Geological Magazine



Original Article

A re-evaluation of Chinshakiangosaurus chunghoensis Ye vide Dong 1992 (Dinosauria, Sauropodomorpha): implications for cranial evolution in basal sauropod dinosaurs


PAUL UPCHURCH a1c1, PAUL M. BARRETT a2, ZHAO XIJIN a3 and XU XING a3a4
a1 Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK
a2 Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
a3 Institute of Vertebrate Paleontology and Paleoanthropology, Academica Sinica, P.O. Box 643, Beijing 100044, People's Republic of China
a4 Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA

Article author query
upchurch p   [Google Scholar] 
barrett pm   [Google Scholar] 
xijin z   [Google Scholar] 
xing x   [Google Scholar] 
 

Abstract

Re-description of the left dentary of Chinshakiangosaurus chunghoensis reveals that it possesses an unusual combination of ‘prosauropod’ and ‘sauropod’ character states. Cladistic analysis places Chinshakiangosaurus as one of the most basal sauropods known currently. Mapping of dentary and dental characters onto the most parsimonious topologies yields insights into the sequence of acquisition of a number of feeding-related characters. For example, it seems that basal sauropodomorphs (traditional prosauropod taxa) possessed a fleshy cheek that attached to the mandible along a marked ridge, and that the same structure was present in the most basal sauropods. The early sauropod skull developed a lateral plate that reinforced the bases of the tooth crowns labially, and had wrinkled tooth enamel and a concavity on the mesial portion of the lingual part of each crown, while retaining a fleshy cheek and a relatively weak symphysis. More advanced sauropods (eusauropods) lost the cheek, perhaps in order to increase the gape of the jaws in response to a change in feeding style that involved collection of larger quantities of poor quality foliage.

(Received June 9 2005)
(Accepted June 8 2006)


Key Words: dentary; Dinosauria; phylogeny; Sauropoda; Sauropodomorpha.

Correspondence:
c1 Author for correspondence: p.upchurch@ucl.ac.uk


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