Chasmosaurinae

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Cladus: Avemetatarsalia
Cladus: Ornithodira
Subtaxon: Dinosauromorpha
Cladus: Dinosauriformes
Cladus: Dracohors
Cladus: Dinosauria
Ordo: †Ornithischia
Cladus: †Genasauria
Cladus: †Neornithischia
Cladus: †Cerapoda
Cladus: †Marginocephalia
Subordo: †Ceratopsia
Cladus: †Neoceratopsia
Superfamilia: †Ceratopsoidea

Familia: †Ceratopsidae
Subfamillia: †Chasmosaurinae
Tribus: Triceratopsini

Genera: Agujaceratops – Anchiceratops – Arrhinoceratops – Bravoceratops – Chasmosaurus – Coahuilaceratops – Eotriceratops – Judiceratops – Kosmoceratops – Mercuriceratops – Mojoceratops – Navajoceratops – Nedoceratops – Ojoceratops – Pentaceratops – Regaliceratops – Tatankaceratops – Terminocavus – Titanoceratops – Torosaurus – Triceratops – Spiclypeus – Utahceratops – Vagaceratops

Name

Chasmosaurinae Lambe, 1914

Synonymy

Ceratopsinae Abel, 1919

References

Lambe, L.M. 1915: On Eoceratops canadensis, gen. nov., with remarks on other genera of Cretaceous horned dinosaurs. Canada Geological Survey Museum Bulletin 12, Geological Series 24: 1–49.
Dodson, P., Forster, C.A. and Sampson, S.D. 2004. Ceratopsidae. In D. B. Weishampel, P. Dodson & H. Osmólska (eds.), The Dinosauria (second edition). University of California Press, Berkeley 494-513.
Sampson, S.D.; Loewen, M.A.; Farke, A.A.; Roberts, E.M.; Forster, C.A.; Smith, J.A. & Titus, A.L. 2010: New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism. PLoS ONE 5 (9): e12292. DOI: 10.1371/journal.pone.0012292
Longrich, N.R. 2011: Titanoceratops ouranous, a giant horned dinosaur from the Late Campanian of New Mexico. Cretaceous Research 32 (3): 264–276. DOI: 10.1016/j.cretres.2010.12.007

Chasmosaurinae is a subfamily of ceratopsid dinosaurs. They were one of the most successful groups of herbivores of their time. Chasmosaurines appeared in the early Campanian, and became extinct, along with all other non-avian dinosaurs, during the Cretaceous–Paleogene extinction event. Broadly, the most distinguishing features of chasmosaurines are prominent brow horns and long frills lacking long spines; centrosaurines generally had short brow horns and relatively shorter frills, and often had long spines projecting from their frills.[citation needed]

Chasmosaurines evolved in western North America (Laramidia). They are currently known definitively from rocks in western Canada, the western United States, and northern Mexico. They were highly diverse and among the most species-rich groups of dinosaurs, with new species frequently described. This high diversity of named species is likely a result of the frill. The distinctive shape of the frill with the hornlets on its edges (epoccipitals) make it possible to recognize species from incomplete or fragmentary remains.[citation needed]
Classification

Below is the result of a phylogenetic analysis by Mallon et al., following the traditional epiparietal homology scheme from their description of Spiclypeus shipporum. Bravoceratops and Eotriceratops were removed because it was found that they decrease resolution in the analysis because of the authors' new interpretation of epiparietal configurations. Regaliceratops was not resolved as a member of the Triceratopsini.[1]
Chasmosaurinae

Kosmoceratops richardsoni

Vagaceratops irvinensis

Spiclypeus shipporum

Pentaceratops sternbergii

Utahceratops gettyi

Agujaceratops mariscalensis

Mojoceratops perifania

Chasmosaurus belli

Chasmosaurus russelli

Coahuilaceratops magnacuerna

Anchiceratops ornatus

Regaliceratops peterhewsi

Arrhinoceratops brachyops

Triceratopsini

Ojoceratops fowleri

Titanoceratops ouranos

Nedoceratops hatcheri

Torosaurus latus

"Torosaurus" utahensis

Triceratops prorsus

Triceratops horridus

The findings of a phylogenetic study done by Fowler and Freedman in 2020. The work of Fowler et al. is given below. The authors proposed that two distinct and roughly contemporaneous lineages of chasmosaurines existed in the late Cretaceous: a northern "Chasmosaurus" lineage with a heart-shaped frill margin that flattens and curls over onto itself, and a southern "Pentaceratops" lineage with a pinched shut indentation in the heart-shaped frill margin. According to the cladogram below, the Triceratopsini may have derived from this later lineage. To improve resolution, certain species based on partial or immature remains (Bravoceratops and Agujaceratops) were excluded, as in the Mallon et al. study above. While this new study did not yield a single "Pentaceratops lineage," was not recovered by this revised analysis as they had predicted based on frill shape, the authors speculated that this may be due to some specimens included as Pentaceratops sternbergii being misclassified, and possibly referable to other species pending further study. The authors also noted that some newer species included in the previous analysis by Mallon et al. (Spiclypeus, Regaliceratops, etc.) had yet to be coded into their revised dataset.[2]
Chasmosaurinae

Chasmosaurus russelli

Chasmosaurus belli

Vagaceratops irvinensis

Kosmoceratops richardsoni

Utahceratops gettyi

Pentaceratops sternbergii

Coahuilaceratops magnacuerna

Navajoceratops sullivani

Terminocavus sealeyi

Anchiceratops ornatus

Arrhinoceratops brachyops

Triceratopsini

References

Jordan C. Mallon; Christopher J. Ott; Peter L. Larson; Edward M. Iuliano; David C. Evans (2016). "Spiclypeus shipporum gen. et sp. nov., a Boldly Audacious New Chasmosaurine Ceratopsid (Dinosauria: Ornithischia) from the Judith River Formation (Upper Cretaceous: Campanian) of Montana, USA". PLOS ONE. 11 (5): e0154218. Bibcode:2016PLoSO..1154218M. doi:10.1371/journal.pone.0154218. PMC 4871577. PMID 27191389.
Fowler DW, Freedman Fowler EA (2020). "Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs: evidence from the Campanian of New Mexico". PeerJ. 8. e9251. doi:10.7717/peerj.9251.