpus shunan. Such assemblages indicate that small and large sauropodomorphs may have co-existed (Xing et al. 2016b). Xing et al. (2021d) described a diverse size range of sauropod trackways from the Middle Jurassic Chaya Group of Eastern Tibet, China. ...
A newly discovered dinosaur tracksite in the Middle Jurassic Xietan Formation of the Zigui Basin, is the first reported from Hubei Province, China. Access to the site is difficult due to the steep inclination (~60°) of the track-bearing beds. The tracks are poorly preserved and occur in a fragmented mudstone substrate. However, it is possible to identify a sauropod trackway and isolated tridactyl (theropod) tracks, suggesting a saurischian dominated ichnofauna. The preserved sauropod trackway falls into the range of a typical wide gauge sequence and, together with the overall shape of the imprints and low heteropody, points to the ichnogenus Brontopodus. The tracks are of relatively small size and can possibly be attributed to juveniles of a large species or, alternatively, to adults of a small species of eusauropods. The tridactyl tracks are incomplete and cannot be assigned to a distinct ichnotaxon with certainty.
... These areas also yield basal sauropods, such as Tonganosaurus . Sites in Gulin County, Sichuan Province primarily preserve trackways most likely representing the basal sauropodomorph Liujianpus shunan, together with the classic sauropod ichnogenus Brontopodus (Xing et al. 2016a). They indicate that basal sauropodomorphs and sauropods coexisted in the Lufeng and Sichuan basins in China during the Early Jurassic, and that the former were eventually replaced by more advanced sauropods in the Middle Jurassic, although they had been dominant during the Early Jurassic. ...
... Another putative basal sauropod, Chinshakiangosaurus (Dong 1992), from the Lower Jurassic Fengjiahe Formation, is known only from a dentary and partial associated postcranium (Upchurch et al. 2007;McPhee et al., 2016). Gongxianosaurus, from the Dongyuemiao Member, Ziliujing Formation, Sichuan Province, is represented by a relatively complete skeleton, with an estimated total body length of approximately 14 m (He et al. 1998 DZWII-S1 only preserves three tracks, but the complete DZWII-S1-LM1 shows an affinity to sauropod tracks, and is similar to manus tracks of Brontopodus (Farlow et al. 1989;Lockley et al., 2002) and Liujianpus shunan (Xing et al., 2016a). Therefore, given the absence of other morphological characteristics, we provisionally refer to it as an indeterminate sauropod trackway. ...
The newly discovered large (350 m²) Yantan dinosaur tracksite, in the Lower Jurassic Ziliujing Formation of Guizhou Province, China, reveals at least 250 footprints of which ∼97 can be resolved into trackways of sauropodomorphs. All the trackways are sub parallel likely indicating gregarious behavior. One theropod track (cf. Grallator) was recorded. The sauropodomorph tracks predominantly represent quadrupedal progression (Morphotype A), and footprint morphology is similar to the ichnospecies Liujianpusshunan, characterized by outward pes rotation. Three trackways indicate bipedal progression, and two of these (Morphotype B) indicate inward pes rotation, accompanied by elongate pes digit scratch marks. For the latter phenomenon three possible scenarios are discussed: (1) significant rotation changes accompanying changes in gait, (2) swimming behavior, (3) formation of undertracks. Sedimentological evidence indicates the tracks were made on a linguloid rippled, muddy, immature sandstone substrate characterized by significant differences in substrate consistency across the track-bearing surface. Microbially induced sedimentary structures (MISS) characterized by distinctive wrinkle marks indicate a stressed, probably semi-arid, paleoenvironment that was not conducive to habitation by invertebrate organisms. This is consistent with other evidence that Lower Jurassic sauropodomorph tracks are often associated with semi-arid paleoenvironments. © 2018 China University of Geosciences (Beijing) and Peking University
... These areas also yield basal sauropods, such as Tonganosaurus . Sites in Gulin County, Sichuan Province primarily preserve trackways most likely representing the basal sauropodomorph Liujianpus shunan, together with the classic sauropod ichnogenus Brontopodus (Xing et al. 2016a). They indicate that basal sauropodomorphs and sauropods coexisted in the Lufeng and Sichuan basins in China during the Early Jurassic, and that the former were eventually replaced by more advanced sauropods in the Middle Jurassic, although they had been dominant during the Early Jurassic. ...
... Another putative basal sauropod, Chinshakiangosaurus (Dong 1992), from the Lower Jurassic Fengjiahe Formation, is known only from a dentary and partial associated postcranium (Upchurch et al. 2007;McPhee et al., 2016). Gongxianosaurus, from the Dongyuemiao Member, Ziliujing Formation, Sichuan Province, is represented by a relatively complete skeleton, with an estimated total body length of approximately 14 m (He et al. 1998 DZWII-S1 only preserves three tracks, but the complete DZWII-S1-LM1 shows an affinity to sauropod tracks, and is similar to manus tracks of Brontopodus (Farlow et al. 1989;Lockley et al., 2002) and Liujianpus shunan (Xing et al., 2016a). Therefore, given the absence of other morphological characteristics, we provisionally refer to it as an indeterminate sauropod trackway. ...
Sauropod tracks from the Early Jurassic Maanshan Member of the Ziliujing Formation in the Dazhuanwan area of Guizhou represent the first Jurassic dinosaur track record for this province. The best preserved and longest trackway is narrow gauge (Brontopodus type), and indicates a relatively small trackmaker (footprint length ~35.0 cm). In conjunction with sauropodomorph skeletal remains these tracks suggest that basal sauropodomorphs and primitive sauropods coexisted in this region during the Early Jurassic. This pattern is same in the Lufeng and Sichuan basins. Thus, sauropod tracks from southwest China are diverse in the Early Jurassic, and include narrow gauge Parabrontopodus, wide gauge Brontopodus-type, and basal sauropodomorph tracks.
... Sauropod trackway no. 6 of the Zhaojue tracksite, Sichuan Province (Xing et al. 2015b), and trackway TDGZ-S1 from the Tangdigezhuang tracksite, Shandong Province, China (Xing et al. 2015c) also show a similar ''off-tracking '' phenomenon, and Xing et al. (2015c) also discuss ''offtracking'' in further detail. CHB-S2 has a much less obvious ''off-tracking'' and this may be related to the very tight turn and abrupt change in direction. ...
... More recently, a large site from the Lower Cretaceous Feitianshan Formation of the Zhaojue area, Sichuan, yielded a turning trackway with an abrupt 180°turn (Xing et al. 2015b), and a site from the Early Cretaceous Dasheng Group, of Shandong Province a rather wide or broad semicircular turn of almost 180° (Xing et al. 2015c). Another trackway with even two quite pronounced turns is figured in Castanera et al. 2014 (Fig. 2, trackway PM-N5-P2). ...
An Early Jurassic sauropod dinosaur tracksite in the Lower Jurassic Zhenzhuchong Formation at the Changhebian site in Dazu County, Sichuan, is known to have yielded the trackway of a turning sauropod. A re-study of the site shows that all in all there are more than 100 tracks organized in at least three sauropod trackways. The narrow turn in one of the trackways is confirmed and analyzed in greater detail. All of the trackways show a wide gauge similar to Brontopodus-type trackways, but simultaneously exhibit high heteropody typical for Parabrontopodus-type trackways. The relative length of pes digits I, II and III is difficult to determine, but is suggestive of a primitive condition where digit I is less well developed than in Brontopodus. Thus far, they are the stratigraphically oldest sauropod trackways known from Asia being Hettangian in age. Previously, the trackway with the narrow turn was reported as the first turning sauropod trackway from Asia, but recently several other turning trackways have been reported suggesting that this behaviour is more commonly found than previously assumed and is now documented from the Early Jurassic to Late Cretaceous. Most of these examples show tight turns of between ~90° and as much as 180° suggesting that despite their large size sauropods could quite easily and abruptly change their direction of movement.
... Sauro• pod remains are far less common, but include, for exam• ple, the basal sauropod Gongxianosaurus shibeiensis [4] and the eusauropod Tonganosaurus hei [5] . The exact taxonomic position of Gongxianosaurus is currently disputed [6][7] , while Tonganosaurus is confidently assign• able to the Mamenchisauridae [5] . The Gulin tracks from the Lower Jurassic Ziliujing Formation record the coexistence of basal sauropodomorphs (Liujianpus) and sauropods (Brontopodus) [7] . ...
... The exact taxonomic position of Gongxianosaurus is currently disputed [6][7] , while Tonganosaurus is confidently assign• able to the Mamenchisauridae [5] . The Gulin tracks from the Lower Jurassic Ziliujing Formation record the coexistence of basal sauropodomorphs (Liujianpus) and sauropods (Brontopodus) [7] . ...
Dinosaur track and bone records often occur at different locations. However, a few formations show a close correspondence between bones and tracks that correspond to likely trackmakers. In this paper, the authors report sauropod tracks (Brontopodus) in very close geographic and stratigraphic proximity to the type locality of the eusauropod Tonganosaurus hei in the middle-upper parts of the Lower Jurassic Yimen Formation in Tongbao Village, Huili County, Panxi region of Sichuan Province. This Huili tracktrackmaker correlation is possibly existent, but still needs more evidence to confirm. As the first Jurassic sauropod tracks found in the Panxi region, the Tongbao Brontopodus tracks have provided evidence indicating coexistence of primitive sauropod and basal sauropodomorphs in Southwest China during Early Jurassic.
... The authors considered non-neosauropod eusauropods, likely from the Turiasauria clade, as possible trackmakers, suggesting that wide-gauge sauropod trackways were not exclusively produced by Titanosauriformes (Santos et al. 2009;Castanera et al. 2016;Meyer et al. 2018). Subsequently, various authors have compared the Polyonyx gomesi morphotype to sauropod tracks of the Middle Jurassic to Early Cretaceous age (e.g., Royo-Torres 2009;Alcalá et al. 2014;Castanera et al. 2014;Xing et al. 2014Xing et al. , 2016Torcida et al. 2015Torcida et al. , 2021Moreau et al. 2020;Poropat et al. 2021;Tomaselli et al. 2021). However, thus far, only sauropod tracks from the Middle-?Upper Jurassic of Morocco have been tentatively referred to this ichnogenus (Oukassou et al. 2019;Klein et al. 2023). ...
The Galinha dinosaur tracksite (Portugal) was declared a Natural Monument in 1996 and is currently designated as Ourém/Torres Novas Dinosaur Footprints Natural Monu ment. This tracksite yields a completely new and unique morphology of sauropod tracks from the Middle Jurassic (Bajocian-Bathonian). This new morphotype was named Polyonyx by Santos et al. (2009). However, recently it has been brought to our attention that this ichnotaxon name "Polyonyx" is preoccupied by the porcellanid decapod Polyonyx Stimpson, 1858 (Crustacea: Decapoda: Anomura: Porcellanidae). The priority is given to the latter and to avoid homonymy, the former is issued the new replacement name Galinhapodus igen. nov., creating the new replace ment combination name Galinhapodus gomesi.
... These tracks are common in Late Jurassic and Early Cretaceous strata in North America, Europe and North Africa (Farlow et al. 1989;Lockley et al. 1994;Marty et al. 2010). The coexistence of basal sauropodiforms and basal eusauropods is also recorded by the cooccurrence of Liujianpus and Brontopodus (Xing et al. 2016b). ...
We report five new dinosaur track sites in Chaya County, about 120 km southeast of Changdu City. The track assemblages are dominated by sauropods (45 tracks), which have been identified tentatively as cf. Brontopodus. Also present are two thyreophoran trackways consisting of 13 tracks that show strong similarities with the ichnogenus Deltapodus, the potential trackmakers of which were probably stegosaurids. The sauropod tracks from the Chaya region are dominated by large tracks with different affinities if compared to those of the Changdu area. The isolated sauropod tracks from Changdu and Chaya regions show similar morphological patterns, but those from the Chaya region lack large scale tracks. This paper compares and discusses the known ichno and body fossil records of sauropods, theropods, and ornithischians from the Middle Jurassic of Yunnan, Sichuan, and eastern Tibet and their importance for our understanding of dinosaur faunas from this region. The absence of basal neornithischian records in the
Yunnan and Changdu regions is likely a preservational bias but also an ecological pecularity cannot be completely excluded. The palaeogeographic position of the four sampled skeleton and track sites suggests the possible existence of a corridor through which faunal exchanges were taking place throughout the Jurassic.
... The digit V trace of titanosaur pes imprints and typical sauropod tracks (e.g.: Brontopodus birdi Farlow et al., 1989) is a small lobe on the lateral side of the footprint, or digit IV and V are difficult to distinguish (Stettner et al., 2018;Tomaselli et al., 2022). Some sauropod digit I, II, III and IV traces along the front of the footprint have been reported from southwestern China, such as the Cretaceous tracks from the Zhaojue locality (Xing et al., 2021b) and the Jurassic Liujianpus shunan from the Gulin locality (Xing et al., 2015b) of Sichuan Province. However, all of these footprints have a morphology that is different from the materials described here. ...
... Liujianpus differs from other sauropodomorph tracks by four nearly equidimensional, elongate pes digit traces oriented subparallel to the pes axis and a sub-circular manus with five discrete blunt digit traces (Xing et al. 2016c). Brontopodus is one of the most common and well-known Jurassic-Cretaceous sauropod track types with a global distribution (Farlow et al. 1989). ...
Two newly discovered dinosaur track locations near the town of Bijie in Guizhou Province, southwestern China are named the Yuanbaoqing and Yejiatian tracksites. They represent the Lower Jurassic Maanshan Member of the Zijiujing Formation and Upper Jurassic Xiashaximiao Formation, respectively. The former Yuanbaoqing tracksite reveals a minimum of three Anomoepus trackways and two poorly preserved incomplete sauropod trackways, tentatively assigned here to cf. Brontopodus. They occur in shallow lake to shoreline facies depositional environments. The Yejiatian site shows a well-preserved, narrow-gauge sauropod trackway in a delta plain facies which is identified as Parabrontopodus. The occurrences enhance the local faunal record in Guizhou Province were previous tracksite reports for these stratigraphic intervals are sparse. In the broader regional context of southwestern China the track record is consistent with the body fossil record in both the Lower and Upper Jurassic of this region.
... Globally, Late Triassic to Early Jurassic tracks attributed to basal sauropodomorph dinosaurs are represented by the ichnogenera Otozoum, Pseudotetrasauropus, Evazoum and Kalosauropus (Figures 5 -7), commonly referred to as the OPEK plexus (Lockley et al. 2006), and included under the ichnofamily Otozoidae (Lull 1904), whose representatives were previously considered of 'prosauropod,' rather than true sauropod affinity. There are other locally-known ichnogenera of purported sauropodomorph affinity such as Liujianpus (Xing et al. 2016), considered to display characteristics intermediate between those of basal sauropodomorph tracks like Otozoum and true sauropod tracks like Brontopodus. Although members of the OPEK plexus share many common features (e.g. ...
Kalosauropus, the ‘beautiful reptile track’, was collected from the Sinemurian–Pliensbachian lower Clarens Formation (upper Stormberg Group) in Lesotho in the 1950s. It was formally described in 2003 when it was transferred to Otozoum, an ichnogenus known in North America, Europe and Africa, and associated with basal sauropodomorphs. This transfer has been questioned due to the significant morphological differences between these two tracks, leaving Kalosauropus in taxonomical limbo. Using digital imaging techniques, herein we demonstrate that diagnostic and quantifiable morphological differences between Kalosauropus and Otozoum justify their separation as two independent ichnogenera. The size-range of Kalosauropus reported from a single site indicates that the bipedal trackmakers were likely juveniles or small-bodied animals. The co-occurrence of morphologically similar but different sized tracks suggests social behaviour among these Early Jurassic trackmakers. Using osteological evidence and foot bone measurements, we also show that Kalosauropus may be attributed to a bipedal massospondylid, representing the iconic and common basal sauropodomorph family from the Early Jurassic of southern Africa. Reinstating Kalosauropus thus not only expands the Early Jurassic sauropodomorph footprint record in southern Gondwana, but also provides a more nuanced understanding of the ichnotaxonomic complexities surrounding the early dinosaurian track record that spans the Triassic-Jurassic boundary globally.
... (3) The sauropod tracks Brontopodus and Brontopodus-type from the entire Chinese Jurassic, representing 10 sites, account for 72% of all track sites. Except the Brontopodus-type in the Lower Jurassic Jiaoyuan site which is considered narrow gauge (Xing et al., 2016e), and the trackways from the Upper Jurassic Guxian site that are considered mediumÀwide gauge (Xing et al., in press), all others are wide gauge. The Jurassic Brontopodus from China is also significantly larger than Parabrontopodus and Liujianpus. ...
The Xixipo dinosaur tracksite in the Chuanjie Formation of Yunnan Province is one of the 14 Chinese sites yielding sauropod tracks from between the Triassic–Jurassic and Jurassic–Cretaceous boundaries, but is only one of the two that represent the Middle Jurassic. Although it is a small site, it adds incrementally to the overall track record of the region and allows comparison with the body fossil record and classification of the Chuanjie Formation as a Type 3b or Type 4b deposit in which both the body fossil and trace fossil record, in this case representing sauropodomorphs, are similar in composition and frequency of occurrence. We argue that the sauropod trace and body fossil records, while based on different categories of evidence, are very important. Integrating and correlating all available data from both records increases our understanding of sauropod communities, and both are equally valuable for this. In addition, we also discuss narrow to wide gauge, coeval sauropod trackways from China, and the relationship between the potential trackmaker of China's Jurassic Brontopodus-type trackways and mamenchisaurids and, beginning from the Late Jurassic, representatives of this type and titanosauriform sauropods.
... The Daanzhai Member of Ziliujing Formation Jiaoyuan tracksite, Gulin County, Sichuan Province. These are attributed to basal sauropodomorph tracks Liujianpus shunan and sauropod tracks Brontopodus-type(Xing et al. 2016c). (3) The Ma'anshan Member of the Ziliujing Formation Hejie tracksite, Zigong City, Sichuan Province. ...
The newly discovered Maoshajing tracksite in the Lower Jurassic Longtoushan Group of Guizhou Province, China is dominated by well-preserved medium-sized theropod tracks of the Grallator-Eubrontes plexus type, and associated with a few sauropod tracks. This saurischian dominated ichnofauna is typical of the Lower Jurassic biochron of China and elsewhere. It is also consistent with the sparse body fossil record, making it a type 2a deposit in which tracks are more abundant, and therefore also more important in providing a useful census of the tetrapod fauna. It is argued that small tracksite surfaces are more useful in ‘capturing’ (registering) evidence of small and potentially more active theropod movements than the activity of larger saurischians (sauropodomorphs) which may have been less abundant and less active in areas of any given size.
... The wide-gauge of the Cretaceous Brontopodus-type trackways suggests they were left by titanosaurian sauropods (Wilson and Carrano 1999;Lockley et al. 2002). Though some Jurassic middle- wide-gauge sauropod tracks are referred to Brontopodus-type tracks, multiple trackmakers are possible, including macronarians/titanosauriformes, some mamenchisaurids (Xing et al. 2016b), and basal sauropods, such us Shunosaurus (Xing et al. 2016b(Xing et al. , 2016c. Although Carrano (2005) argued that Macronaria generally first appeared in the Late Jurassic, camarasaurs, brachiosaurs, and titanosaurs originated earlier, closer to the Middle Jurassic. ...
A sauropod track assemblage from a surface in the Upper Jurassic fluvial Tianchihe Formation at the Guanxi site, Shanxi Province, China, is re-documented and analysed in detail, together with a recently discovered new locality situated nearby. In contrast to earlier reports, the former includes four trackways plus isolated tracks (41 tracks in total) instead of five trackways (37 tracks in total) identified earlier, with pes prints reaching more than 60 cm in length. The new site has three pes-manus track pairs belonging to smaller individuals, with pes prints being about 20 cm in length. The absence of larger sized tracks at this locality suggests the possible presence of size-differentiated groups representing juveniles or subadults. Track morphology, heteropody and the medium-wide gauge trackway pattern at both sites support an assignment to the ichnogenus Brontopodus. Trackmakers were eusauropods, possibly mamenchisaurids or more advanced forms such as macronarians. Results of re-investigation allow a new interpretation of trackway orientations and trackmaker behaviour, respectively, as well as a calculation of progression speeds that suggest walking movement. ARTICLE HISTORY
... In our comparative statistical analysis, we analyzed the 10 Tafaytour trackways as well as other small-sized sauropod trackways based on data taken from the literature (Lockley et al., 1986(Lockley et al., , 2002a(Lockley et al., , 2002b(Lockley et al., , 2004(Lockley et al., , 2006(Lockley et al., , 2014Lim et al., 1989;Lockley and Santos, 1993;Dalla Vecchia, 1994;Meyer et al., 1994;Gierli nski and Sawicki, 1998;Lee et al., 2000;Dalla Vecchia et al., 2001;Huh et al., 2003;P erez-Lorente, 2003;Day et al., 2004;Nicosia et al., 2007;Marty, 2008;Gonz alez Riga and Calvo, 2009;Castanera et al., 2011;Xing et al., 2011Xing et al., , 2013Xing et al., , 2014aXing et al., , 2014bXing et al., , 2014cXing et al., , 2015aXing et al., , 2016bXing et al., , 2016cXing et al., , 2016dKim and Lockley, 2012;Marty et al., 2013;Fern andez-Baldor, 2015;Mazin et al., 2016), resulting in a total of 79 trackways (Supplementary Data 2). Besides Morocco, the included trackways come from Switzerland, Germany, England, France, Italy, Croatia, Spain, Portugal, China, Korea, the U.S.A., Argentina, and Bolivia and range from the Lower Jurassic to the Upper Cretaceous. ...
Forelimb posture in sauropod dinosaurs is still poorly understood. Although a laterally directed (semisupinated) manus is the plesiomorphic condition in sauropodomorphs, the sauropod track record prevailingly shows anterolateral to anterior manus orientations, suggesting a high degree of manus pronation. The ?Middle Jurassic Tafaytour tracksites described herein preserve at least 10 trackways, nine of which show laterally oriented, and in two examples even posterolaterally oriented, manual impressions. Located in the Argana Basin of the Western High Atlas, Morocco, the tracksite yields hundreds of footprints on a highly bioturbated surface, including examples with well-preserved digit and claw impressions. Footprint morphology and trackway configuration vary greatly between trackways. A literature review indicates that laterally directed manual impressions are restricted to small- and medium-sized trackmakers. Statistical analysis was performed on a larger sample (n = 79) of small sauropod trackways from around the world, indicating that lateral manual orientations are correlated with low locomotion speeds and narrow trackway gauges. Manus pronation in sauropods is hypothesized to occur when the forelimb is actively contributing to the propulsion of the animal, which would be the case at faster speeds or at wider trackway gauges where the center of mass is located more anteriorly. We present new approaches to the quantitative analysis of trackway data. Mean configuration plots allow for direct graphical comparisons of different trackways. Two types of trackway asymmetries are defined and quantified. The apparent glenoacetabular distance (GAD) represents a feasible proxy for body size, at least for the smaller sauropod trackmakers analyzed herein.
SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
Citation for this article: Lallensack, J. N., S. Ishigaki, A. Lagnaoui, M. Buchwitz, and O. Wings. 2019. Forelimb orientation and locomotion of sauropod dinosaurs: insights from the ?Middle Jurassic Tafaytour tracksites (Argana Basin, Morocco). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1512501.
... Outwards rotated pes impressions are also commonly observed in other trackways that possibly pertain to basal sauropods (e.g., cf. Lockley et al. 2001Lockley et al. , 2006aXing et al. 2016). This feature, therefore, might be characteristic for sauropods in general or for an even more inclusive grouping. ...
The Late Triassic (Norian–early Rhaetian) Fleming Fjord Formation of central East Greenland preserves a diverse fossil fauna, including both body and trace fossils. Trackways of large quadrupedal archosaurs, although already reported in 1994 and mentioned in subsequent publications, are here described and figured in detail for the first time, based on photogrammetric data collected during fieldwork in 2012. Two trackways can be referred to Eosauropus, while a third, bipedal trackway may be referred to Evazoum, both of which have been considered to represent sauropodomorph dinosaur tracks. Both the Evazoum and the Eosauropus trackways are distinctly larger than other trackways referred to the respective ichnogenera. The trackmaker of the best preserved Eosauropus trackway is constrained using a synapomorphy-based approach. The quadrupedal posture, the entaxonic pes structure, and five weight-bearing digits indicate a derived sauropodiform trackmaker. Other features exhibited by the tracks, including the semi-digitigrade pes and the laterally deflected unguals, are commonly considered synapomorphies of more exclusive clades within Sauropoda. The present trackway documents an early acquisition of a eusauropod-like pes anatomy while retaining a well-developed claw on pedal digit IV, which is reduced in eusauropods. Although unequivocal evidence for sauropod dinosaurs is no older than the Early Jurassic, the present trackway provides evidence for a possible Triassic origin of the group.
... Riley and Huchzermeyer, 1999;Platt et al., 1990Platt et al., , 2006Platt et al., , 2009Wilkinson and Rice, 2000;Oliveros et al., 2006;Simpson, 2006;Buden and Haglelgam, 2010;Chang et al., 2012Chang et al., , 2015G omez Velasco, F. 2012;Bezuijen et al., 2013;Stuart and Stuart, 2013;Sam et al., 2015). Comparisons of fossil trackways of quadrupedal archosaurs, whether crocodylians or other forms (e.g., Klein, 2000, 2002;Lockley and Meyer, 2000;Rainforth, 2003;Gand et al., 2007;Porchetti and Nicosia, 2007;Romano et al., 2007;Avanzini and Petti, 2008;Lockley et al., 2009;Marty et al., 2010;Petti et al., 2010;Klein et al., 2011;Li et al., 2012;Contessi, 2013;Boutakiout et al., 2014;Masrour and P erez-Lorente, 2014;McCrea et al., 2014;Xing et al., 2015;Castanera et al., 2016;Stevens et al., 2016;Mateus et al., 2017), with modern crocodylian trackways may allow inferences about terrestrial locomotion of the extinct trackmakers (Carpenter, 2009). Consequently, we believe that detailed information about traces made by extant crocodylian species will be of considerable value for interpreting traces attributed to living crocodylians as well as those of ancient crocodylomorphs and other quadrupedal archosaurs. ...
We documented trackways of free-living Crocodylus acutus on beaches at the mouths of Tamarindo and Ventanas estuaries, Costa Rica. Our crocodiles had estimated total lengths of 1–3 meters or more. Manus prints have five digits, with digits I–III bearing claw marks. Pes prints have four digits, with claw marks on digits I–III. The pes is plantigrade. Claws generally dig into the substrate. Apart from claw marks, digit I and the heel of the pes are usually the most deeply impressed parts of footprints. Trackways are wide-gauge. Pes prints are usually positioned just behind ipsilateral manus prints of the same set and may overlap them. Manus and pes prints angle slightly outward with respect to the crocodile's direction of movement. Claw-bearing digits of both the manus and pes may create curved, concave-toward-the-midline drag marks as the autopodium is protracted. The tail mark varies in depth and clarity, and in shape from nearly linear to markedly sinuous. Sometimes the tail mark hugs the trackway midline, but sometimes it is closer to, or even cuts across, prints of one side. American crocodile footprints and trackways are similar to those observed in other extant crocodylian species, indicating substantial trackway conservatism across the group.
Dinosaur footprints often occur in Late TriassicEarly Jurassic continental sedimentary rocks. While many such tracks can readily be associated with the kinds of dinosaurs that made them, the makers of some footprints have been controversial. Large tridactyl (three-toed) footprints of the ichnogenus Eubrontes are thought by most paleontologists to have been made by theropod dinosaurs, but some workers think their makers were basal sauropodomorph (prosauropod) dinosaurs. The four-toed footprint Otozoum is usually interpreted as a prosauropod print, but some workers instead attribute it to an ornithischian (basal thyreophoran) dinosaur or even a pseudosuchian archosaur. These issues prompted us to do a new study of the proportions of the hindfeet of bipedal and potentially bipedal dinosaurs and other archosaurs, adding new measurements to previously available data. Foot skeletons of theropod dinosaurs differ from those of bipedal ornithischian dinosaurs in having relatively longer phalanges from the middle portions of toes, narrower phalanges, relatively shorter unguals, and a relatively shorter inner toe (digit Ibut some members of both groups lose digit I altogether). Theropod feet differ from feet of prosauropods in having slightly narrower phalanges, relatively shorter unguals, and a relatively shorter digit I, but some smaller basal sauropodomorphs are harder to distinguish from theropods in these features. Feet of small to medium-sized ornithischians that retain digit I are very similar to those of most basal sauropodomorphs and also some pseudosuchians. Our results suggest that most (but perhaps not all) morphologically well-preserved Eubrontes are more likely to have been made by theropods than bipedal sauropodomorphs. It is more difficult to determine the most likely maker(s) of Otozoum.
