Pachyrhinosaurini

Pachyrhinosaurini was a tribe of centrosaurine dinosaurs. The clade existed during the Late Cretaceous, about 84.9 to 66 million years ago, evolving during the earliest Campanian,[2] and becoming extinct in the Maastrichtian.[3][4] The tribe contains three genera: Einiosaurus, Achelousaurus, and Pachyrhinosaurus. Pachyrhinosaurus and Achelousaurus form the clade of pachyrhinosaurins called the Pachyrostra ("thick-snouts"), characterized primarily by their nasal bosses.

Pachyrhinosaurini Temporal range: Late Cretaceous, 84.9–69 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Skull of a Pachyrhinosaurus canadensis
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Order:	†Ornithischia
Family:	†Ceratopsidae
Subfamily:	†Centrosaurinae
Clade:	†Eucentrosaura
Tribe:	†Pachyrhinosaurini Fiorillo & Tykoski, 2012
Type species
†Pachyrhinosaurus canadensis Sternberg, 1950
Subdivisions[1]
†Einiosaurus †Stellasaurus †Styracosaurus? †Pachyrostra †Achelousaurus †Pachyrhinosaurus

Classification

Pachyrhinosaurini was defined in 2012 by Fiorillo & Tykoski. It was defined as all centrosaurine ceratopsids more closely related to Pachyrhinosaurus canadensis than to Centrosaurus apertus. It was defined during the description of Pachyrhinosaurus perotorum, a species from Alaska.[3]

The cladogram below represents the findings of Lund et al., 2016, in their description of Machairoceratops cronusi. Wendiceratops pinhornensis, Xenoceratops foremostensis, and Sinoceratops zhuchengensis were resolved as members of the Pachyrhinosaurini and Einiosaurus was resolved as a pachyrostran and the sister taxon of Achelousaurus.

Ceratopsidae

Chasmosaurinae    Centrosaurinae      Machairoceratops cronusi         Albertaceratops nesmoi     Diabloceratops eatoni         Avaceratops lammersi     Nasutoceratops titusi            Centrosaurini      Rubeosaurus ovatus     Styracosaurus albertensis         Spinops sternbergorum       Centrosaurus apertus     Coronosaurus brinkmani          Pachyrhinosaurini      Xenoceratops foremostensis     Sinoceratops zhuchengensis         Wendiceratops pinhornensis    Pachyrostra      Einiosaurus procurvicornis     Achelousaurus horneri         Pachyrhinosaurus canadensis       Pachyrhinosaurus lakustai     Pachyrhinosaurus perotorum

The cladogram below represents a more recent phylogenetic analysis that included Pachyrhinosaurini by Chiba et al. (2017). Wendiceratops, Xenoceratops, and Sinoceratops were not resolved as members of the Pachyrhinosaurini and Einiosaurus was not resolved as a pachyrostran.[5]

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       Centrosaurus apertus     Spinops sternbergorum         Pachyrhinosaurini   Einiosaurus procurvicornis   Pachyrostra   Achelousaurus horneri       Pachyrhinosaurus canadensis       Pachyrhinosaurus lakustai     Pachyrhinosaurus perotorum

See also

• Timeline of ceratopsian research

References

1. Sampson, S.D.; Lund, E.K.; Loewen, M.A.; Farke, A.A.; Clayton, K.E. (2013). "A remarkable short-snouted horned dinosaur from the Late Cretaceous (late Campanian) of southern Laramidia". Proceedings of the Royal Society B. 1766. 280 (1766): 4. doi:10.1098/rspb.2013.1186. PMC 3730592. PMID 23864598.
2. Gilmore, C.W. (1930). "On dinosaurian reptiles from the Two Medicine Formation of Montana". Proceedings of the United States National Museum. 77 (16): 1–39. doi:10.5479/si.00963801.77-2839.1.
3. Fiorillo, A.R. & Tykoski, R.S. (2012). "A new Maastrichtian species of the centrosaurine ceratopsid Pachyrhinosaurus from the North Slope of Alaska". Acta Palaeontologica Polonica. 57 (3): 561. doi:10.4202/app.2011.0033.CS1 maint: uses authors parameter (link)
4. Fiorillo, A.R. & Gangloff, R.A. (2001). "Theropod teeth from the Prince Creek Formation (Cretaceous) of northern Alaska, with speculations on Arctic dinosaur paleoecology". Journal of Vertebrate Paleontology. 20 (4): 675–682. doi:10.1671/0272-4634(2000)020[0675:TTFTPC]2.0.CO;2.CS1 maint: uses authors parameter (link)
5. 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. in press (2): 272–288. doi:10.1017/jpa.2017.62.