Centrosaurus
| Centrosaurus | ||||||||||||
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Centrosaurus apertus skull with the nasal horn slightly curved back, exhibited at the Royal Ontario Museum |
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| Temporal occurrence | ||||||||||||
| Upper Cretaceous (late Campanium ) | ||||||||||||
| 76.4 to 72 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Centrosaurus | ||||||||||||
| Lambe , 1904 | ||||||||||||
| species | ||||||||||||
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Centrosaurus ("sharp-tip lizard") is a genus of dinosaurs from the Ceratopsidae familywithin the Ceratopsia . They were quadruped herbivores that lived in the Upper Cretaceous (late Campanium ). These dinosaurs were characterized by the long nasal horn and the neck shield. In addition to the species C. apertus ,which was already known at the beginning of the 20th century,another species was first described in 2005 with C. brinkmani .
features
General
Centrosaurus reached a length of around 6 meters and was thus a medium-sized representative of the Ceratopsidae, its weight is estimated at around 2.7 tons. The physique resembled that of the other Ceratopsidae, they were sturdy animals with large, massive skulls and powerful limbs, with the hind legs being significantly longer than the front legs.
Skull and teeth
He was a typical representative of the Centrosaurinae , the group with a short neck shield and longer nasal horns than forehead horns. The snout was pointed and, like all Ceratopsia, was formed from the rostral bone (in front of the upper jaw) and the predentals (in front of the lower jaw). As with all Ceratopsidae, the dentition consisted of tooth batteries, these are teeth arranged in rows, which were replaced by the following tooth when they were worn out. There were around 28 to 31 tooth positions. The occlusal surfaces of the dentition were almost vertical, which suggests that the teeth were mainly used for cutting.
The nasal bone had a long horn that curved forward in some specimens. On the forehead above the eyes Centrosaurus had two more, but very short horns, which depending on the species protruded upwards (in C. apertus ) or sideways outwards (in C. brinkmani ). The neck shield typical of the Ceratopsidae was formed relatively briefly from the parietal and scaled bones . It had two paired openings, its edge was provided with bony humps ( Epoccipitalia ). In the middle of the shield edge were two hook-shaped horns bent forward. In C. brinkmani these hook-shaped horns were provided with small, finger-shaped growths.
Trunk skeleton
The head and neck were connected by a powerful ball joint, which presumably allowed the head to move quickly. The first cervical vertebrae had fused to form the syncervical . The limbs were built robustly and were probably provided with strong muscles. The pool is, as with all Ceratopsidae, from a board-like ilium , pubis a long extension ( Präbubis ) and a slightly curved seat leg . The legs were columnar, the feet were short and strong. The front feet had five hoof-like toes and the hind feet four.
Integument (skin)
When Centrosaurus was found , remnants of the integument (skin) could be seen on the thigh . This was covered with large, round plates, the spaces in between were filled with small, irregularly shaped plates.
Paleobiology
Habitat and social behavior
The find area of Centrosaurus (today's Canadian province Alberta ) was characterized by meandering rivers and swampy forest areas in the Cretaceous period . Other pelvic dinosaurs such as Hadrosauridae , other Ceratopsidae , Pachycephalosauria and Ankylosauria , but also theropods such as Caenagnathidae , Dromaeosauridae or Tyrannosauridae and numerous other animals are known from this region (see fossil finds from the Judith River group ).
From Centrosaurus are bone beds ( "bone bed"), known mass deposits of hundreds of individuals. A fossil field discovered by Philip Currie in 1978 contained the bones of more than 500 individuals. It is likely that these animals lived together in groups for at least part of the year. Seasonal migratory behavior is also possible, possibly in connection with reproduction. It is conceivable that - similar to today's reindeer or wildebeest - they crossed the rivers in large groups and sometimes numerous animals perished at the same time.
Function of the horns and neck shields
Horns and neck shields are often associated with defense against predators. However, what speaks against this theory is that the neck shield was very thin and provided with paired windows and so would hardly have been suitable as protection against neck bites. Nor could the hook-shaped horns on the edge of the shield be used for defense purposes. The theory that the neck shield acted as a starting point for enlarged masticatory muscles is also rejected today. According to today's perspective, the headdress primarily served to identify the individual species as well as to interact with conspecifics - either through display, threatening gestures or in fights, which were probably about territorial boundaries or mating privileges.
posture
The question of the posture of Centrosaurus and other Ceratopsidae has turned out to be difficult to answer. Older depictions show these animals mostly with vertical hind legs spread wide apart, kinked front legs, in which the humerus bones were held almost horizontally. In the meantime, it was assumed that the front legs were completely stretched out. More recent studies, however, suspect that these animals had their forelegs almost straight, i.e. parallel to the longitudinal plane of the body ( parasagittal ), and with only slightly angled elbows.
food
Like all Ceratopsidae, Centrosaurus had tooth batteries with chewing surfaces arranged almost vertically. The teeth were aligned for a cutting, not grinding, motion. The pointed muzzle is an indication of an ability to selectively eat food, the structure of the lower jaw indicates a high bite force. Centrosaurus probably ate hard, fibrous plants.
