Einiosaurus
| Einiosaurus | ||||||||||||
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Live reconstruction of Einiosaurus |
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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 | ||||||||||||
| Einiosaurus | ||||||||||||
| Sampson , 1995 | ||||||||||||
| Art | ||||||||||||
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Einiosaurus is a genus of pelvic dinosaurs from the group of Ceratopsidae within the Ceratopsia .
features
With a length of around six meters, Einiosaurus was a medium-sized representative of the Ceratopsidae. As with all animals in this group, the head was large and massive. The pointed snout was composed of the rostral bone (in front of the upper jaw) and the predentale (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. The occlusal surfaces of the teeth were almost vertical.
On the nasal bone sat a large, laterally compressed horn, which in some individuals was bent forward. There were two more horns above the eyes, albeit very small and rounded. The neck shield formed from the parietal bone and the scaly bone was relatively short and provided with two pair of openings. At the rear edge of the shield sat two long, backward-pointing, slightly curved horns.
The physique resembled that of the other Ceratopsidae. The torso was stocky and the limbs were sturdy. The hind legs, which ended in four hoof-like toes, were significantly longer than the front legs. Einiosaurus moved quadruped (on all fours).
Paleobiology
Bone beds are known from Einiosaurus , in which the remains of numerous animals of different ages have been found. It is assumed that these animals lived together at least for a time in larger groups and perished together in a natural disaster (flood or drought).
Horns and neck shields of the Ceratopsidae are often associated with the defense against predators. The headdress of Einiosaurus with the nose horn bent forward and the shield horns protruding backwards should not have been very well suited for defense purposes. The neck shield was also too thin to act as a protection against neck bites. 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. It may have been about territorial boundaries or mating privileges.
The Einiosaurus tooth batteries with the vertical occlusal surfaces were designed for a cutting, but not a grinding movement. The pointed muzzle is an indication of an ability to selectively eat food, the structure of the lower jaw indicates a high bite force. This dinosaur probably lived on tough, fibrous plants.
Discovery and naming
The fossil remains of Einiosaurus were found in the Two Medicine Formation in the US state of Montana and first described in 1995 . The generic name is derived from einio , the word for buffalo in the Blackfoot language , and the Greek sauros / σαῦρος (= "lizard") and can be translated as "buffalo lizard". The type and only known species is E. procurvicornis . The finds are dated in the Upper Cretaceous (late Campanium ) to an age of approx. 76 to 72 million years.
Systematics
Einiosaurus is classified within the Ceratopsidae in the subfamily of Centrosaurinae , which were mostly characterized by a large nasal horn, small super-eye horns and short neck shields. Its position within the Centrosaurinae is controversial. It is considered either as a sister taxon of the Achelousaurus - Pachyrhinosaurus clade or the Styracosaurus - Centrosaurus clade or as a basic representative of the Centrosaurinae.
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| Systematic position of Einiosaurus 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, Einiosaurus represents the sister genus to a common taxon from Achelousaurus and Pachyrhinosaurus . It was also placed in this position in a phylogenetic analysis in 2012.
literature
- 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.
Web links
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 , pp. 260-261, online .
- ↑ SD Sampson: Two new horned dinosaurs from the upper Cretaceous Two Medicine Formation of Montana; with a phylogenetic analysis of the Centrosaurinae (Ornithischia: Ceratopsidae). In: Journal of Vertebrate Paleontology , Volume 15, Issue 4, pp. 743-760, 1995. (Abstract)
- ↑ 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 .