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Buck-Toothed, Rabbitlike Dinosaur's Remains Found
Unusual Fossil Found In Northeastern China
Posted: 3:05 p.m. EDT September 18, 2002
A bucktoothed, rabbit-like dinosaur related to Tyrannosaurus Rex and other
predators lived in China 128 million years ago, researchers report.
The fossil of the unusual Incisivosaurus was found in the Yixian formation
near Beipiao City in northeast China, an area that has already produced
many unusual fossils, including dinosaurs with feathers.
Incisivosaurus is part of a group of dinosaurs known as oviraptors, small
two-legged dinosaurs that had parrot-like beaks. Incisivosaurus, however,
is the oldest oviraptor found to date and lacks the bird-like features
found in others of its group, the researchers report in Thursday's issue
of the journal Nature.
Instead of having a beak, Incisivosaurus has a long skull and jaws filled
with teeth for grinding. However, in its most unusual characteristic, it
sports two large buck teeth at the front of its jaw similar to those used
by rodents for gnawing.
The buck teeth suggest the dinosaur was an herbivore rather than a
meat-eater like its relatives, reported Xing Xu and colleagues at the
Chinese Academy of Sciences.
Other paleontologists said buck teeth alone do not mean Incisivosaurus was
a plant-eater. But they said the discovery shakes up the traditional view
of theropod dinosaurs, which are widely assumed to have long, sharp teeth.
"The classic view of predatory dinosaur (theropod) teeth is that they are
all basically the same and are shaped more or less like serrated steak
knives,"said geologist Joshua Smith of Washington University in St. Louis.
"However, it is becoming more and more obvious as we begin to look closely
at theropod teeth that they are far more complex than we have been led to
believe and that the steak-knife view isn't accurate. This is true of
Tyrannosaurus, and with new discoveries like Masiakasaurus last year in
Madagascar and now Incisivosaurus in China, it is becoming apparent that
it is true of other theropods as well."
The size of the teeth in the fossil vary widely. The front teeth appear
two to three times longer than teeth further back, which is almost unheard
of, Smith said.