| Baotianmansaurus | |
|---|---|
 | |
| Holotype specimen at theHenan Geological Museum | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Somphospondyli |
| Genus: | †Baotianmansaurus Zhang X.et al., 2009 |
| Type species | |
| Baotianmansaurus henanensis Zhang X.et al., 2009 | |
Baotianmansaurus is anextinctgenus ofsomphospondyliansauropod. Its fossils were discovered in theLate CretaceousGaogou Formation ofHenan Province,China. The type and only species isB. henanensis — named after the province in which it was found.[1]
The fossils ofBaotianmansaurus were discovered at a locality called Neixiang, nearNanyang City in theHenan Province ofChina. This locality is part of theBaotianman National Nature Reserve corresponds to the rocks of theGaogou Formation. Dinosaur body fossils in this formation are rare, but a wide variety ofegg fossils from dinosaurs and other animals have been found. Theholotype, and only known specimen ofBaotianmansaurus was given the designation 41HIII-0200 and is stored at theHenan Geological Museum inZhengzhou.[1]
It was described and given a name in April 2009 by a team of researchers including Zhang Xingliao,Lü Junchang, Xu Li, Li Jinhua, Hu Weiyong, Jia Songhai, Ji Qiang, and Zhang Chengjun in conjunction with the Henan Geological Museum, theChinese Academy of Geological Sciences, andLanzhou University. The genus was named"Baotianmansaurus" after the Baotianman Nature Reserve and the traditionalGreek wordsaûros (σαῦρος), Latinized assaurus, meaning "lizard". The species epithet,"henanensis" is after the Henan province in which it was found.[1]
Baotianmansaurus was a medium-sized sauropod. It was a very large animal in absolute terms, but not nearly as large as the largest of its contemporaries. The authors of its description did not provide an estimate of its in-life size, nor did they provide any measurements of the elements preserved.[1] Rubén Molina-Pérez and Asier Larramendi estimated the full size ofBaotianmansaurus at about 22.5 m (74 ft) long, 5.3 m (17 ft) tall at the shoulder, and weighing 21 t (46,000 lb)[2]Gregory S. Paul published a slightly smaller estimate of 20 m (66 ft) long and weighing 15 t (33,000 lb).[3]
Theholotype ofBaotianmansaurus is relatively incomplete. It consists of an incompletedorsal vertebra from the upper back, another vertebra from the lower back, fiveribs, two partialsacral vertebrae, an incompletecaudal vertebra, the distal end of ascapula, and several bone fragments that were not able to be identified. These remains were sufficient to name a new genus and species.Baotianmansaurus can be distinguished from all othersauropods by the presence of the followingautapomorphies: a spongy character of the back vertebrae, shortneural spines on the vertebrae of the middle back, a developed system of 11e on the vertebrae, apneumatic ribs, amphicoelous caudal vertebrae that are shorter than they are wide, and several specific features of the vertebral laminae.[1]
The exact affinities ofBaotianmansaurus have been controversial since it was first described. Zhang and colleagues originally assigned it to an indeterminate position inTitanosauriformes, outside of bothBrachiosauridae andSomphospondyli. They remarked that it bears one of theautapomorphies of Somphospondyli, but that this was insufficient to assign it to that clade.[1] Subsequent authors have recovered a wide variety ofphylogenetic positions for the genus. Philip Mannion and colleagues found it to be a member ofSaltasauridae, closely related toOpisthocoelicaudia.[4] Alexander Averianov and Hans Dieter-Sues suggested that it was atitanosaur outside of the cladeLithostrotia.[5] A 2011 review of the evolution of Titanosauriformes found it to belong toEuhelopodidae.[6]
A 2019 examination of sauropods from theTendaguru Formation found a close relationship betweenBaotianmansaurus,Dongyangosaurus, and theDiamantinasauria.[7] The next year, a phylogenetic analysis corroborated a close relationship withDongyangosaurus as well as withJiangshanosaurus in a clade at the base of Titanosauria.[8] More recent analyses using various datasets have recoveredBaotianmansaurus as either a non-titanosaur somphospondylian closely related toHuanghetitan or a basal member of Titanosauria closely related toAndesaurus andAbdarainurus.[9][10] The classification of titanosaurs and their relatives has generally been controversial, partly due to the fragmentary nature of many specimens, so the exact affinities ofBaotianmansaurus remain unresolved, beyond it being a member of the large clade Somphospondyli.[11] However, a close relationship withDongyangosaurus has been corroborated by multiple analyses.[7][9]
