Xinjiangtitan

Xinjiangtitan Temporal range: Middle Jurassic
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Suborder:	†Sauropodomorpha
Family:	†Mamenchisauridae
Genus:	†Xinjiangtitan Wu et al., 2013
Type species
†Xinjiangtitan shanshanesis Wu et al., 2013

Xinjiangtitan is an extinct genus of mamenchisaurid sauropod known from the Middle Jurassic Qigu Formation in Piqan County of Xinjiang, northwestern China. Estimates of body length for the holotype are approximately 30–32 m (98–105 ft) in length, making Xinjiangtitan one of the longest sauropods known.^[1]

Discovery

Xinjiangtitan was first described and named by Wu Wen-hao, Zhou Chang-fu, Oliver Wings, Toru Sekiha and Dong Zhiming in 2013 and the type species is Xinjiangtitan shanshanesis. The generic name is derived from Xinjiang where the bones were discovered in 2012, and from titan, giant in Greek mythology. The specific name, shanshanesis, is derived from an alternative name for the county where it was found, Shanshan, named after the ancient Shanshan Kingdom. The specific name is occasionally misspelled as "shanshanensis" or "shashaensis", which are invalid spellings even though the correct form would indeed have been "shanshanensis" rather than shanshanesis, as the Latin suffix "-ensis" meaning "from", was used to create the name. Xinjiangtitan is known solely from the holotype SSV12001, a partial but, apart from some erosion, well preserved in situ postcranial skeleton including the first two caudal vertebrae, the last two cervical vertebrae, and all dorsal (12) and sacral vertebrae (5), as well as several cervical, dorsal and sacral ribs, a partial left leg (including the femur, tibia, fibula and a metatarsal), left and right pubic bones and right ischium.^[1]

Description

Xinjiangtitan was diagnosed based on the following traits: the presence of a ventral keel on the penultimate cervical centrum that forms a small semicircular process under the distal articular facet; both cervical vertebrae are relatively elongated; the sacricostal yoke excepts the first sacral rib; and an extremely robust femur.

The series of dorsal vertebrae has a length of 372 centimetres. The thighbone is 165 centimetres long, and the tibia is 98 cm.

It was estimated at 30–32 m (98–105 ft).^[1]

Phylogeny

Among sauropods, a phylogenetic analysis places Xinjiangtitan as the sister taxon of Mamenchisaurus, the only other mamenchisaurid included. Xinjiangtitan shares several derived characters with diplodocids, including prominent ambiens process of pubis, relatively short hind limb and fourth trochanter on the femur that is caudomedially developed.^[1]

References