Monolophosaurus

Monolophosaurus
Temporal range: Middle Jurassic, 165 Ma
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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 (about 168-161 Ma) of the 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 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. 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]

Contents

Discovery and classification

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

  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". http://www.dinosauria.com/dml/names/dinom.htm. 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. http://doc.rero.ch/lm.php?url=1000,43,39,20091210005526-ZZ/PAL_E2326.pdf. 
  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. http://articles.latimes.com/1987-10-23/news/mn-10753_1_dinosaur-fossil. 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. http://sites.google.com/site/brusatte/Brusatteetal2010MonolophosaurusSkull.pdf?attredirects=0. 
  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. http://geolmag.geoscienceworld.org/cgi/content/full/147/1/13. 
  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

External links