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Reptilia - Ceratopsidae

Triceratops was named by Marsh (1889). It is not extant. It is the type genus of Triceratopsini.

It was synonymized subjectively with Agathaumas by Baur (1891) and Lydekker (1893).

It was assigned to Ceratopsia by Zittel (1890); to Scelidosauria by Seeley (1892); to Ceratopidae by Mansel-Pleydell (1902); to Agathaumidae by Lull (1906); to Eoceratopsinae by Lambe (1915); to Monocloninae by Tatarinov (1964); to Ceratopsia by Marsh (1890), Gadow (1897), Tornier (1913), Lull (1924) and Ostrom (1965); to Ceratopsinae by Nopcsa (1928), Huene (1950) and Sereno (1998); to Ceratopsidae by Marsh (1889), Marsh (1891), Marsh (1895), Depéret (1896), Marsh (1896), Lambe (1899), Hay (1902), Lambe (1905), Hatcher et al. (1907), Huene (1909), von Zittel (1911), Brown (1914), Brown (1914), Matthew (1915), Joleaud (1922), Gregory and Mook (1925), Huene (1927), Russell (1930), Lull (1933), Chakravarti (1934), Sternberg (1949), Romer (1956), Parsch (1963), Estes (1964), Kuhn (1964), Romer (1966), Swinton (1970), McIntosh (1981), Russell (1984), Breithaupt (1985), Ostrom and Wellnhofer (1986), Clemens (1986), Tokaryk (1986), Carroll (1988), Eberth (1997), Makovicky (2001) and You and Dodson (2003); to Chasmosaurinae by Dodson and Currie (1990), Lehman (1990), Forster (1996), Vickaryous and Ryan (1997), Dodson (1997), Dodson (1997), Dodson et al. (2004), Farke (2004), Diem and Archibald (2005), Wu et al. (2007), Ryan (2007), Hunt and Lehman (2008), Scannella and Horner (2010), Longrich (2010), Xu et al. (2010), Ryan et al. (2010), Farke (2011), Maidment and Barrett (2011), Fiorillo and Tykoski (2012) and Longrich and Field (2012); and to Triceratopsini by Longrich (2014).

