Xenoceratops
| Xenoceratops | ||||||||||||
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Skull of Xenoceratops foremostensis |
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| Temporal occurrence | ||||||||||||
| Upper Cretaceous ( Campanium ) | ||||||||||||
| 78 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Xenoceratops | ||||||||||||
| Ryan et al., 2012 | ||||||||||||
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Xenoceratops is a genus of pelvic dinosaur from the Ceratopsidae family . Its only known representative, Xenoceratops foremostensis , lived around 78 million years ago in the late Cretaceous in western North America . The fossil remains of the species wereexcavatedin the Canadian Foremost Formation in the 1950sanddescribedas a new genus and species in November 2012. Osteological analyzes show them to be the most original representatives of the Centrosaurinae .
features
From xenoceratops only the structure of is not yet parietal known. It shows the shape of an arch, typical of Centrosaurinae , which connects to the top of the skull and, in living animals, was covered with skin so that it formed a large neck shield. Reconstructions of the Xenoceratops skull suggest that the pronotum was covered with a large hump on the cheeks and had four other, smaller bony humps on the sides. At the two apexes of the pronotum there were presumably two horn-like appendages that pointed upwards at an angle. This is inferred from the shape of the parietal arches, which enclosed high, oval windows, which is also the case with Diabloceratops or Albertaceratops . Both genera had two large, upturned horns on the upper edge of their pronotum. In its other morphology , Xenoceratops with features such as a beak-shaped snout, strong trunk and large head probably corresponded to the typical structure of the Ceratopsidae.
Site, fossil material and stratigraphy
All Xenoceratops fossils are found in southern Alberta , near the border with Saskatchewan and the United States . It is an outcrop of the Foremost Formation between the villages of Medicine Hat in the north, Manyberries in the east, Onefour in the southeast and Foremost in the west. The Foremost Formation originates from the middle Cenomanian and forms a transition from marine sediments of the Western Interior Seaway to the non-marine Oldman Formation . It consists mainly of marine sediments, but also includes continental deposits. The Xenoceratops remains came from an accumulation of bones that lay between oyster deposits and the taber coal layer and was embedded in a layer of shale . They belong to different, fully grown individuals. The find layer is dated to an age of around 78 million years and was located on the northeast coast of the continent Laramidia , which roughly corresponds to the mountainous western part of today's North America.
Paleoecology
Very little is known about the paleoecology of Xenoceratops . Like all ceratopsians, the animals were probably herbivores. The habitat of Xenoceratops was probably an ecosystem located on or near the beach. Its paleofauna has only been explored fragmentarily; in addition to Xenoceratops, it also included the pachycephalosaur Colepiocephale lambei . Other species could only be described using teeth. However, most of the large dinosaur families of the Late Cretaceous Period were probably represented in the Foremost ecosystem, as isolated bone finds suggest.
Systematics and taxonomy
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| Systematic position of Xenoceratops according to Ryan et al. (2012). The genus is part of the Centrosaurinae and is its most basic representative. |
The later type series of Xenoceratops was found in 1958 in the badlands of Chin Coulee , about 7 km northwest of Foremost by Wann Langston . After being stored in the Canadian Museum of Nature for over 50 years , Michael Ryan , David Evans, and Kieran Shepherd identified the fossils as a ceratopsid . They described it as Xenoceratops foremostensis , the holotype includes a parietal bone ( inventory number CMN 53282). The ancient Greek Xenos ("foreign") in the genus name refers to the absence of other ceratopsids in the foremost formation, ceratops (ancient Greek for "horn face") classifies the genus in its family. The specific epithet foremostensis refers to the site in southern Alberta.
The systematic analysis of fine osteological features carried out by Ryan and colleagues classifies Xenoceratops as the most basic representatives of the Centrosaurinae , which are characterized by long nasal horns and relatively short neck shields and reduced frontal horns. Xenoceratops forms the sister taxon to all other centrosaurines and is one of their earliest known representatives. Only Diabloceratops is slightly older, around 79 million years old, but branches off a little later in the family tree.
In 2015, the family tree of Evans & Ryan (2015) was slightly modified on the occasion of the first description of the Wendiceratops, also found in Canada . Accordingly, Diabloceratops is the most basal genus and the sister taxon of all other known Centrosaurinae, followed by a common taxon from Nasutoceratops and Avaceratops . According to this analysis, Xenoceratops is the sister taxon of the following genera, the phylogenetic representation of which, however, also clearly differs from Ryan et al. (2012) differs.
swell
literature
- 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 .
Individual evidence
- ↑ a b c Ryan et al. 2012, pp. 1252-1260.
- ↑ a b Ryan et al. 2012, pp. 1251-1252.
- ↑ Ryan et al. 2012, p. 1252.
- ↑ Ryan et al. 2012, p. 1260.
- ↑ 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 .
