An Addition to the Dinosaur Freeway Megatracksite,Dakota Group (Upper Cretaceous), Bent County,Colorado

A newly discovered dinosaur tracksite in the Upper Cretaceous Dakota Group of southeastern Colorado preserves tracks attributable to ornithopod, theropod, and possibly ankylosaurid dinosaurs. Minimally 79 tracks occur at the site, and are comprised predominantly of ornithopod prints preserved as natural sandstone casts. Nine ornithopod tracks are preserved in situ, and all but one of these trends in a northeasterly direction. The high density of ornithopod tracks coupled with the similar trend of those in situ suggest gregarious behavior. Size distribution of the ornithopod tracks indicates that some juveniles are present, with sub-adults most abundant and lesser numbers of mature adults. Considerable size variation exists within the nine in situ tracks with similar trends. Thus, the site could record the passage of a mixed herd composed of several age classes. This may be the only reported Dakota tracksite where ornithopod, theropod, and ankylosaurid prints occur together.     

Behaviour of Dinosaurian Track-Makers in the Winton Formation (Cretaceous,Albian–Cenomanian) at Lark Quarry,Western Queensland,Australia: Running or Swimming?

A remarkable assemblage of dinosaur trackways in the Winton Formation (Albian–Cenomanian) at Lark Quarry, in western Queensland, Australia, has long been regarded as evidence of a stampede involving small theropods, whose tracks were classified in the ichnogenus Skartopus, and small ornithopods, whose tracks represented a second ichnogenus, Wintonopus. However, one recently-published study has claimed that existing interpretation of Lark Quarry is incorrect: it maintains that all the track-makers were ornithopods, that the ichnogenus Skartopus is a variant form of Wintonopus, and that most of the Lark Quarry track-makers were not running but more probably swimming downstream in a current of water. Those iconoclastic claims are investigated here and shown to be untenable. They derive from overgeneralized interpretation of the Lark Quarry track assemblage and invoke ad hoc auxiliary hypotheses which are either untestable or demonstrably incorrect. Closer inspection of the evidence underpinning those claims corroborates the existing interpretation of Lark Quarry as the site of a dinosaurian stampede and confirms the validity of the original distinction between theropod tracks (Skartopus) and ornithopod tracks (Wintonopus).     

Dinosaur Tracks from the Cedar Mountain Formation (Lower Cretaceous), Arches National Park,Utah

The seventh and largest known dinosaur tracksite from the Cedar Mountain Formation is reported from two important stratigraphic levels in the Ruby Ranch Member within the boundaries of Arches National Park. Previous reports of sites with a few isolated tracks are of limited utility in indicating the fauna represented by track makers. The Arches site reveals evidence of several theropod morphotypes, including a possible match for the coelurosaur Nedcolbertia and an apparently didactyl Utahraptor-like dromeosaurid. Sauropod tracks indicate a wide-gauge morphotype (cf. Brontopodus). Ornithischian tracks suggest the presence of an iguandontid-like ornithopod and a large ankylosaur. Dinosaur track diversity is high in comparison with other early Cretaceous vertebrate ichnofaunas, and it correlates well with faunal lists derived from skeletal remains, thus providing a convincing census of the known fauna.     

Aptian dinosaur footprints from the Apulian platform (Bisceglie,Southern Italy) in the framework of periadriatic ichnosites

New dinosaur tracks have been found near Bisceglie (Bari, Apulia), on loose blocks ascribed to the Corato Member (late Bedoulian to early Gargasian) of the Calcare di Bari Fm. The material consists of isolated footprints as well as of short trackways of quadrupedal and bipedal dinosaurs. The new tracksite has yielded a quite differentiated dinosaur ichnocoenosis, including theropod, sauropod, thyreophoran and ornithopod footprints.The discovery of early Aptian dinosaur footprints in the limestone of the carbonate platform of southern Italy gives new insights on dinosaur distribution, and new palaeontological constraints for the palaeogeographic reconstruction of the Mediterranean Tethys during the Cretaceous. The analysis of this and others ichnosites of the periadriatic carbonate platforms, gives evidence of repeated emersions and of widespread land-vertebrates dwelling. The characteristics of the associations suggest that the trackmakers did not constitute a real coevolved association but the occasional co-occurrence of taxa after migration.The results emphasize the need of both structural and environmental continuity and walking ways between a southern continent and the periadriatic carbonate platforms during the Early Cretaceous.     

