Mounted skeleton of Triceratops horridus, copyright Allie Caulfield.

Belongs within: Ceratopsia.

The Ceratopsidae are a group of large quadrupedal dinosaurs with large brow and/or nasal horns known from the late Campanian to Maastrichtian epochs of the late Cretaceous in North America (Dodson et al. 2004). In general, members of the subfamily Centrosaurinae had large nasal horns and only small or indistinct brow horns; the latter were usually much more developed in members of the subfamily Chasmosaurinae.

Characters (from Dodson et al. 2004): External nares greatly enlarged; premaxillary septum prominent; antorbital fenestra greatly reduced in size; nasal horn-core present; lacrimal reduced; frontal eliminated from orbital margin; dentary articulation set well below alveolar margin; basioccipital excluded from foramen magnum; suproccipital excluded from foramen magnum; marginal undulations on frill augmented by epoccipitals; tooth row extending caudad to coronoid process; quadrate-quadratojugal-jugal laterally stacked; shallow supracranial cavity complex present; squamosal bearing an elongate groove receiving quadrate; parietal fenestra with largest dimension oriented axially; olfactory tract exits surrounded by interorbital ossifications; number of exits for cranial nerves X, XI, XII reduced to two; more than two replacement teeth in each vertical series; teeth lacking subsidiary ridges; teeth with two roots; atlantal neural arch steeply inclined caudally; ten or more sacral vertebrae; sternum short and broad; illium bearing laterally everted shelf on dorsal rim; supracetabular process (“antitrochanter” present); ischium gently to greatly decurved; greater and cranial trochanters fused together on femur; femur longer than tibia; pedal unguals hooflike.

    |    |--+--Pentaceratops Osborn 1923DFS04
    |    |  |    `--P. sternbergii Osborn 1923DFS04 [=Chasmosaurus sternbergiP10; incl. P. fenestratus Wiman 1930DFS04]
    |    |  `--Chasmosaurus Lambe 1914 [incl. Eoceratops Lambe 1915, Protorosaurus Lambe 1914]DFS04
    |    |       |--C. belli (Lambe 1902) (see below for synonymy)DFS04
    |    |       |--C. irvinensis Holmes, Forster et al. 2001DFS04
    |    |       |--C. mariscalensis Lehman 1989DFS04 [=Agujaceratops mariscalensisP10, Pentaceratops mariscalensisP10]
    |    |       `--C. russelli Sternberg 1940DFS04
    |    `--+--+--Anchiceratops Brown 1914DFS04
    |       |  |    `--A. ornatus Brown 1914 [incl. A. longirostris Sternberg 1929]DFS04
    |       |  `--Arrhinoceratops Parks 1925DFS04
    |       |       `--A. brachyops Parks 1925SBL05
    |       `--+--+--‘Diceratops’ Lull 1905 non Foerster 1869DFS04
    |          |  |    `--D. hatcheri Lull 1905DFS04
    |          |  `--Torosaurus Marsh 1891DFS04
    |          |       |--*T. latus (Marsh 1891) [incl. T. gladius Marsh 1891]SBL05
    |          |       `--T. utahensis (Gilmore 1946) [=Arrhinoceratops utahensis]SBL05
    |          `--Triceratops Marsh 1889 [incl. Sterrholophus Marsh 1891]DFS04
    |               |--T. alticornis (Marsh 1887) (n. d.)N85, DFS04 [=Bison alticornisN85]
    |               |--T. galeus Marsh 1889 (n. d.)DFS04
    |               |--T. horridus Marsh 1889DFS04 (see below for synonymy)
    |               |--T. ingens Lull 1915 (n. d.)DFS04
    |               |--T. maximus Brown 1933 (n. d.)DFS04
    |               |--T. sulcatus Marsh 1890 (n. d.)DFS04
    |               `--T. xerinsularis [=Eotriceratops xerinsularis]P10
         |  i. s.: Avaceratops Dodson 1986DFS04
         |           `--A. lammersi Dodson 1986DFS04
         |         Monoclonius Cope 1876DFS04
         |           |--M. albertensisP88
         |           |--M. apertusP88
         |           |--M. crassus Cope 1876 [incl. M. lowei Sternberg 1940]DFS04
         |           |--M. fissus Cope 1876 (n. d.)DFS04
         |           |--M. recurvicornis Cope 1889 (n. d.)DFS04
         |           `--M. sphenocerus Cope 1889 (n. d.)DFS04
         |         Brachyceratops Gilmore 1914DFS04
         |           `--B. montanensis Gilmore 1914DFS04
         |         AlbertaceratopsP10
         |           |--A. eatoni [=Diabloceratops eatoni]P10
         |           `--A. nesmoiP10
         |--Einiosaurus Sampson 1995DFS04
         |    `--E. procurvicornis Sampson 1995DFS04 [=Centrosaurus procurvicornisP10]
         |--+--Pachyrhinosaurus Sternberg 1950DFS04
         |  |    `--P. canadensis Sternberg 1950DFS04 [=Centrosaurus canadensisP10]
         |  `--Achelousaurus Sampson 1995DFS04
         |       `--A. horneri Sampson 1995DFS04 [=Centrosaurus horneriP10]
         `--+--Styracosaurus Lambe 1913DFS04
            |    |--S. albertensis Lambe 1913DFS04 (see below for synonymy)
            |    |--S. ovatus Gilmore 1930 (n. d.)DFS04 [=Centrosaurus ovatusP10]
            |    `--S. sphenocerusD07
            `--Centrosaurus Lambe 1904 [incl. Eucentrosaurus Chure & McIntosh 1989]DFS04
                 |--C. apertusDFS04 (see below for synonymy)
                 |--C. brinkmaniP10
                 |--C. lakustai [=Pachyrhinosaurus lakustai]P10
                 `--C. nasicornisP10

