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The largest of all the dinosaurs, the sauropod Argentinosaurus huincolensis J.F.Bonaparte and R. Coria, 1993, from Huincul, Province of Neuquén, Argentina. A dinosaur of these dimensions can explain the very large sauropod hind-tracks from the Andes, NE Brazil, Western Australia etc. An exposition of replicas of Argentinian dinosaur skeletons at Padua, Italy, 2016.
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A preliminary study of the Humaca dinosaur tracksite, in the Departamiento Chuquisaca (Bolivia), has revealed 11 parallel trackways of subadult sauropods travelling to the WNW as a group. The nearby Cal Orcko site preserves more variable trackway orientations produced by larger individuals. The Humaca trackways are interpreted as evidence of social...
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LATE CRETACEOUS VERTEBRATE ICHNOFACIES OF BOLIVIA—FACTS AS IMPLICATIONS
MEYER, Christian A., Inst. of Geol. & Palaeont. Univ. of Basel, Bemoullistr. 32,44 Basel, Switzerland; LOCKLEY, Martin G., Dept. of Geology, Univ. of Colorado, Larimer Street P.O.Box 173364, Denver, Co. 80217-3364; LEONARDI Giuseppe, Parrocchia Sant’Artema, Via Modigliani, Mont...
Citations
... The tetrapod ichnological record from Bolivia is of great importance in the context of the worldwide Cretaceous dinosaur track record (Lucas 2007;Meyer et al. 2020). Different ichnosites in the Chuquisaca Department, namely Cal Orck'o (Sucre Area), Humaca and Niñu Mayu (Maragua Area), as well as the Toro Toro ichnosite in the Potosí Department, reveal a quite high abundance and diversity of theropod, sauropod, ankylosaur and ornithopod footprints (Leonardi 1994;McCrea et al. 2001;Lockley et al. 2002a;Meyer et al. 2016Meyer et al. , 2018Meyer et al. , 2020Riguetti et al. 2021) assigned to taxa typical of latest Cretaceous times (Hunt and Lucas 2006). This record mainly occurs in inland (Lockley et al. 2002a;Meyer et al. 2018) or coastal (Tomaselli et al. 2021) lacustrine environments, related to coastline variations of either the Pacific or the Atlantic (Marquillas et al. 2011). ...
... Different ichnosites in the Chuquisaca Department, namely Cal Orck'o (Sucre Area), Humaca and Niñu Mayu (Maragua Area), as well as the Toro Toro ichnosite in the Potosí Department, reveal a quite high abundance and diversity of theropod, sauropod, ankylosaur and ornithopod footprints (Leonardi 1994;McCrea et al. 2001;Lockley et al. 2002a;Meyer et al. 2016Meyer et al. , 2018Meyer et al. , 2020Riguetti et al. 2021) assigned to taxa typical of latest Cretaceous times (Hunt and Lucas 2006). This record mainly occurs in inland (Lockley et al. 2002a;Meyer et al. 2018) or coastal (Tomaselli et al. 2021) lacustrine environments, related to coastline variations of either the Pacific or the Atlantic (Marquillas et al. 2011). The latter possibility is supported by the Atlantic transgressive event vastly recognised in northwestern Argentina (e.g. ...
... As a result of this ichnotaxonomic framework, sauropod footprints were referred to as Parabrontopodus or Brontopodus according to the trackway gauge (Lockley et al. 1994a), and many other sauropod tracks and trackways were later classified accordingly (e.g. Gierlinski et al. 2004;Moreno;Benton 2005;Lockley et al. 2002a;Vila et al. 2008). On the other hand, gauge configurations and shift between different gauge conditions have been largely discussed and turned out to be possibly related to different biological taxa, different ontogeny (e.g. ...
