Pachyrhinosaurini is a

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English language, English is in the discipline of anthropology. This definition is contested, in p ...

centrosaurine Centrosaurinae (from the Greek, meaning "pointed lizards") is a subfamily of ceratopsid dinosaurs, a group of large quadrupedal ornithischians. Centrosaurine fossil remains are known primarily from the northern region of Laramidia (modern day Al ...

dinosaurs. The clade existed during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

, about 84.9 to 68.5 million years ago, evolving during the earliest

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...

, and becoming extinct in the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

. The tribe contains three genera: ''

Einiosaurus ''Einiosaurus'' is a genus of herbivorous centrosaurine ceratopsian dinosaur from the Upper Cretaceous (Campanian stage) of northwestern Montana. The name means 'buffalo lizard', in a combination of Blackfeet Indian ''eini'' and Latinized Ancient ...

'', ''

Achelousaurus ''Achelousaurus'' () is a genus of centrosaurine ceratopsid dinosaur that lived during the Late Cretaceous Period of what is now North America, about 74.2 million years ago. The first fossils of ''Achelousaurus'' were collected in Mont ...

'', and ''

Pachyrhinosaurus ''Pachyrhinosaurus'' (meaning in Greek "thick-nosed lizard", from ' (), thick; ' (), nose; and (), lizard) is an extinct genus of centrosaurine ceratopsid dinosaur from the Late Cretaceous period of North America. The first examples were discove ...

''. ''Pachyrhinosaurus'' and ''Achelousaurus'' form the clade of pachyrhinosaurins called the Pachyrostra ("thick-snouts"), characterized primarily by their nasal bosses.

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. The

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

below represents the findings of Lund et al., 2016, in their description of ''

Machairoceratops cronusi ''Machairoceratops'' (meaning "bent sword horned face"), previously known as the "Wahweap centrosaurine B", is an extinct genus of centrosaurine ceratopsian dinosaur known from the Late Cretaceous Wahweap Formation (late Campanian stage) of Gran ...

''. '' Wendiceratops pinhornensis'', ''

Xenoceratops foremostensis ''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 speci ...

'', and '' Sinoceratops zhuchengensis'' were resolved as members of the Pachyrhinosaurini and ''

'' was resolved as a pachyrostran and the sister taxon of ''

''. The

below represents a more recent phylogenetic analysis that included Pachyrhinosaurini by Chiba ''et al.'' (2017). ''

Wendiceratops ''Wendiceratops'' is a genus of herbivorous centrosaurine ceratopsian dinosaur from the Late Cretaceous of Canada. Discovery In 2010, Canadian fossil hunter Wendy Sloboda found a centrosaurine bonebed in the Pinhorn Provincial Grazing Reserv ...

'', ''

Xenoceratops ''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 speci ...

'', and ''

Sinoceratops ''Sinoceratops'' is an extinct genus of ceratopsian dinosaur that lived approximately 73 million years ago during the latter part of the Cretaceous Period in what is now Shandong province in China. It was named in 2010 by Xu Xing ''et al.'' fo ...

'' were not resolved as members of the Pachyrhinosaurini and ''

'' was not resolved as a pachyrostran.

References

Centrosaurines {{ceratopsian-stub

Classification

See also

References