"Psittacosaurus" was one of the earliest ceratopsians, but closer to "Triceratops" than "Yinlong". Once in its own family, Psittacosauridae, with other genera like "Hongshanosaurus", it is now considered to be senior synonym of the latter and an early offshoot of the branch that led to more derived forms. The genera closely related to "Psittacosaurus" are all from Asia, with the exception of "Aquilops", from North America. The first species was either "P. lujiatunensis" or closely related, and it may have given rise to later forms of "Psittacosaurus".