... Walsh et al., 2009, demonstrate a certain correlation between hearing range, complexity of vocalization, and aggregational behaviour in extant reptiles and birds (see also Gleich et al., 2005;Hanson et al., 2021). Following their conclusions and other studies suggesting (age-segregated) gregariousness in sauropodomorphs on the basis of nesting sites, body, and ichnofossils (e.g., Lockley et al., 2002;Sander et al., 2008;Myers and Fiorillo, 2009;Pol et al., 2021a), it appears plausible that Europasaurus lived in groups with conspecifics (although it is not clear whether this took place perennial or seasonal, e.g., for 'brooding'), which made airborne communication crucial. Furthermore, taphonomic reasons (femora count suggests at least 21 individuals in close temporal and spatial connection with very young and very old individuals being rarely represented; Scheil et al., 2018) and evidence for two morphotypes in the cranial and postcranial material of Europasaurus may suggest some form of social cohesion (Carballido and Sander, 2013;Marpmann et al., 2014). ...
... Although Europasaurus represents an island dwarf (adults were probably not as dangerous for their juveniles), having roamed islands not exceeding an area of three times modern-day Bavaria (Sander et al., 2006), this taxon seemingly retained characteristics potentially associated with precociality (and therefore potentially r-strategy; Sander et al., 2008;Myers and Fiorillo, 2009;Hallett and Wedel, 2016) from its large-bodied ancestors. As also suggested by the taphonomic circumstances (Sander et al., 2006;Carballido and Sander, 2013;Marpmann et al., 2014;Scheil et al., 2018; see also Supplementary file 1), Europasaurus individuals likely stayed in a certain social cohesion, and potentially practiced colonial nesting as is known from other sauropodomorphs (Lockley et al., 2002;Sander et al., 2008;Myers and Fiorillo, 2009;Pol et al., 2021a). In concert with the approximate auditory capabilities offered here, our findings add hints towards the nature of aggregation with a certain complexity of reproductive and social behaviours for these little real-life titans, thriving in Europe some 154 Ma ago. ...
Macronaria, a group of mostly colossal sauropod dinosaurs, comprised the largest terrestrial vertebrates of Earth's history. However, some of the smallest sauropods belong to this group as well. The Late Jurassic macronarian island dwarf Europasaurus holgeri is one of the most peculiar and best-studied sauropods worldwide. So far, the braincase material of this taxon from Germany pended greater attention. With the aid of micro-computed tomography (microCT), we report on the neuroanatomy of the nearly complete braincase of an adult individual, as well as the inner ears (endosseous labyrinths) of one other adult and several juveniles (the latter also containing novel vascular cavities). The presence of large and morphologically adult inner ears in juvenile material suggests precociality. Our findings add to the diversity of neurovascular anatomy in sauropod braincases and buttress the perception of sauropods as fast-growing and autonomous giants with manifold facets of reproductive and social behaviour. This suggests that - apart from sheer size - little separated Europasaurus from its large-bodied relatives.
... Several parallel trackways and bone beds evidence have suggested gregarious behaviour for several dinosaur taxa, including ceratopsids, ornithopods, theropods, and sauropods (Gillette and Lockley, 1989;Lockley, 1991;Myers and Fiorillo, 2009). However, the ichnological record provides most of the firm evidence of social behaviours, with many tracksites exhibiting evidence of gregarious behaviour (Lockley et al., 1994a,b;Lockley et al., 2002;Myers and Fiorillo, 2009). The origin and preservation of a track is related to many distinct environmental factors, concerning especially the substrate cohesiveness, plasticity, grain size, texture and water content. ...
... In the sauropod tracks, both pes and manus impressions have been found. They are similar to Brontopodus-like tracks, which are related to titanosauriforms (Lockley et al., 1994b(Lockley et al., , 2002Wilson and Carrano, 1999;Wright, 2005;Marty et al., 2010). Pes impressions are entaxonic and always longer than wide, with a shape that is variable from slightly elliptical to bell shaped, having a narrow "heel" and a wider anterior area. ...
... Some tracksites have also revealed that in some cases herds protected their young by keeping them in the centres of migrating groups (i.e., Thulborn and Wade, 1989;Malkani, 2007;Diedrich, 2010;Romano et al., 2018). The study of trackways can estimate dinosaur's gait and speed and provide information about the way of locomotion of dinosaurs, by measuring the pace and stride, or determine the gregarious behaviour (e.g., Ostrom, 1972; Lockley et al., 2002;Santos, 2008). In the case of the new tracksite described in this study, trackways have not yet been clearly identified, and it is not possible to measure the distance between eventual parallel trackways in order to estimate the speed at which the individual animals were moving as a group. ...
