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Behavior of hadrosaurs as interpreted from footprints in the "Mesaverde" Group (Campanian) of Colorado, Utah, and Wyoming

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... Tracks have the additional capacity to reveal possible morphological changes (particularly of soft tissue) and gait changes associated with growth, although unequivocal referral of different sized or shaped prints to a single taxon (or ichnotaxon) is difficult (Hornung et al., 2016). Among dinosaurs, possible ontogenetic changes have been proposed on the basis of ichnology for some non-avian theropods (Olsen, 1980;Olsen et al., 1998;Clark et al., 2005;Pascual-Arribas and Hernández-Medrano, 2011), ornithopods (Currie and Sarjeant, 1979;Carpenter, 1992;Lockley, 1994;Matsukawa et al., 1999;Hornung et al., 2016), and a nodosaurid (McCrea et al., 2014a:fig. 68). ...
... To date, tracks attributed to tyrannosaurids have been reported from Canada, the U.S.A., Mexico, China and Mongolia (e.g., Lockley, 1988;Carpenter, 1992;Currie et al., 2003;Manning et al., 2008;Ishigaki et al., 2009;Lockley et al., 2011a;McCrea et al., 2005McCrea et al., , 2014aMcCrea et al., , 2014bSmith et al., 2016;Rivera-Sylva et al., 2017;Nakajima et al., 2018;Xing et al., 2019; see Supplementary Material for a review). Most of these tracks exceed 45 cm in length and were presumably produced by subadult or adult animals based on their large size. ...
... In order to explore whether the results of our Wapiti Formation dataset reflect broader patterns within tyrannosaurids, a further eight tracks attributed to tyrannosaurids from other geological contexts were selected from the literature and incorporated into a second (global) geometric morphometric analysis (Fig. S1). These include tracks from Lockley (1988), Carpenter (1992, fig. 2), the figured outline shows wider digital impressions and more anterior hypices than what we interpret from the provided photographs. ...
Article
Fossil tracks should theoretically capture differences in pedal anatomy between growth stages of the same taxon, particularly those related to the soft tissue of the foot, providing a more realistic view of pedal ontogeny than skeletal material alone. However, recognizing these ontogenetic trajectories is complicated by the influence of preservation and kinematics on track morphology, as well as the inherent difficulty of referring different tracks to a single taxon. Here, we explore differences in track morphology from a collection of tracks attributed to tyrannosaurids from Unit 4 of the Wapiti Formation (upper Campanian) in western Canada. Along with morphology, close geographic and stratigraphic associations suggest that the tracks pertain to similar tyrannosaurid trackmakers. A geometric morphometric analysis of the track outlines reveals size-dependent increase in relative track robusticity, driven primarily by an increase in 'heel' breadth and surface area. This relationship is lost when the dataset is expanded to include tyrannosaurid tracks globally, which we attribute to increased stratigraphic and taxonomic 'noise' within the global dataset that masks the tightly constrained patterns obtained from the Wapiti Formation tracks. Although there is some substrate and kinematic influence on certain aspects of track morphology, we hypothesize that the observed size-dependent relationship reflects genuine expansion in the breadth of the heel soft tissues and probably their overall surface area associated with growth. Increased pedal robusticity likely assisted with weight bearing and locomotor stability as body mass increased over ontogeny, supporting previous hypotheses that some tyrannosaurids underwent a growth-related reduction in relative agility and/or cursorial performance.
... A variety of tetrapod tracks are known from the Blackhawk Formation and a number of other rock units that make up the larger stratigraphic unit known as the "Mesaverde" Group sensu lato (Carpenter, 1992). The Mesaverde Group is well known as a coal-bearing sequence, interpreted as part of a wave-dominated delta system along the coastal plain of the Cretaceous Western Interior Seaway. ...
... Because most of these were never studied in context, much of the early 20 th century literature was anecdotal and of limited scientific interest (Peterson, 1924;Strevell, 1932;Brown, 1938;Look, 1951Look, , 1955Bird 1985). It has only been since the 1980s that descriptions of tetrapod tracks from the Mesaverde Group have appeared in the scientific literature (Lockley et al., 1983(Lockley et al., , 20112018a;Balsley, 1986, 1989;Parker and Rowley, 1989;Robison, 1991;Lockley, 1999;Carpenter, 1992;Lockley and Foster, 1993). These reports have dealt mostly with dinosaur tracks, identified only generally as hadrosaurian, theropodan or ceratopsian (e.g., Parker and Balsley, 1989;Carpenter, 1992;Lockley and Hunt, 1995a). ...
