The ceratopsid family also includes the small Protoceratopsids that are equally distributed in North America and Asia (Dodson, 1996).

Protoceratopsids, tend to be more rudimentary with respect to their headgear than other ceratopsids, and presumably include the ancestors of the ceratopsids.

Recently addmitted into the ceratopsid family was the small Psittacosaurus from Asia.

Psittacosaurus is considered to be the primitive, ancestral structure of Ceratopsia. In fact, this genus is so generalized in its structure that it doesn't have any horns and displays only the most meager of frills.

Psittacosaurus possessed all of the key evolutionary novelties of the Ceratopsia even though it had only the most basic of frills (Lucas, 1994).

(Sims, 1994) Protoceratops tends to be more rudimentary with respect to its headgear than ceratopsids, and presumably includes the ancestors of the ceratopsids.

(Carnegie Museum, 1997) Psittacosaurus is so generalized in its structure that it doesn't have any horns and displays only the most meager of frills.