Xenoceratops

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Xenoceratops
Temporal range: Late Cretaceous
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Clade: Marginocephalia
Family: Ceratopsidae
Subfamily: Centrosaurinae
Genus: Xenoceratops
Ryan, Evans & Shepherd, 2012
Type species
Xenoceratops foremostensis
Ryan, Evans & Shepherd, 2012

Xenoceratops is a genus of centrosaurine ceratopsid dinosaur known from the Late Cretaceous (middle Campanian stage) of Alberta, Canada. The genus has one known species, Xenoceratops foremostensis. Its remains were discovered in the Foremost Formation.

Etymology[edit]

Xenoceratops is named from the Greek xenos, meaning foreign, and ceratops, meaning horned face. The combination is in reference to the lack of ceratopsian species known from the Foremost Formation. The specific ephithet foremostensis is named after the town of Foremost, Alberta.[1]

Discovery[edit]

In 1958, Wann Langston, Jr. excavated skull fragments from the Foremost Formation near Foremost, Alberta.[2][3] The formation is very poorly understood in regards to dinosaur fauna;[4] 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.[3] They discovered it to be a new species and genus, and it was described in 2012 by Ryan, Evans and Kieran M. Shepherd.[4]

At the time of discovery, Xenoceratops foremostensis is the oldest known taxon of ceratopsid dinosaur in Canada.[1] It is also the first ceratopsian described from the Foremost Formation in Alberta.[5]

Description[edit]

Xenoceratops is based on CMN (Canadian Museum of Nature) 53282, a parietal.[1] 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.[6] These bones appear to belong to at least three adult-sized individuals.[1] Another fragmentary skull in the collections of the Royal Tyrrell Museum of Palaeontology is thought to belong to this genus as well.[5]

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.[1] The anterior corners of the parietal have a large triangular knob.[7] Unlike most other centrosaurines, the midline bar of the frill has no bumps or other ornamentation.[8] Xenoceratops probably had a nasal and brow horn configuration comparable to that of other basasl 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.[5] Similarly, the form of the nasal bone fragment suggests a long, low structure like that of Medusaceratops.[9]

Classification[edit]

(After Ryan et al. 2012[5]):

 Ceratopidae 

 Chasmosaurinae


 Centrosaurinae 

 Xenoceratops




 Diabloceratops




 Avaceratops




 Albertaceratops





 Spinops




 Centrosaurus




 Coronosaurus



 Styracosaurus







 Sinoceratops




 Rubeosaurus




 Einiosaurus




 Achelousaurus



 Pachyrhinosaurus












See also[edit]

References[edit]

  1. ^ a b c d e f Ryan, Evans & Shepherd 2012, p. 1252.
  2. ^ Ryan, Evans & Shepherd 2012, p. 1253.
  3. ^ a b Tutton, Michael (November 8, 2012). "Fossilized horn that sat in museum for decades leads to new Alberta dinosaur discovery". The Canadian Press. Retrieved November 9, 2012. 
  4. ^ a b Ryan, Evans & Shepherd 2012, p. 1251.
  5. ^ a b c d Ryan, Evans & Shepherd 2012, p. 1260.
  6. ^ Ryan, Evans & Shepherd 2012, p. 1252–1253.
  7. ^ Ryan, Evans & Shepherd 2012, p. 1254.
  8. ^ Ryan, Evans & Shepherd 2012, p. 1256.
  9. ^ Ryan, Evans & Shepherd 2012, p. 1260–1261.

Bibliography[edit]

  • 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. doi:10.1139/e2012-056.