We described a dinosaur tracksite found in the uppermost part of the Areia do Mastro Formation (lowermost Barremian, Lower Cretaceous), located at 1.5 km north of Cabo Espichel (Sesimbra, Portugal). The studied tracks are distributed in a heavily trampled limestone bed which crops out alongside the rocky beach. The studied trampled surface is highly dinoturbated, 541 tracks assigned to sauropods, ornithopods and theropods were identified. The majority of footprints (336) were produced by the herbivores. The dinoturbated level is a micritic nodular limestone, deposited in a very shallow subtidal to intertidal lagoon environment. Due to the intense bioturbation and limited exposed area, it is difficult to clearly define trackways, but the tracks can provide information about the producers and their behaviours. It is inferred that dinosaurs crossed this area at different times; the herbivores (sauropods and ornithopods) may possibly used the coastal area as passage between feeding spots, while carnivores frequented the area to hunt in groups or individually.
... The association of different trackways can provide information about herd speed, direction, size and structure (relative position of juveniles and adults during their movement), and their composition (juvenile-adult relationship) (Lockley 1986;). In South America, herding has been proposed in Brazil (Leonardi 1989;Carvalho 2000), Bolivia (Leonardi 1984(Leonardi , 1989Lockley et al. 2002), and Argentina (González Riga and Ortiz David 2011;Tomaselli 2014). In 1989, Leonardi described some tracksites localities according to their distribution by behavior. ...
... In Toro Toro tracksite, Leonardi (1984Leonardi ( , 1989 described eight parallel trackways of large sauropods (six adults and two juveniles), which walked together in a front of about 200 m. This record represented the first documentation of probable social behavior among Late Cretaceous sauropods (presumably derived lithostrotian titanosaurs) in South America (Lockley et al. 2002). On the other hand, in Humaca tracksite, Lockley et al. (2002) described a social group of at least 11 sub-adult titanosaurs moving in west-southwest direction. ...
... This record represented the first documentation of probable social behavior among Late Cretaceous sauropods (presumably derived lithostrotian titanosaurs) in South America (Lockley et al. 2002). On the other hand, in Humaca tracksite, Lockley et al. (2002) described a social group of at least 11 sub-adult titanosaurs moving in west-southwest direction. The trackmakers were traveling close together, as the total spacing perpendicular to the direction of travel is only 20 m (average spacing about 2 m). ...
After the extinction of rebbachisaurids during the Cenomanian–Turonian interval, titanosaurs were the only group of sauropods to face the K–Pg event. This same global pattern also holds for the end-Cretaceous (Campanian–Maastrichtian) titanosaur record in South America, where their remains can be found from southern Argentina to Ecuador, with more frequent findings in Argentina and Brazil. In this chapter, we review these fossil findings and the main aspects of the taxonomy, systematics, and paleogeographic implications of this record and briefly discuss the importance of these occurrences for the understanding of titanosaur evolution. The diversity and abundance of end-Cretaceous titanosaur taxa in South America represent about 25% of the known Titanosauria species in the world, which makes them the most common group of large terrestrial herbivores of that time. Cretaceous titanosaurs from South America also vary highly in morphology and size, comprising small to large-sized taxa, for example. Their record mainly consists of appendicular and axial remains, including rare skull material, but also comprises eggs, nests, footprints, and coprolites. In South America, by the end of the Late Cretaceous, titanosaurs were generally represented by more derived titanosaurians that are mainly taxonomically assigned to more derived species within Aeolosaurini and Saltasaurinae.
