"It's truly amazing that this animal seems to have had such a highly-evolved heart. The implications completely floored me," said Science co-author Dale Russell, of the North Carolina State Museum of Natural Sciences and North Carolina State University. Russell's research team also includes Paul Fisher, Michael Stoskopf, and Reese Barrick, of North Carolina State University, Kuzmitz, a physician in private practice, and Hammer, whose company is called Hammer and Hammer Paleotek.

Four-chambered hearts deliver completely oxygenated blood to the body, which fuels the relatively fast metabolisms of birds and mammals. In contrast, living reptiles tend to be more sluggish and can get by with less oxygen.

The team therefore suspects that their dinosaur may have also had a metabolic rate higher than that of a typical reptile. Since most modern animals with high metabolic rates are also warm-blooded, this prospect leads to the tantalizing possibility that the dinosaur was also warm-blooded.

The dinosaur has yet to be formally classified, but currently goes by the name "Willo." It's a two-legged, 13 foot-long thescelosaur, a member of the ornithiscian, or "bird-hipped," group of dinosaurs.

Although their name indicates otherwise, the saurischian, or "lizard-hipped," dinosaurs are actually the ones that many researchers suspect eventually gave rise to birds. Therefore it might be concluded that the ancestors to both ornithiscian and saurischian dinosaurs also had advanced hearts and high metabolisms. The age difference between Willo and the ancestral dinosaurs is so great, however, that four-chambered hearts may also have arisen independently
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Contact: Heather Singmaster
hsingmas@aaas.org
202-326-6414
American Association for the Advancement of Science
20-Apr-2000