Writing in the Journal of Systematic Palaeontology, Clark and fellow GWU researcher Jonah Choiniere the skull, mandible and partial skeleton of the dinosaur showed the new theropod was just more than 3 feet long and probably weighed about 3 pounds, walking on its hind legs.
Members of the new species, dubbed Aorun zhaio, weren't necessarily small dinosaurs, they said, because the fossil uncovered was that of a youngster.
"We were able to look at microscopic details of Aorun's bones and they showed that the animal was less than a year old when it died on the banks of a stream," Choiniere said.
"All that was exposed on the surface was a bit of the leg," Clark said. "We were pleasantly surprised to find a skull buried in the rock, too."
Aorun lived more than 161 million years ago and its small, numerous teeth suggest it would have eaten prey such as lizards and small relatives of modern mammals, the researchers said. Most species of theropods were carnivorous, although some were herbivores.