How sauropod dinosaurs were able to withstand the forces associated with their immense size represents one of the most challenging biomechanical scenarios in the evolution of terrestrial tetrapods, but also one lacking robust biomechanical testing. Here, we use finite element analyses to quantify the biomechanical effects of foot skeletal postures with and without the presence of a soft tissue pad in sauropodomorphs. We find that none of the models can maintain bone stresses that fall within optimal bone safety factors in the absence of a soft tissue pad. Our findings suggest that a soft tissue pad in sauropods would have reduced bone stresses by combining the mechanical advantages of a functionally plantigrade foot with the plesiomorphic skeletally digitigrade saurischian condition. The acquisition of a developed soft tissue pad by the Late Triassic-Early Jurassic may represent one of the key adaptations for the evolution of gigantism that has become emblematic of these dinosaurs.
A new dinosaur tracksite is reported from continental red beds of the Jurassic (Late Bathonian-?Callovian) Isli Formation along the northern flank of the Aït Ali ou Ikkou Syncline of the Imilchil area, Central High Atlas, Morocco. The succession was deposited in a fluvio-lacustrine environment, and contains at least fourteen track-bearing levels. The diverse dinosaur-dominated ichnofauna includes the footprints of crocodylomorphs, pterosaurs, theropods, sauropods and ornithischians, together with numerous invertebrate traces. Here, we focus on a long sauropod trackway, which comprises nine consecutive manus-pes sets preserved as concave epireliefs. The low heteropody and asymmetry of manus prints with a large digit I (pollex) impression oriented medially, and a large triangular claw trace, which is posteriorly oriented, are characteristic of the ichnogenus Polyonyx. Different from typical Polyonyx is the narrow gauge pattern compared to the wide gauge observed in the type trackway from Portugal. Additional material from Morocco, similar to Polyonyx, comprises the trackway of a very small (?juvenile) individual found close to the main trackway, as well as a short trackway from a different locality in the Isli Formation. Our data from the Moroccan High Atlas indicates the presence of basal eusauropods in the Middle Jurassic-Early Cretaceous interval in the northwestern part of Gondwana for the first time, and suggests they inhabited a lacustrine paleoenvironment.
Horseshoe crabs (Chelicerata, Xiphosura) from Mesozoic deposits are extremely rare in the fossil record of the African continent. Here we report new evidence of the occurrence of xiphosurans in North Africa. These are horseshoe crab traces, including the ichnogenera Kouphichnium (repichnia) and Selenichnites (fodinichnia and/or domichnia), which have been discovered in Middle Jurassic strata of the Imilchil area (Central High Atlas, Morocco). They are preserved on upper and lower bed surfaces of sandy limestones and marls in the upper parts of the Tislit and Imilchil formations (late Bajocian-early Bathonian).
The Selenichnites traces, measuring up to 30 cm in width, co-occur with theropod and birdlike tracks. The reported Kouphichnium is the first record from Mesozoic deposits of Morocco, while Selenichnites is the second occurrence in Jurassic strata of Africa. These ichnogenera evidence different behaviour of horseshoe crabs, i.e. Selenichnites is the result of burrowing activity when searching for food in the sediment, and Kouphichnium is a regular locomotion trace left on the sediment surface, occasionally leaving an impression of the telson.
The combination of sedimentological data and ichnological analysis indicates a shallow-water subtidal depositional environment preceding the Bathonian regression of the Atlas domain.
Palaeobiogeographically, the discoveries indicate the presence of horseshoe crabs at the southern margin of the Tethys. Furthermore, they enhance our knowledge of their previously scarcely documented distribution in Gondwana during the Mesozoic.
Upper Triassic and Middle Jurassic strata of the Xichang Basin in Sichuan Province, southwestern China, yielded important dinosaur ichnofossils. From the Xujiahe Formation of the Yiguojiao tracksite, we report a Late Triassic footprint assemblage in China and the first discovery of diagnostic Triassic sauropodomorph tracks in this region. The tracks share a number of features in common with the ichnogenera Eosauropus (Late Triassic) and Liujianpus (Early Jurassic). The neighboring Bingtu tracksite is stratigraphically younger (Shaximiao Formation, Middle Jurassic) and preserves small tridactyl theropod tracks that represent the first occurrence of the ichnotaxon Carmelopodus in China and Asia. While these tracks are morphologically comparable to those from the Middle Jurassic type locality in North America, the specimens from China show the proximal margin of the digit IV impression in a more cranial position, which may indicate a trackmaker with a relatively short metatarsal IV. In addition to the skeletal record, the Carmelopodus footprints document the presence of small theropods in the dinosaur fauna of the Middle Jurassic Shaximiao Formation.
Extensive and well-preserved tracksites in the coastally exposed Lower Cretaceous (Valanginian–Barremian) Broome Sandstone of the Dampier Peninsula provide almost the entire fossil record of dinosaurs from the western half of the Australian continent. Tracks near the town of Broome were described in the late 1960s as Megalosauropus broomensis and attributed to a medium-sized theropod trackmaker. Brief reports in the early 1990s suggested the occurrence of at least another nine types of tracks, referable to theropod, sauropod, ornithopod, and thyreophoran trackmakers, at scattered tracksites spread over more than 80 km of coastline north of Broome, potentially representing one of the world's most diverse dinosaurian ichnofaunas. More recently, it has been proposed that this number could be as high as 16 and that the sites are spread over more than 200 km. However, the only substantial research that has been published on these more recent discoveries is a preliminary study of the sauropod tracks and an account of the ways in which the heavy passage of sauropod trackmakers may have shaped the Dampier Peninsula's Early Cretaceous landscape. With the other types of dinosaurian tracks in the Broome Sandstone remaining undescribed, and the full extent and nature of the Dampier Peninsula's dinosaurian tracksites yet to be adequately addressed, the overall scientific significance of the ichnofauna has remained enigmatic.
At the request of the area's Goolarabooloo Traditional Custodians, 400+ hours of ichnological survey work was undertaken from 2011 to 2016 on the 25 km stretch of coastline in the Yanijarri–Lurujarri section of the Dampier Peninsula, inclusive of the coastline at Walmadany (James Price Point). Forty-eight discrete dinosaurian tracksites were identified in this area, and thousands of tracks were examined and measured in situ and using three-dimensional photogrammetry. Tracksites were concentrated in three main areas along the coast: Yanijarri in the north, Walmadany in the middle, and Kardilakan–Jajal Buru in the south. Lithofacies analysis revealed 16 repeated facies types that occurred in three distinctive lithofacies associations, indicative of an environmental transgression between the distal fluvial to deltaic portions of a large braid plain, with migrating sand bodies and periodic sheet floods. The main dinosaurian track-bearing horizons seem to have been generated between periodic sheet floods that blanketed the preexisting sand bodies within the braid plain portion of a tidally influenced delta, with much of the original, gently undulating topography now preserved over large expanses of the present day intertidal reef system. Of the tracks examined, 150 could be identified and are assignable to a least eleven and possibly as many as 21 different track types: five different types of theropod tracks, at least six types of sauropod tracks, four types of ornithopod tracks, and six types of thyreophoran tracks. Eleven of these track types can formally be assigned or compared to existing or new ichnotaxa, whereas the remaining ten represent morphotypes that, although distinct, are currently too poorly represented to confidently assign to existing or new ichnotaxa. Among the ichnotaxa that we have recognized, only two (Megalosauropus broomensis and Wintonopus latomorum) belong to existing ichnotaxa, and two compare to existing ichnotaxa but display a suite of morphological features suggesting that they may be distinct in their own right and are therefore placed in open nomenclature. Six of the ichnotaxa that we have identified are new: one theropod ichnotaxon, Yangtzepus clarkei, ichnosp. nov.; one sauropod ichnotaxon, Oobardjidama foulkesi, ichnogen. et ichnosp. nov.; two ornithopod ichnotaxa, Wintonopus middletonae, ichnosp. nov., and Walmadanyichnus hunteri, ichnogen. et ichnosp. nov.; and two thyreophoran ichnotaxa, Garbina roeorum, ichnogen. et ichnosp. nov., and Luluichnus mueckei, ichnogen. et ichnosp. nov. The level of diversity of the main track types is comparable across areas where tracksites are concentrated: Kardilakan–Jajal Buru (12), Walmadany (11), and Yanijarri (10).
The overall diversity of the dinosaurian ichnofauna of the Broome Sandstone in the Yanijarri–Lurujarri section of the Dampier Peninsula is unparalleled in Australia, and even globally. In addition to being the primary record of non-avian dinosaurs in the western half of Australia, this ichnofauna provides our only detailed glimpse of Australia's dinosaurian fauna during the first half of the Early Cretaceous. It indicates that the general composition of Australia's mid-Cretaceous dinosaurian fauna was already in place by the Valanginian–Barremian. Both sauropods and ornithopods were diverse and abundant, and thyreophorans were the only type of quadrupedal ornithischians. Important aspects of the fauna that are not seen in the Australian mid-Cretaceous body fossil record are the presence of stegosaurians, an overall higher diversity of thyreophorans and theropods, and the presence of large-bodied hadrosauroid-like ornithopods and very large-bodied sauropods. In many respects, these differences suggest a holdover from the Late Jurassic, when the majority of dinosaurian clades had a more cosmopolitan distribution prior to the fragmentation of Pangea. Although the record for the Lower Cretaceous of Gondwana is sparse, a similar mix of taxa occurs in the Barremian–lower Aptian La Amarga Formation of Argentina and the Berriasian–Hauterivian Kirkwood Formation of South Africa. The persistence of this fauna across the Jurassic-Cretaceous boundary in South America, Africa, and Australia might be characteristic of Gondwanan dinosaurian faunas more broadly. It suggests that the extinction event that affected Laurasian dinosaurian faunas across the Jurassic-Cretaceous boundary may not have been as extreme in Gondwana, and this difference may have foreshadowed the onset of Laurasian-Eurogondwanan provincialism. The disappearance of stegosaurians and the apparent drop in diversity of theropods by the mid-Cretaceous suggests that, similar to South America, Australia passed through a period of faunal turnover between the Valanginian and Aptian. -------- In: Society of Vertebrate Paleontology Memoir (Journal of Vertebrate Paleontology Vol. 36, supplement to 6, November 2016).
PART I I - THE DINOSAUR TRACKS IN THEIR PALEOENVIRONMENT
8
Giuseppe LEONARDI and Paolo MIETTO
THE LIASSIC DINOSAUR TRACKS OF THE LAVINI DI MARCO
INTRODUCTION
Three dinosaur tracks (ROLM 1, 9 and 11) were discovered for the first time at the Lavini di Marco in 1988 by Luciano Chemini. Many other footprints and tracks were found during July 1991 by a systematic field exploration of the site carried out by the research team from Museo Tridentino di Scienze Naturali and Museo Civico of Rovereto, which were led by the authors, from 1991 on. The site is one of the richest of Europe, with about 70 tracks and at least 90 isolated footprints, left by a total of about 140 individuals; total individuals are more than 200 if one considers indeterminate and unstudied specimens.
Most of the footprints are found along the “colatoi”, at the “hinge” and on the “laste alte”. The “colatoi” are regions of the mountain flank were debris and soil have been cleared away by water flow after heavy rains. The “hinge” is a zone of “knee-like” flexure of the rocky layers, high on the mountain flank; the “laste alte” is a wide, smooth and sloping flat area made by the surface of a rocky layer or few rocky layers (i.e. the topographic and stratigraphic surface coincide) high on the mount flank. In order to identify the different “colatoi” we named them “colatoio Chemini”, “colatoio of the sauropod”, “colatoio of the theropods” and “colatoio of the ornithopods” (see Fig. XX in the Italian text).
The footprints and tracks testify to the presence of many dinosaurs. The most abundant are theropods (about 80) probably Ceratosauria, then there are about 15 early sauropods, some advanced ornithopods, about 20 bipedal dinosaurs (possibly small-size primitive ornithopods), about 10 footprints or tracks of indeterminable plant-eaters (probably sauropods) and finally, some unidentified dinosaurian footprints.
The description and study of this material was carried out following methods and terminology of Leonardi (ed.) and co-authors (1987a).
Most of the fossil footprints are not true footprints but are underprints. When we tried to clean the footprints of the rocky infilling, we were not sure about which of the many surfaces was the true printed surface. In many cases the visible part of the footprint is made by non-coeval surfaces. In ROLM 2 and 9, for example, the bottom of each footprint is the true printed surface because it presents a flat pebble breccia, due to the crushing of the mud-cracked original sedimentary surface by the dinosaur foot. However, their lateral wall has a different age, because it is cut across a number of levels. The surface of the displacement rim and the surrounding field surface do not correspond to the soft and waterlogged surface on which the dinosaurs stepped, which was eroded, but a deeper and more consistent level. So each extant footprint is composed by three kinds of non-coeval surfaces.
DESCRIPTION
THEROPODS
The dinosaurs represented by tridactyl footprints, with slender and clawed digits of predators, are the most common in the site. The footprints are shallow, sometimes difficult to identify, and the tracks are incomplete or represented by few footprints. This means that the authors were light and relatively quick. Up to now about eighty individuals have been identified; however there is one surface that was over trampled by tridactyl dinosaurs that is waiting for to be studied on the “laste alte”. Therefore, the number will increase.
Identification of the footprints is difficult because of their shallowness. The morphology of the prints differs greatly in the same track, showing that it is also influenced by gait, foot stance and substrate condition. Some of the tridactyl footprints could belong to primitive ornitischians, some of which had theropod-like feet, functionally tridactyl and clawed. We consider here as theropod all the footprints that clearly do not to belong to ornithischians.
Theropod footprints can be grouped into the following categories:
1) tetradactyl (Italian text-figs. 8.4, 8.5, 8.7),
2) with wide interdigital II-IV angle (Italian text-figs. 8.3/9-15),
3) small-sized, with short and stout digits, (Italian text-figs. 8.3/20-23),
4) with long , wedge-like “heels”, (Italian text-figs. 8.4/3, 4, 11,12),
5) with broad and/or spatulated digit III, (Italian text-figs. 8.3/16-18),
6) with long, slender and sinuous digit III, (Italian text-figs. 8.3/1-8),
7) others, subdivided into:
a) “crescent”-shaped footprints, (ROLM60, ROLM154/3),
b) footprints with anomalous nails (Italian text-fig. 8.4/10),
c) grouped digits, (Italian text-fig. 8.4/6),
d) repeated prints, (Italian text-fig. 8.4/7),
e) scratches (Italian text-fig. 8.4/8),
SAUROPODS
The first sauropod track was found on June 1992 (ROLM75). Up to now ROLM 1, 2, 4, 11, 14, 21, 26, 28, 33, 61, 67, 75, 126, 173, 200 and possibly several more (Italian text-figs. 8.16-26, 8.28), can be attributed to sauropod trackmakers. Because of the poor state of preservation no new ichnotaxonomic name was given to this material. The two best preserved tracks are herein described.
ROLM 75 (Italian text-figs. 8.16, 8.24-8.26): quadrupedal, narrow gauge track, 7 m long, slightly curved, with 10 pes-manus sets. The pes-manus axis is directed outwards (32°) with respect to the trackway midline. The ratio stride/pedal footprint length is rather low (about 3), testifying the slow walking gait of the trackmaker. The pace angulation of pedes is very low (mean=95°) as is that of the manus (about 60°) because the manual print is in front and lateral to the pedal. The latter is usually pyriform and deeper anteriorly; digit prints are sometimes present, with a variable number (1 to 4) of small, short, pointed and clawed marks. However, the pes was probably pentadactyl. The hypex are very “open” and blunt. We think that sometimes the collapsing mud totally obliterated the marks of the claws. The manual prints are kidney-shaped, crescent-like or, in one case, nearly horseshoe-like, with a marked indentation in the posterior margin. This shape is partly due to the deformation caused by the overprinting of the pes. The digital prints of the manus, rarely left or preserved, are short and pointed, with hypex wide and blunt (footprints 4 or 6); it is difficult to state the actual number of digits. The track is irregular, because of the gait of the trackmaker and the variable substrate condition. There are many middle to large-size theropod footprints and associated tracks.
ROLM 28 (Italian text-figs. 8.16, 8.18, 8.19): is a short track, with 5 incomplete pes-manus sets and some underprints. There are several differences to ROLM 75: larger size (the average pes length is 52 cm against 45 cm), higher pace angulation and, consequently, narrower track, the pes-manus axis is outwardly directed to a lesser degree.
ROLM61 is similar to ROLM75 and 28. However, ROLM1, 2, 11, 26 and perhaps 126 are morphologically different: the anterior margin of the pes presents three or four digit prints with the shape of rounded lobes, manual prints are shallow or absent, perhaps totally overprinted by the pes. These trackways are narrow gauged, manual prints are often, but not always, laterally placed and do not diverge from the midline.
POSSIBLE ORNITHOPODS
There are very deep (up to 15 cm) and evident tridactyl or tetradactyl footprints. The two best examples of these specimens are described here.
ROLM 64 (Italian text-figs. 8.31-8.32, 8.40-8.41): a straight, bipedal or perhaps semibipedal track, 14 m long with 24 footprints. The animal was slowly walking with alternating short (left-right) and long (right-left) paces. We cannot exclude that the trackmaker was limping. There are huge expulsion rims with interference between adjacent rims and the mud sometimes collapsed into the footprint. The footprints generally have an oval or pyriform shape, and are tetradactyl (but the mark of digit I is rarely preserved) with digit II-IV large and hoof-like and digit I (footprint 23) medially placed as a spur, short and rounded, impressed only when the foot sank deeply into the mud.
ROLM 63 (Italian text-figs. 8.30, 8.39): bipedal track, composed of three non-consecutive footprints (a right, a left, then the right is missing and a left one follows). Also in this case digit I seems to be present. The footprints are deep (up to 8 cm). The first footprint shows three, hoof-like, toes separated from the “plantar” pad; digit III is particularly short. In the second footprint the mark of the digit II is narrow and spatulated because the mud collapsed into it.
The animal was walking slowly, with alternating short (left-right) and long (right-left) paces. Also in this case, we cannot exclude that the trackmaker was limping. There are huge expulsion rims with interference between adjacent rims and the mud sometimes collapsed into the footprint. The third preserved footprint shows the mark of digit I.
OTHER TRACKS
Other footprints and tracks, poorly preserved, belong to the same form: track ROLM9 (Italian text-figs. 8.28, 8.37), 181 (Italian text-fig. 8.29) and 30 (Italian text-fig. 8.38).
Other tracks can be identified as ornithopodian:
- ROLM 192 (Italian text-figs. 8.34, 8.35) differs from the others because of the stronger foot, with footprints deeper laterally, the “heel” is much longer and triangular, wedge-shaped because of a digit IV mark which is developed posteriorly behind the phalangeal-metatarsal articulation.
- ROLM50, a lighter form, with slender digits but ending with a hoof.
- Some tridactyl footprints with digits, a little broader than those of the theropods and without claws, could belong to less specialized and less advanced ornithopods like, for example, the “fabrosaurids” (Italian text-figs. 8.4/13-16). In any case, they will be considered as unidentified bipedals in the statistics.
FOOTPRINTS AND TRACKMAKER IDENTIFICATION
THEROPODS
Ichnologic determination of the tracks
It is very difficult and often impossible to give formal names to the ichnological material being studied because of the poor and incomplete preservation and the high morphological variability of the footprints on the same track. Besides, the hind feet of the tridactyl dinosaurs are basically the same in most ornithopods and theropods, mainly those of small to medium-size taxa. Therefore the following classification is only indicative.
Morphofamily Anchisauripodidae Lull, 1904
Grallator Hitchock, 1858: about 15 footprints could belong to this ichnotaxon (ROLM32, 37, 39, 74, 89, 93, 97, 120, 128, 140, 141, 151, 152, and 206).
Morphofamily Eubrontidae Lull, 1904
Eubrontes Hitchock, 1845: about 10 footprints could belong to this ichnotaxon (ROLM31, 36, 38-41, 44,71, 130 and 193).
Footprints comparable to Columbosauripus Sternberg, 1932: ROLM60, 76 and 96 can be morphologically compared to this Cretaceous ichnogenus.
Footprints resembling other ichnogenera
a) Some large footprints such as ROLM 13 and 41 resemble the anterior part of Bueckemburgichnus maximus Kuhn 1958.
b) ROLM70 presents features of Saltopoides igalensis Lapparent and Montenat, 1967.
c) ROLM5 shares with some genera attributed to theropods the presence of a spur-like, facing backward digit; otherwise it resembles the Grallator.
d) ROLM 49, 87, 89, 120, 132-133, 158 could belong to Coelurosaurichnus but this ichnogenus was demonstrated to be invalid (= Grallator).
In conclusion the identified ichnotaxa are Grallator, Eubrontes and that with short and broad digits. This association is similar to others found in the Lower Liassic; however, theropod footprints are of little use for biostratigraphical purposes. Noteworthy is the absence of the morphofamily Gigandipodidae Lull, 1904.
Classification of the trackmaker
The trackmaker must be found in the suborder Ceratosauria (Italian text-figs. 8.13-8.15, 8.44, 8.47, 8.54, 8.56) rather than of the suborder Carnosauria or Coelurosauria as reported in the past, mainly in paleoichnological papers. Ceratosauria was the only theropod group definitely alive during Early Jurassic times.
SAUROPODS
Ichnologic determination of the tracks
The tracks are attributed to primitive sauropods but more advanced from the ichnological point of view. They are the oldest sauropod tracks found up to now in the world. The diagnostic features are: quadrupedality with marked heteropody, characteristic shape of the manual (crescent-like etc.) and pedal prints, strong positive (outwards) divarication, short and pointed digits on the hind feet and, when present, also in the fore feet, with hypexes open, blunt and rounded; relatively low pace angulation.
Because of these typical sauropodian features, we do not attribute the tracks to prosauropods.
Since they are narrow-gauged, we do not compare them with the wide-gauged ones, like Brontopodus Farlow, Pittman & Hawthorne, 1989. They resemble Parabrontopodus Lockley, Farlow & Meyer, 1994 of the Upper Jurassic of USA and the holotype of Breviparopus Dutuit & Ouazzou, 1980, Upper Jurassic of Morocco. With the latter they share the marked positive (outwards) divarication of the pes-manus set, the manual prints placed rather laterally and their overall shape, the forward directed foot nails, the short pedal prints and their overall shape. The differences are: the manual print of Breviparopus never presents large nail marks and hypexes, the distance manus-pes is shorter, the footprints are larger (more than twice the size).
The differences reported above between ROLM75 and ROLM28 are not sufficient to classify them into two separate ichnospecies; anyway, we do not create a new ichnotaxon because of the poor preservation.
Identification of the trackmaker
The lateral position of the manual prints suggests a sauropod as the trackmaker with a rather broad shoulder girdle and particularly well developed fore-limbs. This, as well as the age, suggest the attribution to the poorly known family Vulcanodontidae Cooper, 1984. However, we cannot exclude a member of the Cetiosauridae Seeley, 1874 or, in every case, a member of the Eosauropoda Bonaparte, 1986a as being the trackmaker.
POSSIBLE ORNITHOPODS
Ichnologic determination of the tracks
The main aspect to stress is that up to now large, iguanodontid-like footprints have never been found in the Lower Jurassic. The footprints under examination are different from the coeval Moyenisauropus Ellemberger and Anomoepus E. Hitchcock, 1848, belonging to primitive ornithopods, perhaps “fabrosaurids”. They never present the mark of the true heel, digits II-IV are much shorter, mainly digit III, and hoof-like. Besides, they are much larger and the tracks are in most cases bipedal. They show a striking similarity to the Late Jurassic and Early Cretaceous footprints attributed to iguanodontids. Similarities exist also with hadrosaurids. However, all the footprints of large ornithopods lack the mark of digit I.
Discussion about the trackmakers
The trackmakers could be identified as large, graviportal ornithopods, very ancient but not very primitive from an ichnological point of view. They could be related to iguanodontids (Italian text-figs. 8.43, 8.47). The presence of digit I is a primitive character since it is not present in the iguanodontids and hadrosaurids, with the exception of Camptosaurus Marsh. If the footprints under examination are actually ornithopodian, we are not brave enough to attribute them to the family Iguanodontidae sensu stricto but we think that they could be at the base of this family or belonging to an unknown family strictly related to it. The presence of iguanodontids in the Lower Jurassic would record this group about 40 (taking into account Callovosaurus Galton) or also 50 millions before the comparison of the first bones in the fossil record.
However, we cannot ignore, mainly for the track ROLM64, another hypothesis: that the trackmaker could be a sauropod. Therefore, we avoid giving a formal name to the large “ornithopod” tracks and we will name them provisionally as “advanced ornithopods”.
DESCRIPTION AND DISCUSSION ABOUT ICHNOASSOCIATIONS
There are five levels with footprints in a section five metres thick (levels 101, 104, 105, 106, 115 and 120). The main levels (104, 105, 106, 115) are concentrated in less than two metres. The richest levels are 105 and 106.
ROLM 3-7, 49-51, 53-54, 59-76, 85-104, 107, 110, 112-116, 118, 120-124, 130-133, 140-146, 150-154, 156, 158, 174-175, 206-207 are found on the level 105, for a total of 84 individuals (57 theropods, 4 sauropods, 2 indeterminate plant-eaters, 17 indeterminate bipeds, 4 possible advanced ornithopods and a dozen unidentified footprints).
ROLM1-2, 9, 11-12, 14-15, 18, 20-23, 25-41, 43-44, 47-48, 125-128, 135-136, 159, 171, 173, 181, 192-193, 197-200 are found on level 106, for a total of 49 individuals (21 theropods, 11 sauropods, 5 indeterminate plant-eaters, 6 indeterminate bipedals, 6 possible advanced ornithopods and 8 indeterminable footprints). The associations in the two levels are different: carnivorous are dominant in the level 105 (67% against 33% - but only 12% are certain - plant-eaters) whereas the reverse happens in level 106 (57% plant-eaters, 43% carnivorous). These differences probably depend on different distribution of the microenvironments at each of these two levels.
THE ICHNOFAUNA OF THE LAVINI DI MARCO COMPARED TO OTHERS COEVAL
As the stratigraphic position of the ichnofauna is indicated as Lower Jurassic, a comparison has been made with Lower Jurassic ichnofaunas all over the world, with emphasis on the differences.
Veillon (Vandée, France; Rhetian-Early Hettangian) - Prosauropods are absent in both ichnofaunas but neither are sauropods found here. Ornithopods are absent and crocodylomorph footprints (Batrachopus E. Hitchock and Dahutherium Montenat) are present. Only theropods seem to be similar in both sites.
Saint-Laurent-deTrèves (Causses, Lozère, France; Late Hettangian) - Only theropods are represented and correspond to those found at the Lavini di Marco.
“Oppidum de Grézac” (Lodève, Herault, France; Late Hettangian) - The same considerations for Saint-Laurent-deTrèves are valid.
Holy Cross Mountains (Poland; Early and Late Hettangian) - Theropod (11%) and ornithopod (89%) footprints are found in the Late Hettangian, only theropods in the Early Hettangian. The presence of ornithopod footprints, identified as Moyenisauropus and Anomoepus E. Hitchock, are the most strikingly similar to the association described here. However, large ornithopods with hoof-ending digits are not present, as are also sauropods.
Pécs region (Hungary, Early Sinemurian) - Here only theropods (Grallator and Kayentipus Welles) are represented, therefore comparisons are impossible.
Hogänas (Sweden; Rhaetian and Early Hettangian) - Here also only theropod footprints are found.
Neyzae, Kerman and Zerab (Iran; Sinemurian/Pliesbachian) - Few footprints and short tracks attributed to Grallator and mainly to large ornithopods are reported, but unfortunately comparisons are not possible because of the poor numbers. The Iranian and our associations would be similar due of the presence of theropods and large ornithopods and different mainly because of the absence of sauropods in Iran.
Jinning (Yunnan, China; Liassic) - Also here only theropod footprints are present.
