Ceratopsoidea

Ceratopsoidea is a clade of coronosaurian ceratopsian dinosaurs, defined as the group containing Ceratops and Triceratops but not Protoceratops. It brings together the family Ceratopsidae — the large, elaborately horned and frilled quadrupeds that dominated Late Cretaceous North America, such as Triceratops — with a handful of closely related but more basal animals like Zuniceratops that approach the ceratopsid condition without belonging to it. This grouping sits apart from the Asian protoceratopsids, the other major branch of Coronosauria. Ceratopsidae, the derived heart of the clade, is further divided into the short-frilled centrosaurines and the long-frilled chasmosaurines. Ceratopsoids and their immediate ancestors were long presumed endemic to western North America, though later finds such as Turanoceratops raised the possibility of an Asian origin.