The imagery on this page is the basis for a paper entitled Dispersal and diversity in the earliest North American sauropodomorph dinosaurs, with a description of a new taxon, by T.B. Rowe, H.-D. Sues and R.R. Reisz (2010, Proceedings of the Royal Society B, Biological Sciences, FirstCite). The Summary is as follows:

       Sauropodomorph dinosaurs originated in the Southern Hemisphere in the Middle or Late Triassic and are commonly portrayed as spreading rapidly to all corners of Pangaea as part of a uniform Late Triassic to Early Jurassic cosmopolitan dinosaur fauna. Under this model, dispersal allegedly inhibited dinosaurian diversification, while vicariance and local extinction enhanced it. However, apomorphy-based analyses of the known fossil record indicate that sauropodomorphs were absent in North America until the Early Jurassic, reframing the temporal context of their arrival. We describe a new taxon from the Kayenta Formation of Arizona that comprises the third diagnosable sauropodomorph from the Early Jurassic of North America. We analysed its relationships to test whether sauropodomorphs reached North America in a single sweepstakes event or in separate dispersals. Our finding of separate arrivals by all three taxa suggests dispersal as a chief factor in dinosaurian diversification during at least the early Mesozoic. It questions whether a ‘cosmopolitan’ dinosaur fauna ever existed, and corroborates that vicariance, extinction and dispersal did not operate uniformly in time or under uniform conditions during the Mesozoic. Their relative importance is best measured in narrow time slices and circumscribed geographical regions.

This specimen was collected from the Lower Jurassic Kayenta Formation, Dilophosaurus Quarry, Navajo Nation. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Timothy Rowe of The University of Texas at Austin. Funding for scanning and image processing was provided in part by a National Science Foundation Assembling the Tree of Life grant (IIS-0531767) to Dr. Rowe.

This specimen was scanned by Matthew Colbert on 4 April 2007 along the horizontal axis for a total of 425 slices. Each 1024x1024 pixel slice is 0.1668 mm thick, with an interslice spacing of 0.1668 mm and a field of reconstruction of 79 mm.

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