“Jeholosauripus” ichnofaunas of Liaoning and Hebei (China, Rhaetian-Liassic) - Also here only the theropod “Jeholosauripus” Yabe, Inai & Shikama (= Grallator s-satoi (Yabe, Inai & Shikama) was found.
“Changpeipus” Young ichnofaunas of Liaoning and Jilin (China, Middle Jurassic or less probably Liassic) - Also here only theropod footprints are found.
Lesotho (Southern Africa, Hettangian-Sinemurian) - There is more variability in the theropod ichnotaxonomy of this ichnofauna; prosauropods seem to be absent in the Liassic levels and the presence of sauropod tracks is doubtful. The small ornithopod Moyenisauropus (=Anomoepus) present here, is absent in the Lavini di Marco. Tritiylodontid therapsids and early mammals are abundant in Lesotho but absent at the Lavini.
Spring Grange (Zimbawe, Late Triassic or Liassic) - Also here only theropod footprints are found.
Newark Supergroup (eastern coast of North America, Liassic) - The similarity of the theropod footprints of the two ichnofaunas is noteworthy. However, here sauropods and large ornithopods are absent, whereas small ornithopods (Anomoepus) and crocodylomorphs are present.
Glenn Canyon Group (South western U.S.A., Liassic) - The differences with the ichnofauna of the Lavini di Marco are the absence of sauropods and large ornithopods, and the presence of the prosauropods, Anomoepus, and crocodylomorphs (Batrachopus).
Botucatu Formation (Southern Brazil and neighbouring countries; Liassic?) - It represents a desert eolian environment. The differences with the Lavini di Marco are found in the presence of possible small ornithopods, tritylodontid therapsids, early mammals and mammaloids; the latter two are abundant. Sauropods, prosauropods and crocodylomorphs are absent.
Queensland (Australia; Late Liassic) - Here Anomoepus prints are present, these are not found at the Lavini di Marco, together with footprints of large theropods.
Therefore, the ichnofauna of the Lavini di Marco is quite different from the others that are more or less coheval, except in the case of theropods. The most striking characteristics of this comparison are 1) the absence of prosauropods (the most common plant-eaters during Liassic times), crocodyilomorphs, therapsids, protomammals, mammals and, in general, of small quadrupedal animals, 2) the presence of early sauropods and, if the identification is correct, of early but advanced ornithopods. Consequently, the ichnoassociation found at the Lavini di Marco does not fit in with the Liassic “Anomoepus-Grallator (Eubrontes) Zone” of Haubold (1986). The presence of sauropods and early large ornithopods would suggest a younger age but the absence of mammals, mammaloids and crocodylomorphs does not support this dating. If the Hettangian/Sinemurian dating is correct, we must admit that the dinosaur fauna in the carbonate platform environment of this region was different and more evolved than in other regions of the world.
BEHAVIOUR OF THE ROVERETO DINOSAURS
The study of the ichnologic evidence is the main tool to gain knowledge of the behaviour of extinct animals.
SPEEDS AND GAITS - The tracks that allow the estimation of speeds at the Lavini di Marco are relatively few, only 35. The estimated (theoretical or predicted) walking speed for Rovereto forms (cfr Thulborn, 1990, p. 293ss) is about 3-4 km/hr for small bipeds (foot length<25 cm), 4-5 km/hr for larger bipeds (26 cm <foot length< 35 cm), 5-6 km/hr for graviportal plant-eaters with pedal prints ranging 36 to 52 cm, 5-6 km/hr for sauropods.
The real speeds, calculated from the tracks of Rovereto, are in most cases lower than these estimated walking speeds and are all less than 6 kph, with the single exception being ROLM59, a small ceratosaurid with a hind foot 13.5 cm long (10-12 kph). Calculated speeds for the relatively small ceratosaurids range from 7.5 to 11 kph; those for sauropods only 1.2-2.5 kph, the presumed ornithopods standing in the middle, with 1.4-2.2 kph. The speed of indeterminate bipeds, probably small to mid-size ornithopods, range 3.2-7.2 kph. High speeds, often used to support the theory of “warm-blooded” dinosaurs, were not found at the Lavini di Marco.
The manner of gait, estimated on the basis of the stride length/height at hip ratio (cfr Thulborn, 1990, p. 263-266), was almost always walking gait (SL/h = 0.45-1.75) but in ROLM59, which was fast trotting or almost running (SL/h = 2.7).
DIRECTIONS (Italian text-fig. 8.50) - Dinosaurs often followed preferential paths because of topographical constraints as lake or sea coasts. There are 116 tracks and single footprints useful for measuring trackmaker walking direction. The NNE quadrant presents 44% of all directions, the ESE one 17.2%, SSW 28.3%, WNW 10.3%. Therefore there is a preferential corridor along an axis NNE-SSW. The two main beds with footprints (105 and 106) present a different direction from this corridor, with a counter clockwise rotation of about 30°. In level 105 the axis was NNE-SSW, in the other level it was N-S. This trend is the same for each single taxonomical group (58 theropods, 14 sauropods, 18 indeterminate bipeds). The dinosaurs of the Lavini di Marco were not moving in packs or herds but their direction was landscape-controlled. A change of the coastline direction is hypothesized to explain the change of direction between level 105 and 106. This is in agreement with the indications provided by geochemical data (see next chapter).
STANCE - In no case is the mark of the tail is preserved, as is usual for dinosaur tracks. All the trackways are rather narrow, attesting a full erect stance. The presumed iguanodontids were nearly all bipedal and in few cases, semi-bipedal, which is different from the most accepted view of the prevailing quadrupedality of these dinosaurs.
SOCIAL BEHAVIOUR - Social behaviour of theropods and sauropods is testified in some ichnosites. In contrast, the 140 individuals investigated at the Lavini di Marco, do not show any social behaviour.
MIGRATIONS - What is the meaning of the preferential N or S directions of the Rovereto tracks? Until coeval facies on the Trento Platform that are different from tidal flats are discovered, the existence of connections between this platform and others placed south and north of it is demonstrated, or the evidence of wide emerged areas found, the hypothesis of individual migration cannot be considered. We think is most logical to admit that the dinosaurs of the Lavini di Marco lived in that place, moving when a route to other lands was disposable. Another explanation of the dinosaur presence on the tidal flat could be related to their reproductive behaviour.
THE DINOSAUR COMMUNITY
The paleoichnological record is generally biased toward the preservation of footprints of large animals. Small outcrops cannot preserve the footprints of all taxa living in the surrounding region. The site of Lavini di Marco is wide and the represented environment is quite uniform.
Plant-eaters and Predators
Predators are prevalent (57%) over the plant-eaters (43%), with these percentages respectively 33% and 67% at level 105 and 57% - 43% at level 106. This differs from the theoretical ecological model of a prevalence of plant-eaters and a small number of predators. The abundance of predator footprints against the plant-eater footprints could be caused by a different level of activity of their respective trackmakers and/or by the grouping of certain taxa in particular environments: theropods could have been more abundant around pools of fresh water. The prevalence of theropods is a characteristic of many tracksites.
Weights and sizes (Italian text-figs 8.48-8.49)
Ceratosaurids which produced footprints 12-15 cm long, could reach a total body length of two to three metres and a weight of 12 to 25 kg. The larger ceratosaurids of Rovereto, with footprints 25-35 cm long, probably had the general body appearance and size of Dilophosaurus Welles, 6 to 7 m long with a weight of 280-500 kgs; the largest (footprints length: 38 cm) could reach the size of Ceratosaurus Marsh (6 to 7 m long and weighting 600 to 1200 kgs). The smallest ceratosaurid with footprints 8 cm long (ROLM212-215) was 1.5 m long with a weight of about 4 kg; it is not possible to state if it was a juvenile or a small-sized adult. The largest ceratosaurid footprint (38 cm long) comes from a level at the top of the Membro Inferiore. Some tridactyl footprints 10 to 15 cm long (ROLM211), here reported as “indeterminate bipeds” but perhaps belonging to basal ornithischians or ancestors of Thyreophora like Scutellosaurus Colbert, indicate small, bipedal plant-eaters, 1.5 to perhaps 2 m long, weighting a few kilograms. It is possible that similar footprints but longer (up to 20 cm) could belong to ancestors of the hypsilophodontids. If the large (20 to 47 cm long) tridactyl footprints with rounded hooves (ROLM9, 30, 63 and 64) actually belong to advanced ornithopods, they could have been imprinted by a dinosaur with the size of Camptosaurus Marsh, 7 m long and weighting up to 700 kg, or Tenontosaurus Ostrom, 7 m long and weighting up to 800-900 kg. Hind footprints 30 to 50 cm long testifies to the presence of relatively small sauropods, 7 to 10 m long and weighting 1 to 3 tons.
Diets and metabolism (Italian text-fig. 8.53-55)
The diet of the Rovereto trackmakers is herein minutely discussed.
The large plant-eaters (> 1 ton) were almost certainly cold-blooded, like the living large mammals partly are. The average daily forage requirement (fresh forage) can be estimated as 3 kg for a cold-blooded sauropod weighting one ton, 6 kg for a two-ton sauropod and 9 kg for a three-ton one. The yearly need would be respectively 1095, 2190 and 3285 kg. The average daily forage requirement would have been respectively 21, 42 and 64 kg in the case of a warm-blooded sauropod, a requirement seven times higher. The yearly need would have been 7.665, 15.330 and 23.360 kg.
We cannot estimate the vegetal biomass per unit of surface needed for the dinosaurs at the Lavini di Marco. The needs were probably rather high, requiring relatively abundant vegetation, with a high yearly productivity. Cases of high biomass concentration per surface unit are known among living reptiles. For example, the biomass of the giant turtles of the Aldabra atoll reaches 46tons/square km. This animal biomass would daily consume about 720 kg of fresh vegetation per square kilometre. The atoll is nearly entirely covered by bush and presents mangrove along the lagoon coast. In the case of the Lavini di Marco a biomass of 46 tons per square kilometre would roughly correspond to about 30 sauropods per square kilometre. The surface is about a quarter of square kilometre at the outcrop and the sauropod tracks are about 15 (possibly not coeval).
Juveniles and adults (Italian text-fig. 8.43-44)
Most of the footprint lengths established fall into a narrow range. There is a large number of values between 16 and 25 cm for theropods (73%; 14% of the footprints is higher, 13% lower) (Italian text-fig. 8.44) and between 36 and 48 cm for the sauropods (75%; 17% of the footprints is higher, 8% lower) (Italian text-fig. 8.43). Theropod and sauropod footprint lengths have a gaussian distribution, the sauropod ones are skewed toward larger sizes.
Plant-eater and predator interaction
The tracks at the Lavini di Marco are, as a rule, linear straight and do not show mutual behaviours. The trackmakers were just passing through. Some tracks of large plant-eaters are associated to those of carnivorous dinosaurs, sometimes moving more or less in the same direction or crossing one another but without clear evidence of interaction. The only possible example of some interaction is that of ROLM209 (Italian text-fig. 8.26) and ROLM174 (both theropods), impressed on the expulsion rim of sauropod footprints (track ROLM75) when the sediment was still plastic: it is difficult to think that the predators were not aware of the sauropod.
THE MEGAICHNOSITE OF THE CALCARI GRIGI DI NORIGLIO
The Calcari Grigi di Noriglio Formation outcropping area is defined as a megatracksite (sensu Lockley, 1994, modified) composed by the single tracksites of the Lavini di Marco, Chizzola (Leonardi, this volume), Alti Lessini (Mietto e Roghi, 1994; Roghi, 1994; Avanzini, pers. comm.), Becco di Filadonna (Avanzini, 1998), Mt Pasubio (Avanzini, 1998). It outcrops in an area about 2000 km2 wide in the Adige Valley, Southern Trentino, Sette Comuni (Asiago) Plateau and Mts Lessini. Before Alpine orogeny this surface was obviously wider. The case of the “Calcari Grigi di Noriglio megatracksite” is that of a megatracksite where the fossil footprints are most informative because they are the only dinosaur evidence (Case 1, according to the Lockley’s classification of the vertebrate paleontologic sites; Lockley, 1994, pp. 93-94).
PALAEOENVIRONMENTAL AND PALAEOGEOGRAPHIC IMPLICATIONS
Fossil footprints can provide important support for other scientific disciplines, mainly for paleoecology (paleoenvironmental data) and paleogeography. The recent discoveries of abundant dinosaur footprints in the Triassic, Jurassic and Cretaceous carbonate platforms of Northern Italy and Istria changed the palaeoenvironmental and palaeogeographic hypotheses about this area, formerly based on geologic data only.
(((The depositional environment of the Lavini di Marco site was a tidal flat. The dinosaurs therefore could not live there during high tide, when currents destroyed footprints and other structures and wore away the conglobating sediments. During the slow withdrawal of the sea, wide surfaces covered by plastic materials emerged, which were suitable for faunal colonization, and was able to cast the feet of the animals. The abundance of footprints at different levels therefore indicates periodical regressions.))
The Trento Platform was without doubt a carbonate platform but large dinosaur associations could not live at the water line. Where would those large animals go during high tide? The huge plant-eaters would not be able to find a sufficient supply of food to survive on small islands. One of the following possible solutions must be considered:
a) the existence of a continental area very close to the Lavini di Marco, or at least a wide island, of which the Trento Platform was a fringe area;
b) the presence of abundant terrestrial vegetation in the topographically higher parts of the platform. There is little evidence of this, but even in strongly continental lithostratigraphic units, like for example the Cretaceous Oldman Formation of Canada, plants and pollens are rare;
c) the presence of a quantity of algae on the platform channels and basins to feed plant-eater dinosaurs (also in this case, no evidence).
The geographic affinity of the dinosaur fauna seems to be Gondwanian, and African in particular, especially due of the presence of early sauropods, whose oldest remains were found in Southern Africa and India.
LIASSIC TETRAPODS NOT FOUND AT THE LAVINI DI MARCO
Amphibians were rare during Early Jurassic; the only group which could be present in the Lavini di Marco is that of primitive frogs but this is unlikely because of the salty environment. The Lower Jurassic is also comparatively poor in reptiles. However, at the Lavini di Marco we found the footprints of the last primitive diapsids, of sphenodontids and of kuehnosaurids but substrate conditions were not the best for the preservation of the footprints of such small animals. The absence of footprints of small primitive crocodiles, mainly protosuchids, is astonishing but it could be due to the particular environment. Among dinosaurs, scelidosaurs and, above all, prosauropods are absent. Actually we cannot completely exclude that some poorly preserved footprints identified as sauropodian could be prosauropodian. Besides, we cannot exclude that ROLM192, identified as ornithopodian, is actually prosauropodian. The relatively small footprints of the tritylodont and tritelodont synapsids could be present but they have not been found up to now. The total absence of evidence of primitive mammals is surprising; perhaps they were too small and/or preferred dryer and higher environments.
Anyway, dinosaurs seem to occupy all the ecological niches at the Lavini di Marco as in many other regions of the world, leaving no room to other tetrapods.
GIUSEPPE LEONARDI and PAOLO MIETTO (Eds)
THE ITALIAN DINOSAURS
Note that many chapters of this book are here in my page of ResearchGate with full text, abstract and images. Search for chapters of year 2000.
A VERY EXPANDED ABSTRACT IN ENGLISH (THE ORIGINAL TEXT IS IN ITALIAN WITH THIS EXPANDED ABSTRACT AT THE END OF THE BOOK)
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THE JURASSIC TRACKS OF THE LAVINI DI MARCO SITE (ROVERETO, TRENTO PROVINCE) IN THE CONTEST OF THE DINOSAURS OF ITALY
SUMMARIES
FABIO M. DALLA VECCHIA, EDITOR
PART I - Introduction and general data
1 - G. LEONARDI and P. MIETTO - Introduction
2 - G. A. VENZO - Geographic-geologic framing and account of geologic studies and researches on the Lavini di Marco.
3 - A. GORFER - The Lavini di Marco: landscape, history, erudition
4 - S. ABRAM, P. LORENZI and F. PROSSER - Naturalistic and environmental aspects of the Lavini di Marco
5 - D. MASETTI - The geology of the Lavini di Marco
6 - C. BROGLIO LORIGA - Paleontological aspects of the Calcari Grigi formation
7 - G. LEONARDI - Account on the dinosaurs
PART II - The dinosaur tracks in their paleoenvironment
8 - G. LEONARDI and P. MIETTO - The Liassic dinosaur tracks of the Lavini di Marco
9 - M. AVANZINI, S. FRISIA and M. RINALDO - The Lavini di Marco during Early Jurassic: reconstruction of an ancient bioenvironment
PART III - Tetrapod paleontology of Italy and neighbour countries
10 - G. LEONARDI - The dinosaurs of Italy and neighbour countries
11 - M. A. CONTI, G. LEONARDI, P. MIETTO and U. NICOSIA - Footprints of non-dinosaurian tetrapods in the Paleozoic and Mesozoic of Italy
12 - F. M. DALLA VECCHIA - Bone remains of Paleozoic and Mesozoic tetrapods of Italy
PART IV - Other contributions
13 - G. OROMBELLI and U. SAURO - Geomorphological aspects of the landslides of Mt. Zugna
14 - M. AVANZINI and D. ZAMPIERI - The Lavini di Marco: geological-structural aspects
15 - O. GROAZ and L. VERONESE - Historical and instrumental seismicity in the Lagarina Valley
16 - P. ARZARELLO, F. FINOTTI, G. GALEAZZO, M. LANZINGER, M. MEZZANOTTE and L. VERONESE - The Park of the Rovereto dinosaur tracks: preservation, exploitation and “musealization”
ENGLISH TRANSLATION OF SOME ITALIAN TERMS REPORTED IN THE TEXT
Colatoio (pl. colatoi) = natural drainer or gully
Dante Alighieri = Italian poet (1265-1321)
Laste di Lizzana = toponym; “lasta” (pl. laste) is a local word indicating wide, flat, rocky bed surfaces on the flank of a mountain or flat slabs of rock; Lizzana is a village; therefore the literal translation is “wide, flat rocky bed surfaces on the flank of the mountain near Lizzana”.
Laste alte = toponym; topographically high, upper “laste”.
Lavini di Marco = toponym; “lavini” is a local word for “landslide accumulation”, Marco is a small village, therefore its literal translation is “landslide accumulation of Marco”.
Marocche = local name for a mix landslide-moraine
ENGLISH TRANSLATION OF LITHOSTRATIGRAPHIC TERMS
Biancone = Biancone (Big White) Formation
Calcare Massiccio = Massive Limestone Formation
Calcare del Vajont = Vajont Limestone Formation; Vajont is a locality in the Western Carnic Pre-alps near the border between Friuli-Venezia Giulia and Veneto Regions.
Calcare Selcifero = Cherty Limestone Formation
Calcari Grigi (also Calcari Grigi di Noriglio) = Grey Limestone Formation, more correctly Grey Limestone of Noriglio Formation; Noriglio is a small town village near Rovereto.
Corna = Corna (corna= horns) Formation
Dolomia Principale = Main Dolostone Formation, Hauptdolomit of German-speaking Authors.
Membro di Rotzo = Rotzo Member of Grey Limestone Formation, called also Medium Member; Rotzo is a small village of the Sette Comuni (or Asiago) Plateau
Membro Inferiore = Lower Member of Grey Limestone Formation
Membro Medio = Medium Member of Grey Limestone Formation, also called Rotzo Member
Membro Superiore = Upper Member of Grey Limestone Formation
Oolite di Massone = Oolite of Massone Formation; Massone is a village.
Oolite di San Vigilio = Oolite of San Vigilio Formation; San Vigilio is a village.
Rosso Ammonitico Inferiore = Lower Rosso Ammonitico Formation
Rosso Ammonitico Superiore = Upper Rosso Ammonitico Formation
Scaglia Rossa = Red Scaglia Formation
Scaglia Variegata = Variegated Scaglia Formation
Scisti ad Aptici = Shale with Aptychi Formation
Scisti a Fucoidi = Shale with Chondrites Formation
PART I - INTRODUCTION AND GENERAL DATA
1
Giuseppe LEONARDI and Paolo MIETTO
INTRODUCTION
One morning at the end of 1980, Luciano Chemini, an amateur naturalist from Rovereto (in the Province of Trento, Northern Italy), was walking around the steep slopes of Mt Zugna, at Vallon close to the Lavini di Marco. The Lavini di Marco is a chaotic accumulation of debris and boulders at the base of the mountain and are due to a large landslide. The area where Chemini was walking, known is known as the Laste di Lizzana and is a part of the scare caused to the mountain by the landslide. Somewhere, bands of the steep rocky floor (called colatoi=drainers) are cleaned of debris by running water. The low-angled light of the early morning sun emphasized some strange, rounded depressions crossing the colatoio. They were regularly spaced and surrounded by a rim. “These are the footprints of a prehistoric animal”, Chemini thought. This is how the tracks later known as ROLM 9 and the dinosaur tracksite of the Lavini di Marco were discovered.
Chemini reported the discovery to Michele Lanzinger, then curator of the Museo Tridentino di Scienze Naturali of Trento. Many months passed. When an exhibition of Chinese dinosaurs took place at Trento, Michele Lanzinger called upon one of the editors of this volume (Giuseppe Leonardi) to make an inspection of the tracksite. On July 23th 1991 it became clear that the Lavini were full of dinosaur footprints. A preliminary description of the tracks found at the colatoio, now known as colatoio Chemini in honour of the finder, were published in 1992.
The Museo Tridentino di Scienze Naturali of Trento and the Museo Civico of Rovereto immediately acted to protect and study the site. A task force, led by the editors of this volume, was set up to carry out a multidisciplinary and exhaustive study of the site. Systematic fieldwork began in June 1992 and led to the discovery of hundreds of tracks and footprints spread over a very wide area along the flanks of Mt. Zugna. It is a spectacular site, easy to reach and situated in a beautiful natural landscape.
This volume is dedicated to the different aspects of the site, with particular emphasis, of course, on the paleontological and geological (sedimentology but also geomorphology, structural geology and seismicity). Several chapters are dedicated to evidence of other paleoichnological sites in Italy and neighbouring regions, and Italian Paleozoic and Mesozoic tetrapod osteological materials.
It is clear that much more work must be done before we can fully understand the meaning of the Lavini di Marco site.
2
Giulio Antonio VENZO
GEOGRAPHIC-GEOLOGIC FRAMING AND ACCOUNT OF GEOLOGIC STUDIES AND RESEARCHES REGARDING THE LAVINI DI MARCO
Val Lagarina or Vallagarina is the part of the Adige river Valley between Murazzi (12 km south of Trento) and Rivoli Veronese. On its left side from Lizzana (near Rovereto) stretching 6 km southward, there is an accumulation of contiguous, large landslides known as the Lavini. Many researchers use this term not only for the accumulation but also for the whole flank of the mountain where the main landslide originated.
The dinosaur footprints are situated on the wide bed surfaces (laste) exposed by the falling of the overlaying strata. The lithostratigraphic unit is the Liassic Calcari Grigi di Noriglio.
Many scholars wrote about the Lavini and their origins. Most famous is the citation by Dante Alighieri in the canto XII of the Inferno in his Divina Commedia (1314?).
Qual è quella ruina, che nel fianco
di qua da Trento l’'Adice percosse,
o per tremoto o per sostegno manco,
che da cima del monte, onde si mosse,
al piano è sí la roccia discoscesa,
ch'alcuna via darebbe a chi sù fosse:
cotal di quel burrato era la scesa;
……
The poet describes the landslide accumulation and its possible origins, without using the names of localities except for those of the Adige valley and Trento (see the next chapter for the discussion about the actual location of the landslide mentioned by Dante).
Geological studies began in the XIX century and focused on attempts to date and identify the origin of the event that caused the accumulation. Interpretations were different and sometimes bizarre.
The accumulation was considered to be the result of multiple, different events by Canestrini (1922), Sacco (1940), Fuganti (1969), and Perna (1974). According to some authors, it would have destroyed the village of Lagaris (Neumayr, 1889) or Lagare (Montandon, 1933).
The date of the accumulation event/s was believed to be: a) a “long time ago” (Pasini, 1836; Noriller, 1871), b) end of Ice ages (de Mortillet, 1861; Paglia, 1875; De Cobelli, 1877; Suda, 1886; Canestrini, 1922; Fabiani & Trevisan, 1939; Sacco, 1940), c) beginning of the Postglacial (Taramelli, 1881), d) historical times (Gümbel, 1872; Vacek, 1911), e) more events occurring in different ages, the main one during the interglacial Riss-Wurm period, the lesser during the Postglacial (Fuganti, 1969), f) historical times due to the superficial karst corrosion (Heim, 1932), g) uncertain between 833 and 883 A.D. (Schwinner, 1912), h) in 883 A.D. following the Annals of Fulda (von Mojsisovics, 1863; Giovannelli, 1869; Penck, 1886; Neumayr, 1889; Montandon, 1933), i) possibly in 883 A.D. or on 21 July 365 or 369 A.D. (Eisbacher & Clague, 1984), l) more events during different ages, the last in 883 A.D (Perna, 1974).
The origin of the accumulation was identified as the result of two main kinds of events:
1) a landslide a) without particular causes (von Mojsisovics, 1863; Penck, 1886; Neumayr, 1889; Heim, 1932; Montandon, 1933), b) without particular causes but criticizing all other causes reported in literature (Schwinner, 1912), c) caused by the steep franapoggio dip of the stone beds and the presence of marly, plastic levels (Benecke, 1866; Gümbel, 1872; Taramelli, 1881), d) caused by the steep franapoggio dip of the stone beds and an earthquake (Eisbacher & Clague, 1984), e) caused by heavy rains and melting snow in rocks ready to fall as the result of previous earthquakes (Giovannelli, 1869), f) breakage and throwing into the air of the rocks, caused by the rising from the inner of the Earth of an unspecified elastic substance (Noriller, 1871), g) caused in great part by the retreating of the glacier (Canestrini, 1922), h) mixed geomorphological causes (also glacial exaration and fluvial erosion), but no earthquake (Fuganti, 1969), i) caused mainly by the steep franapoggio dip of the stone beds, presence of marly, plastic levels, lesser pressure after the retreat of the glacier, hard rains and earthquakes (Perna, 1974).
2) a mixed landslide-moraine or moraine: a) as a “secondary moraine” (de Mortillet, 1861; Fabiani & Trevisan, 1939; Abele, 1974), b) caused by an earthquake or the undermining of the base of the mountain (as hypothesized by Dante) but reworked by glaciers (Paglia, 1875), c) caused by the steep franapoggio dip of the stone beds, presence of marly, plastic levels and pressure of the glacier, and reworked by the latter (de Cobelli, 1877), d) caused by the steep franapoggio dip of the stone beds, presence of marly, plastic levels, retreat of the glacier, and partial reworking by the latter (Sacco, 1940), e) moraine in general (Suda, 1886)..
The last study of the Lavini was carried out by Orombelli & Sauro (1988), which identifies seven landslides under the name “Lavini di Marco”. In the text they consider only the main landslide as “Lavini di Marco”, the accumulation of which is considered to be formed by two contiguous landslides (Lavini and Gran Ruina). They identify at least two events, the main one which took place in 883 A.D., and another much older landslide that occurred more than 4000 years ago, (see chapter 13).
3
Aldo GORFER
THE LAVINI DI MARCO: LANDSCAPE, HISTORY, ERUDITION
Few natural phenomena in the Alps have been the subject such controversial geologic, historic, philological and literary interpretations as the Lavini di Marco. The descriptions of the Lavini are mostly confined to the interpretation of the causes of the event or to the debate on the probable mention of it in Dante’s Divina Comedia. The Lavini are mentioned by Innocenzo a Prato at the end of the XVI century and considered to be the result of a strong earthquake that took place in 369 A.D. All the sources of the XVII century cited earthquakes as causes of the origin of the Lavini [for more recent mentions, see the preceding chapter]. The site of accumulation of the landslide was an obligatory stop along the “grande route” connecting the Mediterranean with Continental Europe. This position led to its description by many travellers, who include the Englishman Albanis Beaumont who visited the Lavini in 1786, and the Frenchman Mercey.
The name Lavini or Slavini comes from the late Latin word labina which means “landslide”. The toponym (Labino de Marco) already existed in 1270. The oldest iconographic representation of the Lavini is a map drawn in 1438. The area is reported in most other maps that include the areas surrounding Rovereto: the early ones (1785, 1757, 1774, 1800-1801, 1810), were made under the Austro-Hungarian government (1820, 1862-63, 1894 and 1916), those made by the Italian Kingdom (1927 and 1940) and the Italian Republic (1959, 1965 and 1983).
