"P. lujiatunensis", named in 2006 by Chinese paleontologist Zhou Chang-Fu and three Chinese colleagues, is one of the oldest-known species, based on four skulls from the lower beds of Yixian Formation, near the village of Lujiatun. While this bed has been dated differently by different authors, from 128 Ma in the Barremian stage, to 125 Ma in the earliest Aptian, revised dating methods have shown them to be about 123 million years old. "P. lujiatunensis" was contemporaneous with another psittacosaurid species, "Hongshanosaurus houi", which was found in the same beds. It is potentially synonymous with "H. houi"; Sereno (2010), who proposed that "Hongshanosaurus" is a synonym of "Psittacosaurus", opted to leave "P. lujiatunensis" and "H. houi" separate species due to the inadequacies of the latter's type specimen.