... It has only been since the 1980s that descriptions of tetrapod tracks from the Mesaverde Group have appeared in the scientific literature (Lockley et al., 1983(Lockley et al., , 20112018a;Balsley, 1986, 1989;Parker and Rowley, 1989;Robison, 1991;Lockley, 1999;Carpenter, 1992;Lockley and Foster, 1993). These reports have dealt mostly with dinosaur tracks, identified only generally as hadrosaurian, theropodan or ceratopsian (e.g., Parker and Balsley, 1989;Carpenter, 1992;Lockley and Hunt, 1995a). Non-dinosaurian tracks have been placed in unnamed categories, such as bird and frog (Robison, 1991). ...
Article
The only described Cretaceous frog tracksite known from North America, from outcrops of the Blackhawk Formation in Meetinghouse Canyon, Utah, had previously, additionally yielded only a small number relatively large, unnamed tetradactyl avian theropod (bird) tracks. Unnamed avian dinosaur (bird) and non-avian dinosaur tracks had also been reported from the nearby locality of Straight Canyon. These two localities were revisited with the aim of collecting additional material, with the result that a third site was discovered. Collectively, tracks of avian and non-dinosaurs, pterosaurs, crocodylians and turtles were discovered, together with invertebrate traces. These include representatives of the following ichnogenera (with inferred trackmaker in parentheses): grallatorid similar to Kalohipus (non-avian theropod), Saurexallopus (?avian or non-avian theropod), Hadrosauropodus isp. (hadrosaur), Ceratopsipes isp. (ceratopsian), Pteraichnis isp., (pterosaur), Mehliella and Hatcherichus (crocodylian), Chelonipus (turtle) and Ranipes (frog). This tetrapod ichnodiversity of nine ichnogenera is one of the highest known for any Cretaceous formation.
... Hadrosaurids-Closely associated and aligned large ornithopod trackways are a long-documented phenomenon known from Cretaceous tracksites around the world (e.g., [2,3,77,[111][112][113][114][115]). Skeletal and other evidence, including rare nesting sites (e.g., [116][117][118]) and common hadrosaurid-dominated bonebeds (e.g., [20,25,[119][120][121][122][123]) further indicate widespread herding behaviour among these dinosaurs. ...
... Alaskan ichnoassemblages within the Chignik and lower Cantwell formations are most often dominated by Hadrosauropodus, although the latter unit is probably early Maastrichtian in age [29,31,32]. Similarly, late Campanian track horizons within the Oldman, Dinosaur Park, Horseshoe Canyon, and St. Mary River formations of southern Alberta, as well as the 'Mesaverde Group' of Utah, Wyoming, Colorado, and the Fruitland Formation of New Mexico, are all hadrosaurid-dominated [3,43,60,75,87,[145][146][147][148][149][150][151][152][153] and references therein] (Fig 16). In Mexico, ichnofaunas of the Cerro del Pueblo Formation are hadrosaurid-dominated in terms of footprint abundance, although theropod tracks occur at a larger number of tracksites [139,[154][155][156]. ...
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The Wapiti Formation of northwest Alberta and northeast British Columbia, Canada, preserves an Upper Cretaceous terrestrial vertebrate fauna that is latitudinally situated between those documented further north in Alaska and those from southern Alberta and the contiguous U.S.A. Therefore, the Wapiti Formation is important for identifying broad patterns in vertebrate ecology, diversity, and distribution across Laramidia during the latest Cretaceous. Tracksites are especially useful as they provide a range of palaeoecological, palaeoenvironmental, and behavioural data that are complementary to the skeletal record. Here, we describe the Tyrants Aisle locality, the largest in-situ tracksite known from the Wapiti Formation. The site occurs in the lower part of Unit 4 of the formation (~72.5 Ma, upper Campanian), exposed along the southern bank of the Redwillow River. More than 100 tracks are documented across at least three distinct track-bearing layers, which were deposited on an alluvial floodplain. Hadrosaurid tracks are most abundant, and are referable to Hadrosauropodus based on track width exceeding track length, broad digits, and rounded or bilobed heel margins. We suggest the hadrosaurid trackmaker was Edmontosaurus regalis based on stratigraphic context. Tyrannosaurids, probable troodontids, possible ornithomimids, and possible azhdarchid pterosaurs represent minor but notable elements of the ichnofauna, as the latter is unknown from skeletal remains within the Wapiti Formation, and all others are poorly represented. Possible social behaviour is inferred for some of the hadrosaurid and small theropod-like trackmakers based on trackway alignment, suitable spacing and consistent preservation. On a broad taxonomic level (i.e., family or above), ichnofaunal compositions indicate that hadrosaurids were palaeoecologically dominant across Laramidia during the late Campanian within both high-and low-latitude deposits, although the role of depositional environment requires further testing.
