Nanshiungosaurus is a Therizinosaurid theropod from Cretaceous China.
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 907 kg (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 tretadactyl 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)
Classification[]
Nanshiungosaurus was in 1979 by Dong assigned to the Titanosaurinae, based on the assumption it was a sauropod genus, more specifically a titanosaurine (titanosaur). During this same year, the paleontologist Altangerel Perle described and named Segnosaurus also erecting the Segnosauridae to contain this strange taxon. After the findings of Nanshiungosaurus and Segnosaurus, more complete relatives started to be discovered, but their anatomical traits were so aberrant compared to other theropods to the point of being considered as Late Cretaceous sauropodomorph dinosaurs. In 1990, the paleontologists Rinchen Barsbold and Teresa Maryańska noted the striking similarities between the pelvises of Nanshiungosaurus and Segnosaurus, such as the ophisthopubic condition and large iliac blade. They concluded that the former was part of the Segnosauria and found this group to be a rare and aberrant group of saurischians in a position subject to change among sauropodomorphs and theropods. Dong also agreed with these similarities and placed the genus within the Segnosauridae in 1992. Nevertheless, the description of Alxasaurus in 1993 proved that the long-aberrant segnosaurs were tetanuran theropod dinosaurs and Segnosauridae was a junior synonym of the older name Therizinosauridae. Segnosauria also became synonymous with Therizinosauria. In 1997, with the description and naming of "N". bohlini, Dong and You placed the therizinosaurids Nanshiungosaurus and the former into a separate Nanshiungosauridae. They did not provide authentic traits or bases behind this new grouping. In 2010, Zanno performed one of the most complete analyses of the Therizinosauria at that point and noted that these two species do not pertain to the same genus and therefore the use of the Nanshiungosauridae was invalid and represents a synonym of Therizinosauridae.
Nanshiungosaurus features multiple therizinosaurid traits such as an ophisthopubic pelvis, elongated iliac blade and an expanded obturator process. In her phylogenetic analysis, Zanno recovered this taxon as a derived therizinosaurid closer to Nothronychus and Segnosaurus. The therizinosaurid placement of Nanshiungosaurus has been widely followed and corroborated by most cladistic analyses. The extensive phylogenetic analysis conducted by Hartman and colleagues in 2019 based on Zanno's 2010 analysis, recovers Nanshiungosaurus in a more derived position than Neimongosaurus or Therizinosaurus.
Paleoecology[]
Nanshiungosaurus was one of the last therizinosaurs to exist. The fossil remains were unearthed from the Nanxiong Formation, which has been dated to the latest Maastrichtian stage about 66.7 ± 0.3 million years ago. This formation is mainly composed by purplish mudstones and siltstones, and was deposited in a floodplain environment, under a relatively warm, humid subtropical climate. Oviraptorid eggs are particularly common on the formation with at least five well-preserved egg clutches. Moreover, a fossilized female oviraptorid with two eggs is known from the formation. The tracks of ornithopod dinosaurs are locally abundant at the Nanxiong region.
The therizinosaurid Nanshiungosaurus was a bulky high-browser in its ecosystem, and shared its habitat with multiple oviraptorosaur species such as Banji, Ganzhousaurus, Corythoraptor, Nankangia, Huanansaurus or Shixinggia. However, it is possible that some of these oviraptorosaurs did not actually live together given the poor stratigraphic analysis of the formation. Additional dinosaurs are represented by the fast-running, long-snouted tyrannosaurid Qianzhousaurus, the sauropod Gannansaurus, and the very sparse remains of hadrosaurid dinosaurs such as Microhadrosaurus (now a nomen dubium). Other reptiles that composed the fauna were the terrestrial or semiaquatic nanhsiungchelyid turtles Nanhsiungchelys and Jiangxichelys, squamates Chianghsia and Tianyusaurus, and the crocodilian Jiangxisuchus.
In the Media[]
- Nanshiungosaurus was originally supposed to appear in the movie Disney Dinosaur but was cut and it's concept art is shown.
- Several individuals are also seen in the second Dino King film, where they are shown as scaly dinosaurs.
Gallery[]
Nanshiungosaurus/Gallery