Kelmayisaurus

Kelmayisaurus
Temporal range: Early Cretaceous
Maxilla and dentary
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: †Carcharodontosauridae
Genus: †Kelmayisaurus
Dong, 1973
Species

Kelmayisaurus is an extinct genus of carcharodontosaurid theropod dinosaur from the early Cretaceous. It was roughly 9-11 meters (30-36 feet) Its name refers to the petroleum-producing city of Karamay in the Xinjiang province of western China near where it was found.

Discovery and species

Kelmayisaurus is known from the holotype and only specimen IVPP V 4022. It consists of a complete left dentary (lower jaw with teeth) and partial left maxilla. The specimen was found in the Lianmugin Formation of the Tugulu Group, dating to the ?Valanginian-Albian stages, around 140 to 100 million years ago. The discovery locality is near Wuerho in the Junggar Basin.[1] It was first named and described by Chinese paleontologist Dong Zhiming in 1973 and the type species is Kelmayisaurus petrolicus.[2] A supposed second species, K. "gigantus", was mentioned by Grady in a children book in 1993 as a gigantic vertebral column coming from a 22 m long specimen,[3] but is a nomen nudum and probably does not pertain to Kelmayisaurus. It may be a sauropod instead.[4]

Classification

Kelmayisaurus has been thought to be a nomen dubium due to its scanty remains,[5] and its phylogenetic position was uncertain. It has usually been regarded as a basal tetanuran of uncertain affinities.[6][7] However, Kelmayisaurus is diagnosable by the form and presence of a deeply inset accessory groove on the lateral side of the dentary, the main toothbearing bone of the lower jaw. Some of its features are like those of carcharodontosaurians, but they are also seen in large megalosauroids like Megalosaurus and Torvosaurus.[8]

In 2011, a redescription of the holotype by Stephen L. Brusatte, Roger B. J. Benson and Xing Xu found Kelmayisaurus to be valid genus of Carcharodontosauridae with a single autapomorphy. A phylogenetic analysis of Tetanurae recovered K. petrolicus as a basal carcharodontosaurid in a trichotomy with Eocarcharia and a clade comprising more derived carcharodontosaurids.[1]

References

  1. 1 2 Brusatte, Stephen L.; Benson, Roger B.J.; Xu, Xing; Stephen L. Brusatte, Roger B. J. Benson and Xing Xu (2011). "A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous of China" (PDF). Acta Palaeontologica Polonica. in press: 65. doi:10.4202/app.2010.0125.
  2. ↑ Dong, Z. (1973). "Dinosaurs from Wuerho". Reports of Paleontological Expedition to Sinkiang (II): Pterosaurian Fauna from Wuerho, Sinkiang. Memoirs of the Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica 11: 45-52.
  3. ↑ Grady, 1993. The Dinosaur Project: The Story of the Greatest Dinosaur Expedition Ever Mounted. Edmonton: Ex Terra Foundation; Toronto: Macfarlane Walter & Ross. ISBN 0-921912-46-3. 261 pp.
  4. ↑ http://dml.cmnh.org/2003Jul/msg00355.html
  5. ↑ Rauhut, Oliver W. M.; Xu, Xing (2005). "The small theropod dinosaurs Tugulusaurus and Phaedrolosaurus from the Early Cretaceous of Xinjiang, China". Journal of Vertebrate Paleontology. 25: 107–118. doi:10.1671/0272-4634(2005)025[0107:TSTDTA]2.0.CO;2. ISSN 0272-4634.
  6. ↑ Molnar, R.E., Kurzanov, S.M., Dong, Z. (1990): Carnosauria. In: D.B. Weishampel, P. Dodson, P., H. Osmólska (ed.), The Dinosauria. University of California Press, Berkeley, 169-209.
  7. ↑ Holtz, T.R., Molnar, R.E., Currie P.J. (2004): Basal Tetanurae. In: D.B. Weishampel, P. Dodson, P., H. Osmólska (ed.), The Dinosauria, 2nd edn. University of California Press, Berkeley, 71-110.
  8. ↑ Brusatte, S. L., Benson, R. B. J., and Xu, X. (2010). "The evolution of large-bodied theropod dinosaurs during the Mesozoic in Asia". Journal of Iberian Geology. 36: 275–296. doi:10.5209/rev_jige.2010.v36.n2.12. Retrieved 27 December 2011.



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