Two new dinosaur tracksites from the Lower Cretaceous Jiaguan Formation of Sichuan Basin,China: specific preservation and ichnotaxonomy

Two new dinosaur tracksites are reported from the Lower Cretaceous Jiaguan Formation in the Sichuan Basin, Qijiang District of Chongqing. These are the Gaoqing-Yongsheng and the Huibu tracksites, which represent the 13th and 14th reports from this formation. The Gaoqing-Yongsheng tracksite reveals the trackway of a large biped (ornithopod) in association with isolated sauropod tracks and large indeterminate undertracks with radial cracks. These features are preserved as natural casts with pebble infillings in a coarse, cross bedded and very thick bedded sandstone sequence. The Huibu tracksite reveals isolated theropod tracks and ornithopod tracks, the latter having a quadripartite, Caririchnium-like morphology, preserved in a thin bedded sandstone sequence with intercalated mudstone.     

Dinosaur Tracks,Myths and Buildings: The Jin Ji (Golden Chicken) Stones from Zizhou Area,Northern Shaanxi,China

For centuries, dinosaur footprints have influenced popular legends and myths in the surroundings of important tracksites. In many regions of China, track-bearing slabs were utilized as building materials and integrated in houses, yards, or cave dwellings, often serving as auspicious symbols or aesthetic decorations. Special birds such as the golden pheasant, widely distributed in China, may have inspired people to consider them as mythic trackmakers. The Zizhou area in northern Shaanxi, China, is famous for tracksites in the lower portion of the early Middle Jurassic Yan'an Formation. Sandstones with dinosaur tracks from these localities have been collected since the Ming Dynasty (1368–1644) and are used by villagers as cellar covers, stalls, or millstones. Besides their historical importance, the slabs are a valuable resource for ichnological research. Well-preserved theropod, ornithopod, and stegosaur tracks such as Kayentapus, Eubrontes, Anomoepus and Deltapodus incorporated into manmade structures can be seen while simply walking through some small villages of this area.     

Review of Dinosaur Tail Traces

Since 1858, when Hitchcock first recorded dinosaur tail traces from the Jurassic of Massachusetts, USA, a number of dinosaur tail traces have been reported. Although considered rare, at least 38 records of dinosaur tail traces have previously been reported in the literature. These occurrences are herein reviewed in order to understand their geographic and stratigraphic distribution, types of tail trace makers, and characteristics of dinosaur tail traces. Several terms for dinosaur tail traces have been employed and they are divided into tail impressions (TIs) for resting traces, and tail drag impressions (TDIs) for locomotion traces. Possible criteria for distinguishing, measuring and comparing TIs and TDIs are suggested. In addition, herringbone structures, one of the characteristic features of tail traces associated with ornithopod and theropod tracks, are discussed. Estimated speeds of tail trace makers are shown to be rather low. Finally, the abundance of tail traces associated with bipedal, rather than quadrupedal, dinosaurs is considered a reflection of behavior.     

Hints of the Early Jehol Biota: Important Dinosaur Footprint Assemblages from the Jurassic-Cretaceous Boundary Tuchengzi Formation in Beijing,China

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 ichnofaunas 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 ornithischian tracks cannot be positively confirmed. Purported occurrences are re-evaluated here, the trackways and imprints, except of a single possible specimen, re-assigned to theropods. Palecologically the Tuchengzi ichnofauna is characteristic of semi-arid fluvio-lacustrine 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.     

The Fossil Record of Vertebrate Tracks in Mexico

The fossil record of vertebrate tracks in Mexico is taxonomically rich and geographically diverse, and ranges in age from Middle Jurassic to Pleistocene and possibly Holocene. Middle Jurassic saurischian dinosaur tracks from Oaxaca represent the oldest record of vertebrate tracks in Mexico. Tracks attributed to Late Jurassic theropods and ornithopods are known from Michoacán. Theropod tracks of supposed Jurassic age are known from Durango. Lower Cretaceous Saurischian and ornithopod tracks are known from southern Puebla. Central Mexico has yielded Late Cretaceous hadrosaurid and sauropod tracks (Puebla), and tracks belonging to Theropoda and Ornithopoda (El Aguaje, Michoacan). In Coahuila several tracksites occur within the Cerro del Pueblo Formation and include tracks of mesoreptiles, pterosaurs, small to large theropods, bipedal and quadrupedal ornithopods, birds and possibly a mammal. A tracksite in the Olmos Formation includes tracks of turtles, crocodilians, medium-sized theropods, small ornithopods, and birds. Bird tracks of supposed Eocene age are known from Sinaloa. Two important Pleistocene ichnofaunas occur in the states of Puebla (Tepexi de Rodríguez) and Jalisco (San Juan de los Lagos), and include tracks of camelids, artiodactyls, small ungulates, elephants, large felids and birds. Pleistocene human tracks occur in Coahuila and Jalisco. Mexico's track record provides important insights into vertebrate diversity, paleoecology, and paleoenvironments. Given the rate of new discoveries since 1998, there is no doubt that new sites await to be found.     

