Yunnanosaurus

Taxobox
name = "Yunnanosaurus"
fossil_range = Early - Middle Jurassic

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image_width = 250px
image_caption = "Yunnanosaurus huangi"
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Saurischia
subordo = Sauropodomorpha
infraordo = Prosauropoda
familia = Yunnanosauridae
familia_authority = Young, 1942
genus = "Yunnanosaurus"
genus_authority = Young, 1942
subdivision_ranks = Species
subdivision ="Y. huangi" Young, 1942 (type) "Y. youngi" Lu "et al.", 2007

"Yunnanosaurus" is a genus of prosauropod dinosaur from the Early to Middle Jurassic Period, a position in time that makes it one of the last prosauropods. It is closely related to "Lufengosaurus". Known from two valid species, "Yunnanosaurus" ranged in size from 7 meters (23 feet) long and 2 m (7 ft) high to 13 m (42 ft) long in the largest species.

Discovery

C. C. Young discovered the first "Yunnanosaurus" skeletons in the Lufeng Formation of Yunnan, China.the Lufeng Formation of Yunnan, China The fossil find was composed over twenty incomplete skeletons, including two skulls, and were excavated by Tsun Yi Wang.the Lufeng Formation of Yunnan, China

Dentition

There were more than sixty spoon shaped teeth in the jaws of "Yunnanosaurus", and were unique among prosauropods in that its teeth were self-sharpening because they " [wore] against each other as the animal fed.""Yunnanosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. "The Age of Dinosaurs". Publications International, LTD. p. 47. ISBN 0-7853-0443-6.] Scientists consider these teeth to be advanced compared to other prosauropods, as they share features with the sauropods.

However, scientists do not consider "Yunannosaurus" to be especially close to the sauropods in phylogeny because the remaining portions of the animals body are distinctly prosauropod in design. This critical difference implies that the similarity in dentition between "Yunnanosaurus" and sauropods might be an example of convergent evolution.

Classification

The type species, "Y. huangi", was named by C. C. Young in 1942, and he erected the family Yunnanosauridae to contain it, though the family currently comprises only this genus.Young, C. C. (1942). "Yunnanosaurus huangi" Young (gen. et sp. nov.), a new Prosauropoda from the red beds at Lufeng, Yunnan." "Bulletin of the Geological Society of China", 22 (1-2): 63-104.] Young also named a second species, "Y. robustus", in 1951,Young, C. C. (1951). "The Lufeng saurischian fauna in China." "Paleontologica Sinica", ser. C, 13: 1-96.] but this has since been included in the type species. The confusion in classification arose due to that the earliest specimens were of juveniles while the "Y. robustus" specimens represented fully grown adults.

In 2007, Lu and colleagues described another species of "Yunnanosaurus", "Y. youngi" (named in honor of C. C. Young). In addition to various skeletal differences, at 13 meters (42 ft) long "Y. youngi" was significantly larger than "Y. huangi" (which reached only 7 meters [23 ft] ), and "Y. youngi" is found later in the fossil record, hailing from the Middle Jurassic.Lu, J., Li, T., Zhong, S., Azuma, Y., Fujita, M., Dong, Z., and Ji, Q. (2007). "New yunnanosaurid dinosaur (Dinosauria, Prosauropoda) from the Middle Jurassic Zhanghe Formation of Yuanmou, Yunnan Province of China." "Memoir of the Fukui Prefectural Dinosaur Museum", 6: 1-15.]

References

External links

* [http://www.dinoruss.com/de_4/5a6b9ec.htm "Yunnanosaurus" in the Dinosaur Encyclopaedia] at Dino Russ's Lair