Yinlong

Taxobox
name = "Yinlong"
fossil_range = Late Jurassic

---

image_width = 200px
image_caption =
regnum = Animalia
phylum = Chordata
classis = Sauropsid
superordo = Dinosauria
ordo = Ornithischia
subordo = Cerapoda
infraordo = Ceratopsia
genus = "Yinlong"
genus_authority = Xu "et al.", 2006
subdivision_ranks = Species
subdivision =
*"Y. downsi" Xu "et al.", 2006 (type)

"Yinlong" (meaning "hidden dragon") is a genus of basal ceratopsian dinosaur from the Late Jurassic Period of central Asia. It was a small, primarily bipedal herbivore, approximately 1.2 meters (4 ft) long. "Yinlong" is the oldest and most primitive ceratopsian known to science.

Discovery and Species

A coalition of American and Chinese paleontologists, including Xu Xing, Catherine Forster, Jim Clark, and Mo Jinyou, described and named "Yinlong" in 2006. The generic name is derived from the Mandarin Chinese words 隱 ("yǐn": "hidden") and 龍 ("lóng": "dragon"), a reference to the movie "Crouching Tiger, Hidden Dragon", large portions of which were filmed in the western Chinese province of Xinjiang, near the locality where this animal's fossil remains were discovered. "Long" is the word most often used in the Chinese media when referring to dinosaurs, thus having been incorporated into several other Chinese dinosaur names ("Dilong", "Mei long" and "Guanlong").

"Yinlong" Species

*"Y. downsi" (type)

The species was named after the late Will Downs, a frequent participant in paleontological expeditions to China, who died the year before "Yinlong" was discovered.

The known fossil material of "Yinlong" consists of a single exceptionally well-preserved skeleton, complete with skull, of a nearly adult animal, found in 2004 in the Middle-Late Jurassic strata of the Shishugou Formation located in Xinjiang Province, China. "Yinlong" was discovered in an upper section of this formation which dates to the Oxfordian stage of the Late Jurassic, or approximately 161 to 156 million years ago. All other described ceratopsians are known from the later Cretaceous Period.

Classification

A small rostral bone on the end of the upper jaw clearly identifies "Yinlong" as a ceratopsian, although the skull displays several features, especially the ornamentation of the squamosal bone of the skull roof, which were previously thought to be unique to pachycephalosaurians. The presence of these features in "Yinlong" indicates these as actual synapomorphies (unique features) of the larger group Marginocephalia, which contains both the pachycephalosaurs and the ceratopsians, although these features have been lost in all known ceratopsians more derived than "Yinlong". The addition of these characters further strengthens the support for Marginocephalia. "Yinlong" also preserves skull features reminiscent of the family Heterodontosauridae, providing support for the hypothesis that heterodontosaurids are closely related to marginocephalians (Cooper, 1985; Zhao "et al"., 1999; You "et al"., 2003). The group containing Marginocephalia and Heterodontosauridae has been named Heterodontosauriformes (Xu "et al"., 2006).

Diet

"Yinlong" was discovered with seven gastroliths preserved in the abdominal cavity. Gastroliths, stones stored in the digestive tract and used to grind plant material, are also found in other ceratopsians such as "Psittacosaurus", and are also widely distributed in most other dinosaur groups, as well as in many types of birds.

In popular culture

"Yinlong" made its first appearance in popular culture on the National Geographic Channel documentary "Dino Death Trap" as a prey item of "Guanlong". The documentary called "Yinlong" "a little ancestor of the giant dinosaurs like "Triceratops", while contrasting the shape of "Yinlong"'s head to those of the later ceratopsian. The documentary highlighted the importance of the find, and stated that the fossil remains "give a snap-shot of dinosaur evolution".cite episode| title = Dino Death Trap (National Geographic)| episodelink = | series = | serieslink = | airdate = 2007-12-09| season = | url= http://www.youtube.com/watch?v=cn25SkgKgtU&feature=related| number = ]

References

*Cooper, M.R. 1985. "A revision of the ornithischian dinosaur "Kangnasaurus coetzeei" Haughton, with a classification of the Ornithischia." "Annals of the South African Museum" 95: 281-317.
*Xu X., Forster, C.A., Clark, J.M., & Mo J. 2006. "A basal ceratopsian with transitional features from the Late Jurassic of northwestern China." "Proceedings of the Royal Society B: Biological Sciences". doi:10.1098/rspb.2006.3566 [published online]
*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: 15–20.
*Zhao X., Cheng Z., & Xu X. 1999. "The earliest ceratopsian from the Tuchengzi Formation of Liaoning, China." "Journal of Vertebrate Paleontology" 19(4): 681-691.

External links

* [http://www.gwu.edu/~newsctr/fossilfind/ GW News Center] , featuring a link to the original paper, pictures, and a press release on the discovery of "Yinlong" (site operated by George Washington University)