... Gregarious behaviour among dinosaurs has been inferred from parallel trackways in various groups (e.g. Ostrom 1972;Currie and Sarjeant 1979;Currie 1983;Carpenter 1992;Barnes and Lockley 1994;Cotton et al. 1998;Heredia et al. 2020). Based on the body-fossil evidence, gregarious behaviour has been assumed in several studies of ornithopods (e.g. ...
... The Upper Jurassic record is found in Spain and Portugal, and is characterized by small, medium and large theropod (Grallator, Eubrontes, Kayentapus-Megalosauripus and undetermined ichnogenus), small and medium ornithopod (Anomoepus and undetermined ichnogenus), large sauropod (Brontopodus, Parabrontopodus and undetermined ichnogenus), medium to large stegosaur (Deltapodus) and medium to large undetermined dinosaurs tracks (Santisteban et al. 2007;Piñuela Suárez 2015;Piñuela et al. 2016;Rauhut et al. 2018;de Souza Carvalho et al. in press). During the Lower (Lockley et al. 1983(Lockley et al. , 2011(Lockley et al. , 2017(Lockley et al. , 2018Lockley and Conrad 1989;Carpenter 1992;Lockley and Hunt 1995;Rylaarsdam et al. 2006;González Riga and Calvo 2009;González-Riga et al. 2015;Flaig et al. 2018). ...
Article
Albian dinosaur tracks from the Monte Grande Formation (Basque-Cantabrian Basin) are described. Sedimentary succession shows seven different facies associations (FA) with four track-bearing levels (levels 1-4) of a braid delta system. The FA4, a proximal crevasse subdelta, preserves in levels 2 and 3 theropod, possibly sauropod and undetermined dinosaur tracks, as well as Ophiomorpha and Skolithos traces. The FA5, a middle crevasse subdelta, presents undetermined cross-section tracks in levels 1 and 4, besides Ophiomorpha , Skolithos and locally Teichichnus in other layers. Both FA have the same general ichnoassociation, although with preservational variations. The sedimentary succession represents an area with periods of crevasse subdelta progradation and colonisation of opportunistic organisms, and other periods of subdelta abandonment represented by short sedimentary hiatuses in which the water sheet would be shallow or even absent and where dinosaurs would be roaming. Particularly, the traces of levels 2 and 3 represent the same ichnocoenosis constituting two different suites and may be envisaged as penecontemporaneous, produced within a short term preservational window. This tracksite is one of the scarce Albian dinosaur ichnological records in the southwestern European island palaeoarchipelago and one of the few worldwide localities where Albian dinosaur tracks have been found in deltaic facies.
... The possible gregarious behavior of dinosaurs has been reported many times, such as multiple (sub-) parallel trackways, the congregation of eggs and nests, or the concentration of skeletons of a single or similar species (Ostrom, 1972;Horner and Makela, 1979;Currie, 1998;Kobayashi and Lü, 2003). Although there are many reports on multiple parallel ornithopod trackways in the world, most of them were imprinted by only adults or a mixed group of adults and juveniles (Carpenter, 1992;Matsukawa et al., 2001;Zhang et al., 2006;Xing et al., 2007Xing et al., , 2015Kim et al., 2009;Lockley et al., 2012c;Fiorillo et al., 2014;Piñuela et al., 2016). Although evidence of the juvenile communities had been reported among various dinosaur taxa such as ornithomimids, sauropods, and ceratopsians based on their body fossils (Varricchio et al., 2008;Myers and Fiorillo, 2009;Zhao et al., 2013), the ichnological evidence for proving is relatively rare in ornithopod dinosaurs. ...