Discovery and naming
The fossil remains of Centrosaurus were discovered in the Judith River Group in the Canadian province of Alberta and first described by Lawrence Lambe in 1904 . The name is derived from the ancient Greek kentron / κέντρον (= "pointed") and sauros / σαῦρος (= "lizard") and alludes to the hook-shaped horns on the edge of the shield. ( Kentrosaurus , the name of a stegosaur , is derived from the same words .) Type species is C. apertus , in 2005 a second species was described with C. brinkmani , which differs, among other things, in the construction of the horns above the eyes and the horns of the shield. The finds are dated in the Upper Cretaceous (late Campanium ) to an age of approx. 76.5 to 75 million years.
Systematics
Centrosaurus is the type of Centrosaurinae , one of the two subfamilies of the Ceratopsidae . A close relative is Styracosaurus , with which it is often summarized in the genus group of Centrosaurini. The subject of scientific discussions is still the question of whether the close relative Monoclonius is not a synonym for Centrosaurus , possibly juvenile or female animals.
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| Systematic position of Centrosaurus according to Evans & Ryan (2015). |
In 2015, the family tree of the Centrosaurinae was revised by Evans & Ryan (2015) on the occasion of the first description of the Wendiceratops found in Canada . Accordingly, Centrosaurus represents the sister genus to Spinops , the common taxon is compared to a sister group of Coronosaurus and Styracosaurus . In a phylogenetic analysis in 2012, it was still considered to be a sister species of a common group of Styracosaurus and Coronosaurus .
literature
- Barry Cox, Dougal Dixon , Brian Gardiner, Robert JG Savage: Dinosaurs and Other Animals of Ancient Times. The great encyclopedia of prehistoric wildlife. Special edition. Gondrom, Bindlach 1994, ISBN 3-8112-1138-2 .
- Peter Dodson , Catherine A. Forster, Scott D. Sampson: Ceratopsidae. 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. 494-513.
- David Lambert: dinosaurs. Dorling Kindersley, Munich 2002, ISBN 3-8310-9016-5 .
- John Malma, Steve Parker: The Empire of the Dinosaurs. Parragon Books Ltd, Bath 2006, ISBN 1-40548-228-1 .
- Michael J. Ryan, Anthony P. Russell: A new centrosaurine ceratopsid from the Oldman Formation of Alberta and its implications for centrosaurine taxonomy and systematics. In: Canadian Journal of Earth Sciences. Vol. 42, No. 7, 2005, ISSN 0008-4077 , pp. 1369-1387, doi : 10.1139 / E05-029 , digitized version (PDF; 2.0 MB) ( Memento from February 25, 2012 in the Internet Archive ).
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 260, online ( memento of the original from July 13, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. .
- ^ Gregory S. Paul, Per Christiansen: Forelimb Posture in Neoceratopsian Dinosaurs: Implications for Gait and Locomotion. In: Paleobiology. Vol. 26, No. 3, 2000, ISSN 0094-8373 , pp. 450-465, doi : 10.1666 / 0094-8373 (2000) 026 <0450: FPINDI> 2.0.CO; 2 .
- ↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide ( Memento of October 13, 2011 in the Internet Archive )
- ↑ David C. Evans , Michael J. Ryan : Cranial Anatomy of Wendiceratops pinhornensis gen. Et sp. nov., a Centrosaurine Ceratopsid (Dinosauria: Ornithischia) from the Oldman Formation (Campanian), Alberta, Canada, and the Evolution of Ceratopsid Nasal Ornamentation. PLOS ONE 10 (7): e0130007. doi : 10.1371 / journal.pone.0130007 .
- ↑ Michael J. Ryan, David C. Evans, Kieran M. Shepherd: A New Ceratopsid from the Foremost Formation (Middle Campanian) of Alberta. In: Canadian Journal of Earth Sciences , Vol. 49, No. 11, 2012, ISSN 0008-4077 , pp. 1251-1262, doi : 10.1139 / e2012-056 .