... The association of different trackways can provide information about herd speed, direction, size and structure (relative position of juveniles and adults during their movement), and their composition (juvenile-adult relationship) (Lockley 1986;Myers and Fiorillo 2009). In South America, herding has been proposed in Brazil (Leonardi 1989;Carvalho 2000), Bolivia (Leonardi 1984(Leonardi , 1989Lockley et al. 2002), and Argentina (González Riga and Ortiz David 2011;Tomaselli 2014). In 1989, Leonardi described some tracksites localities according to their distribution by behavior. ...
... In Toro Toro tracksite, Leonardi (1984Leonardi ( , 1989 described eight parallel trackways of large sauropods (six adults and two juveniles), which walked together in a front of about 200 m. This record represented the first documentation of probable social behavior among Late Cretaceous sauropods (presumably derived lithostrotian titanosaurs) in South America (Lockley et al. 2002). On the other hand, in Humaca tracksite, Lockley et al. (2002) described a social group of at least 11 sub-adult titanosaurs moving in west-southwest direction. ...
... This record represented the first documentation of probable social behavior among Late Cretaceous sauropods (presumably derived lithostrotian titanosaurs) in South America (Lockley et al. 2002). On the other hand, in Humaca tracksite, Lockley et al. (2002) described a social group of at least 11 sub-adult titanosaurs moving in west-southwest direction. The trackmakers were traveling close together, as the total spacing perpendicular to the direction of travel is only 20 m (average spacing about 2 m). ...
Forty years ago, L. Branisa and G. Leonardi discovered the first sauropodomorph tracks in South America during expeditions to Toro Toro (Bolivia). Since then, numerous findings, mainly in Argentina, Bolivia, and Brazil, have increased the record. The first research lines mainly covered morphological description, ichnotaxonomic identification, and behavioral analyzes (e.g., gregariousness and speed). Some Cretaceous tracksites allowed the description of three new ichnotaxa: Sauropodichnus giganteus (Calvo in Ameghiniana 28:241–258, 1991), Titanopodus mendozensis (González Riga and Calvo in Palaeontology 52:631–640, 2009), and Calorckosauripus lazari (Meyer et al. in Ann Soc Geol Pol 88:223–241, 2018), the former two corresponding to Argentina, and the latter to Bolivia. A new research line named ‘ichnology and comparative anatomy’ has become relevant in the last years linking the skeletal information to the ichnological record, thus providing an integral interpretation of the set. This kind of approach allowed making more accurate inferences about paleoecological aspects, including limb posture, gauge, gait, speed, and size diversity recorded. In sum, this chapter aims to provide an overview of the South American sauropodomorph ichnotaxonomy, the history of the discoveries, and the results of new research lines in development.
... However, it is worth considering if ontogenetic variation is partitioning these trackways. Trackway ontogenetic variability has been previously suggested by Lockley et al. (2002) but behavioral factors may also play a role in trackway pattern (i.e., such a turning during locomotion; see Swiss examples in Meyer, 1993;Marty, 2008;Stevens et al., 2016, fig. 13.7;and globally Meyer et al., 1994;Mezga and Bajraktarević, 1999;Wright, 2005;Ishigaki and Matsumoto, 2009;Xing et al., 2015a;Goodell et al., 2021;Lockley et al., 2021). ...
Ichnogeneric classification of sauropod trackways is determined using qualitative and quantitative descriptions of morphological parameters. More recently, the validity of several of these parameters has been called into question (e.g., trackway gauge). This paper aims to test traditional and more novel landmark-based geometric morphometric (GM) analysis to describe sauropod tracks and trackways. The Courtedoux-Tchâfouè (TCH) tracksite, in NW Switzerland, has been used as a test site because it hosted several Late Jurassic sauropod track-bearing levels, over a short time period (∼40 ka), creating a time capsule of sauropod activity. Exploratory statistical analyses suggest that the TCH trackway dataset can be partitioned into clusters based on trackway parameters (e.g., width of pes angulation pattern/pes length) that demonstrate differences between trackways. Nevertheless, clustering reflected a moderate degree of intercluster similarity and a continuum in TCH trackway morphologies. The GM analysis of TCH pes impressions, from several trackways, indicates a similar morphotype and did not significantly differentiate pes tracks from various stratigraphic levels. Currently, the results indicate that neither linear nor landmark-based geometric morphometric methods strongly segregate tracks at TCH nor show a time-control (i.e., via stratigraphic level) over the short interval studied. The methods reinforce that sauropod pes impression shape is conservative and that combining morphological methods to be inclusive of sauropod trackway data is important. The TCH site demonstrates that variability may reflect morphological continuums and behavioural factors and does not unambiguously differentiate unique sauropod trackmakers. More exploration on the minimum number of trackway parameters as predictors of sauropod ichnotaxonomy is needed. Integrating complementary techniques will provide more insight and practical means of identification and delineation of sauropod tracks and their trackways.
