Hongshanosaurus: (Meaning “Red Hill lizard”); Pronounced: hong-SHAN-oh-SAWR-us.
Hongshanosaurus is a genus of psitticosaurid ceratopsian dinosaur from the Early Aptian of the Early Cretaceous Period. It lived in what is now eastern Asia. The only species known is H. houi. The species name honors Hou Lianhai, a professor at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing. Lianhai is the curator of the specimen. The fossils were discovered in the Yixian Formation of Liaoning, China, located at Lujiatun village, Beipiao, Western Liaoning Province, China. The exact age of the formation was in dispute until radiometric dating based it positively in the Early Cretaceous, most likely the Barremian age of 130 to 125 MYA.
Although two skulls are the only fossil material described, 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 dinosaur is known solely from those two skulls. Based on comparisons to other similar relatives, this bipedal herbivore has been described as small with a bony beak at the end of the upper and lower jaws. The skull of the holotype specimen was only 2 inches long. A larger adult skull was also found, measuring 8 inches long.
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 skulls 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.
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).
Hongshanosaurus houi is still potentially a nomen nudem; Sereno (2010), who proposed that Hongshanosaurus is a junior synonym of Psittacosaurus despite others who say there are enough differences in the skull to differentiate tham.