The debate about the interpretation of the meaning of Dante’s citation of a large landslide accumulation (“ruina”) along the Adige river valley, began as early as 1324 and became fierce during the XVIII-XIX centuries. The main topics of the debate were whether the mentioned landslide that of the Lavini or not, what was the cause of it and whether Dante visited the area and when. Nowadays, the identification of Dante’s “ruina” with the Lavini is accepted by the Divina Commedia annotators with prudent reservation. It is generally accepted that Dante visited this part of Italy between 1302 and 1304, and almost definitely before 1308.
4
Sergio ABRAM, Pietro LORENZI and Filippo PROSSER
NATURALISTIC AND ENVIRONMENTAL ASPECTS OF THE LAVINI DI MARCO
The botanical aspects considered here, concerns two main areas: Mt Cengialto and the small lakes of Marco. The rare endemic Iris cengialti was found in the first area. The woods in the area belong to the alleanza Orno-Ostryon and are characterized by manna-ash, carpino nero e roverella.
Several rare species were recently found in the second area. Teucrium scordium, Potamogeton pectinatus, Carex gracilis, Polygonum minus, Bidens frondosa, Catabrosa aquatica, Ranunculus rionii, Veronica anagalloides, Alisma lanceolatum, Alisma gramineum, Sparganium minimum, Polygonum minus, Carex gracilis, Teucrium scordonia, Rorippa amphibia, Gratiola officinalis, Potentilla reptans, Agrostis stolonifera, Myriophyllum verticillatum, Phragmites australis, Typha latifolia and Salix alba can be found here.
At Lavini several extint species are documented: Hornungia petraea, Teucrium botrys, Lychnis viscaria, Minuartia capillacea. Le specie presenti attulmente sono tipiche dell’ambiente carsico Hieracium praealtum, H. tephropogon, H. dollineri, H. illyricum, H. pospichalii, H. pseudopsammogenes, Inula ensifolia, Rhamnus saxatilis, Epimedium alpinum, Hieracium porrifolium, H. illyricum, H. dollineri, Chamaecytisus purpureus, Euphorbia angulata, Salix glabra, Euphrasia tricuspidata. The rare Daphne alpina, a characteristic of the landslide block environment, is particularly abundant here. The alleanza Orno-Ostryon is the final result of the colonization of vegetation in this environment but it is arrived at over a long period of time and only gradually on the unstable landslide ground. The most important plant environments are:
- Potentilletalia caulescentis: vegetation on cliffs, characterized mainly by Potentilla caulescens, Asplenium trichomanes and A. ruta-muraria
- Stipetum calamagrostis: vegetation of the mobile debris.
- Euphrasio tricuspidatae-Selserietum albicantis: new association characterized mainly by Euphrasia tricuspidata and living on small lembi erbosi on rocky ground.
- Cotino-Amelanchieretum ovalis: brush vegetation, mainly made up of Amelanchier ovalis, Cotinus coggygria, Viburnum lantana but also with trees (Pinus sylvestris, Ostrya carpinifolia and Fraxinus ornus). In humid places Frangula alnus and Salix appendiculata are present.
- Vegetazione di margine (Geranietea sanguinei).
- Vegetazione delle aree boscate su marocca and on the "laste": this is the vegetation type that is most difficult to define.
- Woods with Pinus nigra: this species is not autoctonous.
- Woods of the alleanza Tilio-Acerion: present at the talus of old landslides and in narrow, small valleys in the marocche and on cliffs. Consisting of Tilia cordata, Ulmus glabra and Philadelphus coronarius.
- Woods with Carpinus betulus and sometimes Tilia cordata.
- Woods with Quercus cerris and Quercus petraea characteristic of siliceous soils formed of morenic deposits.
Species with altimontana-subalpina distribution (Rhododendron hirsutum, Pinus mugo, Rhamnus pumilus, Senecio rupestris, Polystichum lonchitis, Dentaria enneaphyllos, Dryopteris villarii, Saxifraga caesia, Paederota bonarota, Valeriana saxatilis, Salix retusa, S. reticulata, Mnium orthorhynchum, Myurella julacea, Drepanocladus uncinatus, Huperzia selago, Rhododendron ferrugineum, Vaccinium vitis-idaea, V. myrtillus) are found at a surprisingly low altitude. This phenomenon is known as “dealpinization” and is due to particularly cold local climatic conditions.
A census of the ornithological fauna and the mammalian fauna was done during the years 1988-89. The area of the Lavini is frequented by a lower number of species with respect to nearby areas. The birds of the area are the eagle (Aquila chrysaetos), the short-toed eagle (Circaetus gallicus), the black kite (Milvus migrans), the honey buzzard (Pernis apivorus), the buzzard (Buteo buteo), the sparrowhawk (Accipiter nisus), the hobby (Falco subbuteo), the kestrel (Falco tinnunculus), the eagle owl (Bubo bubo), the long-eared owl (Asio otus), the rock partridge (Alectoris graeca), the hazel grouse (Bonasa bonasia), the black grouse (Tetrao = Lyrurus tetrix), the blue rock thrush (Monticola solitarius), the rock thrush (Monticola saxatilis), the black birol (Turdus merula), the weathear (Oenanthe oenanthe), the great grey shrike (Lanius excubitor), the Bonelli’s warbler (Phylloscopus bonelli), the melodious warbler (Hippolais polyglotta), the spotted flycatcher (Muscicapa striata), the rock bunting (Emberiza cia), the ortolan bunting (Emberiza hortulana), the wall creeper (Tichodroma muraria), the blackcap (Sylvia atricapilla), the whitethroat (Sylvia communis), the gold crest (Regulus regulus), the long-tailed tit (Aegithalos caudatus), the blue tit (Parus caeruleus), the great tit (Parus major), the crested tit (Parus cristatus), the coal tit (Parus ater), the marsh tit (Parus palustris), the linnett (Carduelis cannabina), the carrion crow (Corvus corone), the raven (Corvus corax), the hoopoe (Upupa epops), the cuckoo (Cuculus canorus), and the nightjar (Caprimulgus europaeus).
The mammals recorded are micromammals (Sorex sp., Microtus sp. and Apodemus sp.) hedgehogs, martens, hares, foxes, badgers, some bats (Barbastella barbastellus, Nyctalus noctula, Pipistrellus kuhli), weasels, and roe deer.
Snakes are represented by vipers (Vipera aspis), Coluber viridiflavus, Elaphe longissima, Coronella austriaca, C. girondica, Natrix tassellata, N. natrix. Common are the lizards Podarcis muralis and Lacerta viridis, and also Anguis fragilis is present.
Amphibians are limited to the wet areas. They are salamanders (Salamandra salamandra), toads (Bufo bufo and B. viridis), and frogs (Rana dalmatina, R. esculenta, Bombina variegata, and Hyla arborea). Triturus alpestris is present in the small lakes of Marco.
5
Daniele MASETTI
THE GEOLOGY OF THE LAVINI DI MARCO
THE MESOZOIC SUCCESSION IN THE ADIGE RIVER VALLEY AND VENETIAN PRE-ALPS: ITS ARRANGEMENT IN THE SCENARIO OF THE TETHYS EVOLUTION
The stratigraphic succession of the Adige River valley is a pile of carbonate rocks more than 1500 m thick, deposited in marine environments between the end of the Triassic and the Late Cretaceous. The main part is constituted by the Dolomia Principale (Late Triassic), Calcari Grigi (Early to Mid Liassic) and Oolite di San Vigilio (Late Liassic-Early Dogger). These lithostratigraphic units, which represent the lower part of the Mesozoic succession, originated from shallow water deposits of a carbonate platform. The upper part, only 200 m thick, is made up of prevailing pelagic carbonates (Rosso Ammonitico, Mid-Late Jurassic; Biancone, mainly Early Cretaceous; Scaglia Rossa, Late Cretaceous).
During the Late Triassic, the present Adige valley, the Dolomites and the Venetian Pre-alps were part of the wide carbonate platform that developed along the western (?) coasts of the Paleotethys margin of the African continent. At the end of the Triassic the disruption of the Pangea began and the carbonate platform where the Dolomia Principale was depositing began to be dismembered into blocks N-S oriented and with differential subsidence. Some blocks became basins during Early Liassic (Belluno Basin) and later (?)the Lombardian Basin also began to form. Other blocks (Eastern Lombardy, Veneto and Friuli) remained carbonate platforms during the Liassic but the wetter climate led to the formation of limestone instead of dolostone. Above the Dolomia Principale deposited the Membro Inferiore of the Calcari Grigi on the Trento and Friuli Platforms; the Corna in Eastern Lombardy. Lower Liassic carbonate platforms exist elsewhere in Italy: the Calcare Massiccio of the Appennine, from Tuscany to Marche down as far as southern Italy.
Between the Early and the Middle Liassic (~195 m.y.a.) wide parts of the carbonate platforms drowned because of crustal straining due to the opening of the Ligurian Ocean to the west. The Lombardian carbonate platform of the Corna was covered by the basin deposits of the Medolo Formation. On the Trento Platform the oolitic Membro Medio of the Calcari Grigi was deposited above the Membro Inferiore. In the Northern Apennines the Calcare Massiccio was covered by the Calcari Selciferi basin or by Rosso Ammonitico facies. In the Southern Apennines the carbonate platform deposition went on undisturbed.
During the passage between Early and Middle Jurassic (180 m.y.a.) the Trento Platform drowned and became an oceanic plateau where the pelagic Rosso Ammonitico Inferiore was deposited. A high production of oolitic sands along the western margins of the Friuli Platform led to the infilling of the nearby Belluno Basin by turbidity currents (Calcare del Vajont).
During the passage between Middle and Late Jurassic (160 m.y.a.) there was an increase of silica sedimentation with the formation of the Radiolariti (derived from radiolarian ooze) in the Lombardy Basin. The Scisti ad Aptici was deposited on the western Trento Plateau, while in the Eastern Trento Plateau and in the infilled Belluno Basin the Fonzaso Formation formed. The Upper Jurassic is represented in the Venetian Alps by the Rosso Ammonitico Superiore. The widespread deposition of pelagic limestone began at the end of the Late Jurassic (Maiolica in Lombardy and Apennines, and Biancone in Veneto) due to the boom of the carbonate plankton. This kind of deposition characterized the Early Cretaceous.
Around the beginning of the Late Cretaceous the deposition of pelagic carbonate ooze was replaced by alternations of limestone, greenish marls and black levels rich in organic matter (Scaglia Variegata in Veneto and Scisti a Fucoidi in the Apennines). Above these alternations began the sedimentation of the emipelagic Scaglia Rossa. Rudist “reefs” developed on the Friuli Platform.
The beginning of the Alpine orogeny led to the uplifting of the region in the Early Tertiary and the plateau became a carbonate platform again. Tertiary carbonate platforms were surrounded by basins where the deposition of Flysch, a product of the erosion of the arising Alpine chain, began.
THE TRENTO PLATFORM AND ITS LIASSIC FORMATIONS
The Liassic shallow water limestones of the Trento Platform can be divided into two sequences. The first is made up of Calcari Grigi and Oolite di Massone (Early-Middle Lias) placed between the Dolomia Principale and a discordance at the top, corresponding to a temporal hiatus wider and wider going from west to east. The second sequence (San Vigilio Group) is Late Liassic-Early Dogger and is placed between the hiatus and the Rosso Ammonitico Inferiore, but can only be found in the western sector of the platform.
THE CALCARI GRIGI FORMATION
The Calcari Grigi were informally divided by Bosellini & Broglio-Loriga (1972) into Membro Inferiore (more than 100 metres thick) where the footprints were found, Membro Medio (or oolitic) and Membro di Rotzo or Membro Superiore [for their datation see chapter 6]. The Membro di Rotzo is the most studied and the better known.
THE MEMBRO INFERIORE OF THE CALCARI GRIGI OF THE ADIGE VALLEY
The lowermost part of this member is made of alternances of limestones in metric beds and levels of green clay, without evidence of tidal deposits. In contrast, structures typical of the tidal environment (stromatolites etc.) characterize the upper part of the member where the dinosaur footprints are found, several tens of metres below the passage to the Membro Medio.
Therefore, peritidal cycles due to the concurrent action of subsidence and carbonate deposition, constitute the upper part of the Membro Inferiore [this part is described in detail in chapter 9].
The subtidal facies, representing the lower 2/3 of the cycle, is mainly made up of homogeneous micritic, peloidal-fossiliferous limestones, completely reworked by bioturbation. Sometimes accumulations of large bivalves are present. There are both storm layers and colonies with individuals in life position. The intertidal facies are undistinguishable from the subtidal.
The supratidal facies are characterized by peculiar sedimentary structures such as storm-bacterial lamination (stromatolites), mud cracks, teepees, birdseyes, flat pebble breccias etc..
The causes of the peritidal cyclicity are autocyclical (sedimentologic) or allocyclical (glacioeustatic) without the possibility of knowing at present which one was prevalent.
Fig. XX shows a hypothetical paleogeography of Italy during an imprecise moment of the Early Lias.
THE BASAL SUBTIDAL UNIT OF THE MEMBRO INFERIORE
As mentioned above, this unit is characterized by the prevailing subtidal micrites and absence of peritidal facies. This basal part is the most typical and widespread of the Membro Inferiore; it has a thickness in excess of 100 m at the eastern sector of the platform, where it represents the whole member. It is gradually replaced by the peritidal unit to the west, where the latter reaches a maximum thickness of 50 m in the Adige Valley. The basal unit is made up of cycles about one metre thick with subtidal micrites poor in fossil content at the base and centimetric levels of green clay at the top. The origin of the clay levels is controversial: caused by subaerial exposure and limestone dissolution or by “starvation” of the lagoon with restricted circulation and the end of carbonate production. The cause of the cycles is glacioeustatic, as shown by their gerarchic organization into two orders of magnitude.
THE OOLITIC MEMBRO MEDIO
The Membro Medio originated from oolitic sands organized into submarine dunes by tidal currents. It is a wedge-shaped lithosoma thicker to the west, (more than 200 m in the Sarca River valley, Trento) and thinner to the east (150 m in the Group of Mt Baldo, 30-40 mt in the Sette Comuni Plateau where it ends east of Gallio). This member is similar to the Oolite di Massone. Biostratigraphic data suggests that this unit becomes younger from west to east. It represents a drowning of the region caused by the collapse of the western sector of the platform.
THE MEMBRO DI ROTZO
This member is rich in plants remains and bivalve banks (“Lithiotis banks”). Its western margin of deposition was situated in correspondence to the Mt Baldo Group, the eastern coincided with the Mt Grappa Massif. Its geometry is similar to that of the Membro Medio and their eastern terminations coincide. It is characterized by high clay content and a particular cyclicity. Each cycle is composed of alternations of marl-limestone at the base and Lithiotis mounds or fossiliferous calcarenites at the top. Lithiotis banks, tabular or lenticular (mounds) biogenic bodies up to 2-3 m thick, are frequent mainly in the upper part of the member. Each cycle is shallowing-upward according to the life needs of the bivalves. These cycles are interpreted as being formed in a low-angle ramp setting, with the deepest part to the west, where it was bordered by the littoral sand body of the Oolite di Massone (ramp-lagoon depositionary model).
6
Carmen BROGLIO LORIGA
PALEONTOLOGICAL ASPECTS OF THE CALCARI GRIGI
This chapter deals with the fossils found in the Calcari Grigi and excludes reptile footprints. The paleontology of this formation is essentially that of its Membro Superiore, or Membro di Rotzo, because of its fossil richness. In contrast the Membro Medio and Membro Inferiore are relatively poor in of fossils.
THE MEMBRO DI ROTZO AND THE LITHIOTIS FACIES
The fossils of this member are both marine invertebrates and terrestrial plants. They were first studied in 1764 but were subject to more detailed analysis during the 19th century. The Lithiotis facies, which takes its name from the bivalve Lithiotis problematica Gümbel, is typical of the member and is characterized by mounds or banks of this and other large, oyster-like bivalves. Other organisms are brachiopods, gastropods and foraminifers; less common are individual and colonial corals, porifera, echinoderms, ostracods and ammonoids. Vertebrates are represented by fish teeth (Pycnodus). Most of these organisms belong to the domine of shallow waters. Fossil vegetalia are shallow waters red and green calcareous algae and terrestrial Equisetatae, Filicatae, Coniferophytinae, Cicadophytinae and several parataxa of palinomorphs.
LARGE BIVALVES
The large bivalves are the peculiar component of the Lithiotis facies. They are represented by the following genera: Lithiotis Gümbel, Cochlearites Reis, Lithioperna Accorsi Benini, Mytiloperna von Yhering, Gervilleioperna Krumbeck, Pseudopachymytilus Krumbeck
Other less common but characteristic bivalves of the Liassic biofacies are: Opisoma Stoliczka, Protodiceras (Gümbel), Pachyrisma (Pachyrisma) Morris & Lycett, Pachyrisma (Durga) Böhm, Pachyrisma (Pachymegalodon) Gümbel.
They are characterized by a large, thick shell with a small body cavity. The shell of Lithiotis, Cochlearites and Lithioperna often reaches a height of 25-30 cm and a thickness of 1-1.5 cm. Lithiotis and Cochlearites have a spoon-shaped shell; that of Lithioperna is cup-like. However, there is a wide variability of shell shape, convexity, thickness and ornamentation.
SMALL BIVALVES
The small bivalves are rather diversified; the most common are Gervilleioperna ombonii Negri, Pseudopachymytilus mirabilis (Lepsius) and the megalodontacea Protodiceras pumilus (Gümbel), Pachyrisma (Pachymegalodon) chamaeformis (Schlotheim), Pachyrisma (Durga) crassa (Böhm) and P. (Durga) nicolisi (Böhm). Gervilleioperna ombonii lived in the upper-subtidal mud, Pseudopachymytilus mirabilis in the intertidal mud, forming dense populations (mounds, see below) like the living mussels.
THE “LITHIOTIS MOUNDS”
In life these were associations of gregarious bivalves mixed with mud and in relief above the muddy bottom. Lens-like mounds with upward concavity, 25-50 cm thick correspond to communities of the smaller bivalves Pseudopachymytilus mirabilis, Gervilleioperna ombonii and Neomegalodon pumilus. The characteristic thick mounds, tabular or most frequently lens-like with upward concavity (up to 2-3 mt thick), with chaotic distribution of large bivalve shells are mono-specific associations of Lithiotis problematica, Cochlearites loppianus and Lithioperna scutata, with a prevalence of the second. The small bivalves began the colonization of the muddy bottom forming a firm base for the successive development of the colony of large bivalves.
GREGARIOUS GASTROPODS: THE GROUP “TEREBRA-NORIGLIENSIS”
Gastropods are present at different levels of Calcari Grigi but identified taxa are very few (Patella conoidea Lepsius, Patella (Scurria?) tirolensis Tausch, Emarginula orthogonia Tausch, cf. Neritopsis ?oldae Stoppani, Natica ssp., Chemnitzia terebra Benecke, Nerinea (Aptixiella) norigliensis Tausch) and rare in respect to bivalves. The turriculate gastropods Chemnitzia terebra and Nerinea (Aptixiella) norigliensis (possibly synonyms) are abundant, gregarious and identify a biofacies in the lower part of the Membro di Rotzo. They are found in the most marginal part of the platform where the waters were well oxygenated and rich in nutrients.
BRACHIOPODS
These stenoaline animals are well represented. Tausch (1890) found the genera Terebratula, Waldhemia and Spiriferina, now revised or in need of revision. At present the terebratulids are considered the most characteristic brachiopods of the unit with the species Hesperithyris renierii (Catullo), Lychnothyris rotzoana (Schauroth), Lobothyris punctata (Sowerby) and are referred to the Pliensbachian.
FORAMINIFERS AND CALCAREOUS ALGAE
The Foraminifera are diversified, the most characteristic taxa being the following: Orbitopsella gr. primaeva Hottinger, Orbitopsella gr praecursor (Gümbel), Orbitopsella cf. dubari Hottinger, Lituosepta recoarensis Cati, Planisepta compressa (Hottinger), Amijiella amij (Henson), Haurania deserta Henson, and Vidalina martana Farinacci. Like bivalves, they form oligotypic or even monotypic associations.
Orbitopsella and Planisepta (= Labyrinthina) compressa are important biostratigraphic markers. Glomospira was the only foraminifers to live in the restricted, oxygen-depleted lagoon.
Calcareous algae are represented mainly by Palaeodasycladus mediterraneus (Pia) (green algae, Dasycladales), Solenopora sp. (red algae), Thaumatoporella parvovesiculifera (Raineri) (incertae sedis). Palaeodasycladus mediterraneus is a biostratigraphic marker of the Liassic and has a wide geographical distribution.
TERRESTRIAL flora
Terrestrial flora is of particular interest in a book devoted to land animals as the dinosaurs were. The flora of the Calcari Grigi was described mainly by de Zigno (1856-1885) and more recently by Wesley (1956, 1958, 1966). According to Wesley floristic association was dominated by Bennettitales, followed by conifers, Caytoniales, Filicales (Dipteridaceae, Dickinsoniaceae, Mathoniaceae and perhaps Gleicheniaceae) and Equisetales. Study of palinomorphs (Van Erve, 1977) showed that the ferns are as nearly common as the gymnosperms in the sample, Caytoniales are relatively rare and Licopodophyta are also present.
According to Wesley, the habitat was a coastal, mangrove-like, salty swamp with the conifers living on nearby uplands and a few ferns living far from the brackish waters. The predominance of xerophitic plants would suggest a relatively arid climate. The more abundant fern evidence in the palinomorph sample would suggest a somewhat more humid climate.
The affinities to the generic level show that the megaflora of the Calcari Grigi is different from those of coeval European associations (Württemberg, southern Poland, Eastern and southern France) because of the presence of Gleichenites, Dichopteris, Cycadopteris, Sphenozamites, Dactylethrophyllum, Yuccites and Phyllotheca. Some resemblance exists with megaflora from the Lower Jurassic of Lorraine and Middle Jurassic of Sardinia. The equisetales Phylloteca brogniartiana suggests a Gondwanian affinity of the macroflora, which however is not supported by the palynomorphs.
COMMUNITIES AND LIFE ENVIRONMENTS
The following communities/ environments are identifiable in the Membro di Rotzo:
1) terrestrial - represented by the plants; mangrove community along the coast, community with ferns and conifers in hypothetical inner uplands.
2) swamp - remains of herbaceous plants
3) restricted lagoon - eurialine foraminifers and ostracods
4) intertidal-upper subtidal - Pseudopachymytilus and Gervilleioperna mounds
5) subtidal - a) low energy, Lithiotis, Cochlearites, and Lithioperna mounds; b) mid-energy with prairie-like bottom, Orbitopsella community; c) outer limit of the lagoon with (1) moderate wave motion (Labyrinthina compressa community) or (2) below the level of wave action (“terebra-norigliensis” gastropod community and, perhaps, a community with megalodontaceans).
PALEONTOLOGY OF THE MEMBRO INFERIORE AND MEMBRO MEDIO
The fossils in these members are much rarer and have not been the subject of a great deal of study. Brachiopods at the base of the Membro Inferiore are represented by “Terebratula” dubiosa Haas and Pisirhynchia uhligi Haas. Small foraminifers (Textulariidae, Ataxophragmiidae and the rare lituolid Mancyna cf. termieri) are found at various levels. The most important microfossil from a chronostratigraphical point of view is the alga Palaeodasycladus mediterraneus (Pia) which is considered to be a Liassic marker. There are also solenoporacean algae, ostracods, small gastropods and echinoderm remains.
The microbiofacies of the Membro Medio is similar, with the addition of nodosariform foraminifers and the alga Solenopora cf. liasica Le Maitre. Among the macrofauna, chetetid spongia and several valves of pectiniformes bivalvs are also found.
THE AMMONOIDS OF THE CALCARI GRIGI
Ammonoids, the basic biostatigraphic markers for the Mesozoic, are rather rare in the Calcari Grigi. They were only found in the western part of the Trento Platform; in every case they were collected in the debris near outcrops of the Calcari Grigi. The following taxa were found: Harpoceras cornacaldense Tausch, Fuciniceras (Protogrammoceras) sp., Fuciniceras suejense tinctum Wiedenmayer, Juraphyllites libertus (Gemmellaro), Charmasseiceras sp.. Harpoceras cornacaldense was attributed to the subgenus Fuciniceras (Protogrammoceras) (Sarti, 1981). Also an ammonoid association found into an isolated boulder found near Sospirolo, Mis Valley (Belluno) was attributed to the Calcari Grigi (but there is no general agreement on this attribution). The following taxa were identified: Partschiceras tenuistriatum (Meneghini), Partschiceras cf. retroplicatum (Geyer), Juraphyllites libertus (Gemmellaro), Harpophylloceras eximium (Hauer), Liparoceras (Becheiceras) bechei (Sowerby), Androgynoceras striatum (Reincke), Protogrammoceras celebratum (Fucini), Protogrammoceras dilectum (Fucini).
THE AGE OF THE LITHIOTIS FACIES AND OF THE CALCARI GRIGI
The attempt at dating the Calcari Grigi began during the second half of the last century with the description of the plants of the Membro di Rotzo by de Zigno. He dated them as Middle Jurassic on the basis of a comparison with other fossil florae and faunae found in Europe.
The ammonoids Protogrammoceras cornacaldense, Protogrammoceras sp., Juraphyllites libertus and Fuciniceras suejense tinctum indicate the Early and Late Pliensbachian. Data from the palynomorphs suggest that the Membro di Rotzo and the upper part of the Membro Medio are Late Pliensbachian-Early Toarcian.
At present dating is mainly based on the calcareous algae and, above all, foraminifers with the identification of three biozones. The reference point is the Orbitopsella Zone; fixed its cronostratigraphic collocation, dating of the levels above and below it is done according to their stratigraphical position with respect to that Zone. The Orbitopsella Zone is recognized in the Lower Jurassic series of carbonate platforms all over the world; in Northern Africa its dating (based on ammonoids) is Carixian. The Planisepta compressa Zone, corresponding to the uppermost part of the Membro di Rotzo, above the Orbitopsella Zone, is referable to the Late Pliensbachian. The horizon with plant remains is consequently Domerian, and placed between the Orbitopsella Zone and the Lituosepta Zone. Below the Calcari Grigi there is the Late Triassic Dolomia Principale, and their boundary is considered isochronous. Consequently, the Membro Inferiore and Membro Medio are Hettangian and Sinemurian in toto if the Orbitopsella Zone is Carixian, or are Hettangian-Sinemurian p.p. if the Zone extends into the Sinemurian. Actually the dating of Membro Inferiore and Membro Medio are not based on good biostratigraphic markers excluding the Early Sinemurian ammonoid Charmasseiceras. There seems to be continuity of sedimentation, without wide hiatuses, between the Dolomia Principale and the Membro Inferiore and between the latter and the Membro Medio. Palaeodasycladus mediterraneus, a biomarker of the Liassic, is present in the Membro Inferiore, together with some foraminifers, which are found in the Membro di Rotzo but not in the Triassic. This suggests a Hettangian-Early Sinemurian dating of the Membro Inferiore and Membro Medio.
7
Giuseppe LEONARDI
ACCOUNT ON THE DINOSAURS
This general account does not concern the site in the strict sense and is not reported here.
PART I I - THE DINOSAUR TRACKS IN THEIR PALEOENVIRONMENT
Giuseppe LEONARDI and Paolo MIETTO
THE LIASSIC DINOSAUR TRACKS OF THE LAVINI DI MARCO
INTRODUCTION
Three dinosaur tracks (ROLM 1, 9 and 11) were discovered for the first time at the Lavini di Marco in 1988 by Luciano Chemini. Many other footprints and tracks were found during July 1991 by a systematic field exploration of the site carried out by the research team from Museo Tridentino di Scienze Naturali and Museo Civico of Rovereto, which were led by the authors, from 1991 on. The site is one of the richest of Europe, with about 70 tracks and at least 90 isolated footprints, left by a total of about 140 individuals; total individuals are more than 200 if one considers indeterminate and unstudied specimens.
