for National Geographic News
First noticed by a black market fossil dealer, a new species found in a Utah boneyard may be a missing link in dinosaurs' trend toward vegetarianism. (See pictures of the new dinosaur.)
The 125-million-year-old fossils, from the dinosaur Falcarius utahensis, were discovered in a graveyard of hundreds, if not thousands, of individuals. Though it may have eaten meat, Falcarius's teeth and guts show the first signs of the species's change toward a leafy, green diet, said James Kirkland, a paleontologist at the Utah Geological Survey in Salt Lake City.
"We can see definitive features of eating plants and know its descendents were much more full-time plant-eaters," Kirkland said.
The newly discovered creature was likely cloaked in hairlike feathers and walked on two legs. Adults measured about 13 feet (4 meters) long, head to tail. They stood about 4.5 feet (1.4 meters) tall and had sharp, curved, 4-inch-long (10-centimeter-long) claws.
Kirkland and his colleagues from the University of Utah in Salt Lake City and the George Washington University in Washington, D.C. report the discovery in tomorrow's issue of the science journal Nature.
Falcarius was a member of the therizinosaurs. These feathered dinosaurs with birdlike hips are considered among the weirdest ever discovered.
Until recently, paleontologists argued over where the beasts fit on the evolutionary tree. At first, they were considered giant sea turtles, and then for years they were thought to be long-necked sauropod dinosaurs.
"In the last decade or so we've come to understand that therizinosaurs evolved from a raptorlike group of dinosaurs," said Lindsay Zanno, a graduate student in geology at the University of Utah and a co-author of the new study.
Falcarius, Zanno added, is the most primitive therizinosaur yet discovered and unequivocally demonstrates that the group evolved from Velociraptor-like ancestors.
Velociraptor was the fleet-footed, meat-eating dinosaur popularized in the movie Jurassic Park. The new dinosaur, Falcarius, did not descend directly from Velociraptor. Rather, Kirkland said, they are both descendants of a yet undiscovered common ancestor.
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