Gravitholus
| Gravitholus | ||||||||||||
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Skull roof of Gravitholus |
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| Temporal occurrence | ||||||||||||
| Upper Chalk | ||||||||||||
| 75 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Gravitholus | ||||||||||||
| Wall & Galton , 1979 | ||||||||||||
| Art | ||||||||||||
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Gravitholus is a genus of bird's pelvis dinosaur (Ornithischia) from the group of Pachycephalosauria , the existence of which is controversial.
The fossil remains of Gravitholus were found in the Dinosaur Park Formation in the Canadian province of Alberta and first described in 1979 . The name is derived from the Latin gravis (= "heavy") and the Greek tholos (= "dome") and alludes to the vaulted skull roof. The type species and the only species described is G. albertae . The finds are dated to the Upper Cretaceous (late Campanium ), to an age of around 75 million years.
So far only parts of the skull roof of Gravitholus have been found. As with all pachycephalosaurs, this is composed of the frontal bone and the parietal bone and has the thickening typical of this group of dinosaurs. The top of the skull of this dinosaur was noticeably high and wide, a characteristic was an indentation of the parietal bone. This left the brain less space than in other pachycephalosaurs of comparable size, but the find could also have been a pathologically deformed animal. Otherwise nothing is known about this dinosaur, its length is estimated to be around 3 meters based on comparisons with other pachycephalosaurs.
It is disputed whether Gravitholus is a valid generic name. Some researchers such as R. Sullivan see the findings as too sparse for a precise description and list this dinosaur as the nomen dubium , others see it as a synonym for Stegoceras . However, the shape of the skull roof is unique within the Pachycephalosauria, due to the poor state of preservation and the possible pathological changes, no final judgment can currently be made about the systematic position of Gravitholus .
literature
- Teresa Maryańska , Ralph E. Chapman, David B. Weishampel : Pachycephalosauria. In: David B. Weishampel, Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 464-477.
- Robert M. Sullivan: A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia). In: Spencer G. Lucas, Robert M. Sullivan (Eds.): Late Cretaceous Vertebrates from the Western Interior (= New Mexico Museum of Natural History and Science. Bulletin. 35, ISSN 1524-4156 ). New Mexico Museum of Natural History and Science, Albuquerque NM 2006, pp. 347–365, digital version (PDF; 4.79 MB) .