Most of the footprints are found along the “colatoi”, at the “hinge” and on the “laste alte”. The “colatoi” are regions of the mountain flank were debris and soil have been cleared away by water flow after heavy rains. The “hinge” is a zone of “knee-like” flexure of the rocky layers, high on the mountain flank; the “laste alte” is a wide, smooth and sloping flat area made by the surface of a rocky layer or few rocky layers (i.e. the topographic and stratigraphic surface coincide) high on the mount flank. In order to identify the different “colatoi” we named them “colatoio Chemini”, “colatoio of the sauropod”, “colatoio of the theropods” and “colatoio of the ornithopods” (see Fig. XX in the Italian text).
The footprints and tracks testify to the presence of many dinosaurs. The most abundant are theropods (about 80) probably Ceratosauria, then there are about 15 early sauropods, some advanced ornithopods, about 20 bipedal dinosaurs (possibly small-size primitive ornithopods), about 10 footprints or tracks of indeterminable plant-eaters (probably sauropods) and finally, some unidentified dinosaurian footprints.
The description and study of this material was carried out following methods and terminology of Leonardi (ed.) and co-authors (1987a).
Most of the fossil footprints are not true footprints but are underprints. When we tried to clean the footprints of the rocky infilling, we were not sure about which of the many surfaces was the true printed surface. In many cases the visible part of the footprint is made by non-coeval surfaces. In ROLM 2 and 9, for example, the bottom of each footprint is the true printed surface because it presents a flat pebble breccia, due to the crushing of the mud-cracked original sedimentary surface by the dinosaur foot. However, their lateral wall has a different age, because it is cut across a number of levels. The surface of the displacement rim and the surrounding field surface do not correspond to the soft and waterlogged surface on which the dinosaurs stepped, which was eroded, but a deeper and more consistent level. So each extant footprint is composed by three kinds of non-coeval surfaces.
DESCRIPTION
THEROPODS
The dinosaurs represented by tridactyl footprints, with slender and clawed digits of predators, are the most common in the site. The footprints are shallow, sometimes difficult to identify, and the tracks are incomplete or represented by few footprints. This means that the authors were light and relatively quick. Up to now about eighty individuals have been identified; however there is one surface that was over trampled by tridactyl dinosaurs that is waiting for to be studied on the “laste alte”. Therefore, the number will increase.
Identification of the footprints is difficult because of their shallowness. The morphology of the prints differs greatly in the same track, showing that it is also influenced by gait, foot stance and substrate condition. Some of the tridactyl footprints could belong to primitive ornitischians, some of which had theropod-like feet, functionally tridactyl and clawed. We consider here as theropod all the footprints that clearly do not to belong to ornithischians.
Theropod footprints can be grouped into the following categories:
1) tetradactyl (Italian text-figs. 8.4, 8.5, 8.7),
2) with wide interdigital II-IV angle (Italian text-figs. 8.3/9-15),
3) small-sized, with short and stout digits, (Italian text-figs. 8.3/20-23),
4) with long , wedge-like “heels”, (Italian text-figs. 8.4/3, 4, 11,12),
5) with broad and/or spatulated digit III, (Italian text-figs. 8.3/16-18),
6) with long, slender and sinuous digit III, (Italian text-figs. 8.3/1-8),
7) others, subdivided into:
a) “crescent”-shaped footprints, (ROLM60, ROLM154/3),
b) footprints with anomalous nails (Italian text-fig. 8.4/10),
c) grouped digits, (Italian text-fig. 8.4/6),
d) repeated prints, (Italian text-fig. 8.4/7),
e) scratches (Italian text-fig. 8.4/8),
SAUROPODS
The first sauropod track was found on June 1992 (ROLM75). Up to now ROLM 1, 2, 4, 11, 14, 21, 26, 28, 33, 61, 67, 75, 126, 173, 200 and possibly several more (Italian text-figs. 8.16-26, 8.28), can be attributed to sauropod trackmakers. Because of the poor state of preservation no new ichnotaxonomic name was given to this material. The two best preserved tracks are herein described.
ROLM 75 (Italian text-figs. 8.16, 8.24-8.26): quadrupedal, narrow gauge track, 7 m long, slightly curved, with 10 pes-manus sets. The pes-manus axis is directed outwards (32°) with respect to the trackway midline. The ratio stride/pedal footprint length is rather low (about 3), testifying the slow walking gait of the trackmaker. The pace angulation of pedes is very low (mean=95°) as is that of the manus (about 60°) because the manual print is in front and lateral to the pedal. The latter is usually pyriform and deeper anteriorly; digit prints are sometimes present, with a variable number (1 to 4) of small, short, pointed and clawed marks. However, the pes was probably pentadactyl. The hypex are very “open” and blunt. We think that sometimes the collapsing mud totally obliterated the marks of the claws. The manual prints are kidney-shaped, crescent-like or, in one case, nearly horseshoe-like, with a marked indentation in the posterior margin. This shape is partly due to the deformation caused by the overprinting of the pes. The digital prints of the manus, rarely left or preserved, are short and pointed, with hypex wide and blunt (footprints 4 or 6); it is difficult to state the actual number of digits. The track is irregular, because of the gait of the trackmaker and the variable substrate condition. There are many middle to large-size theropod footprints and associated tracks.
ROLM 28 (Italian text-figs. 8.16, 8.18, 8.19): is a short track, with 5 incomplete pes-manus sets and some underprints. There are several differences to ROLM 75: larger size (the average pes length is 52 cm against 45 cm), higher pace angulation and, consequently, narrower track, the pes-manus axis is outwardly directed to a lesser degree.
ROLM61 is similar to ROLM75 and 28. However, ROLM1, 2, 11, 26 and perhaps 126 are morphologically different: the anterior margin of the pes presents three or four digit prints with the shape of rounded lobes, manual prints are shallow or absent, perhaps totally overprinted by the pes. These trackways are narrow gauged, manual prints are often, but not always, laterally placed and do not diverge from the midline.
POSSIBLE ORNITHOPODS
There are very deep (up to 15 cm) and evident tridactyl or tetradactyl footprints. The two best examples of these specimens are described here.
ROLM 64 (Italian text-figs. 8.31-8.32, 8.40-8.41): a straight, bipedal or perhaps semibipedal track, 14 m long with 24 footprints. The animal was slowly walking with alternating short (left-right) and long (right-left) paces. We cannot exclude that the trackmaker was limping. There are huge expulsion rims with interference between adjacent rims and the mud sometimes collapsed into the footprint. The footprints generally have an oval or pyriform shape, and are tetradactyl (but the mark of digit I is rarely preserved) with digit II-IV large and hoof-like and digit I (footprint 23) medially placed as a spur, short and rounded, impressed only when the foot sank deeply into the mud.
ROLM 63 (Italian text-figs. 8.30, 8.39): bipedal track, composed of three non-consecutive footprints (a right, a left, then the right is missing and a left one follows). Also in this case digit I seems to be present. The footprints are deep (up to 8 cm). The first footprint shows three, hoof-like, toes separated from the “plantar” pad; digit III is particularly short. In the second footprint the mark of the digit II is narrow and spatulated because the mud collapsed into it.
The animal was walking slowly, with alternating short (left-right) and long (right-left) paces. Also in this case, we cannot exclude that the trackmaker was limping. There are huge expulsion rims with interference between adjacent rims and the mud sometimes collapsed into the footprint. The third preserved footprint shows the mark of digit I.
OTHER TRACKS
Other footprints and tracks, poorly preserved, belong to the same form: track ROLM9 (Italian text-figs. 8.28, 8.37), 181 (Italian text-fig. 8.29) and 30 (Italian text-fig. 8.38).
Other tracks can be identified as ornithopodian:
- ROLM 192 (Italian text-figs. 8.34, 8.35) differs from the others because of the stronger foot, with footprints deeper laterally, the “heel” is much longer and triangular, wedge-shaped because of a digit IV mark which is developed posteriorly behind the phalangeal-metatarsal articulation.
- ROLM50, a lighter form, with slender digits but ending with a hoof.
- Some tridactyl footprints with digits, a little broader than those of the theropods and without claws, could belong to less specialized and less advanced ornithopods like, for example, the “fabrosaurids” (Italian text-figs. 8.4/13-16). In any case, they will be considered as unidentified bipedals in the statistics.
FOOTPRINTS AND TRACKMAKER IDENTIFICATION
THEROPODS
Ichnologic determination of the tracks
It is very difficult and often impossible to give formal names to the ichnological material being studied because of the poor and incomplete preservation and the high morphological variability of the footprints on the same track. Besides, the hind feet of the tridactyl dinosaurs are basically the same in most ornithopods and theropods, mainly those of small to medium-size taxa. Therefore the following classification is only indicative.
Morphofamily Anchisauripodidae Lull, 1904
Grallator Hitchock, 1858: about 15 footprints could belong to this ichnotaxon (ROLM32, 37, 39, 74, 89, 93, 97, 120, 128, 140, 141, 151, 152, and 206).
Morphofamily Eubrontidae Lull, 1904
Eubrontes Hitchock, 1845: about 10 footprints could belong to this ichnotaxon (ROLM31, 36, 38-41, 44,71, 130 and 193).
Footprints comparable to Columbosauripus Sternberg, 1932: ROLM60, 76 and 96 can be morphologically compared to this Cretaceous ichnogenus.
Footprints resembling other ichnogenera
a) Some large footprints such as ROLM 13 and 41 resemble the anterior part of Bueckemburgichnus maximus Kuhn 1958.
b) ROLM70 presents features of Saltopoides igalensis Lapparent and Montenat, 1967.
c) ROLM5 shares with some genera attributed to theropods the presence of a spur-like, facing backward digit; otherwise it resembles the Grallator.
d) ROLM 49, 87, 89, 120, 132-133, 158 could belong to Coelurosaurichnus but this ichnogenus was demonstrated to be invalid (= Grallator).
In conclusion the identified ichnotaxa are Grallator, Eubrontes and that with short and broad digits. This association is similar to others found in the Lower Liassic; however, theropod footprints are of little use for biostratigraphical purposes. Noteworthy is the absence of the morphofamily Gigandipodidae Lull, 1904.
Classification of the trackmaker
The trackmaker must be found in the suborder Ceratosauria (Italian text-figs. 8.13-8.15, 8.44, 8.47, 8.54, 8.56) rather than of the suborder Carnosauria or Coelurosauria as reported in the past, mainly in paleoichnological papers. Ceratosauria was the only theropod group definitely alive during Early Jurassic times.
SAUROPODS
Ichnologic determination of the tracks
The tracks are attributed to primitive sauropods but more advanced from the ichnological point of view. They are the oldest sauropod tracks found up to now in the world. The diagnostic features are: quadrupedality with marked heteropody, characteristic shape of the manual (crescent-like etc.) and pedal prints, strong positive (outwards) divarication, short and pointed digits on the hind feet and, when present, also in the fore feet, with hypexes open, blunt and rounded; relatively low pace angulation.
Because of these typical sauropodian features, we do not attribute the tracks to prosauropods.
Since they are narrow-gauged, we do not compare them with the wide-gauged ones, like Brontopodus Farlow, Pittman & Hawthorne, 1989. They resemble Parabrontopodus Lockley, Farlow & Meyer, 1994 of the Upper Jurassic of USA and the holotype of Breviparopus Dutuit & Ouazzou, 1980, Upper Jurassic of Morocco. With the latter they share the marked positive (outwards) divarication of the pes-manus set, the manual prints placed rather laterally and their overall shape, the forward directed foot nails, the short pedal prints and their overall shape. The differences are: the manual print of Breviparopus never presents large nail marks and hypexes, the distance manus-pes is shorter, the footprints are larger (more than twice the size).
The differences reported above between ROLM75 and ROLM28 are not sufficient to classify them into two separate ichnospecies; anyway, we do not create a new ichnotaxon because of the poor preservation.
Identification of the trackmaker
The lateral position of the manual prints suggests a sauropod as the trackmaker with a rather broad shoulder girdle and particularly well developed fore-limbs. This, as well as the age, suggest the attribution to the poorly known family Vulcanodontidae Cooper, 1984. However, we cannot exclude a member of the Cetiosauridae Seeley, 1874 or, in every case, a member of the Eosauropoda Bonaparte, 1986a as being the trackmaker.
POSSIBLE ORNITHOPODS
Ichnologic determination of the tracks
The main aspect to stress is that up to now large, iguanodontid-like footprints have never been found in the Lower Jurassic. The footprints under examination are different from the coeval Moyenisauropus Ellemberger and Anomoepus E. Hitchcock, 1848, belonging to primitive ornithopods, perhaps “fabrosaurids”. They never present the mark of the true heel, digits II-IV are much shorter, mainly digit III, and hoof-like. Besides, they are much larger and the tracks are in most cases bipedal. They show a striking similarity to the Late Jurassic and Early Cretaceous footprints attributed to iguanodontids. Similarities exist also with hadrosaurids. However, all the footprints of large ornithopods lack the mark of digit I.
Discussion about the trackmakers
The trackmakers could be identified as large, graviportal ornithopods, very ancient but not very primitive from an ichnological point of view. They could be related to iguanodontids (Italian text-figs. 8.43, 8.47). The presence of digit I is a primitive character since it is not present in the iguanodontids and hadrosaurids, with the exception of Camptosaurus Marsh. If the footprints under examination are actually ornithopodian, we are not brave enough to attribute them to the family Iguanodontidae sensu stricto but we think that they could be at the base of this family or belonging to an unknown family strictly related to it. The presence of iguanodontids in the Lower Jurassic would record this group about 40 (taking into account Callovosaurus Galton) or also 50 millions before the comparison of the first bones in the fossil record.
However, we cannot ignore, mainly for the track ROLM64, another hypothesis: that the trackmaker could be a sauropod. Therefore, we avoid giving a formal name to the large “ornithopod” tracks and we will name them provisionally as “advanced ornithopods”.
DESCRIPTION AND DISCUSSION ABOUT ICHNOASSOCIATIONS
There are five levels with footprints in a section five metres thick (levels 101, 104, 105, 106, 115 and 120). The main levels (104, 105, 106, 115) are concentrated in less than two metres. The richest levels are 105 and 106.
ROLM 3-7, 49-51, 53-54, 59-76, 85-104, 107, 110, 112-116, 118, 120-124, 130-133, 140-146, 150-154, 156, 158, 174-175, 206-207 are found on the level 105, for a total of 84 individuals (57 theropods, 4 sauropods, 2 indeterminate plant-eaters, 17 indeterminate bipeds, 4 possible advanced ornithopods and a dozen unidentified footprints).
ROLM1-2, 9, 11-12, 14-15, 18, 20-23, 25-41, 43-44, 47-48, 125-128, 135-136, 159, 171, 173, 181, 192-193, 197-200 are found on level 106, for a total of 49 individuals (21 theropods, 11 sauropods, 5 indeterminate plant-eaters, 6 indeterminate bipedals, 6 possible advanced ornithopods and 8 indeterminable footprints). The associations in the two levels are different: carnivorous are dominant in the level 105 (67% against 33% - but only 12% are certain - plant-eaters) whereas the reverse happens in level 106 (57% plant-eaters, 43% carnivorous). These differences probably depend on different distribution of the microenvironments at each of these two levels.
THE ICHNOFAUNA OF THE LAVINI DI MARCO COMPARED TO OTHERS COEVAL
As the stratigraphic position of the ichnofauna is indicated as Lower Jurassic, a comparison has been made with Lower Jurassic ichnofaunas all over the world, with emphasis on the differences.
Veillon (Vandée, France; Rhetian-Early Hettangian) - Prosauropods are absent in both ichnofaunas but neither are sauropods found here. Ornithopods are absent and crocodylomorph footprints (Batrachopus E. Hitchock and Dahutherium Montenat) are present. Only theropods seem to be similar in both sites.
Saint-Laurent-deTrèves (Causses, Lozère, France; Late Hettangian) - Only theropods are represented and correspond to those found at the Lavini di Marco.
“Oppidum de Grézac” (Lodève, Herault, France; Late Hettangian) - The same considerations for Saint-Laurent-deTrèves are valid.
Holy Cross Mountains (Poland; Early and Late Hettangian) - Theropod (11%) and ornithopod (89%) footprints are found in the Late Hettangian, only theropods in the Early Hettangian. The presence of ornithopod footprints, identified as Moyenisauropus and Anomoepus E. Hitchock, are the most strikingly similar to the association described here. However, large ornithopods with hoof-ending digits are not present, as are also sauropods.
Pécs region (Hungary, Early Sinemurian) - Here only theropods (Grallator and Kayentipus Welles) are represented, therefore comparisons are impossible.
Hogänas (Sweden; Rhaetian and Early Hettangian) - Here also only theropod footprints are found.
Neyzae, Kerman and Zerab (Iran; Sinemurian/Pliesbachian) - Few footprints and short tracks attributed to Grallator and mainly to large ornithopods are reported, but unfortunately comparisons are not possible because of the poor numbers. The Iranian and our associations would be similar due of the presence of theropods and large ornithopods and different mainly because of the absence of sauropods in Iran.
Jinning (Yunnan, China; Liassic) - Also here only theropod footprints are present.
“Jeholosauripus” ichnofaunas of Liaoning and Hebei (China, Rhaetian-Liassic) - Also here only the theropod “Jeholosauripus” Yabe, Inai & Shikama (= Grallator s-satoi (Yabe, Inai & Shikama) was found.
“Changpeipus” Young ichnofaunas of Liaoning and Jilin (China, Middle Jurassic or less probably Liassic) - Also here only theropod footprints are found.
Lesotho (Southern Africa, Hettangian-Sinemurian) - There is more variability in the theropod ichnotaxonomy of this ichnofauna; prosauropods seem to be absent in the Liassic levels and the presence of sauropod tracks is doubtful. The small ornithopod Moyenisauropus (=Anomoepus) present here, is absent in the Lavini di Marco. Tritiylodontid therapsids and early mammals are abundant in Lesotho but absent at the Lavini.
Spring Grange (Zimbawe, Late Triassic or Liassic) - Also here only theropod footprints are found.
Newark Supergroup (eastern coast of North America, Liassic) - The similarity of the theropod footprints of the two ichnofaunas is noteworthy. However, here sauropods and large ornithopods are absent, whereas small ornithopods (Anomoepus) and crocodylomorphs are present.
Glenn Canyon Group (South western U.S.A., Liassic) - The differences with the ichnofauna of the Lavini di Marco are the absence of sauropods and large ornithopods, and the presence of the prosauropods, Anomoepus, and crocodylomorphs (Batrachopus).
Botucatu Formation (Southern Brazil and neighbouring countries; Liassic?) - It represents a desert eolian environment. The differences with the Lavini di Marco are found in the presence of possible small ornithopods, tritylodontid therapsids, early mammals and mammaloids; the latter two are abundant. Sauropods, prosauropods and crocodylomorphs are absent.
Queensland (Australia; Late Liassic) - Here Anomoepus prints are present, these are not found at the Lavini di Marco, together with footprints of large theropods.
Therefore, the ichnofauna of the Lavini di Marco is quite different from the others that are more or less coheval, except in the case of theropods. The most striking characteristics of this comparison are 1) the absence of prosauropods (the most common plant-eaters during Liassic times), crocodyilomorphs, therapsids, protomammals, mammals and, in general, of small quadrupedal animals, 2) the presence of early sauropods and, if the identification is correct, of early but advanced ornithopods. Consequently, the ichnoassociation found at the Lavini di Marco does not fit in with the Liassic “Anomoepus-Grallator (Eubrontes) Zone” of Haubold (1986). The presence of sauropods and early large ornithopods would suggest a younger age but the absence of mammals, mammaloids and crocodylomorphs does not support this dating. If the Hettangian/Sinemurian dating is correct, we must admit that the dinosaur fauna in the carbonate platform environment of this region was different and more evolved than in other regions of the world.
BEHAVIOUR OF THE ROVERETO DINOSAURS
The study of the ichnologic evidence is the main tool to gain knowledge of the behaviour of extinct animals.
SPEEDS AND GAITS - The tracks that allow the estimation of speeds at the Lavini di Marco are relatively few, only 35. The estimated (theoretical or predicted) walking speed for Rovereto forms (cfr Thulborn, 1990, p. 293ss) is about 3-4 km/hr for small bipeds (foot length<25 cm), 4-5 km/hr for larger bipeds (26 cm <foot length< 35 cm), 5-6 km/hr for graviportal plant-eaters with pedal prints ranging 36 to 52 cm, 5-6 km/hr for sauropods.
The real speeds, calculated from the tracks of Rovereto, are in most cases lower than these estimated walking speeds and are all less than 6 kph, with the single exception being ROLM59, a small ceratosaurid with a hind foot 13.5 cm long (10-12 kph). Calculated speeds for the relatively small ceratosaurids range from 7.5 to 11 kph; those for sauropods only 1.2-2.5 kph, the presumed ornithopods standing in the middle, with 1.4-2.2 kph. The speed of indeterminate bipeds, probably small to mid-size ornithopods, range 3.2-7.2 kph. High speeds, often used to support the theory of “warm-blooded” dinosaurs, were not found at the Lavini di Marco.
The manner of gait, estimated on the basis of the stride length/height at hip ratio (cfr Thulborn, 1990, p. 263-266), was almost always walking gait (SL/h = 0.45-1.75) but in ROLM59, which was fast trotting or almost running (SL/h = 2.7).
DIRECTIONS (Italian text-fig. 8.50) - Dinosaurs often followed preferential paths because of topographical constraints as lake or sea coasts. There are 116 tracks and single footprints useful for measuring trackmaker walking direction. The NNE quadrant presents 44% of all directions, the ESE one 17.2%, SSW 28.3%, WNW 10.3%. Therefore there is a preferential corridor along an axis NNE-SSW. The two main beds with footprints (105 and 106) present a different direction from this corridor, with a counter clockwise rotation of about 30°. In level 105 the axis was NNE-SSW, in the other level it was N-S. This trend is the same for each single taxonomical group (58 theropods, 14 sauropods, 18 indeterminate bipeds). The dinosaurs of the Lavini di Marco were not moving in packs or herds but their direction was landscape-controlled. A change of the coastline direction is hypothesized to explain the change of direction between level 105 and 106. This is in agreement with the indications provided by geochemical data (see next chapter).
STANCE - In no case is the mark of the tail is preserved, as is usual for dinosaur tracks. All the trackways are rather narrow, attesting a full erect stance. The presumed iguanodontids were nearly all bipedal and in few cases, semi-bipedal, which is different from the most accepted view of the prevailing quadrupedality of these dinosaurs.
SOCIAL BEHAVIOUR - Social behaviour of theropods and sauropods is testified in some ichnosites. In contrast, the 140 individuals investigated at the Lavini di Marco, do not show any social behaviour.
MIGRATIONS - What is the meaning of the preferential N or S directions of the Rovereto tracks? Until coeval facies on the Trento Platform that are different from tidal flats are discovered, the existence of connections between this platform and others placed south and north of it is demonstrated, or the evidence of wide emerged areas found, the hypothesis of individual migration cannot be considered. We think is most logical to admit that the dinosaurs of the Lavini di Marco lived in that place, moving when a route to other lands was disposable. Another explanation of the dinosaur presence on the tidal flat could be related to their reproductive behaviour.
THE DINOSAUR COMMUNITY
The paleoichnological record is generally biased toward the preservation of footprints of large animals. Small outcrops cannot preserve the footprints of all taxa living in the surrounding region. The site of Lavini di Marco is wide and the represented environment is quite uniform.
Plant-eaters and Predators
Predators are prevalent (57%) over the plant-eaters (43%), with these percentages respectively 33% and 67% at level 105 and 57% - 43% at level 106. This differs from the theoretical ecological model of a prevalence of plant-eaters and a small number of predators. The abundance of predator footprints against the plant-eater footprints could be caused by a different level of activity of their respective trackmakers and/or by the grouping of certain taxa in particular environments: theropods could have been more abundant around pools of fresh water. The prevalence of theropods is a characteristic of many tracksites.
Weights and sizes (Italian text-figs 8.48-8.49)
Ceratosaurids which produced footprints 12-15 cm long, could reach a total body length of two to three metres and a weight of 12 to 25 kg. The larger ceratosaurids of Rovereto, with footprints 25-35 cm long, probably had the general body appearance and size of Dilophosaurus Welles, 6 to 7 m long with a weight of 280-500 kgs; the largest (footprints length: 38 cm) could reach the size of Ceratosaurus Marsh (6 to 7 m long and weighting 600 to 1200 kgs). The smallest ceratosaurid with footprints 8 cm long (ROLM212-215) was 1.5 m long with a weight of about 4 kg; it is not possible to state if it was a juvenile or a small-sized adult. The largest ceratosaurid footprint (38 cm long) comes from a level at the top of the Membro Inferiore. Some tridactyl footprints 10 to 15 cm long (ROLM211), here reported as “indeterminate bipeds” but perhaps belonging to basal ornithischians or ancestors of Thyreophora like Scutellosaurus Colbert, indicate small, bipedal plant-eaters, 1.5 to perhaps 2 m long, weighting a few kilograms. It is possible that similar footprints but longer (up to 20 cm) could belong to ancestors of the hypsilophodontids. If the large (20 to 47 cm long) tridactyl footprints with rounded hooves (ROLM9, 30, 63 and 64) actually belong to advanced ornithopods, they could have been imprinted by a dinosaur with the size of Camptosaurus Marsh, 7 m long and weighting up to 700 kg, or Tenontosaurus Ostrom, 7 m long and weighting up to 800-900 kg. Hind footprints 30 to 50 cm long testifies to the presence of relatively small sauropods, 7 to 10 m long and weighting 1 to 3 tons.
Diets and metabolism (Italian text-fig. 8.53-55)
The diet of the Rovereto trackmakers is herein minutely discussed.
The large plant-eaters (> 1 ton) were almost certainly cold-blooded, like the living large mammals partly are. The average daily forage requirement (fresh forage) can be estimated as 3 kg for a cold-blooded sauropod weighting one ton, 6 kg for a two-ton sauropod and 9 kg for a three-ton one. The yearly need would be respectively 1095, 2190 and 3285 kg. The average daily forage requirement would have been respectively 21, 42 and 64 kg in the case of a warm-blooded sauropod, a requirement seven times higher. The yearly need would have been 7.665, 15.330 and 23.360 kg.
We cannot estimate the vegetal biomass per unit of surface needed for the dinosaurs at the Lavini di Marco. The needs were probably rather high, requiring relatively abundant vegetation, with a high yearly productivity. Cases of high biomass concentration per surface unit are known among living reptiles. For example, the biomass of the giant turtles of the Aldabra atoll reaches 46tons/square km. This animal biomass would daily consume about 720 kg of fresh vegetation per square kilometre. The atoll is nearly entirely covered by bush and presents mangrove along the lagoon coast. In the case of the Lavini di Marco a biomass of 46 tons per square kilometre would roughly correspond to about 30 sauropods per square kilometre. The surface is about a quarter of square kilometre at the outcrop and the sauropod tracks are about 15 (possibly not coeval).
Juveniles and adults (Italian text-fig. 8.43-44)
Most of the footprint lengths established fall into a narrow range. There is a large number of values between 16 and 25 cm for theropods (73%; 14% of the footprints is higher, 13% lower) (Italian text-fig. 8.44) and between 36 and 48 cm for the sauropods (75%; 17% of the footprints is higher, 8% lower) (Italian text-fig. 8.43). Theropod and sauropod footprint lengths have a gaussian distribution, the sauropod ones are skewed toward larger sizes.
Plant-eater and predator interaction
The tracks at the Lavini di Marco are, as a rule, linear straight and do not show mutual behaviours. The trackmakers were just passing through. Some tracks of large plant-eaters are associated to those of carnivorous dinosaurs, sometimes moving more or less in the same direction or crossing one another but without clear evidence of interaction. The only possible example of some interaction is that of ROLM209 (Italian text-fig. 8.26) and ROLM174 (both theropods), impressed on the expulsion rim of sauropod footprints (track ROLM75) when the sediment was still plastic: it is difficult to think that the predators were not aware of the sauropod.
THE MEGAICHNOSITE OF THE CALCARI GRIGI DI NORIGLIO
The Calcari Grigi di Noriglio Formation outcropping area is defined as a megatracksite (sensu Lockley, 1994, modified) composed by the single tracksites of the Lavini di Marco, Chizzola (Leonardi, this volume), Alti Lessini (Mietto e Roghi, 1994; Roghi, 1994; Avanzini, pers. comm.), Becco di Filadonna (Avanzini, 1998), Mt Pasubio (Avanzini, 1998). It outcrops in an area about 2000 km2 wide in the Adige Valley, Southern Trentino, Sette Comuni (Asiago) Plateau and Mts Lessini. Before Alpine orogeny this surface was obviously wider. The case of the “Calcari Grigi di Noriglio megatracksite” is that of a megatracksite where the fossil footprints are most informative because they are the only dinosaur evidence (Case 1, according to the Lockley’s classification of the vertebrate paleontologic sites; Lockley, 1994, pp. 93-94).
