Monolophosaurus

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Monolophosaurus
Temporal range: Middle Jurassic, 165Ma
Mounted skeleton in Japan
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Dinosauria
Order: Saurischia
Suborder: Theropoda
(unranked): Tetanurae
Superfamily: Megalosauroidea[1]
Genus: Monolophosaurus
Zhao & Currie 1993
Species
  • M. jiangi Zhao & Currie 1993 (type)

Monolophosaurus (/ˌmɒnɵˌlɒfəˈsɔrəs/ MON-o-LOF-ə-SAWR-əs;[2] meaning "single-crested lizard") was a genus of theropod dinosaur from the Middle Jurassic Shishugou Formation in what is now Xinjiang, China.[3][4] It was named for the single crest on top of its skull. The type and only known individual is estimated at 5 metres (16.5 ft).[4] The area that Monolophosaurus was found showed signs of water, so it is possible that this dinosaur lived on the shore of lakes or ocean.[citation needed] The Monolophosaurus jiangi IVP 84019 had its 10th and possibly 11th neural spines fractured. The tenth is fused to the eleventh. A series of parallel ridges on one of the specimen's dentaries may represent tooth marks.[5]

Discovery and classification[edit]

Mounted skeletons of Monolophosaurus and Tuojiangosaurus, Field Museum, Chicago, Illinois.
Restoration

A nearly complete skeleton was unearthed in 1984. At first, before description in the scientific literature, it was known in the press as "Jiangjunmiaosaurus", a nomen nudum.[3][6]

In 1993 Zhao and Currie named the type species Monolophosaurus jiangi; the species name refers to Jiangjunmiao ("an abandoned desert inn") near which the holotype IVPP 84019 was found.[3][7] Monolophosaurus was originally termed a "megalosaur" and has often since been suggested to be an allosauroid. Carr (2006) even suggested that the "proceratosaurid" "tyrannosauroid" Guanlong was a subadult Monolophosaurus and therefore an "allosauroid",[8] by noting both taxa have a large, thin, and fenestrated midline crest, but this is probably not the case.

Smith et al. (2007) was the first publication to find Monolophosaurus to be a non-neotetanuran tetanuran,[9] by noting many characters previously thought to be exclusive of Allosauroidea to have a more wider distribution. Also, Zhao et al. (2009) noted various primitive features of the skeleton suggesting that Monolophosaurus could be one of the most basal tetanuran dinosaurs instead.[10] Benson (2008, 2010) placed Monolophosaurus in a clade with Chuandongocoelurus that is more basal than Megalosauridae and Spinosauridae in the Megalosauroidea.[1][11] Latter, Benson et al. (2010) found the Chuandongocoelurus/Monolophosaurus clade to be outside of Megalosauroidea and Neotetanurae, near the base of Tetanurae.[12]

References[edit]

  1. ^ a b Benson, Roger 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: 882−935. doi:10.1111/j.1096-3642.2009.00569.x. 
  2. ^ Creisler, Ben (July 7, 2003). "Dinosauria Translation and Pronunciation Guide M". Retrieved August 23, 2010. 
  3. ^ a b c Zhao, Xi-Jin; Currie, Philip J. (1993). "A large crested theropod from the Jurassic of Xinjiang, People's Republic of China". Canadian Journal of Earth Sciences 30: 2027–2036. Bibcode:1993CaJES..30.2027Z. doi:10.1139/e93-178. 
  4. ^ a b Holtz, Thomas R., Jr. (2007). Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. New York: Random House. pp. Genus list "last updated 8/1/2008". ISBN 978-0-375-82419-7. 
  5. ^ Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363.
  6. ^ Holley, David (October 23, 1987). "2nd creature was meat-eater: fossil remains of huge dinosaur found in China". Los Angeles Times. Retrieved August 23, 2010. 
  7. ^ Brusatte, Stephen L.; Benson, Roger B. J.; Currie, Philip J.; Zhao, Xijin (2010). "The skull of Monolophosaurus jiangi (Dinosauria: Theropoda) and its implications for early theropod phylogeny and evolution". Zoological Journal of the Linnean Society 158: 573–607. doi:10.1111/j.1096-3642.2009.00563.x. 
  8. ^ Carr T. 2006. Is Guanlong a tyrannosauroid or a subadult Monolophosaurus? Journal of Vertebrate Paleontology 26:48A.
  9. ^ Smith ND, Makovicky PJ, Hammer WR, Currie PJ. 2007. Osteology of Cryolophosaurus ellioti (Dinosauria:Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution. Zoological Journal of the Linnean Society 151: 377–421.
  10. ^ Zhao, Xijin; Benson, Roger B. J.; Brusatte, Stephen L.; Currie, Philip J. (2010). "The postcranial skeleton of Monolophosaurus jiangi (Dinosauria: Theropoda) from the Middle Jurassic of Xinjiang, China, and a review of Middle Jurassic Chinese theropods". Geological Magazine 147 (1): 13–27. doi:10.1017/S0016756809990240. 
  11. ^ Benson, 2008. A new theropod phylogeny focussing on basal tetanurans, and its implications for European 'megalosaurs' and Middle Jurassic dinosaur endemism. Journal of Vertebrate Paleontology. 51A.
  12. ^ Brusatte, Benson, Currie and Zhao, 2010. The skull of Monolophosaurus jiangi (Dinosauria: Theropoda) and its implications for early theropod phylogeny and evolution. Zoological Journal of the Linnean Society. 158(3), 573-607.

Further reading[edit]

External links[edit]