Xenoceratops

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Xenoceratops
Temporal range: Late Cretaceous,
79.5  Ma
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Xenoceratops.jpg
Reconstructed skull
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Ornithischia
Suborder: Ceratopsia
Family: Ceratopsidae
Subfamily: Centrosaurinae
Genus: Xenoceratops
Ryan, Evans & Shepherd, 2012
Type species
Xenoceratops foremostensis
Ryan, Evans & Shepherd, 2012

Xenoceratops (meaning "alien horned face") is a genus of centrosaurine ceratopsid dinosaur known from the Late Cretaceous (middle Campanian stage), and is known to have lived in what is currently Alberta, Canada. The genus has one known species, Xenoceratops foremostensis. Its remains were discovered in the Foremost Formation. [1]

Contents

Discovery

In 1958, Wann Langston, Jr. excavated skull fragments from the Foremost Formation near Foremost, Alberta. [2] The formation is very poorly understood in regards to dinosaur fauna; [1] aside from teeth, only hadrosaur skeletons and the pachycephalosaurid Colepiocephale have been reported. [1]

Langston stored the fragments in cabinets at the Canadian Museum of Nature in Ottawa. Around 2003, David C. Evans and Michael J. Ryan became curious about the specimens, and more thorough investigation was conducted in 2009. [2] They discovered it to be a new species and genus, and it was described in 2012 by Ryan, Evans, and Kieran M. Shepherd. At the time of discovery, Xenoceratops foremostensis was the oldest known taxon of ceratopsid dinosaur in Canada. It is also the first ceratopsian described from the Foremost Formation. Xenoceratops is named from the Greek xenos, meaning foreign or alien, and ceratops, meaning horned face. The combination is in reference to the lack of ceratopsian species known from the Foremost Formation. The specific epithet foremostensis is named after the town of Foremost, Alberta. [1]

Description

Restoration Xenoceratops NT small.jpg
Restoration

Xenoceratops is based on CMN (Canadian Museum of Nature) 53282, a parietal. This is a skull bone that in ceratopsids makes up the medial (midline) and part of the lateral borders of the distinctive bony frill. Additional skull bones have also been assigned to the genus, including additional parietals, squamosals (bones which make up the rest of the frill's lateral borders), and a partial nasal. These bones appear to belong to at least three adult-sized individuals. Another fragmentary skull in the collections of the Royal Tyrrell Museum of Palaeontology is thought to belong to this genus as well. [1]

Xenoceratops can be distinguished from other ceratopsids by details of the frill's bony ornamentation. The two bony projections closest to the midline of the frill are thick knobs, oriented toward the midline. Next to each knob is a single long flattened straight spike pointing laterally and to the rear. The anterior corners of the parietal have a large triangular knob. Unlike most other centrosaurines, the midline bar of the frill has no bumps or other ornamentation. Xenoceratops probably had a nasal and brow horn configuration comparable to that of other basal centrosaurines. The holotype and associated skull material do not include much of the face, but the Royal Tyrrell skull shows evidence of large brow horns, perhaps similar to those of Albertaceratops and Diabloceratops . Similarly, the form of the nasal bone fragment suggests a long, low structure like that of Medusaceratops . [1]

Classification

Xenoceratops and other dinosaurs in their environment Xenoceratops environment.jpg
Xenoceratops and other dinosaurs in their environment
Skull seen from the front Xenoceratops skull.jpg
Skull seen from the front

The cladogram below follows a phylogenetic analysis by Chiba et al. (2017): [3]

Centrosaurinae

Diabloceratops eatoni

Machairoceratops cronusi

Nasutoceratopsini

Avaceratops lammersi (ANSP 15800)

MOR 692

CMN 8804

Nasutoceratops titusi

Malta new taxon

Xenoceratops foremostensis

Sinoceratops zhuchengensis

Wendiceratops pinhornensis

Albertaceratops nesmoi

Medusaceratops lokii

Eucentrosaura
Centrosaurini

Rubeosaurus ovatus

Styracosaurus albertensis

Coronosaurus brinkmani

Spinops sternbergorum

Centrosaurus apertus

Pachyrhinosaurini

Einiosaurus procurvicornis

Pachyrostra

Achelousaurus horneri

Pachyrhinosaurus canadensis

Pachyrhinosaurus lakustai

Pachyrhinosaurus perotorum

See also

Related Research Articles

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<i>Medusaceratops</i> Extinct genus of dinosaurs

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Coronosaurus is a genus of centrosaurine ceratopsian dinosaurs which lived in the Late Cretaceous, in the middle Campanian stage. Its remains, two bone beds, were discovered by Phillip J. Currie in the Oldman Formation of Alberta, Canada, and its type and only species, Coronosaurus brinkmani, was first described in 2005, as a new species within the genus Centrosaurus. Later studies questioned the presence of a direct relationship, and in 2012 it was named as a separate genus. Coronosaurus means "crowned lizard", coming from "corona", Latin for crown, and "sauros", Greek for lizard; this name refers to the unique, crown-like shape of the horns on the top of its frill.

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Regaliceratops is a monospecific genus of chasmosaurine ceratopsid dinosaur from Alberta, Canada that lived during the Late Cretaceous in what is now the St. Mary River Formation. The type and only species, Regaliceratops peterhewsi, is known only from an adult individual with a nearly complete skull lacking the lower jaw, which was nicknamed "Hellboy". Regaliceratops was named in 2015 by Caleb M. Brown and Donald M. Henderson. Regaliceratops has an estimated length of 5 metres (16 ft) and body mass of 2 metric tons. The skull of Regaliceratops displays features more similar to centrosaurines, which suggests convergent evolution in display morphology in ceratopsids.

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Wendiceratops is a genus of herbivorous centrosaurine ceratopsian dinosaur from the Late Cretaceous of Canada.

<i>Yehuecauhceratops</i> Extinct genus of dinosaurs

Yehuecauhceratops is a genus of horned centrosaurine ceratopsid dinosaur from the Late Cretaceous of Coahuila, Mexico. It contains a single species, Y. mudei, described from two partial specimens by Rivera-Sylva et al. in 2016 and formally named by Rivera-Sylva et al. in 2017. It was a small centrosaurine with a body length of 3 metres (9.8 ft), making it smaller than Agujaceratops and Coahuilaceratops, the other two ceratopsids in its environment; the three may have been ecologically segregated. A ridge bearing a single roughened projection near the bottom of the squamosal bone, which probably supported a small horn, allows Yehuecauhceratops to be distinguished from other centrosaurines. Its affinities to nasutoceratopsin centrosaurines, such as Avaceratops and Nasutoceratops, are supported by various morphological similarities to the former.

References

  1. 1 2 3 4 5 6 Ryan, Michael J.; Evans, David C.; Shepherd, Kieran M. (2012). "A new ceratopsid from the Foremost Formation (middle Campanian) of Alberta". Canadian Journal of Earth Sciences. 49 (11): 1251–1262. Bibcode:2012CaJES..49.1251R. doi: 10.1139/e2012-056 .
  2. 1 2 Tutton, Michael (November 8, 2012). "Fossilized horn that sat in museum for decades leads to new Alberta dinosaur discovery". The Canadian Press. Archived from the original on December 25, 2012. Retrieved November 9, 2012.
  3. Kentaro Chiba; Michael J. Ryan; Federico Fanti; Mark A. Loewen; David C. Evans (2018). "New material and systematic re-evaluation of Medusaceratops lokii (Dinosauria, Ceratopsidae) from the Judith River Formation (Campanian, Montana)". Journal of Paleontology. 92 (2): 272–288. doi:10.1017/jpa.2017.62.