June 2006

GW Professor Leads Discovery of the Oldest Known Ceratopsian

James M. Clark, Ronald B. Weintraub Associate Professor of Biology at GW, and Xu Xing of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, have discovered the oldest-known ceratopsian, a finding that solidifies the close evolutionary evidence between ceratopsians and pachycephalosarians, the “bone-headed” dinosaurs. Roaming the earth 160 million years ago, the new basal ceratopsian dinosaur, Yinlong downsi, appeared 20 million years earlier than the previous oldest ceratopsian and 85 million years earlier than the best-known ceratopsian, Triceratops.

Clark, Xu, and two colleagues announced the discovery in the May 17 online edition of the British science journal, Proceedings of the Royal Society B: Biological Sciences, in a paper titled, “A Basal Ceratopsian with Transitional Features from the Late Jurassic of Northwestern China.” The new discovery’s name, Yinlong downsi, combines both American and Chinese names. “Yinlong” means “hiding dragon” in Chinese, derived from the movie “Crouching Tiger, Hidden Dragon,” which was filmed in the area where the fossils were found. The latter part of the name is in memory of Will Downs, a life-long fossil hunter who joined many paleontological expeditions in China, including one with Clark’s and Xu’s team in 2003, shortly before Downs’ death. Discovered in 2004, the nearly complete skeleton was found with two other specimens of Yinlong on the edge of the Gobi Desert in northwestern China in the Junggar Basin, part of the Xinjiang Province.
Yinlong downsi, an early relative of Triceratops, was much smaller than its ceratopsian descendant measuring a little over four feet once full grown.

Triceratops were large animals approximately the size of a car weighing five tons with large horns and frills making up the skull. Unlike Triceratops, Yinlong downsi has no large horns or frills characteristic of larger ceratopsians. But Yinlong does possess a rostral bone, a distinct beak-like bone at the end of its snout, along with a raised and triangular-shaped skull, common to all ceratopsians.
Field work that led to the discovery of Yinlong was supported by GW, the National Natural Science Foundation of China, the National Geographic Society, and the National Science Foundation Division of Earth Sciences.

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