Centrosaurus
| Centrosaurus Temporal range: Late Cretaceous
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| Centrosaurus, with large nasal horn, exaggerated epoccipitals, and bony processes over the front of the frill. Museum of Victoria | |
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| Genus: | Centrosaurus Lambe, 1904
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C. apertus Lambe, 1904 | |
Centrosaurus (Template:Pron-en SEN-tro-SAW-rəs) is an herbivorous ceratopsian dinosaur from the late Cretaceous of North America. It lived approximately 75 million years ago.
The name Centrosaurus means "pointed lizard" (from Greek kentron/κεντρον = "point or prickle" + sauros/σαυρος = "lizard"), and refers to the series of small hornlets placed along the margin of the frill, not to the horn on its nose (which was unknown when the dinosaur was named). It is not to be confused with the stegosaur Kentrosaurus, whose name is derived from the same Greek word.
Description
Centrosaurus massive body was borne by stocky limbs, although at 18-20 ft (6m) it was not a particularly large dinosaur. Like other centrosaurines, Centrosaurus had a single large horn over the nose..[1] It may curve forwards or backwards in different species.
A pair of small horns is also found over the eyes; in Centrosaurus apertus these are directed upwards, whereas they are directed to the sides in C. brinkmani. The frill of Centrosaurus was moderately long, with fairly large fenestrae and small hornlets along the outer edge.[1]
C. apertus is distinguished by having two large hornlets which hook forwards over the frill, while in C. brinkmani these hornlets are small and covered with small, finger-like growths.
History
The first Centrosaurus remains were discovered by paleontologist Lawrence Lambe in strata along the Red Deer River in Alberta, Canada. Later, vast bonebeds of Centrosaurus were found in Dinosaur Provincial Park, also in Alberta. Some of these beds extend for hundreds of meters and contain thousands of individuals of all ages and all levels of completion. Scientists have speculated that the high density and number of individuals would be explained if they had perished while trying to cross a flooded river.[1]
Classification
Centrosaurus gives its name to the Centrosaurinae subfamily to which it belongs. These were large North American horned dinosaurs characterized by their "prominent nasal horns, subordinate brow horns, short squamosals in a short frill, a tall, deep face relative to the ceratopines, and a projection into the rear of the nasal fenestra."[2] Its closest relatives appear to be Styracosaurus and Monoclonius. It so closely resembles the latter of these that some paleontologists have considered them to represent the same animal.[1]
Other members of the Centrosaurinae clade include Pachyrhinosaurus,[3][4] Avaceratops,[3] Einiosaurus,[4][5] Albertaceratops,[5] Achelousaurus,[4] and possibly Brachyceratops,[6] although Brachyceratops is dubious. Because of the variation between species and even individual specimens of centrosaurines, there has been much debate over which genera and species are valid, particularly whether Centrosaurus and/or Monoclonius are valid genera, undiagnosable, or possibly members of the opposite sex. In 1996, Peter Dodson found enough variation between Centrosaurus, Styracosaurus, and Monoclonius to warrant separate genera, and that Styracosaurus resembled Centrosaurus more closely than either resembled Monoclonius. Dodson also believed one species of Monoclonius, M. nasicornis, may actually have been a female Styracosaurus.[7] His assessments have been partially followed, with other researchers not accepting Monoclonius nasicornis as a female Styracosaurus, or Monoclonius as a valid genus.[8] While sexual dimorphism has been proposed for an earlier ceratopsian, Protoceratops,[9] there is no firm evidence for sexual dimorphism in any ceratopsid.[10][11][12]
Palaeobiology
Like other Ceratopsidae, the jaws of Centrosaurus were designed to shear through tough plant material; the frill provided an attachment for large jaw muscles. The discovery of gigantic bone beds of Centrosaurus in Canada suggest that it was a gregarious animal and could have traveled in large herds.[1] A bone bed composed of Centrosaurus and Styracosaurus remains is known from the Dinosaur Park Formation in what is now Alberta.[13] The mass deaths may have been caused by otherwise non-herding animals gathering around a waterhole during a drought.[14] Centrosaurus is found lower in the formation than Styracosaurus, indicating that Centrosaurus was displaced by Styracosaurus as the environment changed over time.[8]
The large frills and nasal horns of the ceratopsians are among the most distinctive facial adornments of all dinosaurs. Their function has been the subject of debate since the first horned dinosaurs were discovered. Common theories concerning the function of ceratopsian frills and horns include defense from predators, combat within the species, and visual display. A 2009 study of Triceratops and Centrosaurus skull lesions found that bone injuries on the skull were more likely caused by intraspecific combat (horn-to-horn combat) rather than predatory attacks. The frill of Centrosaurus was too thin to be used for defense against predators, although the thicker, solid frill of Triceratops might have evolved to protect the neck. The frill of Centrosaurus was most likely used "for species recognition and/or other forms of visual display".[15]
References
- ^ a b c d e "Centrosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 135. ISBN 0-7853-0443-6.
