Two new species of Psittacosaurus were described by Canadian Dale Russell and Zhao in 1996. The first was named Psittacosaurus neimongoliensis, after the Mandarin Chinese name for Inner Mongolia. It is based on a nearly complete fossil skeleton, including most of the skull, found in the Early Cretaceous Ejinhoro Formation with seven other individuals.
The frontal bone of P. neimongoliensis is distinctly narrow compared to that of other species, resulting in a narrower skull overall. The ischium bone of the pelvis is also longer than the femur, which differs from other species in which these bones are known. The type specimen has a skull length of 13.2 centimeters (5.2 in) and a femoral length of 13 centimeters (5.1 in), but is not fully grown. An adult P. neimongoliensis was probably smaller than P. mongoliensis, with a proportionately longer skull and tail.
Read more about this topic: List Of Psittacosaurus Species