Xuanhanosaurus

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Xuanhanosaurus
Temporal range: Middle Jurassic, 167.7–161.2 Ma
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Xuanhanosaurus qilixiaensis.png
An artist's restoration of Xuanhanosaurus qilixiaensis
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Metriacanthosauridae
Genus: †Xuanhanosaurus
Dong, 1984
Species:
†X. qilixiaensis
Binomial name
†Xuanhanosaurus qilixiaensis
Dong, 1984

Xuanhanosaurus (meaning "Xuanhan lizard") is a genus of theropod dinosaur that lived during the Middle Jurassic of China, around 167.7 to 161.2 million years ago.[1]

Discovery[]

Xuanhanosaurus reconstructed in an outdated quadrupedal position.[2][3]

The type species Xuanhanosaurus qilixiaensis was named by Dong Zhiming in 1984. The generic name refers to Xuanhan County in Sichuan, while the specific name is derived from the town of Qilixia. The holotype specimen, IVPP V.6729, was found in China's Lower Shaximiao Formation. It consists of a partial skeleton without a skull.[3]

Description[]

An X. qilixiaensis specimen compared to an average human male

Xuanhanosaurus was approximately 4.5 meters (15 ft) in length, with a weight of 250 kilograms (550 lb).[4] Xuanhanosaurus had powerful forelimbs, over 65 cm long; this, along with the retention of the fourth metacarpal in the hand, led Dong to suggest that Xuanhanosaurus might have walked on all four legs. If so, it would be the only known four-legged meat-eater among dinosaurs.[3] Later paleontologists have not agreed with Dong's original assessment. They think this dinosaur walked on its hind legs as other theropods did, pronation of the lower arm being impossible. The strong arms could instead have been useful in catching prey.[5]

Phylogeny[]

Assigned by Dong to the Megalosauridae, Xuanhanosaurus was found by in 2009 to belong to a primitive lineage of the Megalosauroidea.[6] A more recent study by Benson and colleagues in 2010 found that it was more likely to be the most primitive known member of the Metriacanthosauridae family.[2] In 2019, Rauhut and Pol recovered Xuanhanosaurus outside of Metriacanthosauridae, as the basalmost member of Allosauroidea.[5]

References[]

  1. ^ Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.
  2. ^ a b Benson, R. B. J.; Carrano, M. T; Brusatte, S. L. (2010). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic". Naturwissenschaften. 97 (1): 71–78. Bibcode:2010NW.....97...71B. doi:10.1007/s00114-009-0614-x. PMID 19826771. Supporting Information
  3. ^ a b c Dong, Z. (1984). "A new theropod dinosaur from the Middle Jurassic of Sichuan Basin". Vertebrata PalAsiatica 22(3):213-218
  4. ^ Paul, G.S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press. p. 86.
  5. ^ a b Rauhut, Oliver W. M.; Pol, Diego (2019-12-11). "Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs". Scientific Reports. 9 (1): 18826. doi:10.1038/s41598-019-53672-7. ISSN 2045-2322. PMC 6906444. PMID 31827108.
  6. ^ Benson, R. B. J. (2010). "A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods". Zoological Journal of the Linnean Society. 158 (4): 882–935. doi:10.1111/j.1096-3642.2009.00569.x.


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