The Marginocephalia, otherwise known as the Pachycephalosaurs and the Ceratopsians, are a group of dinosaurs which are characterized by their bony structure on the back of their heads. Pachycephalosaurs often had dome-shaped skulls which were sometimes decorated with spikes or nodes. Ceratopsians are famous for their horned faces and large bony frills on the back of their head. Both groups were strictly herbivorous.
Distribution & Fossil evidence
Fossils of Pachycephalosaurs and Ceratopsians are mostly found in Western North America and Asia. They probably evolved in Asia, where fossils of many primitive Marginocephalians have been found. They probably migrated to North America where the most famous of Marginocephalians evolved, like Triceratops and Pachycephalosaurus.
There are numerous genuses and species known within the clade of Marginocephalians.