"Also, unlike other early plant-eating dinosaurs, Heterodontosaurus has large, powerful arms and sharp, re-curved claws on its hands, again similar to those of meat-eating dinosaurs," she said, adding that "perhaps Heterodontosaurus represents a transition stage." Of particular interest concerning the newly discovered skull is that the juvenile already had a fully developed set of canines. Other researchers thought these teeth might have emerged later, to be used by fighting adults as for today's wart hogs, but the fact that youngsters had them strengthens the theory that they were used for tearing into flesh for consumption. The researchers, whose findings are published in the fall issue of the Journal of Vertebrate Paleontology, suspect the dinosaur occasionally ate insects, reptiles and small mammals. CT scans and X-rays found the species did not have replacement teeth, like those of most other dinosaurs that replace their teeth throughout their lives. Instead, it had just one adult set, as mammals do today. While Porro said "true mammals and dinosaurs appear at roughly the same time (during the late Triassic) their ancestors diverged much earlier -- over 320 million years ago." It's therefore an open question as to why Heterodontosaurus possessed a more mammalian tooth strategy. Paul Sereno, one of the world's leading paleontologists and an expert on Heterodontosaurus, told Discovery News that he believes "these are some of the most interesting and early of dinosaur finds." "Rare among dinosaurs, these little guys have canines alongside cheek teeth adapted for slicing plants," he said. "The closest modern analog we can think of is the small muntjac deer from China." This deer is an herbivore, but males grow fang-like canines similar to those possessed by Heterodontosaurus. Sereno concluded that the study helps to "shed light on the anatomy of this interesting group of tiny dinosaurs, which have been known previously mainly from a single skeleton." Related Links: Howstuffworks.com: Heterodontosaurus Video: When Dinosaurs Ruled: Carnivores Thrive, Herbivores Die |
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