Nanshiungosaurus (meaning "Nanxiong's lizard") is a genus of therizinosaurid that lived in what is now Asia during the Late Cretaceous of South China. The type species, Nanshiungosaurus brevispinus, was first discovered in 1974 and described in 1979 by Dong Zhiming. It is represented by a single specimen preserving most of the cervical and dorsal vertebrae with the pelvis. A supposed and unlikely second species, "Nanshiungosaurus" bohlini, was found in 1992 and described in 1997. It is also represented by vertebrae but this species however, differs in geological age and lacks authentic characteristics compared to the type, making its affinity to the genus unsupported. It was a large-sized therizinosaurid that is estimated to have cover nearly 5 m (16 ft) in length and to have weighed about 600–907 kg (1,323–2,000 lb). Nanshiungosaurus had a very pneumatized vertebral column with the posterior cervical vertebrae of the long neck being unusually robust and slightly more elongated than the dorsals. It was equipped with a broad torso as seen on the bulky pelvis. As for other therizinosaurids, it had a keratinous beak used when feeding, stocky feet with four weight-bearing toes and large flattened claws. Nanshiungosaurus is classified as a therizinosaurian dinosaur. Along with Therizinosaurus and Segnosaurus, Nanshiungosaurus was one of the earliest therizinosaurs to be described and named. The unusual shape of the pelvis led Dong—the original describer—to interpret the remains as belonging to some dwarf sauropod, but during the 1990s the genus was recognized as a segnosaur (now therizinosaur) based the pelvic similarities with Segnosaurus. At first, the research on therizinosaurs was complicated since sparse remains were known at the time and these had features from multiple dinosaur lineages leading to their interpretation as prosauropod dinosaurs.
History of discovery
In 1974, during a geological expedition at the Nanxiong Basin led by the Institute of Vertebrate Paleontology and Paleoanthropology several fossilized remains of dinosaurs were discovered by the team. Near the village of Dapingcun at the Nanxiong Formation, Guangdong Province, a relatively large and partial skeleton was found in articulation dating back to the Late Cretaceous. The specimen was labelled under the number IVPP V4731 and consisted of 12 cervical (lacking the atlas), 10 dorsal, 5 (actually 6) sacral and the first caudal vertebrae with a nearly complete, bulky pelvis only lacking the right ilium and ischium. Later on, in 1979 the specimen was formally described by the Chinese paleontologist Dong Zhiming and used as the basis for the new genus and species Nanshiungosaurus brevispinus. The generic name, Nanshiungosaurus, refers to the site of provenance Nanxiong city and is derived from the Greek σαῦρος (sauros, meaning lizard). Lastly, the specific name, brevispinus, is derived from the Latin brevis and spina (meaning short and spine, respectively) in reference to the relatively short vertebral spines. When first described, Dong mistakenly thought the specimen to have been a dwarf, strange titanosaurine sauropod characterized by a shorter but thicker neck than other sauropods based on the pelvis structure. In 1997 Dong Zhiming and You Hailu named and described a supposed second species: "Nanshiungosaurus" bohlini, based on a skeleton found in 1992 near Mazongshan. It consists of 11 cervical and 5 dorsal vertebrae with some ribs. The specimen is catalogued as IVPP V11116 coming from the Early Cretaceous, Upper Xinminbao Group. Also, they coined the Nanshiungosauridae to contain "both species". Dong and Yu presented no evidence or argumentation supporting the assignment of the species to Nanshiungosaurus. In 2010, the North American paleontologist Lindsay Zanno considered this referral to be highly improbable since "N". bohlini dates back from the Barremian-Aptian ages and in the view of lack of synapomorphies, she considered that the supposed second species is unrelated to Nanshiungosaurus and might warrant its own genus. In addition, she corrected the number of sacral vertebrae from 5 to 6 and noted that the holotype pelvis from the latter has suffered damage since collection and has been reconstructed with painted plaster in the affected areas. Moreover, the remains of "N". bohlini were recovered from the lower red beds of the Zhonggou Formation in the Gongpoquan Basin, a completely different geological context. As an overall consensus, this dubious specimen is no longer considered to be relatable to Nanshiungosaurus.
Description
Nanshiungosaurus was a relatively large-bodied therizinosaurid, estimated at 5 m (16 ft) long weighing 600–907 kg (1,323–2,000 lb). This taxon can be differentiated by the possession of stocky posterior-most cervical vertebrae with opisthocoel (meaning that they were concave on their posterior sides) centra. Like other derived (advanced) therizinosaurids, Nanshiungosaurus was a pot-bellied animal that had a strong build composed of stout hindlimbs with a functionally tetradactyl pes. The arms ended up in large, recurved claws that were side to side flattened. Though the holotype specimen lacks cranial material, the preserved elements in therizinosaurids Erlikosaurus and Segnosaurus indicate that it had a relatively small skull with coarsely serrated teeth, and developed a prominent rhamphotheca (keratinous beak).
Vertebral column
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