A new species of Psittacosaurus (Dinosauria: Ceratopsia) from the Early Cretaceous Yixian Formation, Liaoning, China

Newly discovered, well-preserved skulls and mandibles from the lowest part of the Early Cretaceous Yixian Formation, western Liaoning Province, China, document the earliest known record of psittacosaurs and provide the basis for recognition of a new species, Psittacosaurus lujiatunensis. This discovery increases the taxonomic diversity of psittacosaurs to eight valid species and extends the stratigraphic range of the family Psittacosauridae from late Barremian-Albian to Hauterivian. Comparative study of the new species with other well-known psittacosaurs indicates that the new taxon is probably the most basal member of the psittacosaur clade now known. This interpretation is in agreement with the temporal distribution of the clade and supports the hypothesis that the Psittacosauridae originated from the basal ceratopsian stem no later than the earliest part of the Cretaceous.