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A new dinosaur tracksite with footprints of non-adult ornithopods was discovered from the Lower Cretaceous Haman Formation (Albian), Gunbuk District, Haman County, South Gyeongsang Province of South Korea in 2018. The tracksite consists of 58 ornithopod footprints (seven short trackways and 26 isolated footprints) within three track-bearing horizons partially exposed on the small creek bottom. Lithofacies and sedimentary structures of the track-bearing horizons and overlying strata suggest a marginal lacustrine environment. All tracks are sub-symmetrical tridactyl and small-to medium-sized pes prints. They have wide, blunt, short digital impressions with a large, rounded heel pad impression. No manus print is observable in the tracksite. Tracks are generally longer than their width with a distinctly developed digit III. Trackways show the inward (negative) rotation of footprints. The morphological characteristics of the footprints are most likely attributable to ichnogenus Caririchnium. A relatively small pes size (lengths range from 13 to 27 cm) indicates that the trackmakers were juvenile to subadult ornithopods when compared with the contemporary large ornithopods in South Korea. The majority of the trackways show preferred orientations with trends of parallel to subparallel groupings on each surface, suggesting gregarious behavior. Notably, the tracksite consists exclusively of juvenile ornithopod dinosaurs, which is an uncommon phenomenon when compared to other ornithopod tracksites with age-mixed or large ornithopod footprints reported from other localities around the world. The absence of the adult ornithopod tracks may be interpreted as the spatial segregation of an ornithopod population based on their ages and the formation of juvenile-only communities without parental care.
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Located in Iron County, Utah, the Parowan Gap dinosaur track site contains over one hundred natural casts of non-avian dinosaur tracks preserved in sandstones and siltstones of the Late Cretaceous (≈83 Ma) Iron Springs Formation. For this study, the authors returned to the area to survey for and describe previously unidentified tracks. Many tracks from this new study occur as in situ casts found on the basal surfaces of sandstones deposited by braided and meandering rivers on the coastal plain of the Western Interior Seaway, with some specimens from fallen talus blocks. Over the course of two years, the research team identified and recorded a total of 31 specimens. The results comprise tracks that resemble a minimum of at least five ichnotaxa including Caririchnium, Amblydactylus, Ceratopsipes, Magnoavipes, and Dromaeosauripus. The most common and well-recognized ichnogenus recorded in the Iron Springs Formation is Caririchnium, which likely represents ornithopod dinosaurs. We also identified two Ceratopsipes tracks in a fallen sandstone block. The pair of tracks are significant because they are the second set from the ichnotaxa found at Parowan Gap. Together the Parowan Gap Ceratopsipes samples represent the oldest ceratopsian tracks in Utah. The potential Dromaeosauripus specimen represents a small theropod dinosaur. This specimen is of great interest because theropod tracks, especially dromaeosaur tracks, are less common in the Iron Springs Formation, with a total of seven tracks reported from previous studies. If this is an appropriate interpretation, it would make the potential Dromaeosauripus track the youngest dromaeosaur trace fossil in Utah.
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The Coniacian-Santonian stages in western North America are characterized by a sparse fossil record. We present here the first account of dinosaur tracks from nine sites in the Frontier Formation (Coniacian-Santonian) of southwestern Montana. Tracks are largely preserved in distal alluvial facies as sandstone casts, with a single example of shallow epirelief impression interpreted as undertrack. Sandstone casts show significant relief, kinematic features (i.e., scale marks), and variable morphologies, arguing for a strong substrate control on their preservation. Putative producers are assigned to ornithopod, ankylosaurian, and theropod dinosaurs in decreasing order of abundance. This record reflects a composition similar to those of other middle Cretaceous formations in North America. Moreover, ankylosaurian tracks of the Frontier Formation represent the first known from Coniacian strata in North America. The incorporation of body and trace fossils yielded by the Frontier Formation indicates the presence of a fauna with North American endemic elements. The establishment of Coniacian-Santonian dinosaurian palaeocommunities akin to those observed in Campanian and Maastrichtian formations may reflect the trend towards provincialism attested for the end of the Mesozoic in North America.
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The dinosaur track record features numerous examples of trackways with elongated metatarsal marks. Such ‘elongate tracks’ are often highly variable and characterized by indistinct outlines and abbreviated or missing digit impressions. Elongate dinosaur tracks are well-known from the Paluxy River bed of Texas, where some have been interpreted as ‘man tracks’ by creationists due to their superficially human-like appearance. The horizontal orientation of the metatarsal marks led to the now widely accepted idea of a facultative plantigrade, or ‘flat-footed’, mode of locomotion in a variety of dinosaurian trackmakers small to large. This hypothesis, however, is at odds with the observation that elongate tracks do not indicate reduced locomotion speeds and increased pace angulation values, but instead are correlated with low anatomical fidelity. We here interpret elongate tracks as deep penetrations of the foot in soft sediment. Sediment may collapse above parts of the descending foot, leaving a shallow surface track that preserves a metatarsal mark. The length of a metatarsal mark is determined by multiple factors and is not necessarily correlated with the length of the metatarsus. Other types of posterior marks in dinosaur footprints, such as drag and slip marks, are reviewed.