Ceratopsidae incertae sedis:
  Turanoceratops Nessov & Kaznyshkina 1989A03, D07
    `--T. tardabilis Nessov, Kaznyshkina & Cherepanov 1989 (n. d.)YD04
  Agathaumas Cope 1872DFS04
    `--A. sylvestris Cope 1872 (n. d.)DFS04
  Polyonax Cope 1874DFS04
    `--P. mortuarius Cope 1874 (n. d.)DFS04
  Dysganus Cope 1876DFS04
    |--D. bicarinatus Cope 1876 (n. d.)DFS04
    |--D. encaustus Cope 1876 (n. d.)DFS04
    |--D. haydenianus Cope 1876 (n. d.)DFS04
    `--D. peiganus Cope 1876 (n. d.)DFS04
  Ceratops montanus Marsh 1888 (n. d.)DFS04
  Notoceratops bonarelli Tapia 1918 (n. d.)DFS04
  Ugrosaurus olsoni Cobabe & FAstovsky 1987 (n. d.)DFS04
Inorganic: Chasmosaurus minilorientalus Okamura 1987O87

Centrosaurus apertusDFS04 [incl. Monoclonius cutleri Brown 1917DFS04, C. cutleriD07, M. dawsoni Lambe 1902DFS04, M. flexus Brown 1914DFS04, Centrosaurus longirostris Sternberg 1940DFS04]

Chasmosaurus belli (Lambe 1902) [=Monoclonius belli; incl. C. brevirostris Lull 1933, M. canadensis Lambe 1902, C. canadensis, Eoceratops canadensis, C. kaiseni Brown 1933]DFS04

Styracosaurus albertensis Lambe 1913DFS04 [=Centrosaurus albertensisP10; incl. Monoclonius nasicornus Brown 1917DFS04, Styracosaurus parksi Brown & Schlaikjer 1937DFS04]

Triceratops horridus Marsh 1889DFS04 [=Ceratops horridusDFS04; incl. T. albertensis Sternberg 1949DFS04, T. brevicornus Hatcher 1905DFS04, T. calicornis Marsh 1898DFS04, T. elatus Marsh 1891DFS04, T. eurycephalus Schlaikjer 1935DFS04, T. flabellatus Marsh 1889DFS04, Sterrholophus flabellatusM96, T. obtusus Marsh 1898DFS04, T. prorsus Marsh 1890DFS04, T. serratus Marsh 1890DFS04]

*Type species of generic name indicated


[A03] Alifanov, V. R. 2003. Two new dinosaurs of the infraorder Neoceratopsia (Ornithischia) from the Upper Cretaceous of the Nemegt Depression, Mongolian People’s Republic. Paleontologicheskii Zhurnal 2003 (5): 77–88 (translated: Paleontological Journal 37 (5): 524–534).

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[DFS04] Dodson, P., C. A. Forster & S. D. Sampson. 2004. Ceratopsidae. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 494–513. University of California Press: Berkeley.

[M96] Marsh, O. C. 1896. The Dinosaurs of North America: Washington.

[N85] Norman, D. 1985. The Illustrated Encyclopedia of Dinosaurs. Salamander Books: London.

[O87] Okamura, C. 1987. New facts: Homo and all Vertebrata were born simultaneously in the former Paleozoic in Japan. Original Report of the Okamura Fossil Laboratory 15: 347–573.

[P88] Paul, G. S. 1988. Predatory Dinosaurs of the World: A Complete Illustrated Guide. Simon & Schuster: New York.

[P10] Paul, G. S. 2010. Dinosaurs: A Field Guide. A & C Black.

[SBL05] Sullivan, R. M., A. C. Boere & S. G Lucas. 2005. Redescription of the ceratopsid dinosaur Torosaurus utahensis (Gilmore, 1946) and a revision of the genus. Journal of Paleontology 79 (3): 564–582.

[YD04] You H. & P. Dodson. 2004. Basal Ceratopsia. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 478–493. University of California Press: Berkeley.

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