Pachyrhinosaurus
| Pachyrhinosaurus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Live reconstruction of Pachyrhinosaurus perotorum |
||||||||||||
| Temporal occurrence | ||||||||||||
| Upper Cretaceous (upper Campanium to lower Maastrichtian ) | ||||||||||||
| 76.4 to 71 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Pachyrhinosaurus | ||||||||||||
| Sternberg , 1950 | ||||||||||||
| species | ||||||||||||
|
||||||||||||
Pachyrhinosaurus (Eng. "Thick-nosed lizard") is a genus of dinosaur from the Ceratopsidae familywithin the Ceratopsia thatlived in what is now North Americaduring the late Upper Cretaceous .
features
With an estimated length of 5.5 to 7 meters, Pachyrhinosaurus was a rather large representative of the Ceratopsidae. His physique resembled that of the rest of this group. They were sturdy animals with a massive head and strong limbs, with the hind legs being significantly longer than the front legs. Instead of a nasal horn as in related dinosaurs, Pachyrhinosaurus wore a thick, bony bulge on the nasal bone . It is sometimes speculated that a keratin horn sat on this bead , but there are no signs of this in the fossil record.
As with all Ceratopsidae, the neck shield was formed from the parietal and scaled bones . It was thin and had a pair of windows. There were one to three large spines on the rear edge of the shield.
The rostral bones (in front of the upper jaw) and the predentals (in front of the lower jaw) formed a pointed snout, as in all Ceratopsidae, which enabled selective feeding. 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 dentition were almost vertical, so the teeth were adapted to a cutting but not grinding chewing activity. Like all Ceratopsia, this dinosaur was herbivorous, presumably it mainly ate hard, fibrous plants.
Paleobiology
Bone beds are known from Pachyrhinosaurus , in which the remains of numerous animals from different ages were found together. It is assumed that these animals lived together at least temporarily in larger associations.
Horns and neck shields of the Ceratopsidae are often associated with the defense against predators. The bony bulge on the nose of Pachyrhinosaurus and the horns on the edge of the shield are unlikely to have been suitable 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.
Find localities and stratigraphic classification
Locations of Pachyrhinosaurus are in North America in the Canadian province of Alberta ( Horseshoe Canyon Formation , St. Mary River Formation, Waptiti Formation) and in the US state of Alaska (Colville group). The finds of twelve incomplete skulls and other material from Bonebeds come from rock layers, the sediments of which were deposited in the period of the early Maastrichtian (approx. 71 million years ago), the last stage of the Cretaceous (and thus the entire Mesozoic Era ). This makes this dinosaur one of the youngest known representatives of the Centrosaurinae.
The first description of the genus comes from Charles Mortram Sternberg from 1950. Its name is derived from the Greek words pachys (= "thick"), rhinos (= "nose") and sauros (= "lizard"). Besides the same time established the genus type species P. canadensis the late since 2008 Campanian originating (before about 76 to 72 million years) Type P. lakustai known. In 2012, P. perotorum, a third species from the early Maastrichtian (about 71 million years ago) of Alaska was added.
Systematics
Pachyrhinosaurus is integrated into the Centrosaurinae within the Ceratopsidae . Its closest relative was probably the Achelousaurus , also characterized by the missing nasal horn . Together they formed the Pachyrhinosaurini tribe .
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Systematic position of Achelousaurus 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, the Pachyrhinosaurini were confirmed and Achelousaurus is the sister genus of Pachyrhinosaurus , the common sister genus is Einiosaurus . He 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.
- Charles M. Sternberg : Pachyrhinosaurus canadensis, representing a new family of Ceratopsia. In: National Museum of Canada. Bulletin. Vol. 118, 1950, ZDB -ID 429576-6 , pp. 109-120.
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. 263-264, online .
- ↑ Brown et al. A New Horned Dinosaur Reveals Convergent Evolution in Cranial Ornamentation in Ceratopsidae . Current Biology, 2015 DOI: 10.1016 / j.cub.2015.04.041
- ^ Philip J. Currie , Wann Langston , Darren H. Tanke: A new species of Pachyrhinosaurus (Dinosauria, Ceratopsidae) from the Upper Cretaceous of Alberta, Canada. In: Philip J. Currie, Wann Langston, Darren H. Tanke: A New Horned Dinosaur from an Upper Cretaceous Bone Bed in Alberta. NRC Research Press, Ottawa 2008, ISBN 978-0-660-19819-4 , pp. 1-108.
- ^ Anthony R. Fiorillo, Ronald S. Tykoski: A new species of the centrosaurine ceratopsid Pachyrhinosaurus from the North Slope (Prince Creek Formation: Maastrichtian) of Alaska. In: Acta Palaeontologica Polonica. Vol. 57, No. 3, 2012, ISSN 0567-7920 , pp. 561-573, doi : 10.4202 / app.2011.0033 .
- ↑ 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 .