Pentaceratops

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Pentaceratops
Skeletal reconstruction of Pentaceratops sternbergii. From Samson et al. (2010) [1]

Skeletal reconstruction of Pentaceratops sternbergii . From Samson et al. (2010)

Temporal occurrence
Upper Cretaceous (late Campanium to early Maastrichtian )
76.4 to 69.9 million years
Locations
Systematics
Marginocephalia
Ceratopsia
Neoceratopsia
Ceratopsidae
Chasmosaurinae
Pentaceratops
Scientific name
Pentaceratops
Osborn , 1923
Art
  • P. sternbergii Osborn, 1923

Pentaceratops ("five-horned face") is a genus ofpelvic dinosaurs from the group of Ceratopsidae within the Ceratopsia . Fossil evidence of the genus comes from the Upper Cretaceous of western North America .

features

Skull of the holotype ( AMNH 6325) of P. sternbergii with partially adherent rock matrix. Photo from Osborn's first description from 1923.

Pentaceratops reached a body length of 7 to 7.5 meters, a height of about 2.5 meters and an estimated weight of up to 5 tons. He was thus one of the largest representatives of the Ceratopsidae. Like other representatives of this group, he had a massive body supported by four strong legs. The hind legs were significantly longer than the front legs, this dinosaur moved like all ceratopsids quadruped (four-legged). Its tail was shorter than that of the related genera.

The skull of Pentaceratops was huge and massive, it reached a length of over 2 meters including the neck shield, which is one of the longest known skulls of all land-dwelling animals. The snout was pointed, 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 teeth arranged in rows, which 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 , two more horns were above the eyes. The cheek region was expansive and wide, so that the skull, together with the pointed snout, had an approximately triangular shape from above. The epijugale , a skull bone, formed a conspicuous cheek horn on each side. The neck shield typical of the Ceratopsidae was formed from the parietal and scaled bones . It was very long and had large, paired openings. The outer edge of the shield was covered with knob-shaped ossifications called epoccipitalia .

Paleobiology

Live reconstruction of Pentaceratops

In contrast to related species, no bone beds were found of Pentaceratops , in which the fossils of numerous animals lay together. Conclusions about social behavior and possible life in herds are therefore not possible from the fossil report .

Horns and neck shields of the Ceratopsidae are often associated with the defense against predators. However, the small shield rim horns and the cheek horns may not have been very well suited for defense purposes. The neck shield was also too thin to protect 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 Pentaceratops 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 Pentaceratops were found in the US state of New Mexico and first described by Henry Fairfield Osborn in 1923 . The generic name is derived from the Greek words penta / πέντα (= "five"), keras / κέρας (= "horn") and - ops / ωψ (= "face") and plays on the nasal horn, the two super-eye horns and the two cheek horns.

The type species was P. sternbergii , a second species ( P. fenestratus ) described in 1930 is now considered a synonym for P. sternbergii . The type epithet honors Charles H. Sternberg , an eminent amateur palaeontologist and explorer of the fossil deposits in western North America. A total of nine at least partially preserved skulls and one complete and several partial skeletons have been preserved. The finds are dated in the Upper Cretaceous (late Campanian to early Maastrichtian ) to an age of 76 to 69 million years.

In 2014 a second species was described, Pentaceratops aquilonius from the upper Campanium of Alberta. It is smaller and differs from P. sternbergii in the shape of the neck shield and the arrangement of the ossifications on the outer edge of the shield .

Systematics

Pentaceratops is classified within the Ceratopsidae in the Chasmosaurinae , which were characterized by a mostly long neck shield and long outer horns. Its closest relatives are Chasmosaurus and Agujaceratops , with whom it forms a clade of basal Chasmosaurinae.

literature

Individual evidence

  1. ↑ 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 .
  2. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ u. a. 2010, ISBN 978-0-691-13720-9 , p. 272, online .
  3. ^ A b Henry Fairfield Osborn : A new genus and species of Ceratopsia from New Mexico, Pentaceratops sternbergii (= American Museum Novitates. No. 93, ISSN  0003-0082 ). The American Museum of Natural History, New York NY 1923, p. 3, online .
  4. ↑ Nicholas R. Longrich. 2014. The horned dinosaurs Pentaceratops and Kosmoceratops from the upper Campanian of Alberta and implications for dinosaur biogeography . In: Cretaceous Research , Volume 51, Pages 292-308; doi: 10.1016 / j.cretres.2014.06.011

Web links

Commons : Pentaceratops  - collection of images, videos and audio files