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Hamadachelys escuilliei (Tong and Buffetaut, 1996) is a pelomedusoid pleurodire from the late Cretaceous (Cenomanian) of Hamada du Guir, southern Morocco. It is one of the oldest-known members of the Podocnemididae, and is related to the extant South American taxa Podocnemis and Peltocephalus, and to the Madagascan Erymnochelys.

This specimen, the holotype, is a nearly complete juvenile skull with some crushing in the inner ear region. The mandible and two hyoid bones, probably the first branchial horns, were removed during specimen preparation and therefore do not appear on the CT scans. This specimen was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Gene Gaffney of the American Museum of Natural History, Dr. Haiyan Tong of the University of Paris, and Dr. Jean le Loeuff of the Musée des Dinosaures, Espéraza, France. Funding for scanning was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe.

The specimen was scanned by Richard Ketcham and Matthew Colbert on 16 March 1999 along the coronal axis for a total of 342 slices, each slice 0.14 mm thick, with an interslice spacing of 0.14 mm. The animations displayed were reduced for optimal Web delivery from the original, much higher resolution CT data.

Literature

de Broin, F. 1988. Les Tortues et le Gondwana. Studia geologica Salamanticensia. Studia Palaeochelonologica II:103-142.

Gaffney, E. S. 1972. An illustrated glossary of turtle skull nomenclature. American Museum Novitates 2486:1-33.

Gaffney, E. S. 1979. Comparative cranial morphology of recent and fossil turtles. Bulletin of the American Museum of Natural History 164:65-376.

Gaffney, E. S. 1990. Comparative osteology of the Triassic turtle Proganochelys. Bulletin of the American Museum of Natural History 194:1-263.

Meylan, P. A. 1996. Skeletal morphology and relationships of the early cretaceous side-necked turtle, Araripemys barretoi (Testudines: Pelomedusoides: Araripemydidae), from the Santana Formation of Brazil. Journal of Vertebrate Paleontology 16:20-33.

Pritchard, P. C. H., and P. Trebbau. 1984. The turtles of Venezuela. Society for the Study of Amphibians and Reptiles Contributions to Herpetology Number 2, 403 pp.

Schumacher, G. H. 1973. The head muscles and hyolaryngeal skeleton of turtles and crocodilians; pp: 101-199 in C. Gans and T. S. Parsons (eds.), Biology of the Reptilia, Volume 14. Academic Press, New York.

Tong, T., and E. Buffetaut. 1996. A new genus and species of pleurodiran turtle from the Cretaceous of southern Morocco. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 199:133-150.

Tong, H., E. S. Gaffney, and E. Buffetaut. 1998. Foxemys, a new sidenecked turtle (Bothremydidae: Pelomedusoides) from the late Cretaceous of France. American Museum Novitates 3251:1-19.

Links

Gene Gaffney's Phylogeny of Turtles (AMNH) (requires Flash plug-in)

None available.