PALAEOENVIRONMENTAL AND PALAEOGEOGRAPHIC IMPLICATIONS
Fossil footprints can provide important support for other scientific disciplines, mainly for paleoecology (paleoenvironmental data) and paleogeography. The recent discoveries of abundant dinosaur footprints in the Triassic, Jurassic and Cretaceous carbonate platforms of Northern Italy and Istria changed the palaeoenvironmental and palaeogeographic hypotheses about this area, formerly based on geologic data only.
(((The depositional environment of the Lavini di Marco site was a tidal flat. The dinosaurs therefore could not live there during high tide, when currents destroyed footprints and other structures and wore away the conglobating sediments. During the slow withdrawal of the sea, wide surfaces covered by plastic materials emerged, which were suitable for faunal colonization, and was able to cast the feet of the animals. The abundance of footprints at different levels therefore indicates periodical regressions.))
The Trento Platform was without doubt a carbonate platform but large dinosaur associations could not live at the water line. Where would those large animals go during high tide? The huge plant-eaters would not be able to find a sufficient supply of food to survive on small islands. One of the following possible solutions must be considered:
a) the existence of a continental area very close to the Lavini di Marco, or at least a wide island, of which the Trento Platform was a fringe area;
b) the presence of abundant terrestrial vegetation in the topographically higher parts of the platform. There is little evidence of this, but even in strongly continental lithostratigraphic units, like for example the Cretaceous Oldman Formation of Canada, plants and pollens are rare;
c) the presence of a quantity of algae on the platform channels and basins to feed plant-eater dinosaurs (also in this case, no evidence).
The geographic affinity of the dinosaur fauna seems to be Gondwanian, and African in particular, especially due of the presence of early sauropods, whose oldest remains were found in Southern Africa and India.
LIASSIC TETRAPODS NOT FOUND AT THE LAVINI DI MARCO
Amphibians were rare during Early Jurassic; the only group which could be present in the Lavini di Marco is that of primitive frogs but this is unlikely because of the salty environment. The Lower Jurassic is also comparatively poor in reptiles. However, at the Lavini di Marco we found the footprints of the last primitive diapsids, of sphenodontids and of kuehnosaurids but substrate conditions were not the best for the preservation of the footprints of such small animals. The absence of footprints of small primitive crocodiles, mainly protosuchids, is astonishing but it could be due to the particular environment. Among dinosaurs, scelidosaurs and, above all, prosauropods are absent. Actually we cannot completely exclude that some poorly preserved footprints identified as sauropodian could be prosauropodian. Besides, we cannot exclude that ROLM192, identified as ornithopodian, is actually prosauropodian. The relatively small footprints of the tritylodont and tritelodont synapsids could be present but they have not been found up to now. The total absence of evidence of primitive mammals is surprising; perhaps they were too small and/or preferred dryer and higher environments.
Anyway, dinosaurs seem to occupy all the ecological niches at the Lavini di Marco as in many other regions of the world, leaving no room to other tetrapods.
9
Marco AVANZINI, Silvia FRISIA and Matteo RINALDO
THE LAVINI DI MARCO DURING THE EARLY LIASSIC; RECONSTRUCTION OF AN ANCIENT BIOENVIRONMENT
The tidal flat where the Calcari Grigi deposited at the Triassic-Jurassic transition was located in the tropical belt, characterized by high temperatures without wide thermal ranges. Early dolomitization is indicative of a relatively arid climate and this suggests very arid conditions during the previous deposition of the Late Triassic Dolomia Principale.
The central part of the Membro Inferiore is characterized by the presence of inter-supratidal environments with fossilized cianobacterial mats (stromatolites); this interval is only 20 m thick at Mt Zugna and some of these stromatolitic levels were printed by dinosaurs. Sedimentologic, ichnologic and geochemical characteristics of the tracksite can be studied laterally and vertically.
Six rocky layers with footprints have been found up to now. They are located in a section about 5 m thick and correspond to the stratigraphic levels 101, 104, 105, 106, 115 and 120 (Italian text-fig. XX). Each single level can be traced over an area of a hundred of metres.
CALCAREOUS AND DOLOMITIC LEVELS
The levels 104A, 105 and 106 partim are calcareous and made by stromatolites and mud with bioclasts (ostracodes, small bivalves, calcareous algae, etc.). Abundant iron oxides concentrated into veins, laminae or globular bodies, fragments of red carbonated mud, small holes filled by silt and spatic calcite and particular chemical transformations are indicative of subaerial exposure of these levels.
Level 104A: level 104 is a subtidal layer with a mean thickness of 70 cm but very variable because of its rough upper surface which is distinguished as 104A. The depressions present in this upper part of the layer were filled by laminate mud covered by a crust of dolomite, calcite, clay and iron oxide. The topographic characteristics of level 104 are reminiscent of the lateral microkarstification of today’s tropical islands.
Level 105: it is an alternance of stromatolitic bands, peloidal grey muds and reddish muds, its thickness ranges from 15 mm to 100 mm. Its upper part presents mud-cracking, showing polygons with a diameter of 10-30 up to 50 mm. The reddish horizons probably formed in the topographically higher parts. Where the mud-cracks are larger, along the “colatoio of the ornithopods” this level is comparable to a paleosoil. Footprints of small theropods are common where level 105 is thinner. Footprints of large animals deformed the stromatolitic levels, have fragments of reddish paleosoils sticking into them.
The dolomitized levels show structures of dissolution and dedolomitization which testifies the influence of fresh waters. Dolomitization stops abruptly at contact with the overhanging layer, extending bottomwards along fractures caused by drying and dinoturbation. Probably dolomitization here was caused by dolomite sovrassature fluids due to rapid evaporation of marine water inundating the tidal flat. Dolomitized levels with footprints are 101, 106 partim and 115.
Level 106: it is the richest in dinosaur footprints, it is 100 to 150 mm thick and presents a high lateral variability of the facies. Stromatolites and flat pebbles breccias are common. Footprints are deep north of the “colatoio Chemini” and cut this level and part of level 105; in some cases at the base of the colatoio they reach level 104.
GEOCHEMICAL DATA
The high value of Na in some levels suggests the presence of ipersaline fluids during the diagenesis, low values of Sr at the top of level 104 could be related to fresh water influx.
Analysis of the isotopes points out a diagenesis of marine kind for both the calcareous and dolomitic levels. There is little geochemical evidence of the presence of soils with vegetation. Anyway sedimentologic structures and isotopic data indicate that fresh water played a role in the diagenesis of the layers with footprints.
RECONSTRUCTION IN TIME AND SPACE OF THE PALEOENVIRONMENT OF THE LAVINI DI MARCO
“Time” 104: emersion and karstification of the tidal flat occurred. However, diagenesis was mainly influenced by marine water. The red crust at the top, dissolution phenomena and values of the ratios of oxygen isotopes found in the calcite cements, indicate that the dinosaurs walked on a surface where the presence of fresh water was not sufficient to influence the diagenesis. After a period of some thousands of years, during which the level emerged, sedimentation began again with stromatolitic laminae marking the rising of the sea level.
“Time” 105: this level shows a vertical alternance of several emersions and drownings with strong environmental changes in a few centimetres of geological record. The events were:
a) formation of thin paleosoils, in association with early cementation,
b) microkarstification caused by fresh water,
c) mud deposition, perhaps by storms,
d) imbibition of this mud and deformation caused by dinosaur printing,
e) oxidation and drying of the dinoturbated surface,
f) cementation of the surface.
The influence of both marine and fresh waters are testified respectively by the presence of the marine alga Thaumatoporella and the values of the isotopic ratios, and by the absence of typical marine organisms (foraminifers, brachiopods, etc.) and microtextures. Diagenetic and sedimentologic features seem to indicate a prevalence of emersion and a coastline possibly far away. Comparison with present carbonate platforms in tropical humid climate shows that the lenses of fresh waters were ephemeral, climate was semiarid and vegetation scarce when level 105 formed.
“Time” 106: level 106 was less exposed to subaerial alteration [weathering]. In the northern outcropping area it represents sedimentation in a wide brackish pond. The southern area was less wet, characterized by a series of emerged bars with shallow pools intercalated, and was probably topographically slightly higher. The presence of black pebbles, usually considered the consequence of plant burning, would suggest the presence of vegetation.
The dinosaur footprints were printed in two different paleoenvironments in a palaeogeographic contest of a tidal flat placed at the margins of a continent. The calcareous levels are characterized by the alternation of subaerial exposures and the development of ephemeral lenses of fresh or brackish waters. The dolomitic levels correspond to marine transgressions and a higher influence of salty waters.
Plant remains (thin lignite beds, root fragments) are scarce but present in the Membro Inferiore. Besides sedimentologic evidence of pedogenesis are often found on the surfaces bearing the dinosaur footprints. This means that plants were present in the semiarid environment of the Lavini di Marco.
THE MECHANISMS OF PRESERVATION OF THE FOOTPRINTS
The main factor influencing the preservation of the footprints is the nature of the printed sediments. The preservation on the top surface of level 106 was probably caused by two main events: hardening of the substrate due to long subaerial exposition and subsequent covering by mud due to the transgression which deposited the level 107. The substrate deformed by the footprints in the “colatoio Chemini” was a “sandwich” of plastic, semilithified sediments, elastic cianobacterial laminae and semiliquid muds from levels 105 and 106. The mechanical features of the cianobacterial mat avoided the mud to fill the print after foot withdrawal. Marine water soon soaked the deformed sediment; this favoured its early cementation and the preservation of the footprints.
THE CONTRIBUTION OF SEDIMENTOLOGY TO THE STUDY OF THE DINOSAUR FOOTPRINTS AT THE LAVINI DI MARCO
Thanks to the sedimentologic study it was possible to identify some reference levels outcropping over wide areas of the Lavini di Marco and to recognize the sequence of the levels with footprints. Sedimentologic features permitted the reconstruction the sequence in which the dinosaurs traversed some parts of the site and the sedimentologic analysis shows that it is very difficult to state on which surface the animals actually walked, since underprints are formed into many other surfaces. Sometimes it is possible to recognize the space and temporal association of two prints, as is the case of the sauropod track ROLM75 which preserves the print of a theropod on the expulsion rim of a footprint. The tracks disappear when they reach dry areas like those where mud-cracks are found. A footprint left in very fluid mud has more chance of being preserved, and more so, as an underprint in the underlying more cohesive layer, because of the collapse of the fluid mud and the infilling of the depression. In the case of quadrupedal tracks at some outcropping places of level 106 (e.g. ROLM1 and ROLM2), the manual prints were much shallower than pedal prints and left a shallow or no underprint at all. The erosion of the original printed surface led to the preservation of apparently semi-bipedal tracks which in turn caused the wrong preliminary identification of the trackmaker. Cianobacterial mats are more suitable for the good preservation of true prints because of their mechanical properties. The slippery nature of the surface was probably responsible of the slow gait of the trackmakers, the different lengths of consecutive paces and the dragging marks.
PART III - TETRAPOD PALEONTOLOGY OF ITALY AND NEIGHBOURING COUNTRIES
10
Giuseppe LEONARDI
THE DINOSAURS OF ITALY AND NEIGHBOURING COUNTRIES
INTRODUCTION
Ten years ago Italy was considered a country almost without dinosaur evidence. This view of things changed after the publication of a paper by Mietto (1988) regarding Triassic dinosaurian tracks in the Dolomites and, above all, after the discovery of the Lavini di Marco site. Even if Italy is not very rich in dinosaur evidence, about a dozen of tracksites and two sites with bones have been found.
ITALIAN DINOSAURS
THE DINOSAURS OF THE LAVINI DI MARCO
They are considered here in chapter 8. They were numerous, diversified and sometimes large-sized. In order of decreasing frequency, there were ceratosaurian theropods, sauropods (Vulcanodontidae or primitive Cetiosauridae), advanced ornithopods and primitive ornithopods. Those of Lavini di Marco are the most abundant ichnologic sample in Italy.
CARNIAN (UPPER TRIASSIC) DINOSAURS
Mts Pisani (Agnano, Pisa; codex: AGPM = Agnano-Monti Pisani)
The most ancient dinosaur of Italy is represented by a single, small (6-7 cm long) tridactyl footprint described as Coelurosaurichnus toscanus by Friederich von Huene (1941). The specimen comes from the Quarziti Viola Zonate at the top of the Quarziti di Monte Serra, clastic sediments of deltaic plain of Late Carnian age. Leonardi & Lockley (1995) showed that this footprint is attributable to Grallator.
Lerici (La Spezia)
Here a rather rich footprint association is preserved (see chapter 11). Dinosaurs are represented by some footprints and short tracks attributable to Grallator and/or Anomoepus or Pseudotetrasauropus. The footprints are in the upper part of the Formazione di Montemarcello (Middle Carnian or Norian).
UPPERMOST CARNIAN AND NORIAN (UPPER TRIASSIC) DINOSAURS
Mt Pelmetto (Dolomiti, Belluno; codex: ZAMP = Zoldo Alto-Monte Pelmetto)
The dinosaur footprints in this site are preserved mainly on the surface of a large boulder fallen from the overhanging rocky wall. The original position was at the base of the Dolomia Principale, near the passage to the Formazione di Raibl (Upper Carnian). Three tracks were attributed to small theropods (footprint length = 6-7 cm), another track to a small-size (footprint length = 10-12 cm) primitive ornithischian; a track left by a larger (footprint diameter = about 15 cm) and semibipedal trackmaker was identified as possibly prosauropodian (Mietto, 1988). Many single tridactyl footprints were found on other blocks (P. Mietto, pers. comm).
Tre Cime di Lavaredo (Dolomiti, Belluno; codex: AUTC = Auronzo-Tre Cime)
Here there is a boulder from the Dolomia Principale with a short track (two tridactyl footprints 30 cm long) attributed to Eubrontes (Mietto, 1992).
Puez (Altopiano del Puez, Selva Val Gardena, Bolzano; codex SEPU=Selva Val Gardena-Puez)
In this site there is a probable mid-size tridactyl footprint on a bed surface of the Dolomia Principale (Leonardi & Avanzini, 1994).
Cellina Valley (Pordenone)
Two large tridactyl footprints have been found near Casera Cjasevent. At least another seven boulders with dinosaur footprints are present in the surrounding region (Dalla Vecchia & Mietto, 1998). They all come from the Dolomia Principale.
Other localities
Paolo Mietto has discovered many Carnian and Norian sites in the Eastern Dolomites, mainly with poorly preserved footprints.
JURASSIC DINOSAURS
Chizzola (Ala, Trento; codex ALCH=Ala-Chizzola)
About 3 km before of the site of the Lavini di Marco and belonging to the Calcari Grigi, a large (length = 33 cm) footprint classified here as Eubrontes, and other two tridactyl footprints were found in 1994. They were destroyed by public works in recent times.
Northern Mts Lessini (= Alti Lessini) (Verona, codex VRBL=Verona-Bella Lasta)
Mietto & Roghi (1994) and Roghi (1994) reported the presence of two levels with tridactyl footprints in the “Bella Lasta” area of Mts Lessini. The best preserved footprint, 30 cm long, was attributed to a large ornithopod. This site is more recent than that of the Lavini di Marco, and belongs to the mid-upper part of the Calcari Grigi (Pliensbachian).
Becco di Filadonna (Trento)
Some tens of dinosaur footprints (large tridactyl footprints and a sauropod pair) have been found in this locality near Trento (Avanzini, 1998). The site is slightly younger (base of the Membro Medio of the Calcari Grigi, late Sinemurian) than that of the Lavini di Marco.
Other localities
Marco Avanzini has discovered new dinosaur footprints in the Calcari Grigi of Mt Pasubio and Mts Lessini.
CRETACEOUS DINOSAURS
Porto Corsini (Ravenna)
(Lower Cretaceous - Upper Hauterivian/Lower Barremian)
A large (36 cm long) theropod footprint and a sauropod manual print were found in a limestone boulder at the pier of Porto Corsini (Dalla Vecchia & Venturini, 1995; Dalla Vecchia, 1998). The boulder was quarried at the base of the Cansiglio Plateau (Carnic Pre-alps, Pordenone) in the Calcare di Cellina Formation.
Mt Bernadia (Nimis, Udine)
(Lower Cretaceous - Aptian)
Possible cross-sections of dinosaur footprints are exposed in this site (Venturini, 1995; Dalla Vecchia & Venturini, 1995).
Pietraroia (Benevento)
(Lower Cretaceous - Aptian, Albian)
A nearly complete (the tail is mostly lacking as are the distal hind limbs), articulated skeleton of a very small dinosaur was found at this site and was described and identified by Leonardi & Teruzzi (1994) as a juvenile theropod belonging to the Maniraptora clade. The most striking feature is the preservation of some soft parts such as muscle fibres, the intestine and possibly the liver. For this specimen the taxon Scipionyx samniticus was later instituted, and it was described in detail by C. Dal Sasso and M. Signore in Nature, March 1998.
Villaggio del Pescatore (Duino, Trieste)
(Upper Cretaceous - Senonian)
This site preserves bone remains belonging to Hadrosauria, distributed at different levels (Dalla Vecchia, pers. comm.).
NEIGHBOURING COUNTRIES
SWITZERLAND
More than 800 footprints are preserved in the Ladinian-Carnian at Vieux Emosson, Vallese Canton. Brachychirotherium Beurlen, Isochirotherium and dinosauroid footprints are present. The very badly preserved dinosauroid footprints are perhaps tridactyl, tetradactyl and pentadactyl, testifying to the high diversity of the ichnofauna.
Thirteen tracks are exposed in the Grigioni National Park of Engandina along the western flank of the Piz dal Diavel (Furrer, 1984). The footprints, mainly large tridactyl and dinosauroid, are preserved in the Norian Diavel Formation. A long track with large tetradactyl footprints was attributed to prosauropods.
ISTRIA (CROATIA) AND SLOVENIA
Sauropod bones have recently been discovered in the Upper Hauterivian-Lower Barremian limestones of Southern Istria (Dalla Vecchia, 1994b). Dinosaur footprints are common in the Cretaceous of Istria. Large theropod footprints of Late Barremian age are exposed along the shore of the Main Brioni Island, Southern Istria. Albian tridactyl footprints most of which belong to mid-sized theropods have been found in two sites of the Main Brioni Island and other three sites along the coast of the peninsula (Dalla Vecchia & Tarlao, 1995; Dalla Vecchia et al., 1993). In the Fenoliga Islet (Southern Istria) a long track attributed to a sauropod (Leghissa & Leonardi, 1990) is preserved, together with theropod tracks, on an Upper Cenomanian limestone bed (Gogala, 1975; Gogala & Pavlovec, 1978; Pavlovec & Gogala, 1992).
A track left by a large reptile, probably a dinosaur, preserved in Norian-Rhetian dolostones, is reported from the environs of Idrija, Slovenia (Dalla Vecchia, 1997).
PALEOGEOGRAPHICAL AND PALEOENVIRONMENTAL CONSIDERATIONS
The discoveries of abundant dinosaur evidence in the examined region put up for discussion the previous paleogeographical and paleoenvironmental reconstructions, which pointed to a generalized presence of shallow marine environments. In fact, the dinosaur faunas needed sufficiently wide emerged areas, covered by vegetation and with fresh water, for their survival.
11
M. A. CONTI, Giuseppe LEONARDI, Paolo MIETTO and Umberto NICOSIA
FOOTPRINTS OF NON-DINOSAURIAN TETRAPODS IN THE PALEOZOIC AND MESOZOIC OF ITALY
Researches carried on during the last 30 years have shown that tetrapod footprints are relatively common in the Upper Paleozoic and Triassic rocks of Sardinia and Northern Italy. In this contribution they are grouped following a chronological order.
CARBONIFEROUS ICHNOFAUNAS
Footprints attributed to small microsaur amphibians (Salichnium heringi (Geinitz)) were found in the Upper Carboniferous of Sardinia. Two footprints attributed to Limnopus sp. and Hylopus cf. H. hardingi Dawson come from the Upper Carboniferous of Carnia (NE Italy).
LOWER PERMIAN ICHNOFAUNAS
The Lower Permian ichnological record comes from the Collio Formation of Eastern Lombardy (Val Trompia and Orobian basin) and Western Trentino (Tregiovo). This ichnofauna is revised here and is composed of: Antichnium salamandroides, Camunipes cassinisi, Dromopus lacertoides, D. didactylus, Amphisauropus latus, Ichniotherium cottae, Anhomoichnium orobicum, and an unidentified amphibian and lacertoid ichnotaxon. They belong to two small amphibian taxa, a relatively large plant-eating reptile and six small reptilian taxa. Temnospondylian amphibians, Captorhinida, Araeoscelida, Lepidosauromorpha, Pelicosauria and perhaps Diadectidae are represented.
UPPER PERMIAN ICHNOFAUNAS
A peculiar and very important ichnofauna is that of the Val Gardena Sandstone of NE Italy, dated to 255-265 m.y.a (Changxingian-Djulfian). Footprints have been found mainly in the provinces of Bolzano/Bozen and Trento but specimens also come from the environs of Recoaro (Vicenza) and Carnia (Udine). A revised list of the ichnotaxa and their supposed makers is given in Italian text-fig. 11.12. All footprints belong to reptiles: large plant-eaters such as pareiasaurs (Pachypes dolomiticus), mid-sized plant-eaters like pelicosaurian caseids, large predators like the gorgonopsians and possibly also primitive “thecodonts” (the oldest chirotheroid footprints) and small predators like the primitive cynodonts (Dicynodontipus). Small lacertoid reptiles of uncertain diet are represented by Hyloidichnus tirolensis, Paradoxichnium, Rhynchosauroides (very common), Janusichnium and footprints attributed to Procolophonomorpha.
TRIASSIC ICHNOFAUNAS
LOWER TRIASSIC - Footprints were found in the Werfen Formation of Dolomites, Recoaro area (Vicenza) and Carnia (Udine). Most of them are identifiable as Rhynchosauroides.
LOWER ANISIAN - Rhynchosauroides and Parasynaptichnium gracilis were found in the Gracilis Formation of Recoaro area (Vicenza). Rhynchosauroides is also present in the Conglomerato di Voltago of Valsugana (Trento).
UPPER ANISIAN - The Conglomerato di Richtofen of the Pusteria Valley, Upper Adige Valley, Western Dolomites (Alto Adige) and Eastern Dolomites and the equivalent Conglomerato del Tretto of Recoaro area yielded Rhynchosauroides tirolicus, Chirotheriun cf. rex, Brachychirotherium aff. B. parvum, Synaptichnium sp. and Rotodactylus sp.
UPPER TRIASSIC - Vertebrate footprints are reported from many sites in Northern Italy. Dinosaur footprints and the sites with dinosaur footprints are described in chapter 10.
A rich ichnofauna was found at Mt. Pisano (Pisa and Lucca). It is composed of footprints of a presumed urodelian amphibian and rhynchosauroid and chirotherian footprints; at present it is under revision. The specimens come from the Quarziti Viola Zonate at the top of the Quarziti di Monte Serra, clastic deltaic plain sediments of Early Carnian age.
Archosaurian tracks were found recently in the Upper Carnian marl-dolostone alternations of Dogna valley (Valcanale, Udine province) (Dalla Vecchia, 1996).
A site in the environs of Lerici (La Spezia) is under study. There are two bipedal, tridactyl or tetradactyl dinosaur ichnotaxa, tridactyl footprints with a very developed central digit and stout nails, large Brachychirotherium Beurlen, a smaller chirotheroid taxon, some large footprints with a vaguely chirotherian aspect left by a quadrupedal animal, and many mid-sized footprints of uncertain attribution. The clastic levels with footprints belong to the upper part of the Montemarcello Formation (possibly Middle Carnian or Norian).
A chirotheriod footprint was found in the Upper Carnian site of M. Pelmetto (see chapter 10). “Thecodont”, poorly preserved footprints are found in the Late Carnian Dolomia di Dürrestein of Dolomites.
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12
Fabio Marco DALLA VECCHIA
BONE REMAINS OF PALEOZOIC AND MESOZOIC TETRAPODS IN ITALY
Italy is usually considered a country poor in bone remains of Paleozoic and Mesozoic terrestrial tetrapods. However, the Italian tetrapod record (including truly terrestrial, fresh water, coastal and flying tetrapods) is noteworthy, even if bone remains are not very common. From a systematic point of view most of the main Linnean groups are represented.
Temnospondylian amphibians (Metoposaurus H.v. Meyer) are known from the Ladinian and Carnian of Alto Adige/Süd Tirol; Urodela (Celtedens megacephalum (Costa)) from the Albian of Southern Italy (Pietraroia, Benevento).
Reptilia are much more common.
Remains of non-marine Chelonia are present in the Upper Cretaceous of the Italian Karst (Carso) and Puglia region.
Drepanosaurus unguicaudatus Pinna is a Diapsida incertae sedis from the middle Norian of Lombardy. Sphenodonta were found in the Norian of Lombardy and, with some doubt, in the Albian of Southern Italy (Chometokadmon fitzingeri Costa; Pietraroia, Benevento). In the same localities and formations Squamata (Vallesaurus cenensis Wild, Norian; Costasaurus rusconi (Costa), Albian) were also found.
Protorosauria (Prolacertiformes) are well represented mainly in the Anisian/Ladinian of Lombardy and near Tessin with Tanystropheus longobardicus (Bassani) and Macrocnemus bassanii Nopcsa. Bones belonging to Tanystropheus were also found in the uppermost Ladinian and Upper Norian (T. fossai Wild) of Lombardy, and in the Carnian of Friuli (NE Italy). Langobardisaurus Renesto is present in the middle Norian (Alaun) of Friuli and Lombardy.
Megalancosaurus preonensis Calzavara et al. is a small, strange “thecodont” of uncertain taxonomic position from the middle Norian of Friuli and Lombardy.
The predator rauisuchian Ticinosuchus ferox Krebs is present in the Anisian/Ladinian of Lombardy and near Tessin, and possible dorsal scutes of rauisuchians are present in the Carnian of Alto Adige/Süd Tirol. The plant-eatinf aetosaurs are represented by remains of Aetosaurus ferratus Fraas found in the middle Norian of Lombardy. The crocodile-like phytosaurs are testified to mainly by a complete skull and lower jaw of Mystriosuchus planirostris (H.v.Meyer) from the middle Norian of Lombardy.
Rare is the evidence of non-marine crocodiles: remains of small individuals were found in the Albian of Southern Italy (Pietraroia, Benevento) and in the Senonian of Italian Karst (Duino, Trieste).
Pterosaurs are perhaps the most interesting mesozoic reptiles of Italy. The oldest pterosaurs found up to now in the World come from the Middle Norian of Friuli and Lombardy (Preondactylus buffarinii Wild, Peteinosaurus zambellii Wild, Eudimorphodon ranzii Zambelli and E. rosenfeldi Dalla Vecchia). Dinosaurs, found in the Cretaceous of Campania (Pietraroia, Benevento) and Venezia Giulia (Duino, Trieste), are described elsewhere in this book.
Therapsids could be represented by a jaw with tricuspidate teeth from the Carnian of Dolomites, which could alternatively belong to an immature prolacertiform.
Coastal reptiles, i.e. animals not very well adapted to aquatic life, are rather common mainly in the Triassic.
Nothosauria and Placodontia bones and skeletons are abundant in the Middle Triassic (mainly in Lombardy but also in Veneto and Friuli regions), and Carnian (Alto Adige/Süd Tirol and Friuli). Placodontia are also present in the Norian and Rhetian of Lombardy.
Thalattosauria is a particularly diversified group in the Anisian/Ladinian of Lombardy and near Tessin. Endennasaurus acutirostris Renesto was found in the Middle Norian of Lombardy.
Finally, remains probably belonging to a coastal varanoid was reported from the Upper Cretaceous of Puglia.
PART IV - OTHER CONTRIBUTIONS
13
Giuseppe OROMBELLI and Ugo SAURO (with the contribution of F. FERRARESE)
GEOMORPHOLOGICAL ASPECTS OF THE LANDSLIDES OF MT ZUGNA
The Mt Zugna is a N-S, approximately 10 km long ridge made up of a homoclinalic block with a 20° average slope of the strata (which is about the same immersion of the slope) and a W and NW dip.
