The Protoceratops was a small, herbivorous, or plant-eating, dinosaur that inhabited Asia during the late Cretaceous period, about 65 to 98 million years ago. Protoceratops is classified as a member of the family Protoceratopsidae, which contains small dinosaurs with rudimentary versions of the neck frill, or bony shield, that became more prominent in their later relatives. The Protoceratopsidae belong to the order Ornithischia (the bird-hipped dinosaurs). This order is divided into four suborders; the suborder Ceratopia, which includes Protoceratops, Psittacosaurus, and Leptoceratops, among others, was the last group of ornithiscians to evolve before the mass extinction of dinosaurs at the end of the Cretaceous period.