Late Jurassic footprints reveal walking kinematics of theropod dinosaurs

Avanzini, M., Piñuela, L. & García‐Ramos, J.C. 2011: Late Jurassic footprints reveal walking kinematics of theropod dinosaurs. Lethaia, Vol. 45, pp. 238–252. This study describes a set of theropod footprints collected from the Late Jurassic Lastres Formation (Asturias, N Spain). The footprints are natural casts (tracks and undertracks) grouped into three morphotypes, which are characterized by different size frequency, L/W relationship and divarication angles: ‘Grallatorid’ morphotype, ‘Kayentapus–Magnoavipes’ morphotype, ‘Hispanosauropus’ morphotype. The tracks were produced in firm, stiff and soft sediments. The infills of deep tracks, which are typically formed in soft mud, lack fine anatomical details, but they can reveal the walk kinematics of the trackmaker through the morphology of internal track fills and sinking traces. In all footprints, a horizontal outwardly directed translation movement and rotation are recognizable. The amount and geometry of digit penetration in the ground also show a pronounced difference. It can be inferred from the described sample that different theropoda‐related ichnogenera share common kinematics. □Asturias, dinosaur footprint, late jurassic, theropods, walking kinematics.     

New dinosaur tracksites from the Middle Jurassic of Madagascar: ichnotaxonomical,behavioural and palaeoenvironmental implications

Abstract: New dinosaur tracksites are described from the Bajocian–Bathonian Bemaraha Formation of western Madagascar. Two track‐bearing surfaces can be followed over a distance of at least 4 km, suggesting the existence of a hitherto unrecognized megatracksite. The track assemblage is theropod dominated, but sauropod tracks also occur at one site. Qualitative and quantitative analysis of the abundant theropod track material suggests that most, if not all, theropod footprints are attributable to a single trackmaker and are referred to Kayentapus isp. Although this ichnogenus, originally described from the Lower Jurassic of North America, has never been recorded from Gondwana nor from the Middle Jurassic, track morphology strongly suggests this attribution. Palaeogeographical, sedimentological and ichnological data suggest that the dinosaur tracks formed in an intertidal to supratidal setting where the coastline influenced the preferred walking direction of the animals.     

A Diverse Dinosaur-Bird Footprint Assemblage from the Lance Formation,Upper Cretaceous,Eastern Wyoming: Implications for Ichnotaxonomy

A diverse assemblage of dinosaur and bird tracks from Niobrara County, Wyoming, represents the first vertebrate ichnofauna reported from the bone-rich Lance Formation (Maastrichtian, Upper Cretaceous). The ichnofauna includes a hadrosaur track with skin impressions; three theropod track types, including the tetradactyl track Saurexallopus zerbsti (ichnosp. nov.); a tridactyl dinosaur footprint with a fusiform digit III; possible Tyrannosaurus tracks; four distinctive avian ichnites; and invertebrate traces. The footprints are generally well-preserved and so offer a unique insight into the ecology of a small river valley during the Maastrichtian.

Saurexallopus zerbsti ichnosp. nov. from the Lance is similar to Saurexallopus lovei recently reported from the Maastrichtian, Harebell Formation, of northwestern Wyoming, but is represented by much better material, facilitating amendment of the ichnogenus. Skeletal equivalents for Saurexallopus are not currently known. Similarly, the tridactyl track with fusiform digit III is similar to footprints reported from the coeval Laramie Formation of Colorado and may also be similar to ichnogenus Ornithomimipus from the Edmonton Group of Alberta (though not necessarily of ornithomimid affinity). The hadrosaurian track with the skin impression is reminiscent of a similar ichnite reported from the Maastrichtian, St. Mary River Formation in Alberta, which is herein named Hadrosauropodus langstoni as part of a reassessment of Cretaceous ornithopod track ichnotaxonomy. Such correlations demonstrate the utility of tracks for local or regional biostratigraphy (palichnostratigraphy) in western North America. It is also clear that tracks add to our knowledge of the composition and distribution of dinosaurian and avian components of Maastrichtian faunas. In particular the bird tracks indicate a diversity of at least four species, one of which was a semi-palmate form, hitherto unknown in the ichnological record and named Sarjeantichnus semipalmatus.     

