Xianshanosaurus

Xianshanosaurus Temporal range: Early Cretaceous, Aptian–Albian PreꞒ Ꞓ O S D C P T J K Pg N
Reconstructed skeleton
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Clade:	†Sauropoda
Clade:	†Macronaria
Clade:	†Titanosauriformes
Clade:	†Somphospondyli
Genus:	†Xianshanosaurus Lü et al., 2009
Type species
Xianshanosaurus shijiagouensis Lü et al., 2009

Xianshanosaurus (Chinese: 岘山龙; pinyin: xiànshānlóng)^[1] is a genus of sauropod dinosaur from the Early Cretaceous (Aptian-Albian) of the Ruyang Basin in Henan Province, China. Its type and only species is Xianshanosaurus shijiagouensis. It was described in 2009 by a team of paleontologists led by Lü Junchang. Xianshanosaurus may be a titanosaur, and Daxiatitan may be its closest relative, but its evolutionary relationships remain controversial.

Taxonomy

Xianshanosaurus and its type species X. shijiagouensis were named by Lü Junchang, Xu Li, Jiang Xiaojun, Jia Songhai, Li Ming, Yuan Chongxi, Zhang Xingliao, and Ji Qiang in 2009. The type specimen, accessioned in the Henan Geological Museum, consists of ten caudal vertebrae, a coracoid, a femur, and several ribs. The genus name refers to Xian Mountain (Chinese: 岘山; pinyin: xiànshān), located near where the holotype was found.^[2]

Phylogenetic relationships

When Xianshanosaurus was first described, its discoverers noted that it had an unusual mixture of characteristics of titanosaurs and non-titanosaurian sauropods, and classified it as an indeterminate neosauropod.^[2] In 2011, Philip Mannion and Jorge Calvo tentatively considered it a titanosaur,^[3] and in 2012, Michael D'Emic interpreted it as a lithostrotian titanosaur.^[4]

Studies that have included Xianshanosaurus in phylogenetic analyses have regarded it as an unstable taxon.^[5][6] In several studies, it has been recovered as a titanosaur either close to or within Lithostrotia, with Daxiatitan sometimes recovered as its sister taxon.^[5][7] In contrast, Andrew Moore and colleagues found it to be highly unstable, potentially belonging to Titanosauria, Turiasauria, or Euhelopodidae. In the third case, in which Euhelopodidae was recovered as a non-neosauropod clade equivalent to Mamenchisauridae, Moore et al. recovered Daxiatitan as the sister taxon of Xianshanosaurus.^[6]

Habitat

Xianshanosaurus shared its habitat with Ruyangosaurus, "Huanghetitan" ruyangensis, Yunmenglong, Luoyanggia, and Zhongyuansaurus. The Haoling Formation was initially thought to be Cenomanian in age, but is now considered Aptian-Albian.^[8]

References

1. Xu, Li; Zhang, Xingliao; Lü, Junchang; Jia, Songhai; Pan, Zecheng; Qin, Shuang; Zhu, Hongwei; Zeng, Guangyuan (2010). "The Ruyang gigantic sauropod dinosaurian fauna from Henan Province and discussion on geological time of the fossil-bearing strata". Geological Review. 56 (6): 761–768.
2. Lü, J.; Xu, L.; Jiang, X.; Jia, S.; Li, M.; Yuan, C.; Zhang, X.; Ji, Q. (2009). "A preliminary report on the new dinosaurian fauna from the Cretaceous of the Ruyang Basin, Henan Province of central China". Journal of the Paleontological Society of Korea. 25: 43–56.
3. Mannion, Philip D.; Calvo, Jorge O. (2011). "Anatomy of the basal titanosaur (Dinosauria, Sauropoda) Andesaurus delgadoi from the mid-Cretaceous (Albian-early Cenomanian) Río Limay Formation, Neuquén Province, Argentina: implications for titanosaur systematics". Zoological Journal of the Linnean Society. 163: no. doi:10.1111/j.1096-3642.2011.00699.x. ISSN 0024-4082. S2CID 86633142.
4. D'Emic, Michael D. (2012). "The early evolution of titanosauriform sauropod dinosaurs". Zoological Journal of the Linnean Society. 166 (3): 624–671. doi:10.1111/j.1096-3642.2012.00853.x. hdl:2027.42/94293. ISSN 0024-4082.
5. Mannion, Philip D.; Upchurch, Paul; Barnes, Rosie N.; Mateus, Octávio (2013). "Osteology of the Late Jurassic Portuguese sauropod dinosaur Lusotitan atalaiensis (Macronaria) and the evolutionary history of basal titanosauriforms: Lusotitan and Titanosauriform Evolution". Zoological Journal of the Linnean Society. 168 (1): 98–206. doi:10.1111/zoj.12029. ISSN 0024-4082.
6. Moore, Andrew J.; Upchurch, Paul; Barrett, Paul M.; Clark, James M.; Xu, Xing (2020). "Osteology of Klamelisaurus gobiensis (Dinosauria, Eusauropoda) and the evolutionary history of Middle–Late Jurassic Chinese sauropods". Journal of Systematic Palaeontology. 18 (16): 1299–1393. Bibcode:2020JSPal..18.1299M. doi:10.1080/14772019.2020.1759706. eISSN 1478-0941. ISSN 1477-2019. S2CID 219749618.
7. Mannion, Philip D.; Upchurch, Paul; Jin, Xingsheng; Zheng, Wenjie (2019). "New information on the Cretaceous sauropod dinosaurs of Zhejiang Province, China: impact on Laurasian titanosauriform phylogeny and biogeography". Royal Society Open Science. 6 (8): 191057. Bibcode:2019RSOS....691057M. doi:10.1098/rsos.191057. ISSN 2054-5703. PMC 6731702. PMID 31598266.
8. Xu, L., Pan, Z.C., Wang, Z.H., Zhang, X.L., Jia, S.H., Lü, J.C., Jiang, B.L., 2012. Discovery and significance of the Cretaceous system in Ruyang Basin, Henan Province. Geological Review 58, 601-613.