Ceratopsia are a group of omnivorous and herbivorous, beaked dinosaurs which thrived in North America and Asia during the Cretaceous. They include the bipedal Psittacosauria , some of which bore elaborate, porcupine-like spines, and the quadrupedal Protoceratopsidae and Ceratopsidae, characterized by horns and frills. The group appears to be Asian in origin; but the Ceratopsidae are exclusively known from the Late Cretaceous of North America, where they evolved large size and elaborate horn and frill morphologies. The horns probably served both for display, for defense, and for combat with other members of the species.
Some of the better known Ceratopsia include Psittacosaurus , Protoceratops, Triceratops, Torosaurus, Centrosaurus , and Pachyrhinosaurus .
