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Xing L.,China University of Geosciences | Lockley M.G.,University of Colorado at Denver | Zhang J.,China University of Geosciences | Klein H.,Saurierwelt Palaontologisches Museum | And 6 more authors.
Cretaceous Research | Year: 2015

Here we report a large dinosaur tracksite from an extensive fluvial sandstone surface in the Lower Cretaceous Jiaguan Formation of Sichuan Province, China. The site contains over 250 individual tracks comprising at least 18 recognizable trackways, including the longest theropod trackway (cf. Eubrontes) known from China. This exceptional theropod trackway consists of 81 successive footprints covering a distance of 69m. The tracks are well-preserved and are expressed both as true tracks on the main "upper" surface and as transmitted undertracks on a locally exposed "lower" bed. Also recorded are six other theropod trackways, including small Grallator-like ichnites, eight sauropod trackways (cf. Brontopodus), and three small ornithopod (cf. Ornithopodichnus) trackways with a parallel orientation, which may indicate gregarious behavior. Several trackways of a larger theropod trackmaker show pes imprints with elongated traces of the metatarsals, suggesting extramorphological (substrate-controlled) variation and/or plantigrade posture, which is here interpreted as indicating a change in gait assumed in response to deep and soft sediment. The assemblage indicates a diverse dinosaur fauna in the Lower Cretaceous Sichuan Basin with variously sized theropods, sauropods, and ornithopods. The late occurrence of footprints of the Grallator-Eubrontes plexus in Lower Cretaceous strata is further evidence of the extended stratigraphic range of this morphotype and the distinct palaeobiogeographic distribution of these trackmakers in East Asia. © 2015 Elsevier Ltd.

Buckley L.G.,Peace Region Palaeontology Research Center | Larson D.W.,University of Alberta | Reichel M.,University of Alberta | Samman T.,104 623 9A St. NW
Canadian Journal of Earth Sciences | Year: 2010

Documenting variation in theropod dinosaurs is usually hindered by the lack of a large sample size and specimens representing several ontogenetic stages. Here, variation within 140 disassociated and seven in situ tyrannosaur teeth from the Upper Cretaceous (lower Maastrichtian) monodominant Albertosaurus sarcophagus (Theropoda: Tyrannosauridae) bonebed is documented. This sample represents the largest data set of teeth from one population of A. sarcophagus containing both adult and juvenile specimens. Tooth variation was assessed using multivariate analyses (principal component, discriminant, and canonical variate analyses). Heterodonty in the teeth of A. sarcophagus contributes to the large amount of variation in the data set. Premaxillary teeth are significantly different from maxillary and dentary teeth, but there is no quantifiable difference between a priori identified maxillary and dentary teeth. Juvenile and adult teeth of A. sarcophagus show apparent quantitative differences that are size dependent on closer investigation, suggesting a cautious approach when interpreting multivariate analyses to identify novel tooth morphologies. Multivariate analyses on teeth of A. sarcophagus and published tooth data from other North American tyrannosaurid species reveals species-level clusters with little separation. The degree of separation among tooth clusters may reveal a phylogenetic signal in tyrannosaurid teeth.

Richter U.,Initiative of Independent Palaeobiologists Deutschland IIPD | Mudroch A.,Initiative of Independent Palaeobiologists Deutschland IIPD | Buckley L.G.,Peace Region Palaeontology Research Center
Palaontologische Zeitschrift | Year: 2013

Thirty-seven well-preserved, isolated theropod teeth from the Early Cenomanian Kem Kem beds, Morocco, are identified by using morphometric data and direct comparison with teeth previously described in the literature. Direct comparison reveals that four different morphotypes (MT 1-4) are present in the sample. The teeth of MT 1 are characterised by unserrated carinae and belong to spinosaurid dinosaurs. The teeth of MT 2-4 have serrated carinae, and our data analysis indicates they are of carcharodontosaurid, dromaeosaurid, and abelisaurid origin. Three types of crown enamel ornamentation are present among the teeth of MT 1, which implies that, apart from Spinosaurus aegyptiacus STROMER 1915, more than one species of spinosaurine theropods may be present in the Early Cenomanian of Northern Africa. Our results also confirm the occurrence of abelisaurids, dromaeosaurids, and carcharodontosaurids in Morocco. © 2012 Springer-Verlag.

Lockley M.G.,University of Colorado at Denver | Buckley L.G.,Peace Region Palaeontology Research Center | Foster J.R.,18 East Center St | Kirkland J.I.,Utah Geological Survey | Deblieux D.D.,Utah Geological Survey
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

More than 130 footprints representing ~. 43 trackways of birds (avian theropods) and two non-avian theropods occur as seven separate assemblages on loose blocks recovered from the Poison Strip Member of the Cedar Mountain Formation, near the Stikes Quarry locality in eastern Utah. Six of assemblages, four with bird tracks and two with small non avian theropod tracks, are inferred to originate from the same stratigraphic horizon, and can therefore be considered part of the same ichnofauna. The seventh assemblage comes from a different horizon a few meters above that yielding the other six assemblages. The bird tracks are all attributed to the ichnogenus Aquatilavipes, a track type morphologically similar to those of modern shorebirds. The ichnogenus is also known from broadly coeval ichnofaunas from South Dakota and Canada, and the identification is confirmed by detailed comparative analysis of available Aquatilavipes samples using bivariate and multivariate analyses. This is the first definitive report of bird tracks from the Cedar Mountain Formation and the first evidence of birds from this otherwise richly fossiliferous unit. The ichnofauna is therefore quite unique in comparison with others from this same formation. © 2014 Elsevier B.V.

Xing L.,China University of Geosciences | Lockley M.G.,University of Colorado at Denver | Marty D.,Office de la culture | Klein H.,Saurierwelt Palaontologisches Museum | And 7 more authors.
Cretaceous Research | Year: 2013

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. © 2013 Elsevier Ltd.

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