The main landslide called “i Lavini”, is composed of a wide scar on the flank of the mountain and a broad accumulation at the base of the slope and in the Adige valley below. The whole landslide complex of Mt Zugna is not a unique body but is formed by different landslide accumulations. There are another seven lesser landslides: two landslides at Corna Calda, the landslide of Doss delle Gardene, a landslide at an altitude of 772 m SSE of the Damiano Chiesa cave, the Marco landslide, the Varini landslide and the landslide ok km 346 along State road n.12. Here is some data on the main landslide: length of the fallen part = 5200 m , width of the same =2300 m, thickness = less than 100 m, mean probably less than 20-30 m, total length = 5600 m, maximum difference in height = 1150 m (from 1320 to 170 m a.s.l.). The use of software such as the Geographical Information System (G.I.S.) permitted the estimation of the volume of the landslide accumulations down in the valley (excluding those accumulated on the flanks) of the Lavini, Pinera, Marco and Varini as being about 41.000.000 m3. They extend over a surface of 3.78 km2, with a mean thickness of 10.95 m. The area of depletion for the main (Lavini) accumulation body is about 1.80 km2, with a mean accumulation thickness of 17.5 m.
The accumulation of the main body covers the alluvioni and the terraces of the Adige river therefore the landslide is a postglacial event. The minor landslide of Varini covers soil dated by 14C to 1300 ±100 B.P. (580-895 a.d. following the calibration of Klein et al., 1982). Soil below the landslide of altitude 772 m was dated 5630±80 B.P. The blocks of the main accumulation on the valley bottom shows only embrional corrosion microstructures and degradation of the niche surface is poorly developed (similar to the Varini landslide), both pointing to the recent age of the landslide. The conclusion is that all these landslides are very recent, with an age ranging between 1000 and 2000 years ago, probably between 800 a.d and 1117 a.d.. Only the landslide of altitude 772 m and the southern Corna Calda landslide are older.
Most of the landslides of Mt Zugna can be classified as block rockslides, some of which evolved in debris flow or debris avalanches. The difference in height ranges 300 to 1200 m and the distances passed across are between several tens of metres and 6 km.
The main landslide originated due to the detaching of a set of strata in the upper part of the niche, the thrust of which caused the removal of the corresponding strata downslope. This body began to move as a block, afterwards disintegrating progressively into slabs and boulders and then into finer material. The Costa Stenda ridge divided the body into two parts, the lesser directed to the west forming the lobe of Marco, the large to NW to form the main accumulation of “i Lavini”. The main body slowed down in the funnel-shaped depression delimited by Costa Stenda ridge and Costa Violina ridge (fault of the Vallone and of Lizzana). This bottleneck caused overbanking, the overcoming of the obstacle of Costa Stenda, with the removal of the top of the relief. This removed part broke into large blocks which now constitute the spectacular chaotic accumulation of the “Ruina” of Pinera, just north of Marco. The main body went beyond the depression and expanded at the base of the mountain over the Adige valley bed, stopping nearly two kilometres from the base of the slope.
A sismical shake is considered the most probable cause of these landslides.
14
Marco AVANZINI and Dario ZAMPIERI
THE LAVINI DI MARCO: GEOLOGIC-STRUCTURAL ASPECTS
Between 165 and 130 million years ago the Adriatic (or Apulian) passive continental margin where the Trento Platform was located, saw the opening of the relatively small Ligurian Ocean, separating Laurasia and Africa. The plate movement, initially divergent, at a certain point became convergent, with an abrupt acceleration 85 m.y.a. About 60 m.y.a the convergent movement led. to the closing and disappearance of the ocean with the deformation of the relative sediments against the European continental margin. The collision between European and African Plates caused the rising of the Alpine mountain chain, mainly during the Neogene. The section of Southern Alps including the Trento Platform was characterized by strong crustal shortening, with overthrustings of scales of marine carbonates which forms the present orography of the zone.
The Southern Alps are that part of the Alpine chain placed south of the Insubric Line, running W to E from the Bergamasc Alps to the Pusteria Valley. They are formed by overthrusts directed S-SE.
During Mesozoic times the future Southern Alps were part of the margin of the Tethysian Gulf separating the Gondwana from Laurasia. During the Late Jurassic the region rifted. The rifting structures strongly influenced the successive tectonical evolution of Southern Alps. The Lavini di Marco are placed at the margin of a distensive belt produced by the Jurassic rifting, which separated the Lombardian Basin and the Trento Platform. The progressive drowning of the Platform caused by the rifting advanced from W to E.
Southern Trentino is now characterized by large folds and overthrusts oriented N-NE, known as the “structural system of the Giudicarie”. It represents the reactivation of the W dipping Jurassic distensive faults which created the margin between Lombardian Basin and the Trento Platform. Structural systems with different directions of compression (E-NE, E-W; N-NE; NW-SE) overlap in the area. The Lavini di Marco are placed in the peripheral zone of deformation of the Giudicarie system.
The Mt Zugna-Zugna Torta is a homoclinal structure, therefore a block with stratification dipping always in the same direction. The average dip of strata on the W flank where the landslide developed is the same as the average sloping of the topographical surface.
The flanks of the niche of the main landslide is delimited by two slopes (ridges) which are set in correspondence to two subvertical transcurrent faults (Vallone fault and Lizzana fault) which converge into a single structure near the Damiano Chiesa cave. There are three hinges (homoclinal folds) and are parallel to the vertical ridge of the eastern flank of the niche. They are therefore spatially and genetically associated to the Vallone Fault. They are characterized by a single bed surface with a deeply sloping (up to 60°) tract, which connects the upslope, and downslope with tracts dipping like the slope inside the niche (20-25°). They were caused by the left transpression of the fault; they are the superficial result of a somewhat asymmetrical flower-like structure where the thrust faults created by the transpression do not reach the surface.
The calcite veins found inside the niche are oriented NNW and WNW (with the data reported to the original horizontal position of the strata). These two directions represent the directions of maximum horizontal compressive stress.
The deformation structures in the Lavini di Marco rocks are of two types: those produced before the landslide event (the homocline of the mount, the faults, flexures and the system of veins) and those caused by it ( superficial folds, tensional flexures) or after it.
15
Oscar GROAZ and Luigi VERONESE
HISTORICAL AND INSTRUMENTAL SEISMICITY IN THE LAGARINA VALLEY
The Lagarina Valley does not present the high seismicity of the neighbouring Lake Garda region and the Belluno-Friuli area. According to historical records, the big medieval earthquakes (1117, 1222, 1348) caused damage in this area, as well as in many other areas of northern Italy. Other historical records concern the earthquakes of 1868, 1888 and 1895. Probably the estimated intensity was never higher than the grade 7 of the Mercalli Scale, as the descriptions suggest. The instrumental data are in agreement with this pattern. The main events were on 1968 (6 grade of the M. S.), 1983 and 1989 (6-7 grade of the M. S.).
16
Paolo ARZARELLO, Franco FINOTTI, Giorgio GALEAZZO, Michele LANZINGER, Maurizio MEZZANOTTE and Luigi VERONESE
THE PARK OF THE ROVERETO DINOSAUR TRACK: PRESERVATION, EXPLOITATION AND TRANSFORMATION INTO AN OPEN-AIR MUSEUM
A modern Museum is no longer only the place where material is stored and exhibited but is an instrument for the divulgation and communication of knowledge. This “global” Museum promotes interaction between the users (the citizens) and the territory. Our aim is the realization of an open-air museum at the dinosaur site of the Lavini di Marco.
VIBROMETRIC PROSPECTING
In May 1992 vibrometric investigations were made to estimate the damage that artificial explosions could cause to the footprints. In fact, two places where military bomb-disposal experts blast war surplus are situated in the Lavini area. The results tell us that the risk of alteration of the layers with the footprints is very limited.
FOTOGRAMMETRIC SURVEYING
A fotogrammetric survey was made in order to have a precise and objective map of the layers with the footprints. The geometric survey concerned nine tracks considered to be the most important by the Management of the Civic Museum of Rovereto: ROLM 63, 64, 75 on 1993, ROLM 1, 2, 9, 11, 12, 26 on 1994.
CASTING OF THE FOOTPRINTS
Casts were made of the most important tracks and footprints to prevent the loss of data and source evidence due to the rapid weathering of the limestone. Six tracks were cast: ROLM9, 11, 12, 63. 64, 75. Some parts of the footprints where consolidated with low-concentration Paraloid@ and the surfaces were covered with Trecon Ag@ to better detach the silicon rubber cast. Several layers of the silicon rubber Trecosil 755@ were spread by a brush. This rubber hardens in about 12 hours at a temperature of 15°celsius. A countercast was made with fibreglass and polyester. A mould was realized from the cast using polyester resin added with calcium carbonate and reinforced with mat.
THE PALEONTOLOGICAL TREK OF THE DINOSAURIAN TRACKS
The paleontological importance of the site has as a consequence aroused the interest of many persons. Therefore the problem arose of how to allow scientists, students, tourists, etc to visit the site while satisfying the necessity of protecting the surrounding landscape.
A track was prepared with tables placed at the most meaningful stops to explain the dinosaur tracks and their probable makers to the uninformed tourist. This track allows the tracks along the colatoi without to be seen without trampling on them. It begins at the colatoio Chemini where tracks can be seen in two different areas from elevated stopping places. One side of the colatoio is protected by a low fence. The colatoio was drained to avoid damage caused by flooding. The track also reaches the zone of the “hinge” up along the flank of the mountain. Then it circles around and ends at the starting point.
This route will be improved with regards scientific information by the setting up of explanatory panels.
17 The Lavini di Marco site: an overview
Marco Avanzini, Giuseppe Leonardi, Daniele Masetti and Paolo Mietto
Up until 10 years ago the only evidence of the presence of dinosaurs in Italy was represented by a single footprint of a small predator from the Carnian (Late Triassic) (Carnian terrains), at Monti Pisani.
This apparent total lack of dinosaur fossils was explained by the fact that during the Mesozoic the Italian paleography was dominated by a prevalence of areas submerged by the sea.
In recent years it has been possible to completely refute this prejudice and today we know that the presence of dinosaurs in Italy is documented from the beginning of their evolutionary history to the end. Numerous sites, have been discovered in Trentino, Veneto and Friuli, and also in various Apennine areas in Liguria, Tuscany, Campania and in Puglia’s Murge range, as well as close to Italy’s borders within other countries.
This evidence is mainly limited to tracks, but also includes bone remains and has led to a profound and critical revision of the paleogeographic reconstruction of our country during the Mesozoic especially with regards to the large animal associations represented by the tracks such as those at the Lavini di Marco.
The phenomenon is not restricted to dinosaurs: the presence of tracks of continental vertebrates are documented in many parts of Italy from the upper Palaeozoic to the end of the Mesozoic. Today we have a mass of data available that allows us to document the presence of amphibian but mainly reptile fauna, in the continental environments of the Permo- Carboniferous, in innumerable continental layers that interrupt the continuity of the succession of the strictly marine Triassic, in Triassic and then Jurassic tidal flats. This results in an extremely diversified, rich and in some respects unexpected overall picture. There is no lack of bone remains of continental vertebrates (amphibians, land and flying reptiles), from the Palaeozoic and Mesozoic terrains, even though in truth body fossils of dinosaurs are still very rare. These are faunistic associations consistently and systematically repeated over time, which suggests the existence of an environment favourable to continental tetrapod life.
The area that has to date produced the greatest amount of dinosaur evidence is that of the Lavini di Marco, which is close to the town of Rovereto in southern Trentino. The Lavini di Marco are a series of landslides that detached themselves from the slopes of Monte Zugna about 1200 years ago. The landscape is particularly harsh and desolate, and since Mediaeval times it has represented a challenge to the comprehension of this phenomenon. Today the area still poses a large number of questions and represents, after the discovery of the tracks, a key site to understanding paleogeography, the paleoenvironment and the paleobiology not only of this area and the fauna it conserves but also for the whole Trento Platform and the Southern Alps.
The data recovered to date at the Lavini during eight years of research provides us with a window into a lost world. On six stratigraphical levels, compressed into just 5 metres and in an area of little more than a quarter of a square kilometer, there are footprints and trackways of a large number of carnivorous and herbivorous dinosaurs of various forms and sizes. The number of individuals has still to be defined but it is well over 200 animals.
It all took place almost at the beginning of the Jurassic and more probably in the early Sinemurian, on a large tidal flat which in many ways is comparable to the present coastline of the Persian Gulf.
Many carnivorous theropods attributable to all the several forms of ceratosaurs, of small, medium and large sizes, from 1 to 9 meters long, accompanied - or rather, followed by - a large number of small or large herbivores. Identified amongst these with a certain amount of surprise are a score or so of sauropods, that are up to now the oldest ever found in the world, weighing from 1 to 3 tons, and probably evolved ornithopods, of large dimensions with graviportal hind legs. These latter are not known from the bone remains found in this portion of the Jurassic period, which constitutes a separate problem that has yet to be solved.
Paleontological studies of our material have not only identified the possible authors of the tracks, but have also allowed their comparison with the contemporary ichnofaunas and faunas of the whole world, and have led to a series of considerations, that are in many ways completely new. Many particularly interesting aspects have emerged: the social behavior of the individual, its posture, gait and speed, the directions followed which contribute towards the outlining of some preferential corridors and then of some details of the paleogeography of that time in an extraordinary manner.
Carnivore tracks are more numerous (57%), than those of the herbivores (43%), notwithstanding what the biomass pyramid theory would forecast. This inversion of data probably needs to be placed in relation to the higher level of activity of carnivores than herbivores.
As often occurs in fossil fauna, the presence of hatchling and juvenile individuals is quite rare, and our ichnoassociation is mainly made up of adults, which is also probably because young animals do not leave deep tracks in the sediments and those they did leave would be more easily washed away or eroded.
The carnivores are documented by tracks that vary in length from 8 to 38 centimeters. The examples with smaller body sizes would not have been longer than half a meter, with a body weight of 3 to 4 kilos. The larger carnivores were probably 8 to 9 meters in length and weighed up to 1200 kilos. Among the herbivores, the sauropods for example have left tracks from 35 to 50 cm long, which were left by animals of 7 to 10 meters in length, weighing from 1 to 3 tons.
Animals like these latter undoubtedly consumed a large amount of vegetation. If considered to be “cold blooded” their daily foraging needs would have been modest, from 3 to 9 kilos. If considered “warm blooded” their
needs would have been between 21 and 64 kilos. Whatever the needs the annual consumption of plants would have been impressive.
It was particularly interesting to make a detailed study, of the interrelations between the different groups, and expand them to the world of the hypothetical small and medium sized tetrapods (mesofauna) and marine and continental invertebrates; and finally to the plant world, which is the basis for all animal life.
This latter topic, inserted into a paleogeographic and paleoenvironmental framework, poses a series of questions that are not easily answered as it would appear that there is an absence of the fundamental presupposition that would justify the presence of dinosaurs - especially the large herbivores - in an environment like that reconstructed for Rovereto: the vegetation. It would not appear to be justified to imagine, at the current state of our knowledge, that in the area of the tidal flats of the Lavini di Marco, there was sufficient plant biomass to sustain these large animals. This remains, therefore, the theme on which all current research is concentrated, as well as that foreseen for the immediate future.
It was possible to identify in this field, from amongst the large amount of data collected, two different environmental situations within a larger paleogeographical context of a tidal flat situated at the edge of a continent. The calcareous footprint bearing levels are characterized by the alternation of subareal exposures at the moment in which small amounts of water (both fresh and saltwater) develop on the platform. Analysis of the dolomitized footprint bearing layers, would seem to indicate the approach of the coastline - even if we do not know its exact location - and therefore the hypothesizing of different diagenetic mechanisms. There is also no lack of evidence of more marked subareas at particular times and in areas that are further away from the sea. In general therefore, the environment was characterized by cyclic excursions of the sea level which forced the dinosaurs to adapt to different conditions.
From an alimentary viewpoint, sedimentological and geochemical analysis does not justify the presence of so many dinosaurs in such an inhospitable environment, which was without the ideal vegetation cover essential for the survival of large herbivores.
In summary, sedimentological and diagenetic analysis shows that the geological features of the Lavini di Marco identifies a tidal flat where there was cyclic fluctuations in the sea levels. This tidal flat was characterized by a semi-arid climate and by the presence of slow moving fresh water as indicated by geochemical data.
It is therefore inevitable for one to pose the following question:
Did these dinosaurs live there as would seem logical to assume or were they just passing through? If they were passing through where did they come from? We have debated these questions from the first to the last day of these eight years of research.
Experts in sedimentary fossil environments have passed sentence: the Calcari Grigi at the Lavini di Marco identify an environment very similar to those tidal flats presently found in certain arid tropical areas and southern seas islands. Excellent exotic holiday locations for rich tourists; but with so little vegetation cover the survival of large herbivore dinosaurs would have been problematical. It would also seem that the tidal flat had a semi-arid climate, even harsher than first thought, with a chronic shortage of freshwater.
On the other hand dinosaur experts have declared: that there is no doubt that large herbivores lived on these flats and would have needed many thousands of tons of forage each year to survive and it is difficult that they would have been content with conditions that were so harsh.
The problem is further complicated by the enormous diffusion that carbonate platform environments had during the Early Liassic. Flat plains covered a large part of what is Italy today with small differences in facies. Not one area in Italy, at least not to the knowledge of the authors, features plant fossil content that would make it a candidate, at least according to traditional concepts, as a place for the development of dinosaur fauna similar to the one found at the Lavini di Marco.
Paleoenvironmental analysis clearly evidences that the Liassic carbonate platforms known in outcrops had no or very little vegetation, apart from bacterial moss. If this latter is excluded as a source of food for herbivore dinosaurs, we can only conclude that the mythical land of the
dinosaurs needs to be looked for several hundred kilometers from the Adige Valley. Unless.
All of our knowledge of the facies of platforms are based on the study of their characteristics in the area they appear. Although they are extensive, these areas present large interruptions in correspondence with the Padana and Veneto Plains. It is therefore possible that an area that had continental characteristics, that was habitually subaereal, with scarce vegetation, even forest trees, and was situated to the south of the pre-alpine area, below the present plains (Pianura Padana). A favorable clue to this is supplied by the paleogeography of the Middle Liassic.
Many definitely continental elements that are a feature of this stratigraphic unit, such as clay, carbon deposits derived from higher plants and the non-marine kerogene (an organic substance contained in bituminous rocks that give origin to oil), are distributed in such a way as to suggest their origins as being south of Monti Lessini, below the present Pianura Padana. It is clear that simple clues in a different era to that in which we are interested does not allow us to solve the problem. However, while awaiting new discoveries they do represent a working hypothesis to be taken into consideration.
However, even though this is only an hypothesis, a completely different scenario can be suggested. As often observed here, with little vegetation available, it would seem to be very difficult to justify the presence of large herbivores on the tidal flat in question - and this is also deduced from geological-stratigraphical data and the examination of similar environments of present times.
The problem also reappears for the dinosaur tracks that are also being found in large numbers in the older upper Triassic tidal flat of the Dolomia Principale. Hypothesizing that the Rovereto dinosaurs were in reality emigrants and just passing through would resolve the question of the lack of vegetation in tidal environments or at least it would move it elsewhere.
And what if the key to the solution would lie elsewhere? What else could have caused the large herbivores to come together in such an inhospitable environment? Given also that it had been ascertained that reptiles were not migratory by nature? If it was not food what was it? Perhaps instead food was a necessity linked to reproductive habits?
Available data is therefore contradictory. How can this impasse be resolved?
The migratory hypothesis could perhaps be admitted for large herbivores, mainly the sauropods, but it does not seem probable that all the fauna migrated, that is that all of the protagonists, both large and small, carnivores and herbivores, bipeds and quadrupeds from such different groups with such different needs were just passing through the site studied. If the heavy sauropods, weighing several tons, might have been able to survive a journey of many days, by sustaining themselves with
accumulated fat, perhaps contained in special storage organs, the same cannot be easily said of the small “fabrosaurids”; or for the carnivores, which generally do not migrate en masse together with the herbivores, but rather wait to ambush them as they pass. But one cannot say; we know so little about the lives of dinosaurs, when we try to go into detail! Above all on questions of metabolism, the debate between experts is still open and lively, and sometimes even leads to verbal abuse.
An alternative hypothesis that cannot be discounted is that the vegetation, even though present in small quantities in our area, existed here and there in greater concentrations, even if modest, in areas that have not yet been localised and perhaps together it was sufficient to feed the local fauna, at least for the small and large sized animals.
It is possible that the large number of tracks in the area does not represent so much an abundance of fauna, but wanderings in search of the small amount of food available, on the part of a smaller number of dinosaurs in respect to the more than 200 individuals we spoke of earlier. The mediocre or bad quality of the prints sometimes
does not allow the definite identification of individuals.
Documentation only exists for the terrain that is visible, while large surface areas are still invisible inside the mountain or have been destroyed by erosion. The continuity of the visible strata and the uniformity of the environment and the landscape would seem to be very probable, and in fact seems to be confirmed by the analyses carried out to date, but is not sufficiently representative of the whole truth, which still remains very complex.
Each layer in this environment obviously represents only a moment on the clock of geological time, while long intervals have not left a sign. Many layers were deposited and destroyed, redeposited and again destroyed, perhaps with their vegetation. Various inter-supratidal levels present the marks of destructive tidal movements and the frequent lack of stratification of the subtidal banks speaks of the eternal mobility and mutability of marine environments, that is unfavorable for the conservation of plants, especially those of small dimensions.
These are hypotheses that do not allow the contradictions of the data to be resolved in a convincing manner. But the data does exist; on one hand the dinosaur fauna with an impressive biomass, a harsh, sterile and apparently inhospitable environment on the other; both fascinating and stimulating, but when put together , disconcerting. The enigma that results, here at the Lavini di Marco and the platform of the Dolomia Principale Formation and elsewhere, is still a challenge to geologists and paleontologists, which has the advantage of keeping open research and enlivening intellectual curiosity, while this book is being finished.
In the eight years following the discovery of the dinosaur trackways at Rovereto, the research, notwithstanding the large requirement of personnel and equipment, has in practice been limited to a first still incomplete approach, which, however, has supplied a great deal of original data about the trackways, the authors of the prints and the environment, which allowed us to make many partial conclusions that we believe are worth publishing.
In the meantime, it is essential that the site is preserved. Therefore this initiative plays in important role not only in the cultural use of this immense patrimony, but also in its conservation for future generations.
Dinosaur tracks are reported from three new localities near Imilchil, in the Central High Atlas of Morocco. New dinosaur track assemblages are recognized in Bathonian and Bajocian beds. The Bathonian track assemblage comprises theropod, sauropod and ornithopod footprints. The Bajocian deposits contain a sauropod-thyreophoran track assemblage.
Since their discovery two decades ago, moderately-large, problematic tetrapod footprints, made by a large quadruped, from the upper part of the Upper Triassic Chinle Group in western North America, have posed ichnotaxonomic problems, as well as generating uncertainty about the affinity of the track maker. In the 1980s, they were tentatively considered to be of chirotheriid affinity on the basis of manus morphology, and provisionally labeled Chirotherium isp., but even from the outset, the pes was recognized as similar to that of a small sauropod. In the 1990s, the Chirotherium label was abandoned, and the South African ichnotaxon Tetrasauropus was tentatively applied, implying a sauropodomorph affinity for the track maker. However, due to ichnotaxonomic problems, the label was never formally applied or considered satisfactory. Moreover, at that time there were no sauropods known from the Late Triassic, and diagnostic body fossil evidence of sauropodomorphs was sparse or absent in the Chinle Group. In the 2000s, however, Late Triassic sauropods were reported, and efforts were made by several groups to re-investigate the type material of Tetrasauropus and related ichnotaxa (such as Pseudotetrasauropus) held in the collections of Paul Ellenberger at Montpellier, France. The result of these investigations is a growing consensus that North American " Tetrasauropus " (referred to informally by some authors in quotation marks) is best accommodated in a new ichnotaxon. We herein erect the ichnotaxon Eosauropus cimarronensis ichnogen. et ichnosp. nov. to accommodate this track type and suggest that the few other Northern Hemisphere reports of " Tetrasauropus " also be transferred to Eosauropus. This taxonomic revision does not imply that Eosauropus (formerly North American " Tetrasauropus ") is of undoubted sauropod affinity. However, many recent authors have supported this suggestion, with varying degrees of enthusiasm, and have incorporated extensive discussion of this ichnotaxon and its morphological characteristics into their analyses of sauropod and/ or sauropodomorph phylogenies and inferences about the locomotor evolution of these groups. We hold the position that the morphological similarities between the Eosauropus pes and those of well-documented, post-Triassic sauropods is noteworthy but by no means absolute. If the Eosauropus track maker was not a sauropod, the footprints are an interesting example of convergence.
Evazoum gatewayensis is a new ichnospecies named for distinctive forms of Evazoum from the Upper Triassic Chinle Group of western Colorado that are up to twice the size of the type species of Evazoum, an ichnogenus that has been compared with Kalosauropus, and assigned to the Otozoum, Pseudotetrasauropus, Evazoum, Kalosauropus or OPEK plexus. E. gatewayensis tracks are functionally didactyl, with an enlarged proximal metatarsal-phalangeal pad on digit II, separated by a conspicuous gap from a distal digit II claw trace. This enlarged pad and gap is lacking in other Evazoum and OPEK morphotypes, which also show the trace of digit I in most specimens. Thus, the western Colorado tracks suggest that the trackmaker retracted its digit II claw, as well as keeping digit I above the substrate. This could indicate both a morphological and behavioral difference between this ichnospecies and others in the OPEK plexus. The western Colorado morphotypes, which also appear to be represented by specimens in eastern Utah, and similar footprints from Nova Scotia, show interesting convergence with the tracks of Cretaceous deinonychosaurs, although we infer that the track makers belonged to a different group of archosaurs. Based on current trackway evidence, Evazoum is a variable ichnogenus in size, morphology, and behavior, and like several ichnogenera in the OPEK plexus, is currently represented by more than one ichnospecies.
New reports of dinosaur tracksites in the Tuchengzi Formation in the newly established Yanqing Global Geopark, Beijing, China, support previous inferences that the track assemblages from this formation are saurischian-dominated. More specifically, the assemblages appear theropod-dominated, with the majority of well-preserved tracks conforming to the Grallator type (sensus lato), thus representing relatively small trackmakers. Such ichnofau-nas supplement the skeletal record from this unit that lacks theropods thus far, proving a larger diversity of dinosaur faunas in that region. Sauropods are represented by medium to large sized and narrow and wide-gauge groups, respectively. The latter correspond with earlier discoveries of titanosauriform skeletons in the same unit. Previous records of ornith-ischian tracks cannot be positively confirmed. Purported occurrences are re-evaluated here, the trackways and imprints, except of a single possible specimen, reassigned to the-ropods. Palecologically the Tuchengzi ichnofauna is characteristic of semi-arid fluvio-lacus-trine inland basins with Upper Jurassic-Lower Cretaceous deposits in northern China that all show assemblages with abundant theropod and sauropod tracks and minor components of ornithopod, pterosaur and bird tracks.
A dinosaur footprint assemblage from the Lower Jurassic Ziliujing Formation of Zigong City, Sichuan, China, comprises about 300 tracks of small tridactyl theropods and large sauropods preserved as concave epireliefs (natural molds). The theropod footprints show similarities with both the ichnogenera Grallator and Jialingpus. Three different morphotypes are present, probably related to different substrate conditions and extramorphological variation. A peculiar preservational feature in a morphotype that reflects a gracile trackmaker with extremely slender digits, is the presence of a convex epirelief that occurs at the bottom of the concave digit impressions. It is possibly the result of sediment compaction underweight load when the pes penetrated the substrate, being a resistant residue during exhumation and weathering. The sauropod tracks belong to a trackway with eight imprints consisting of poorly preserved pes and manus tracks and a better preserved set, probably all undertracks. The narrow-gauge trackway pattern resembles the ichnogenus Parabrontopodus well known from the Jurassic but other features such as the minor heteropody are different. The assemblage enriches the dinosaur record from the famous Zigong locality and the evidence from the Lower Jurassic in this area that was restricted to a few skeletal remains and footprints. Furthermore it proves the presence of small theropods, whereas skeletons of the group, well- known from the Middle-Upper Jurassic of Zigong, are of medium to large size only. Remarkable is the dominance of saurischians in these assemblages, which is characteristic of Jurassic dinosaur communities whereas the Cretaceous record shows an increase of ornithopod groups. An overview of the dinosaur trace and body fossil record of the Sichuan Basin supports this view. The paleoenvironment can be designated as a low-latitude tropical freshwater lake as it is indicated by bivalve shells.
