| Liubangosaurus | |
|---|---|
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Somphospondyli |
| Genus: | †Liubangosaurus Mo, Xu, & Buffetaut,2010 |
| Type species | |
| Liubangosaurus hei Mo, Xu, & Buffetaut, 2010 | |
Liubangosaurus (meaning "Liubang lizard", after Liubang village, theholotype locality) is agenus ofsauropoddinosaur that lived during theEarly Cretaceous in what is nowChina.Liubangosaurus is known from the holotype NHMG 8152, five complete and articulated middle-caudal dorsalvertebrae that were collected from theXinlong Formation inFusui County,Guangxi Province. Thetype species isL. hei, which honors He Wenjian, who discovered the site whereLiubangosaurus was discovered.[1]
Sauropod remains were first discovered at the Liubang Quarry in 2001, near the village of the same name (Liubang) which is near the city ofNanning in theGuangxi Province of southern China. This locality corresponds to theNapai Formation, which isEarly Cretaceous in age. Subsequent excavations determined that remains from a minimum of three individual specimens were present in the quarry. The largest of these would eventually be described as the newgenusFusuisaurus. The two smaller specimens were mostly disarticulated, which made it difficult for researchers to distinguish which bones belonged to which individuals. The remains were excavated with the help of theNatural History Museum of Guangxi, which is where the specimens were eventually stored. However, five caudal vertebrae among these remains were articulated, which was deemed sufficient to name and describe the new genus and speciesLiubangosaurus hei. It was fully described and named in 2010 by Mo Jinyou,Xu Xing, and Eric Buffetaut.[1]
Theholotype ofLiubangosaurus was given the specimen number NHMG 8152. It consists of five articulateddorsal vertebrae, believed to represent the fifth through ninth dorsal vertebrae. The largest of these vertebrae (the fifth dorsal) has a total height of 710 mm (28 in).[1] The fragmentary nature of the specimen makes the full size ofLiubangosaurus difficult to estimate. Rubén Molina-Pérez and Asier Larramendi estimated its full size as being 26 m (85 ft) long, 5.4 m (18 ft) tall at the shoulder, and 26 tons[2]
Despite consisting of only five vertebrae, the holotype ofLiubangosaurus preserves severalautapomorphies. These include features of theparapophyses,diapophyses, neural spines, andvertebral laminae. In particular, the vertebrae have a very distinctive "Y-shape" when viewed along their transverse plane.[1]
In their description ofLiubangosaurus, Mo and colleagues conducted aphylogenetic analysis ofneosauropods in order to determine the affinities of the new species. The trees they recovered were not very resolved and recoveredLiubangosaurus in apolytomy with other groups of neosauropods. They suggested that it may be a close relative of theLate Jurassic genusHaplocanthosaurus, however they also caution that this assignment is very tentative due to the fragmentary nature of the holotype.[1] Philip Mannion and colleagues published a comprehensive analysis oftitanosauriform relationships in 2013. They used two different analytical methods to test these relationships, and both methods recovered different relationships forLiubangosaurus.[3] The fragmentary nature ofLiubangosaurus has served to complicate determinations of its phylogenetic affinities. Several recent analyses omit it entirely from their consensus trees.[4][5] Condensed versions of the cladograms recovered by Mo and colleagues and also by Mannion and colleagues are shown below.[1][3]
TheXinlong Formation is anAptian-agedgeological formation that consists mainly of various types ofsiltstones, finesandstones, somemudstones and sandyconglomerates. The depositional environment consisted of various types ofwetlands, which is reflected in the fossils that have been discovered in the area.Bivalve,charophyte,ostracod, andgastropod fossils are common alongside remains fromhybodontiformes,bowfins,gars,turtles, and somecrocodyliformes. Dinosaurs known from the area include thesauropodsAsiatosaurus andFusuisaurus, remains fromspinosaurids, and some indeterminateornithopods.[6]
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