Hongshanosaurus

Taxobox
name = "Hongshanosaurus"
fossil_range = Early Cretaceous


regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Ornithischia
infraordo = Ceratopsia
subordo = Cerapoda
familia = Psittacosauridae
genus = "Hongshanosaurus"
species = "H. houi"
binomial = "Hongshanosaurus houi"
binomial_authority = You, Xu, & Wang, 2003

"Hongshanosaurus" (pronEng|hɒŋˌʃænəˈsɔrəs hawng-SHAN-o-SAWR-us; "Red Hill lizard") is a genus of psittacosaurid ceratopsian dinosaur from the Early Cretaceous Period of eastern Asia. Although two skulls are the only fossil material known, comparisons with close relatives suggest it was a small, bipedal herbivore with a bony beak on the end of both upper and lower jaws. This is one of the many exceptionally well-preserved fossils to be recovered from the Yixian Formation of Liaoning, China.

Discovery and Species

The generic name "Hongshanosaurus" is 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.

"Hongshanosaurus" Species
*"H. houi" (type)

The one named species ("H. houi") honors Hou Lianhai, a professor at the Institute of Vertebrate Paleontology and Paleoanthropology (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.

The holotype specimen of "Hongshanosaurus" is a juvenile skull, completely preserved except for part of the right side and the tip of the upper jaw. This skull is slightly less than 5 centimeters (2 in.) long (You et al. 2003). A much larger adult skull was later described, which is almost 20 centimeters (8 in.) long. It is very similar to skulls of the closely related "Psittacosaurus", although several differences exist which serve to differentiate the two genera. "Hongshanosaurus" has a lower skull than any species of "Psittacosaurus" and the orbit (eye socket) is elliptical instead of round (You & Xu 2005). These skull were recovered from the Yixian Formation of Liaoning China, which is famous for the exceptional preservation of its fossils, including most of the known feathered dinosaurs. The age of this formation has been disputed, but recently radiometric dating has confirmed an Early Cretaceous age, probably in the Barremian stage (130 to 125 million years ago). Several specimens of "Psittacosaurus" have also been recovered from the Yixian, including one with a row of long bristles on the tail which may have had a display function in life. As "Hongshanosaurus" is known only from skull material, it is unknown whether it also had these bristles.

Classification

"Hongshanosaurus" was placed in the family Psittacosauridae when it was first described, but has not been included in any phylogenetic analysis since. The only other genus currently classified in this family is "Psittacosaurus" itself, although that genus includes up to a dozen individual species. Psittacosaurids are extremely basal ceratopsians. The more inclusive group Neoceratopsia is in fact defined to include all ceratopsians more derived than Psittacosauridae (You & Dodson 2004).

References

*You H., Xu X. & Wang X. 2003. A new genus of Psittacosauridae (Dinosauria: Ornithopoda) and the origin and early evolution of marginocephalian dinosaurs. "Acta Geologica Sinica" (English edition) 77(1): 15–20.
*You H. & Dodson, P. 2004. Basal Ceratopsia. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). "The Dinosauria" (2nd Edition). Berkeley: University of California Press. Pp. 478-493.
*You H. & Xu X. 2005. An adult specimen of "Hongshanosaurus houi" (Dinosauria: Psittacosauridae) from the Lower Cretaceous of Western Liaoning Province, China. "Acta Geologica Sinica" (English edition) 79(2): 168-173