Los Cayos Dinosaur Tracksite: An Overview on the Lower Cretaceous Ichno-Diversity of the Cameros Basin (Cornago,La Rioja Province,Spain)

The Los Cayos dinosaur tracksite is located at the eastern sector of the Cameros Basin (Cornago Township, La Rioja province), NE Spain. The sediments consist of interbedded terrigenous siliciclastics and carbonates belonging to the Enciso Group (Early Cretaceous, Aptian in age). The sedimentological and faunal evidence suggests that these sediments were deposited in a low gradient lacustrine environment. Los Cayos constitutes a relatively wide area with at least 6 localities that have yielded dinosaur tracks. More than 2,000 dinosaur tracks have been discovered to date. Medium to large theropod dinosaurs constitute about 95% of the ichnofauna. Ornithopod dinosaur tracks have been reported from only one of the outcrops (Los Cayos D). Los Cayos S has yielded theropod and sauropod tracks. One sauropod trackway shows a narrow-gauge locomotion pattern and a manus print morphology suggesting that the trackmaker was a titanosaurid, or at least a titanosauriform sauropod. Some pterosaur manus impressions, avian-like footprints of small size and possible turtle tracks complete the assemblage of one of the most impressive and best-preserved dinosaur tracksites of the European Lower Cretaceous.     

Ecology,Systematics and Biogeographical Relationships of Dinosaurs,Including a New Theropod,from the Santana Formation (?Albian,Early Cretaceous) of Brazil

Although rare, dinosaurs are well preserved in calcareous nodules of the Santana Formation (Early Cretaceous, ?Albian) of the Araripe Basin, in northeastern Brazil. So far, including only a spinosauroid and three coelurosaurs, the dinosaur fauna appears depauperate. High theropod diversity in assemblages where other dinosaurs are rare or absent is not unique to the Santana Formation. It is seen also in several other assemblages, including Solnhofen and the Maevarano Formation of Madagascar. We consider several factors, including the occurrence of intraguild predation, the possibility that small theropods could subsist in marginal environments, and reliance on coastal resources, that may have been responsible for this apparent ecological imbalance. A new coelurosaur from the Santana Formation, here formally named Mirischia asymmetrica, is shown to be distinct from Santanaraptor placidus [Kellner, A.W.A. () “Short note on a new dinosaur (Theropoda, Coelurosauria) from the Santana Formation (Romualdo Member, Albian) northeastern Brazil”, Boletim do Museu Nacional, Nova Serie, Rio de Janeiro, Brasil 49, 1–8]. Other theropods from the Santana Formation are briefly reviewed. Mirischia is a compsognathid, more similar to the European Compsognathus than to the Asian Sinosauropteryx.     

Theropod and possible ornithopod track assemblages from the Jurassic–Cretaceous boundary Houcheng Formation,Shangyi, northern Hebei,China

Dinosaur track assemblages from the Houcheng Formation in the small continental Shangyi Basin of northern Hebei Province, China bridge a gap in the record of vertebrates from this unit and enrich our knowledge of ichnofaunas from the Jurassic–Cretaceous boundary. Their stratigraphic position between the Middle Jurassic Yan-Liao Biota and the Lower Cretaceous Jehol Biota gives them a special importance. New discoveries allow a re-assessment of theropod and possible ornithopod tracks that are present with several trackways. Seventy-three footprints were examined and documented. Despite their smaller size, the tridactyl mesaxonic theropod tracks show morphological similarities with the ichnogenus Therangospodus known from the Upper Jurassic deposits of North America, Europe, and Central Asia. The possible ornithopod tracks lack an associated manus imprint, suggesting a bipedal trackmaker. These possible ornithopod tracks from the Houcheng Formation provide evidence for the presence of small basal ornithopods or basal Cerapoda in the Upper Jurassic–Lower Cretaceous in this region. The depositional environment was the margin of an extensive shallow lake with fluctuating water levels under seasonally dry climate.     