... The multiple Mussaurus aggregations in the Early Jurassic breeding ground of the Laguna Colorada Formation are interpreted as the oldest skeletal evidence of structured age-segregated gregariousness amongst dinosaurs, pre-dating by over 40 million years reports from Late Jurassic and Cretaceous neosauropods [24][25][26] . Our new findings on Mussaurus adds important insights on the social behaviour of early sauropodomorphs. ...
Sauropodomorph dinosaurs dominated the herbivorous niches during the first 40 million years of dinosaur history (Late Triassic–Early Jurassic), yet palaeobiological factors that influenced their evolutionary success are not fully understood. For instance, knowledge on their behaviour is limited, although herding in sauropodomorphs has been well documented in derived sauropods from the Late Jurassic and Cretaceous. Here we report an exceptional fossil occurrence from Patagonia that includes over 100 eggs and skeletal specimens of 80 individuals of the early sauropodomorph Mussaurus patagonicus, ranging from embryos to fully-grown adults, with an Early Jurassic age as determined by high-precision U–Pb zircon geochronology. Most specimens were found in a restricted area and stratigraphic interval, with some articulated skeletons grouped in clusters of individuals of approximately the same age. Our new discoveries indicate the presence of social cohesion throughout life and age-segregation within a herd structure, in addition to colonial nesting behaviour. These findings provide the earliest evidence of complex social behaviour in Dinosauria, predating previous records by at least 40 My. The presence of sociality in different sauropodomorph lineages suggests a possible Triassic origin of this behaviour, which may have influenced their early success as large terrestrial herbivores.
... In the last three decades, the record of Cretaceous sauropod tracks has been increased significantly in South America , as for example in Bolivia (Leonardi, 1994;Meyer et al., 2001;Lockley et al., 2002a;Meyer et al., 2018;Meyer et al., 2021), Brazil (Leonardi, 1984(Leonardi, , 1989(Leonardi, , 1994Carvalho, 2000;Leonardi and Carvalho, 2002;Leonardi and dos Santos, 2004;de Valais et al., 2015;Carvalho et al., 2021), Chile (Moreno, 2001;Moreno et al., 2004), Colombia (Moreno S anchez et al., 2011) and Peru (Vildoso et al., 2011). Some of the most important discoveries, which are from Argentina, give us information about manus and pes morphology, speed estimation and locomotion of titanosaurs, the largest sauropods from the Cretaceous. ...
A new titanosaur sauropod ichnotaxon named Teratopodus malarguensis gen. et sp. nov is erected based on a unique association of 10 characters. It is represented by new tracks discovered in the upper section of the Anacleto Formation outcropping in the southern Mendoza Province (middle Campanian, Neuquén Basin). Teratopodus diagnosis includes pes tracks with suboval shaped, with a slightly obtuse ‘V-shaped’ heel and three large claws impressions laterally deflected corresponding to the digits I, II and III; and symmetrical kidney-shaped manus tracks with a slightly concave posterior border. Teratopodus has a medium-gauge trackway and a medium degree of heteropody (∼1/3). In addition, a new characterization of the heels impressions in sauropod tracks is proposed here including the postero-latero-medial angle (PLM°); according to this, Teratopodus pes track can be classified into slightly ‘V-shaped’ heel (PLM° = 95°–100°). The trackmakers are two titanosaurs specimens of relatively small-medium sized of ca. 11 m and 14 m length. These tracks are preserved in a poorly drained floodplain deposits with ephemeral channels controlled by flash flood episodes. In this context, the trackmakers walked from a humid ground to a more flooded one, leaving behind one of the best-preserved pes tracks ever recorded in South America.
