A third species of Lujiatun psittacosaur, the first to be named, was described as "Hongshanosaurus houi" in 2003. The generic name "Hongshanosaurus" was derived from the Mandarin Chinese words 紅 ("hóng": "red") and 山 ("shān": "hill"), as well as the Greek word "sauros" ("lizard"). This name refers to the ancient Hongshan culture of northeastern China, who lived in the same general area in which the fossil skull of "Hongshanosaurus" was found. The type and only named species, "H. houi", honours Hou Lianhai, a professor at the IVPP in Beijing, who curated the specimen. Genus and species were both named by Chinese paleontologists You Hailu, Xu Xing, and Wang Xiaolin in 2003. Sereno (2010) regarded its distinct proportions as due to crushing and compression of the "Hongshanosaurus" skulls. He regarded "Hongshanosaurus" as a junior synonym of "Psittacosaurus", and potentially the same as "P. lujiatunensis". He did not synonymise the two species because of difficulties with the holotype skull of "H. houi", instead considering new combination "P. houi" a "nomen dubium" within "Psittacosaurus". Sereno's hypothesis was supported by a morphometric study in 2013, which found "P. houi" and "P. lujiatunensis" to be synonymous. While "P. houi" is the oldest available name, the researchers argued that because the type specimen of "P. lujiatunensis" was better preserved, the correct name for this species should be "P. lujiatunensis" rather than "P. houi", which would normally have priority.