Bizarre Cousin of T. Rex Was a Vegetarian

Livescience has a story of a new dinosaur, Chilesaurus diegosuarezi.  The name is in honor of both Chile and the discoverer, Diego Suarez.  It was discovered by the 7-year-old son of two geologists in 2010.  A few dinosaur vertebrae were spotted by the observant boy during an expedition with his family in Aysen, a region of southern Chile.  The 9.8 foot long animal lived about 145 million years ago during the late Jurassic period.  It is a rare case of a plant eating  theropod.  The original paper appeared in the journal Nature.

Since Diego’s discovery, collaborating Chilean and Argentinian scientists have uncovered more than a dozen Chilesaurus specimens, including four complete skeletons ranging from the size of a turkey to almost 10 feet (3 m) long.

If they had not discovered the complete specimens, researchers may have identified different parts of Chilesaurus as belonging to different species, the scientists said. For instance, the dinosaur’s ilium, the upper, large part of the pelvic bone, looks like that of a theropod. It also had robust forelimbs and likely walked on its hind legs, like other theropods, Novas said. However, Chilesaurus did not have sharp claws like Velociraptor, but instead sported two blunt fingers for hands.

Chilesaurus also had a small skull, long neck and large, clunky feet reminiscent of a sauropodomorph, Novas said. “In the case of Chilesaurus, its legs were more adapted to walk, not to run,” he said. “The hind foot is composed of four well-developed toes, different from the three-toed feet of a theropod.”

Moreover, Chilesaurus had a pubic bone that looks like that of an ornithischian, Novas said. It’s possible that the pubic bone rotated backward over evolutionary time to allow Chilesaurus more room in its gut to digest plant material, the researchers said.

The new species is a “wonderful weirdo,” said Thomas Carr, an associate professor of biology at Carthage College in Wisconsin and a vertebrate paleontologist, who was not involved in the study.

“We’re learning about the rules of dinosaur evolution,” Carr told Live Science. “It shows that the dinosaurs across theropods and sauropodomorphs and even ornithischians tend to follow the same rules in changing their bodies,” when they evolved into herbivores.

Chilesaurus isn’t the only herbivorous theropod. The therizinosauroidae, which lived in present-day Asia and North America, also ate plants.

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