... This is supported by the similar deformation features identified in the individual tracks of each trackmaker, which indicate similar substrate conditionsparticularly with respect to water content-at the time of track formation. This implies that at least some sauropods in the Winton Formation might have been gregarious, a behaviour implied by several sauropod body fossil deposits (Myers & Fiorillo, 2009;Salgado et al., 2012) and many sauropod trackways around the world (Barnes & Lockley, 1994;Castanera et al., 2011;García-Ortiz & Pérez-Lorente, 2014;Lockley et al., 2002;Lockley et al., 2012;Myers & Fiorillo, 2009;Ostrom, 1972), including several trackways from the Broome Sandstone of Western Australia (Thulborn, 2012). As noted above, the two main trackways (AODF 904.S1 and AODF 904.S2) were not made simultaneously (as they appear to cross over), but little time evidently separated their formation based on their similar quality of preservation. ...
The Upper Cretaceous 'upper' Winton Formation of Queensland, Australia is world famous for hosting Dinosaur Stampede National Monument at Lark Quarry Conservation Park, a somewhat controversial tracksite that preserves thousands of tridactyl dinosaur tracks attributed to ornithopods and theropods. Herein, we describe the Snake Creek Tracksite, a new vertebrate ichnoassemblage from the 'upper' Winton Formation, originally situated on Karoola Station but now relocated to the Australian Age of Dinosaurs Museum of Natural History. This site preserves the first sauropod tracks reported from eastern Australia, a small number of theropod and ornithopod tracks, the first fossilised crocodyliform and ?turtle tracks reported from Australia, and possible lungfish and actinopterygian feeding traces. The sauropod trackways are wide-gauge, with manus tracks bearing an ungual impression on digit I, and anteriorly tapered pes tracks with straight or concave forward posterior margins. These tracks support the hypothesis that at least one sauropod taxon from the 'upper' Winton Formation retained a pollex claw (previously hypothesised for Diamantinasaurus matildae based on body fossils). Many of the crocodyliform trackways indicate underwater walking. The Snake Creek Tracksite reconciles the sauropod-, crocodyliform-, turtle-, and lungfish-dominated body fossil record of the 'upper' Winton Formation with its heretofore ornithopod-and theropod-dominated ichnofossil record.
... On the other hand, the Humaca (Ore-Pájla) tracksite was discovered by David Kerumba Mamani in 1995. Lockley et al. (2002) described eleven parallel sauropod trackways belong to the Santonian-late Campanian Chaunaca Formation and compared them with other Maastrichtian sauropod tracksites as Cal Orck'o, Toro-Toro (Bolivia) and Fumanya (Spain) sites (Schulp and Brokx, 1999). They analyzed aspects such as sauropod social behavior and paleoecological and paleoenvironmental contexts. ...
The ichnological Cretaceous sauropod record of South America is analyzed for the first time in relation with skeletal and paleoenvironmental data. The updated database includes 39 tracksites and 71 valid species (53 titanosaurs and 18 non-titanosaurs) from Colombia, Ecuador, Peru, Chile, Brazil and Argentina. The track and bone records analyzed evidence a relationship with continental environments, specifically with fluvial ones. This is observed in all Sauropoda records, indicating an ecological association of the Cretaceous sauropods for these environments. In addition, the paleogeographic reconstruction integrating these records does not evidence any correlation between the distribution of sauropods and the latitudinal range. During the late Campanian–Maastrichtian interval, when the Atlantic transgression event was established, the titanosaur record started to show a singular panorama. The tracksites are preserved not only in continental paleoenvironments but also in marginal-marine ones, being the only last records of titanosaurs associated with that environment in South America. Both the paleoecological aspects based on sauropod Cretaceous record and the paleoenvironmental data collected in this work support the hypothesis that these tracksites were used by titanosaurs as ‘transit areas’ to move among the environments they inhabited.
