Skeletal reconstructions by C. belli
|Upper Cretaceous (late Campanium )|
|76.4 to 72 million years|
|Lambe , 1914|
Chasmosaurus was a rather small representative of the Ceratopsidae with a length of around 5 meters and an estimated weight of 2 tons. His physique resembled that of the rest of this group. The skull was large and massive, the snout, like all representatives of this group of dinosaurs, pointed and resembling a parrot's beak. It was formed from the rostral bone (in front of the upper jaw) and the predentale (in front of the lower jaw). The teeth consisted of tooth batteries, which are rows of teeth that were replaced by the next tooth when they were worn out. The occlusal surfaces of the teeth were almost vertical.
There was a small horn on the nasal bone , and two other small horns were above the eyes. The neck shield typical of the Ceratopsidae was formed from the parietal and scaled bones . It was relatively long and had large, paired openings.
The trunk was sturdy, the limbs stocky. The front limbs, which ended in five toes, were significantly shorter than the hind legs, which had four hoofed toes. Chasmosaurus always moved quadruped (on all fours).
Bone beds are known from Chasmosaurus , in which the remains of numerous animals of different ages have been found. It is conceivable that these animals lived together at least for a time in larger groups.
Horns and neck shields of the Ceratopsidae are often associated with the defense against predators. According to today's point of view, the headdress primarily served to identify the individual species and to interact with conspecifics - either through display, threatening gestures or in fights. It may have been about territorial boundaries or mating privileges.
The Chasmosaurus 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
All fossil remains of Chasmosaurus were in the lineup Dinosaur Park in Alberta ( Canada found). It was first described by Lawrence Lambe in 1914, the type species was C. belli . The name is derived from the Greek words chasma (= "hole, opening") and sauros (= "lizard") and alludes to the large openings in the neck shield. In 1940 a second species was described with C. russelli and in 2001 a third species with C. irvinensis . A former fourth species, C. mariscalensis , is now listed in its own genus Agujaceratops . All finds of Chasmosaurus come from the Upper Cretaceous (late Campanium ) and are approx. 76 to 72 million years old.
Chasmosaurus was first described scientifically in 1914 by the Canadian paleontologist Lawrence Lambe . The genus is classified within the Ceratopsidae in the Chasmosaurinae , which were generally characterized by a short nasal horn and a long neck shield. Chasmosaurus is closely related to Agujaceratops and Pentaceratops , together they form a basal clade within the Chasmosaurinae. Introduced in 2010 by Nicholas R. Longrich genus Mojoceratops is now considered a synonym of Chasmosaurus .
- Peter Dodson, Catherine A. Forster, and Scott D. Sampson: Ceratopsidae. In: D. Weishampel, P. Dodson and H. Osmólska (eds.): The Dinosauria . University of California Press, 2004, ISBN 0-520-24209-2 , pp. 494-513.
- Scott D. Sampson, Mark A. Loewen, Andrew A. Farke, Eric M. Roberts, Catherine A. Forster, Joshua A. Smith, Alan L. Titus: New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism. In: PLoS ONE . Vol. 5, No. 9, 2010, e12292, doi : 10.1371 / journal.pone.0012292 .
- Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , pp. 269-271, online ( memento of the original of July 13, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. .
- Nicholas R. Longrich (2010). Mojoceratops perifania , A New Chasmosaurine Ceratopsid from the Late Campanian of Western Canada. Journal of Paleontology. 84 (4): 681-694. doi: 10.1666 / 09-114.1
- Campbell, JA, Ryan, MJ, Holmes, RB and Schröder-Adams, CJ (2016). A Re-Evaluation of the chasmosaurine ceratopsid genus Chasmosaurus (Dinosauria: Ornithischia) from the Upper Cretaceous (Campanian) Dinosaur Park Formation of Western Canada. PLoS ONE, 11 (1): e0145805. doi: 10.1371 / journal.pone.0145805