Large theropod and sauropod footprints predominated in the continental Zagaje Formation (early Hettangian) exposed in the Sołtyków outcrop. Geological and paleobotanical data indicate an inland seasonal habitat with low and high growing vegetation on the flood plain. The theropod-sauropod ichnofauna also contains occasional footprints of small ornithischians and mammals. The Sołtyków track assemblage, together with other similar assemblages, suggests a wide range of habitats occupied by sauropods.
The Molteno, Elliot, and Clarens formations comprise the continental Stormberg Group of the Karoo Basin of South Africa and Lesotho. The Molteno Formation contains a well preserved macro- and microfloral assemblage but apparently no vertebrates; the Elliot and Clarens formations contain abundant vertebrates but virtually no floral remains. The vertebrate taxa represented by skeletal remains are listed and divided into two assemblages - the lower Stormberg (lower Elliot) and upper Stormberg (upper Elliot and Clarens) assem- blages. The abundant, diagnosable footprint taxa are revised and their names reduced to eight genera. These ichnotaxa also fall into two biostratigraphic zones that parallel the skel- etal assemblages. Comparison of the faunal assemblages with those of the European type section strongly suggests that the lower Stormberg assemblage is Late Triassic (Carnian- Norian) in age while the upper Stormberg assemblage is Early Jurassic (Hettangian-Pliens- bachian) in age. Comparisons with other continental assemblages from other areas suggest that the upper Stormberg (upper Elliot and Clarens formations) assemblage broadly corre- lates with the upper Newark Supergroup of eastern North America, the Glen Canyon of the southwestern United States, and the lower Lufeng Series of China - all thought to be of Early Jurassic age on the basis of floral and/or radiometric evidence. Based on these co- rrelations, previously published paleobiogeographic maps are revised; these show a shift from Late Triassic floral and faunal provinciality to Early Jurassic homogeneity. This shift was synchronous with a widening of the equatorial arid zone.
Dinosaur tracks are biogenic, sedimentary structures
and not body fossils or biological objects in the common
sense. They result from the complex interaction of the
kinematics of the trackmaker, its foot anatomy, and the
substrate properties, and from taphonomic processes
acting prior to the incorporation of the tracks into the
sedimentary record. The objective of this work is an
interdisciplinary study of a large sample of dinosaur
tracks and trackways linking sedimentology with vertebrate
ichnology, palaeontology, and palaeoecology.
Excellent conditions are provided by the Late
Jurassic (Kimmeridgian) Chevenez—Combe Ronde
tracksite, which is one of several tracksites located
on the future course of the Transjurane highway
near Porrentruy (Canton Jura, NW Switzerland).
Here, eight superimposed dinosaur track-bearing
surfaces were systematically excavated level-by-level
within a 0,65 m thick laminite interval, unearthing
almost 1400 dinosaur tracks. The main track level,
located at the base of the interval, is the most diverse
ichnoassemblage composed of 14 trackways of tiny
(Pes Length < 25 cm) and small (25 cm < PL < 50 cm)
sauropods and 43 trackways of minute (PL < 10 cm),
small (10 cm < PL < 20 cm), and medium-sized
(20 cm < PL < 30 cm) bipedal, tridactyl dinosaurs.
The main issues are: (1) identification of true tracks,
undertracks, and overtracks, and their relationships with
substrate properties, their link with the exposure index,
and their utility in the reconstruction of the palaeoenvironment;
(2) implications of the main track level
ichnoassemblage for dinosaur behaviour, the terrestrial
palaeoecosystem, and vertebrate ichnofacies; (3) relationships
between variability in trackway patterns and
configurations with locomotion speed, behaviour, and
substrate properties as well as implications for locomotion
capabilities; (4) Quantification and relevance
of sauropod trackway gauge; and (5) interpretation of
manus-dominated and pes-only sauropod trackways.
The approach is first actualistic by studying
human footprints and processes acting during their
formation and preservation on modern tidal-flats.
In these highly structured environments, microbial
mats are ubiquitous, strongly facies-specific, and
occupy a key position during and after footprint formation.
Undertracks readily form in biolaminated
sediment, whilst underprints and deep tracks are
common in unlaminated, water-saturated sediment.
Most consolidated vertebrate tracks are affected
by taphonomic processes, including renewed
and/or repeated growth of microbial mats leading
to the formation of modified true tracks, internal
overtracks (track fills), and overtracks.
The sauropod tracks and the encasing laminite
interval of the Combe Ronde site are then subject
of detailed sedimentological and taphonomical
analyses. This discloses the sediment properties at
the time of track formation and reveals the processes
modifying the tracks during subaerial exposure
and integrating them into the sedimentary record.
Track morphology, associated track features,
and sedimentary features can be linked with the
exposure index, identifying the palaeoenvironment
as a supratidal flat not located in close proximity
to a coastline. These flats were susceptible for
track recording only during short periods after
wetting due to a rainy period or due to occasional
storms. Longer periods of subaerial exposure prior
to burial are indicated by the presence of internal
overtracks and/or overtracks, and rapid covering
up is indicated by the lack of overtracks on top
of tracks with large displacement rims. Crosssections
of sauropod tracks provide insight into
the consolidation history of the substrate prior to
track formation and into the walking dynamics
of dinosaurs, confirming that sauropods put their
hindfeet in a pronounced plantigrade way on the
ground.
The level-by-level superimposition of the studied
surfaces enables to identify true tracks, undertracks,
and overtracks. The best-defined true tracks
(anatomical morphotypes) of the main track level
are then used for ichnotaxonomy and trackmaker
identification, and the detailed analyses of trackway
parameters, including trackway gauge, provide
insight into the locomotion capabilities of dinosaurs.
The best-defined minute and small tridactyl tracks can
be assigned to the ichnogenus Carmelopodus, extending
it from the Middle Jurassic into the Late Jurassic.
These tracks were likely left by a small theropod dinosaur
similar in size to Compsognathus or Juravenator.
The medium-sized tridactyl tracks of morphotype II
exhibit some of the typical features of the ichnogenus
Therangospodus (attributed to large and robust theropods)
but also some of ornithopod ichnotaxa.
The sauropod trackways show a wide range of patterns
and configurations but are all medium- to widegauge.
Therefore, they are assigned tentatively to the
ichnogenus Brontopodus attributed to derived “brachiosaurid”
or “titanosaurid” dinosaurs. The variability
of the trackways reflects the general locomotion
capabilities of the trackmakers and is an expression of
individual walking style and behaviour, which may be
related to substrate properties. Trackway patterns (the
degree of manus overprinting by the pes) and different
trackway configurations including trackway gauge are
not only related to locomotion speed, and they provide
no evidence of a relationship with ontogeny.
The gauge of sauropod trackways can be
quantified with the pes trackway ratio and the here
defined [WAP/PL]-ratio (Width of the pes Angulation
Pattern / Pes Length). Gauge is possibly related to
the substrate and the behaviour of the trackmaker
adapting to it, but this does not change the overall
medium-gauge to wide-gauge appearance of the
trackways. The manus-dominated and pes-only
sauropod trackways of the Combe Ronde site are
explained by trackmakers exerting more pressure on
the manus than the pes, and by overprinting of the
manus by the pes, respectively.
The alignment of trackways on the main track
level shows no evidence of a nearby shoreline and
of interactions between the different groups of
dinosaurs. It indicates gregarious behaviour amongst
tiny and small sauropods, and suggests that minute
and small bipedal dinosaurs were frequent visitors on
the supratidal flats.
The ichnoassemblage of the main track level is
the first one found in the Jura Mountains displaying
abundant minute and small tridactyl tracks. This is
also typical for the other Ajoie ichnoassemblages,
which further exhibit tracks of tiny to large (up to 1,1
m PL) sauropods, and tracks of medium-sized to large
(up to 0,8 m PL) bipedal dinosaurs. Sauropod
trackways include narrow-gauge and wide-gauge
trackways indicating the presence of “basal” and
derived sauropods. This suggests that dwarfed
insular animals can be excluded as trackmakers of
the tiny and small sauropod trackways of the Ajoie
ichnoassemblages and the Combe Ronde tracksite
and that the Jura carbonate platform was connected
with the landmasses of the London-Brabant Massif
and the Massif Central during periods of emersion.
Dinosaurs used the Jura carbonate platform for the
establishment of in situ, predominantly saurischian
dinosaur populations, but also as a migration corridor
between the massifs.
Because the Ajoie ichnoassemblages are dominated
by small tridactyl tracks, they differ from other
Jurassic tetrapod ichnofacies in carbonate settings,
notably from the Brontopodus ichnofacies. In the
case of those ichnoassemblages commonly attributed
to the Brontopodus ichnofacies, the lack or rareness
of small tridactyl tracks may indicate the absence
of small trackmakers in those palaeoenvironments
or unsuitable conditions for the formation and
preservation of small tracks.
This study highlights the benefits of systematic
and interdisciplinary analyses of dinosaur tracks,
which disclose variations related to behaviour and
to differences in substrate. This allows recognizing
anatomical morphotypes and trackway configurations
representative of typical trackmaker behaviour. The
latter can then also be used in ichnotaxonomical
classification. Similar approaches should be in the
focus of future work and performed on the other
tracksites and ichnoassemblages of the Ajoie.
Together with the evidence from other tracksites of the
Jura Mountains, this will contribute towards a better
understanding of the terrestrial palaeoenvironments
and palaeogeography, and of dinosaur palaeoecology
and palaeobiogeography on the Jura carbonate
platform.
The Galinha tracksite reveals a sequence of Bajocian—Bathonian limestones belonging to the Serra de Aire Formation (West-Central Portugal) and is one of the few sites in the world where Middle Jurassic sauropod dinosaur tracks can be found. This tracksite is characterised by the presence of long, wide gauge sauropod trackways, the Middle Jurassic age of which suggests these dinosaurs were more widely distributed over time than previously thought. Two trackways contain unique pes and manus prints with morphologies that allow a new sauropod ichnotaxon to be described: Polyonyx gomesi igen, et isp. nov. On the basis of different manus/pes prints and trackway features, the proposal is made to subdivide Sauropodomorpha ichno-morphotypes into five groups: Tetrasauropus-like, Otozoum-like, Breviparopus/Parabrontopodus-like; Brontopodus-like, and Polyonyx-like. Polyonyx gomesi igen, et isp. nov. is thought to represent a non-neosauropod eusauropod, with a well developed manus digit I. The posterior orientation of this digit print suggests they were made by a eusauropod dinosaur with a posteriorly rotated pollex. The manus print morphologies observed in two trackways suggest a stage of manus structure intermediate between the primitive non-tubular sauropod manus and the tubular metacarpal arrangement characteristic of more derived sauropods. The low heteropody (manus:pes area ratio 1:2) of the trackway renders it possible they could have been made by eusauropods such as Turiasaurus riodevensis, which has a similar manus:pes area ratio. The Polyonyx igen. nov. trackway was made by non-neosauropod eusauropod, and suggests that wide gauge sauropod trackways were not exclusively made by Titanosauriformes.
Background:
Argentinean basal sauropodomorphs are known by several specimens from different basins; Ischigualasto, El Tranquilo, and Mogna. The Argentinean record is diverse and includes some of the most primitive known sauropodomorphs such as Panphagia and Chromogisaurus, as well as more derived forms, including several massospondylids. Until now, the Massospondylidae were the group of basal sauropodomorphs most widely spread around Pangea with a record in almost all continents, mostly from the southern hemisphere, including the only record from Antarctica.
Methodology/principal finding:
We describe here a new basal sauropodomorph, Leyesaurus marayensis gen. et sp. nov., from the Quebrada del Barro Formation, an Upper Triassic-Lower Jurassic unit that crops out in northwestern Argentina. The new taxon is represented by a partial articulated skeleton that includes the skull, vertebral column, scapular and pelvic girdles, and hindlimb. Leyesaurus is diagnosed by a set of unique features, such as a sharply acute angle (50 degrees) formed by the ascending process of the maxilla and the alveolar margin, a straight ascending process of the maxilla with a longitudinal ridge on its lateral surface, noticeably bulging labial side of the maxillary teeth, greatly elongated cervical vertebrae, and proximal articular surface of metatarsal III that is shelf-like and medially deflected. Phylogenetic analysis recovers Leyesaurus as a basal sauropodomorph, sister taxon of Adeopapposaurus within the Massospondylidae. Moreover, the results suggest that massospondylids achieved a higher diversity than previously thought.
Conclusions/significance:
Our phylogenetic results differ with respect to previous analyses by rejecting the massospondylid affinities of some taxa from the northern hemisphere (e.g., Seitaad, Sarahsaurus). As a result, the new taxon Leyesaurus, coupled with other recent discoveries, suggests that the diversity of massospondylids in the southern hemisphere was higher than in other regions of Pangea. Finally, the close affinities of Leyesaurus with the Lower Jurassic Massospondylus suggest a younger age for the Quebrada del Barro Formation than previously postulated.
A new ichnotaxon is described from the Lower Jurassic (Upper Hettangian-Lower Sinemurian) carbonate tidal flats on the central-eastern Italian Alps. The narrow-gauge trackway is that of a large quadrupedal dinosaur. The pes is functionally tetradactyl with three rounded antero-medially directed digits, and the manus is pentadactyl. This quadrupedal form is close to Otozoum and Pseudotetrasauropus jaquesi both traditionally related to sauropodomorph trackmakers. The similarity with Otozoum is so marked that Lavinipes and Otozoum could be cogeneric. But the overall evidence today is that the Otozoum trackmaker was generally bipedal, whereas the trackmaker of L. cheminii is fully quadrupedal. The manual prints of L. cheminii show five short clawless digits and are different from the tetradactyl slender toed manual prints of Otozoum. The possible sauropodomorph affinity of the L. cheminii trackmaker is here discussed with an attempt to a revision of the Late Triassic-Jurassic tracks which have been traditionally related to sauropod and prosauropod.
Sauropods were a very successful group of dinosaurs during the Jurassic
and Cretaceous periods, but their earlier history is poorly known. Until now,
the earliest reported sauropod bones were from the Early Jurassic1, 2, 3,
and the only tentative evidence of earlier sauropods was in the form of controversial
footprints4, 5. Here we report the discovery of an incomplete
sauropod skeleton from the Late Triassic period of Thailand, which provides
the first osteological evidence of pre-Jurassic sauropods. This dinosaur
is markedly different from prosauropods and substantiates theoretical predictions
that there was a fairly long period of sauropod evolution during the Triassic.
The cranial osteology of many prosauropod dinosaurs remains poorly described, hampering broader systematic studies of basal sauropodomorph interrelationships. Here, we present a detailed re-description of the skull of Lufengosaurus huenei Young. 1941a. from the Lower Lufeng Formation (Lower Jurassic) of China. Lufengosaurus can be diagnosed on the basis of four cranial autapomorphies (the presence of bony bosses on the ascending process of the maxilla, the jugal. and the rostrolateral wing of the parietal, and the presence of a ridge on the lateral surface of the maxilla) and distinguished from all other prosauropods by a unique combination of cranial character states. Previous suggestions that Lufengosaurus is congeneric with either Massospondylus or Yunnanosaurus are rejected on the basis of craniodental evidence. Comparison with published character codings for Lufengosaurus reveals numerous discrepancies that are demonstrated to affect the phylogenetic position of the genus and patterns of sauropodomorph interrelationships.
Yunnanosaurus youngi sp. nov. is erected based on the following characters: the distal ends of the sacral ribs expanded anteroposteriorly and dorsoventrally, forming into a sacrocostal yoke, which is contacting with the inner surface of ilium; the ischium is longer than the pubis. Yunnanosaurus youngi is about 13 meters long, which is longer than Yunnanosaurus huangi (7 meters long). The height exceeding the length for the centra of the posterior dorsal and anterior caudal vertebrae may be a synapopmorphy of Yunnanosauridae and Melanorosauridae. Yunnanosaurus youngi is stratigraphically younger than Y. huangi and it represents a derived form of yunnanosaurids.
The Jiaoyuan tracksite in the Gulin area of Sichuan Province, China represents a typical saurischian-dominated assemblage with trackways of theropods and sauropods. They occur in the Lower Jurassic Da'anzhai Member of the Ziliujing Formation, a sandstone-siltstone succession of fluvial origin and deposited in the southern Sichuan Basin. Four trackways as well as isolated tracks of theropods are documented and analyzed in this first part a study of sauropod tracks will follow elsewhere. Two morphotypes and size-classes, respectively, can be observed. The larger one is 25-34. cm in length and shows weak to moderate mesaxony. The smaller is 7-15. cm in length and moderately mesaxonic. Despite a few similarities with the ichnogenus Kayentapus, the former is assigned here to Eubrontes, well known from Lower Jurassic assemblages, in North America, Europe, and southern Africa. The smaller morphotype resembles typical Grallator tracks except in its wider digit divarication and the metatarsophalangeal pad IV being positioned in line with the long-axis of digit III, similar to Jialingpus described, for example, from Upper Jurassic deposits of Sichuan. A relatively wide digit divarication in Grallator-type tracks is apparently common in Jurassic assemblages of China and may represent a distinct feature related to provinciality of theropod faunas in this region. © 2015 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS.
The name Brontopodus birdi is assigned to sauropod footprints from the Glen Rose Limestone (Lower Cretaceous) and equivalents of Texas and Arkansas. The ichno-taxon is characterized by: U-shaped manus prints, probably made by a hand in which digits II-IV were bound together in a pad and set off from digits I and V; no claw marks on manus tracks; large, laterally directed claw marks on digits I-III of the pes; outward rotation of manus and pes tracks relative to the direction of travel; a relatively broad trackway, in which footprints do not impinge on the trail midline, and in which the outer limits of the trackway are defined by the pes footprints, rather than the manus tracks; step angles usually 100-120°; tail marks rare or absent. The trackmaker is interpreted as a brachiosaurid, perhaps Pleurocoelus. -Authors
The growing database on sauropod tracksites, particularly from China, raises questions about hypotheses that wide-gauge sauropod trackways with low heteropody (Brontopodus) dominate the global sauropod track record in the Cretaceous. It also raises questions about the definition of narrow-, medium- and wide-gauge trackways and the quality of preservation needed to use such labels reliably. A number of Lower Cretaceous sauropod tracksites from China have yielded trackways of small-sized sauropods with pronounced heteropody that have been named Parabrontopodus. These co-occur with medium-sized to large Brontopodus trackways giving rise to at least two possible interpretations regarding sauropod trackmakers at these sites: 1) trackways were left by two different, smaller narrow gauge and larger wide gauge, taxonomic groups, 2) trackmakers belong to the same taxonomic group and were narrow gauge when smaller and wide gauge when larger, therefore not maintaining a constant gauge during ontogeny as inferred from some assemblages. The presence of different taxonomic groups is further evidence that narrow gauge trackmakers, previously considered typical of the Jurassic, persisted into the Early Cretaceous. This could be part of a regional trend in East Asia and some other regions such as the Iberian peninsula in Europe, where similar trackways have been found. Alternatively, this could reflect a previously unrecognized global trend. More track and skeletal data are needed to corroborate these hypotheses, because presently essential parameters are missing.
New dinosaur track assemblages were discovered recently in the Tianjialou Formation of the Lower
Cretaceous Dasheng Group in Shandong Province, China. Theropods are represented by the trackways of
two different medium-sized groups: (1) tridactyl tracks with a typical mesaxonic shape; (2) functionally
didactyl tracks attributed to deinonychosaurian theropods. The latter report, the third from the Cretaceous
of Shandong Province, enlarges the global record of didactyl theropod tracks, until now sparsely
documented from only a few locations in Asia, North America and Europe. A number of features in the
dromaeosaur trackway suggest the assignment to cf. Dromaeosauripus. Several medium-sized trackways
resemble the narrow-gauge, small manus ichnogenus Parabrontopodus, and one large trackway is
characterised by a wide-gauge and large manus, similar to Brontopodus. This suggests the co-occurrence
of two different sauropod groups. A further component in these ichnoassemblages is a tetradactyl
morphotype and trackways of ornithischian affinity that are tentatively attributed to psittacosaurs.
The Late Triassic—Early Jurassic ichnofauna described mainly by Paul Ellenberger from southern Africa (Lesotho) is a valuable window on first phases of dinosaur diversification. Unfortunately, the present taxonomic status of several forms from that ichnofauna is unclear. The revision of this material has been frequently invoked and partially done without reaching many definitive results. Due to the enormous amount of data, a global revision seems at present impossible and must be accomplished in smaller steps. A small number of Ellenberger's ichnogenera including Tetrasauropus, Pseudotetrasauropus, Pentasauropus, Paratetrasauropus, Sauropodopus and Deuterosauropodopus, which different authors have ascribed to basal sauropodomorphs, are here revised in a consistent manner and their attribution to osteological clades is considered. Tetrasauropus and Pseudotetrasauropus are here validated as the only ichnotaxa related to sauropodomorphs. Pentasauropus is retained as valid, and a therapsid trackmaker is suggested. Paratetrasauropus and Sauropodopus are also validated and ascribed to non-dinosaurian trackmakers, and Deuterosauropodopus is synonymized with Sauropodopus.
A reptile footprint fauna was recovered at Lerici, near La Spezia (northern Apennines, Italy) from Triassic sediments, belonging to the upper portion of the Montemarcello Formation. These sediments, of Mid to Late Triassic age, were deposited on a flood plain, during an early stage of rifting. The footprint-bearing levels are Carnian in age and the ichnofauna is unexpectedly diverse, including two chirotherian- and three dinosaur-related forms; consequently our findings are among the more ancient records of a true dinosaur-based ichnocoenosis. Due to the emerging complexity of systematic and stratigraphical problems, we restrict this paper to the description of a new prosauropod-related ichnotaxon named Evazoum siriguii igen. et isp. nov. In attempting to include this ichnotaxon into a convincing systematic framework we were obliged to examine the present confused situation of some different ichnotaxa. The conclusion of this attempt was that an integrated study is urgently needed to shed light on the systematics of quite a large number of prosauropod-related ichnotaxa.
Re-description of the left dentary of Chinshakiangosauruschunghoensis reveals that it possesses an unusual combination of and character states. Cladistic analysis places Chinshakiangosaurus as one of the most basal sauropods known currently. Mapping of dentary and dental characters onto the most parsimonious topologies yields insights into the sequence of acquisition of a number of feeding-related characters. For example, it seems that basal sauropodomorphs (traditional prosauropod taxa) possessed a fleshy cheek that attached to the mandible along a marked ridge, and that the same structure was present in the most basal sauropods. The early sauropod skull developed a lateral plate that reinforced the bases of the tooth crowns labially, and had wrinkled tooth enamel and a concavity on the mesial portion of the lingual part of each crown, while retaining a fleshy cheek and a relatively weak symphysis. More advanced sauropods (eusauropods) lost the cheek, perhaps in order to increase the gape of the jaws in response to a change in feeding style that involved collection of larger quantities of poor quality foliage.
The cranial osteology of many prosauropod dinosaurs remains poorly described, hampering broader systematic studies of basal sauropodomorph interrelationships. Here, we present a detailed re-description of the skull of Lufengosaurus huenei Young, 1941a, from the Lower Lufeng Formation (Lower Jurassic) of China. Lufengosaurus can be diagnosed on the basis of four cranial autapomorphies (the presence of bony bosses on the ascending process of the maxilla, the jugal, and the rostrolateral wing of the parietal, and the presence of a ridge on the lateral surface of the maxilla) and distinguished from all other prosauropods by a unique combination of cranial character states. Previous suggestions that Lufengosaurus is congeneric with either Massospondylus or Yunnanosaurus are rejected on the basis of craniodental evidence. Comparison with published character codings for Lufengosaurus reveals numerous discrepancies that are demonstrated to affect the phylogenetic position of the genus and patterns of sauropodomorph interrelationships.
The paper describes an early and primitive sauropod dinosaur, Gongxianosaurus shibeiensis (gen. et sp. nov.), from the Dongyuemiao Member of the Lower Jurassic Ziliujing Formation in Shibei Township, Gongxian County, Sichuan Province, China, which is one of the 5 dinosaur fossils discovered in Gongxian in 1997. Except the skull which is incomplete, the fossils are well preserved. It has some features of both sauropods and prosauropods. It is an intermediate type in the evolution of dinosaurs from prosauropods to sauropods and provides materials for the study of the origin and evolution of the sauropod dinosaur fauna. The discovery of this new sauropod furnishes a way for the stratigraphic correlation between the Early Jurassic Ziliujing Formation in the Sichuan basin and the Lower Jurassic Lufeng Formation in the Central Yunnan basin.
This paper represents an “editorial” introduction to this issue, which is one of two special issues of Cretaceous Research on the geology and paleontology of East Asia. This paper makes special reference to the results of joint Japanese, Chinese, and North American expeditions that investigated more than 70 fossil footprint sites and other fossiliferous localities in China, Japan, Korea, Laos, Mongolia, and Thailand. More than 50 of the track sites are considered Cretaceous in age, though in some cases dating is uncertain. We herein present summaries of selected important sites not previously described in detail based on new maps, tracings, and replicas of representative type specimens and related materials that have been assembled in accessible reference collections. Other sites are described in detail elsewhere in this issue and are placed in broader paleoenvironmental context in conjunction with papers that deal with floras, invertebrate and vertebrate body fossils, paleoecosystem reconstruction, and their stratigraphic, sedimentological, and tectonic settings in the second of the two special issues.
The first reported sauropod tracks and trackways (ichnogenus Brontopodus) from the Lower and Upper Cretaceous of China occur at multiple stratigraphic levels in the Jing Chuan Formation (Lower Cretaceous, Barremian–Aptian) of the Chabu area, near Otog Qi, Inner Mongolia and in the Jiang Di He Formation (Upper Cretaceous, Turonian–Coniacian), near Kunming, Yunnan Province, People's Republic of China. Sauropod tracks at several sites are quite well preserved and reveal distinctive trackway patterns strongly suggestive of gregarious behaviour among small individuals. The trackways at both sites tend towards being slightly wide gauge with relatively large manus impressions (i.e., heteropody is not strongly developed). They are best accommodated in the ichnogenus Brontopodus, a senior synonym of the little-known Chinese ichnogenus Chuxiongpus. The co-occurrence of sauropod and theropod tracks without evidence of large ornithopods or other ornithischians supports the suggestion that this ‘saurischian’ association is characteristic of many inland basins in the Cretaceous of China.
Newly discovered sauropod material from the Upper Triassic of northeastern Thailand reveals that some of the earliest sauropods had already reached a very large size. A 1 m long humerus is within the size range of large Jurassic sauropods such as Camarasaurus and suggests an animal reaching a length of 12 to 15 m. It took sauropodomorph dinosaurs some 20 million years to produce giant forms, a rapid size increase when compared with that observed in the evolution of other dinosaurs, such as ornithischians. (C) 2002 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.
Otozoum moodii Hitchcock, 1847 is one of the classic Connecticut Valley ichnotaxa established by Edward Hitchcock between 1836 and 1865. The taxon is redescribed, and AC 4/1a re-established as the holotype specimen. Otozoum minus and O. caudatum are synonymised with O. moodii. The syntypes of Kalosauropus pollex (nomen nudum) are described as O. pollex sp. nov. Cladistic, quantitative, and comparative methods of trackmaker identification suggest that Otozoum was made by a prosauropod dinosaur. In quantitative analyses, only those phalanges likely to contribute to footprint morphology were considered; claws were also excluded due to their highly variable styles of impression. Several diagnostic characters distinguish Otozoum from Brachychirotherium, Chirotherium, Batrachopus, Tetrasauropus, and Pseudotetrasauropus; these ichnotaxa are probably attributable to crurotarsan archosaurs. Otozoum is found primarily in Hettangian strata of the Hartford, Deerfield, and Fundy rift basins of eastern North America; it is also present in the Early Jurassic Navajo Sandstone (Colorado Plateau, USA) and Clarens Formation (Lesotho). The taxon is unknown in older strata; Triassic material previously referred to Otozoum (including O. grandcombensis) instead belongs in Pseudotetrasauropus. Correlation of sediments and comparison of faunal assemblages, particularly within the Newark Supergroup, suggest that the Otozoum trackmakers were restricted to arid environments.