- ^ Tweet, J. (2007). "Centrosaurinae". Thescelosaurus. Qwest.net. Retrieved 2009-05-25.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - ^ a b Dodson, P. (1990). "On the status of the ceratopsids Monoclonius and Centrosaurus". In Carpenter, K.; and Currie, P.J. (eds.) (ed.). Dinosaur Systematics: Perspectives and Approaches. Cambridge: Cambridge University Press. pp. 231–243. ISBN 0-521-36672-0.
{{cite book}}:|editor=has generic name (help)CS1 maint: multiple names: editors list (link) - ^ a b c Ryan, M.J. (2005). "A new centrosaurine ceratopsid from the Oldman Formation of Alberta and its implications for centrosaurine taxonomy and systematics". Canadian Journal of Earth Sciences. 42: 1369–1387. doi:10.1139/e05-029.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b Ryan, M.J. (2007). "A new basal centrosaurine ceratopsid from the Oldman Formation, southeastern Alberta". Journal of Paleontology. 81 (2): 376–396. doi:10.1666/0022-3360(2007)81[376:ANBCCF]2.0.CO;2.
{{cite journal}}: Cite has empty unknown parameter:|coauthors=(help) - ^ Dodson, P., Forster, C. A, and Sampson, S. D. (2004) Ceratopsidae. In: Weishampel, D. B., Dodson, P., and Osmólska, H. (eds.), The Dinosauria (second edition). University of California Press:Berkeley, pp. 494–513. ISBN 0-520-24209-2.
- ^ Dodson, P. (1996). The Horned Dinosaurs: A Natural History. Princeton University Press: Princeton, New Jersey, pp. 197–199. ISBN 0-691-02882-6.
- ^ a b Ryan, Michael J. (2005). "Ornithischian Dinosaurs". Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Bloomington: Indiana University Press. pp. 312–348. ISBN 0-253-34595-2.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|editors=ignored (|editor=suggested) (help) - ^ Dodson, P. "Quantitative aspects of relative growth and sexual dimorphism in Protoceratops". Journal of Paleontology. 50: 929–940.
- ^ Forster, C. A. (1990). The cranial morphology and systematics of Triceratops, with a preliminary analysis of ceratopsian phylogeny. Ph.D. Dissertation. University of Pennsylvania, Philadelphia. 227 pp.
- ^ Lehman, T. M. (1998). "A gigantic skull and skeleton of the horned dinosaur Pentaceratops sternbergi from New Mexico". Journal of Paleontology. 72 (5): 894–906.
- ^ Sampson, S. D. (1997). "Craniofacial ontogeny in centrosaurine dinosaurs (Ornithischia: Ceratopsidae): taphonomic and behavioral phylogenetic implications". Zoological Journal of the Linnean Society. 121: 293–337. doi:10.1111/j.1096-3642.1997.tb00340.x.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Eberth, David A. (2005). "Ceratopsian bonebeds: occurrence, origins, and significance". Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Bloomington: Indiana University Press. pp. 501–536. ISBN 0-253-34595-2.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|editors=ignored (|editor=suggested) (help) - ^ Rogers, R. R. (1990). "Taphonomy of three dinosaur bone beds in the Upper Cretaceous Two Medicine Formation, northwestern Montana: Evidence for drought-related mortality". Palaios. 5: 394–41. doi:10.2307/3514834.
- ^ Farke, A.A., Wolff, E.D.S., and Tanke, D.H. (2009) "Evidence of Combat in Triceratops". PLoS ONE 4(1): e4252. doi:10.1371/journal.pone.0004252
