Қытайдың жойылған динозавры - Юннанозавр

Extinct genus of dinosaurs

Yunnanosaurus (/j//uː/,/n//æ//n//oʊ/'/s//ɔːr//ə//s/ yooNANohSORəs) is an extinct genus of sauropodomorph dinosaur that lived approximately 199 to 183 million years ago in what is now the Yunnan Province, in China, for which it was named. Yunnanosaurus was a large sized, moderately built, ground dwelling, quadrupedal herbivore, that could also walk bipedally, and ranged in size from 7 meters (23 feet) long and 2 m (6.5 ft) high to 4 m (13 ft) high in the largest species.

Yang Zhongjian (also known as C. C. Young) discovered the first Yunnanosaurus skeletons in the upper Zhangjiawa Member of the Lufeng Formation of Yunnan, China, dating to the Sinemurian stage of the Early Jurassic. The fossil find was composed of over twenty incomplete skeletons, including two skulls, it was excavated by Tsun Yi Wang. These remains were the basis for the species Y. huangi (the type species) and Y. robustus. In 2007, Lü Junchang 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]). The holotype specimen CXMVZA 185 consists of ten cervical vertebrae, fourteen dorsal vertebrae, three fused sacral vertebrae, seventeen caudal vertebrae, both pubic bones, both ischia, and the right ilium. The skull of this species is not known. The type specimen of Yunnanosaurus youngi was recovered at the Banqing Houshanliangzi locality of the Fengjiahe Formation, previously thought to be from the Zhanghe Formation, in Yuanmou County of Yunnan Province, China. The holotype specimen CXMVZA 185 was collected in 2000 in terrestrial sediments deposited during the Pliensbachian stage of the Early Jurassic period, approximately 191 to 183 million years ago. This specimen is housed in the collection of the Chuxiong Museum. In 2013, Sekiya et al. described the discovery of a juvenile individual which was assigned to Yunnanosaurus robustus.

There were more than sixty spoon shaped teeth in the jaws of Yunnanosaurus, and were unique among early sauropodomorphs in that its teeth were self sharpening because they "[wore] against each other as the animal fed." Scientists consider these teeth to be advanced compared to other early sauropodomorphs, as they share features with the sauropods. Young also named a second species, Y. robustus, in 1951, but this has since been included in the type species. Apaldetti et al. (2011) also found that Yunnanosaurus belonged in Massopoda, but found that this genus was more primitive than both Jingshanosaurus and Anchisaurus.

A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism.