科学家发现新品种食草恐龙

A South Dakota School of Mines & Technology assistant professor and his team have discovered a new species of herbivorous（食草的） dinosaur¹ and today published the first fossil evidence of prehistoric² crocodyliforms feeding on small dinosaurs³. Research by Clint Boyd, Ph.D., provides the first definitive⁴ evidence that plant-eating baby ornithopod（鸟脚亚目恐龙） dinosaurs were a food of choice for the crocodyliform, a now extinct relative of the crocodile family. While conducting their research, the team also discovered that this dinosaur prey⁵ was a previously⁶ unrecognized species of a small ornithopod dinosaur, which has yet to be named.   The evidence found in what is now known as the Grand Staircase Escalante-National Monument in southern Utah dates back to the late Cretaceous period, toward the end of the age of dinosaurs, and was published today in the online journal PLOS ONE. The complete research findings of Boyd and Stephanie K. Drumheller, of the University of Iowa and the University of Tennessee, and Terry A. Gates, of North Carolina State University and the Natural History Museum of Utah, can be accessed online (see journal reference below).   A large number of mostly tiny bits of dinosaur bones were recovered in groups at four locations within the Utah park -- which paleontologists and geologists⁷ know as the Upper Cretaceous (Campanian) Kaiparowits Formation -- leading paleontologists（古生物学者） to believe that crocodyliforms had fed on baby dinosaurs 1-2 meters in total length.   Evidence shows bite marks on bone joints⁸, as well as breakthrough proof of a crocodyliform tooth still embedded⁹ in a dinosaur femur.   The findings are significant because historically dinosaurs have been depicted¹⁰ as the dominant¹¹ species. "The traditional ideas you see in popular literature are that when little baby dinosaurs are either coming out of a nesting grounds or out somewhere on their own, they are normally having to worry about the theropod dinosaurs, the things like raptors or, on bigger scales, the T. rex. So this kind of adds a new dimension," Boyd said. "You had your dominant riverine（河边的） carnivores（食肉动物）, the crocodyliforms, attacking these herbivores as well, so they kind of had it coming from all sides."