The First Iguanodontid Dinosaur Tracks from the Swiss Alps (Schrattenkalk Formation,Aptian)

Until now dinosaur tracks from Switzerland were only known from Triassic and Late Jurassic strata. We report here for the first time the occurrence of ornithopod tracks from the Schrattenkalk Formation (Late Aptian) from the Swiss Central Alps. The locality is situated in an abandoned quarry on the shore of Lake Lucerne close to the village of Beckenried. The steeply inclined surface has more than 50 tracks (in three trackways) of ornithopod dinosaurs that are attributed to iguanodontids. Three trackways can be followed for distances of 25 to 35 m. The lengths the footprints (mean: 30 cm) point to animals ranging in size of from 4 to 6 m, with estimated hip heights between 1.8 and 2 m (hip height 6 FL) and 1.4 to 1.7 m (hip height 5 FL). One of the trackways shows two succesive manus impressions, indicating facultative quadrupedal gait. The track bearing layer consists of shallow water micrites with traces of emersion, and it is overlain by bioclastic grainstones. Previously the Upper Schrattenkalk Member in the Helvetic realm was thought to have formed on a large shelf far away from any continents. The present discovery will shed new light on the paleogeographic position of the Helvetic nappes.     

Small Theropod Teeth from the Late Cretaceous of the San Juan Basin,Northwestern New Mexico and Their Implications for Understanding Latest Cretaceous Dinosaur Evolution

Studying the evolution and biogeographic distribution of dinosaurs during the latest Cretaceous is critical for better understanding the end-Cretaceous extinction event that killed off all non-avian dinosaurs. Western North America contains among the best records of Late Cretaceous terrestrial vertebrates in the world, but is biased against small-bodied dinosaurs. Isolated teeth are the primary evidence for understanding the diversity and evolution of small-bodied theropod dinosaurs during the Late Cretaceous, but few such specimens have been well documented from outside of the northern Rockies, making it difficult to assess Late Cretaceous dinosaur diversity and biogeographic patterns. We describe small theropod teeth from the San Juan Basin of northwestern New Mexico. These specimens were collected from strata spanning Santonian – Maastrichtian. We grouped isolated theropod teeth into several morphotypes, which we assigned to higher-level theropod clades based on possession of phylogenetic synapomorphies. We then used principal components analysis and discriminant function analyses to gauge whether the San Juan Basin teeth overlap with, or are quantitatively distinct from, similar tooth morphotypes from other geographic areas. The San Juan Basin contains a diverse record of small theropods. Late Campanian assemblages differ from approximately co-eval assemblages of the northern Rockies in being less diverse with only rare representatives of troodontids and a Dromaeosaurus-like taxon. We also provide evidence that erect and recurved morphs of a Richardoestesia-like taxon represent a single heterodont species. A late Maastrichtian assemblage is dominated by a distinct troodontid. The differences between northern and southern faunas based on isolated theropod teeth provide evidence for provinciality in the late Campanian and the late Maastrichtian of North America. However, there is no indication that major components of small-bodied theropod diversity were lost during the Maastrichtian in New Mexico. The same pattern seen in northern faunas, which may provide evidence for an abrupt dinosaur extinction.     

A dinosaur ichnocoenosis from the middle jurassic of Yorkshire,UK

An assemblage of dinosaur tracks from the undersurface of a sandstone bed in the Saltwick Formation (Middle Jurassic) of Yorkshire shows a range of morphological types, preservational variants and behavioral styles. The tracks are combinations of transmitted prints and underprints and include three distinct trackways. One trackway was made by an animal walking on exposed damp sand, another was left by an animal swimming diagonally across a current and being swept down current, while the third may have been made by an animal either running or pushing off with its feet as it drifted down current. Environmental conditions that existed during the formation of the trackways varied between crevasse splay floods and exposed damp sand. The morphology of the swimming tracks is sufficiently distinctive to warrant the erection of a new ichnogenus and ichnospecies—Characichnos tridactylus. Previously described material from Kansas, Wyoming and New Mexico can be attributed to this new ichnogenus, while specimens from Germany and Utah are only provisionally referred to it. This indicates a known range from Triassic to Cretaceous.     

Crouching Theropods in Taxonomic Jungles: Ichnological and Ichnotaxonomic Investigations of Footprints with Metatarsal and Ischial Impressions

Tracks and traces of crouching theropods are rare, known from only three specimens from the Lower Jurassic of New England and the Lower to ?mid Jurassic of China. The New England specimens reveal manus, metatarsal and sub-crescentic ischial callosity impressions associated with Grallator-like tracks. The Chinese traces reveal metatarsal traces and a sub-triangular ischial callosity impression associated with Eubrontes-like tracks. All reveal symmetrical crouching postures. Theropod crouching traces should not be confused with ornithopod crouching traces, often assigned to Anomoepus. The ichnotaxonomy surrounding all these traces and associated footprints is very complex, and over split. Suggestions for simplification allow recognition that the North American and Chinese ichnofaunas have many similarities. The ichnotaxonomy is not as complex and confused as it may at first appear.