The term 'neoceratopsian' refers to all ceratopsians with exception of Psittacosaurus. The term 'ceratopsid' refers only to the large horn-bearing dinosaurs of Western North America. Their classification (seen on the left) also implies that there are several evolutionary levels within the Ceratopsia.

Fortunately horned dinosaurs have one of the best fossil records of any group of dinosaurs. There are close to 400 specimens in museum collections around the world (Dodson, 1996). Twenty-three genera and perhaps 30 species have been described to date, and approximately two-thirds of the 23 genera are based on essentially complete skulls and skeletons (Dodson, 1996).