Any member of a genus of quadrupedal dinosaurs found as fossils in Gobi deposits of the Cretaceous period (14465 million years ago).
The hind limbs were more strongly developed than the forelimbs; the back was arched. Adults were about 7 ft (2 m) long and probably weighed about 400 lbs (180 kg). The skull was about one-fifth the body length. Bones in the skull grew backward into a perforated frill. The jaws were beaklike and toothed. There may have been a hornlike structure on top of the snout. Long spines on the well-developed tail suggest that protoceratops was semiaquatic.