2 p.m. February 25, 1998
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New species Dimorphodon weintraubi named in memory of GW Professor Robert Weintraub

Washington -- Professor James M. Clark, at The George Washington University, and four co-authors report in an article in the journal Nature that the foot of a new species of pterosaur -- a group of winged reptiles closely related to dinosaurs -- demonstrates that it could not run on its toes. The new species was found among 180 million year-old rocks in a remote canyon in northeastern Mexico, at a locality discovered by Clark. The specimen is one of the best preserved examples of a primitive pterosaur, and its foot structure indicates that the toes could not bend upward, a finding which contradicts a controversial reconstruction of pterosaurs in which they ran swiftly with the sole of their foot raised above the ground. The study was supported by the National Science Foundation, and the collection was funded by the National Geographic Society.

"The importance of this find is in showing that a critical aspect of one of the two competing models of how pterosaurs moved about on the ground is impossible," said Clark. "The shape of the joints between the foot bones of this pterosaur skeleton prevent the toe bones from moving in the way predicted by the model of active pterosaurs running with only their toes touching the ground. They could only have walked or run with the entire sole of the foot contacting the ground at some point in each stride."

The new species, Dimorphodon weintraubi, is named for the late Dr. Robert Weintraub, former chair and Professor Emeritus of The George Washington University's department of biological sciences, and a major benefactor of GW.

Clark has collected dinosaur-age fossils actively for more than two decades, was involved in the discovery of the Fruita Paleontological Area in western Colorado and, with the American Museum of Natural History, a locality in the Gobi Desert of Mongolia extremely rich with dinosaur embryos and a nesting dinosaur. He discovered the pterosaur site in Mexico in 1982, while a graduate student at the University of Chicago. He received his B.A. and M.A. from the University of California - Berkeley. He joined GW in 1994 as the Ronald B. Weintraub Assistant Professor of Biology in the department of biological sciences.

Clark's co-authors on the paper are Dr. James Hopson of the University of Chicago, Sr. Rene Hernandez and Dra. Marisol Montellano of the Universidad Nacional Autonoma de Mexico, and Dr. David Fastovsky of the University of Rhode Island.

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Last updated August 5, 1999