Huayangosaurus

Taxobox
name = "Huayangosaurus"
fossil_range = Middle Jurassic

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image_width = 200px
image_caption = "Huayangosaurus tianfuensis" displayed in Hong Kong.
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Ornithischia
subordo = Thyreophora
infraordo = Stegosauria
familia = Huayangosauridae
binomial = "Huayangosaurus taibaii"
binomial_authority = Dong, Tang, and Zhou, 1982

"Huayangosaurus" is a genus of stegosaurian dinosaur from the Middle Jurassic of China. The name derives from "Huayang", an alternate name for Sichuan (the province where it was discovered), and "saurus", meaning "lizard". It lived during the Bathonian to Callovian stages, around 165 million years ago, some 20 million years before its famous relative, "Stegosaurus" appeared in North America. At only 4.5 metres long, it was also much smaller than its famous cousin. Found in the Lower Shaximiao Formation, "Huayangosaurus" shared the local Middle Jurassic landscape with the sauropods "Shunosaurus", "Datousaurus", "Omeisaurus" and "Protognathosaurus", the ornithopod "Xiaosaurus" and the carnivorous "Gasosaurus".

Description

Like other stegosaurians, "Huayangosaurus" was a quadrupedal herbivore with a small skull and a spiked tail. Like its more famous relative, "Stegosaurus", "Huayangosaurus" bore the distinctive double row of plates that characterize all the stegosaurians. These plates rose vertically along its arched back. In "Huayangosaurus", the plates were more spike-like than in "Stegosaurus". Like "Stegosaurus", however, it bore two pairs of long spikes extending horizontally near the end of its tail.

"Huayangosaurus" was one of the smallest known stegosaurians, at just 4.5 meters in length.

Discovery and species

"Huayangosaurus" remains from twelve individual animals were recovered from the Dashanpu Quarry near Zigong in Sichuan, and named by Dong, Tang, and Zhou in 1982. The type species is "H. taibaii".Dong, Z., Tang, Z. and Zhou, S.W. (1982). ["Note on the new Mid-Jurassic stegosaur from Sichuan Basin, China"] (in Chinese). "Vertebrata PalAsiatica" 20 (1) :83-87]

Classification

As it is the most basal stegosaurian, it is placed in within its own family "Huayangosauridae". It is also morphologically distinct from later (stegosaurid) forms. Its skull was broader and had premaxillary teeth in the front of its mouth. All later stegosaurians lost these teeth. [Sereno, P & Z-M Dong (1992). The skull of the basal stegosaur "Huayangosaurus taibaii" and a cladistic diagnosis of Stegosauria. "Journal of Vertebrate Paleontology" 51: 318-343]

Palaeobiology

Like many other stegosaurians, it had plates all down its back and spikes on its tail. Two large spikes were above its hips, and may have been used for deterring an attack from above (considering as it was a fairly short in height compared to later stegosaurians). Its plates were smaller than those of "Stegosaurus", with much less surface area. Thus they would have been much less effective heat regulators, one of the postulated functions of plates.

Popular culture

Mounted skeletons of "Huayangosaurus" are on display at the Zigong Dinosaur Museum in Zigong and the Municipal Museum of Chongqing in Sichuan Province in China.

References

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External links

* [http://www.users.qwest.net/~jstweet1/stegosauria.htm Stegosauria]
* [http://www.amonline.net.au/chinese_dinosaurs/factsheets/01.htm "Huayangosaurus" Factsheet - Australian Museum]