Synonymy list
YearName and author
1889Triceratops Marsh pp. 173-174
1890Triceratops sulcatus Marsh
1890Triceratops Marsh p. 418
1890Triceratops sulcatus Marsh p. 422
1890Triceratops Zittel p. 752
1890Triceratops sulcatus Zittel p. 753
1891Sterrholophus Marsh
1891Triceratops Marsh p. 265
1891Sterrholophus Marsh pp. 339-340
1892Triceratops Seeley
1895Sterrholophus Marsh
1895Triceratops Marsh
1896Triceratops Depéret p. 185
1896Sterrholophus Marsh p. 243
1896Triceratops Marsh p. 243
1897Triceratops Gadow p. 205
1899Triceratops Lambe p. 187
1900Triceratops sulcatus Walcott p. 23
1902Triceratops Hay p. 498
1902Sterrholophus Hay p. 499
1902Triceratops sulcatus Hay p. 499
1902Sterrholophus Mansel-Pleydell p. lxxxiv
1902Triceratops Mansel-Pleydell p. lxxxiv
1902Triceratops sulcatus Mansel-Pleydell p. lxxxv
1905Diceratops Hatcher and Lull p. 417
1905Triceratops Lambe p. 23
1905Sterrholophus Lambe p. 24
1906Diceratops Lull p. 144
1906Triceratops Lull p. 144
1907Triceratops Hatcher et al. p. 12
1907Diceratops Hatcher et al. p. 168
1907Triceratops sulcatus Hatcher et al. p. 168
1909Diceratops Huene p. 18
1909Triceratops Huene p. 18
1911Diceratops von Zittel p. 296
1911Triceratops von Zittel p. 296
1913Diceratops Tornier p. 375
1913Triceratops Tornier p. 375
1914Triceratops Brown p. 377
1914Triceratops sulcatus Brown p. 542
1914Triceratops Brown p. 543
1914Triceratops sulcatus Huene p. 584
1915Diceratops Lambe p. 18
1915Triceratops Lambe p. 20
1915Triceratops Matthew p. 30
1920Triceratops sulcatus Pompeckj p. 114
1922Triceratops Joleaud p. 64
1922Diceratops Joleaud p. 65
1924Diceratops Lull p. 244
1924Triceratops Lull p. 244
1925Triceratops Gregory and Mook pp. 4-6
1925Diceratops Gregory and Mook p. 6
1927Diceratops Huene p. 261
1927Triceratops Huene p. 261
1927Triceratops sulcatus Huene p. 261
1928Diceratops Nopcsa p. 185
1928Triceratops Nopcsa p. 185
1930Diceratops Russell p. 140
1930Triceratops Russell p. 140
1930Triceratops sulcatus Russell p. 140
1933Triceratops Lull p. 114
1934Triceratops Chakravarti p. 78
1940Triceratops sulcatus Brown and Schlaikjer p. 4 fig. 3
1949Triceratops Sternberg p. 41 fig. 1
1950Diceratops Huene p. 351
1950Triceratops Huene p. 351
1956Diceratops Romer p. 639
1956Sterrholophus Romer p. 639
1956Triceratops Romer p. 639
1963Triceratops Parsch p. 8
1964Triceratops Estes p. 145
1964Diceratops Kuhn p. 56
1964Triceratops Kuhn p. 59
1964Triceratops sulcatus Kuhn p. 59
1964Triceratops Tatarinov p. 583
1964Sterrholophus Tatarinov p. 585
1965Triceratops Ostrom p. 39
1965Triceratops sulcatus Ostrom p. 39
1966Diceratops Romer p. 371
1966Triceratops Romer p. 371
1970Triceratops Swinton p. 254
1981Triceratops McIntosh p. 41
1984Diceratops Russell p. 27
1984Triceratops Russell p. 27
1985Triceratops Breithaupt p. 167
1986Diceratops Clemens p. 80
1986Triceratops Clemens p. 80
1986Triceratops Ostrom and Wellnhofer p. 156
1986Triceratops Tokaryk p. 193
1988Triceratops Carroll
1990Triceratops Dodson and Currie p. 612
1990Triceratops Lehman p. 212
1996Diceratops Forster p. 261
1996Triceratops Forster p. 268
1997Triceratops Dodson p. 12
1997Triceratops Eberth p. 202
1997Triceratops Vickaryous and Ryan p. 492
1998Triceratops Sereno p. 62
2001Triceratops Makovicky p. 254 fig. 18.3
2003Triceratops You and Dodson
2004Diceratops Dodson et al. p. 496
2004Triceratops Dodson et al. p. 496
2004Triceratops Farke p. 4
2005Triceratops Diem and Archibald p. 251
2007Triceratops Ryan p. 391 fig. 12
2007Nedoceratops Ukrainsky p. 292
2007Diceratops Wu et al. p. 1261 fig. 14
2007Triceratops Wu et al. p. 1261 fig. 14
2008Triceratops Hunt and Lehman p. 1132
2008Diceratus Mateus p. 423
2010Triceratops Longrich p. 692 fig. 10
2010Tatankaceratops Ott and Larson p. 205
2010Diceratops Ryan et al. p. 185
2010Triceratops Ryan et al. p. 185
2010Triceratops Scannella and Horner p. 1166
2010Ojoceratops Sullivan and Lucas p. 171
2010Diceratops Xu et al. p. 1634 fig. 3
2010Triceratops Xu et al. p. 1634 fig. 3
2011Nedoceratops Farke p. 3
2011Triceratops Farke pp. 6-8
2011Ojoceratops Jasinski et al. p. 253
2011Ojoceratops Maidment and Barrett p. 3
2011Tatankaceratops Maidment and Barrett p. 3
2011Triceratops Maidment and Barrett p. 36
2012Triceratops Fiorillo and Tykoski
2012Triceratops Longrich and Field p. 9
2014Triceratops Longrich p. 303 fig. 8
2015Ojoceratops Jasinski p. 79

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phylumChordataHaeckel 1847
OlfactoresJefferies 1991
subclassDipnotetrapodomorpha(Nelson 2006)
SauriaGauthier 1984
Archosauromorpha(Huene 1946)
ArchosauriformesGauthier 1986

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

J. H. Ostrom and P. Wellnhofer 1986Large ceratopsian with three facial horns – two large brow horns composed of postfrontals and frontals and a single nasal horn composed of a separate ossification or as an outgrowth of the nasals; lengths and curvature of horns vary; nasal horn size variable, but always shorter than brown horns, directed up and forward and usually not curved; brow horns project up and forward, and transverse or posterior curvature variable, but usually not present; frill short compared with some other ceratopsids (postorbital length = 1.1 to 1.4 times preorbital length), composed of parietals and long squamosals extending to posterior frill margin; frill margins now horned or bearing spikes, but may support blunt epoccipital bones; frill is not fenestrated except for small lateral and superior temporal fenestra proximally; postfrontal fontanelle usually closed; antorbital fenestra narrow and slit-like; external naris very large; large edentulous turtle-like beak composed of rostral and premaxillae above and predentary below; jugal expanded into a robust ventral process overlapping the quadrate; mandivle massive with a strong laterally placed coronoid process of the denture; teeth "two-rooted" and compressed into large longitudinal shearing batteries; twenty-four presacral vertebrae, including eight cervicals; first four cervicals co-ossified; lumbars lacking; sacral series includes posterior dorsals and proximal caudals up to a total of 10 or 11 segments; limbs as in other ceratopsids.
J. B. Scannella and J. R. Horner 2010Skull bears elongate postorbital horn cores (derived from fusion of the postorbitals and prefrontals early in ontogeny) plus a single variable epinasal horn. Epinasal unites the rostral-nasal-premaxillae complex. The shape of the frontal fontanelle is variable, though generally circular when present; some specimens lack a frontal fontanelle as a result of closure of the frontals and parietal. Parietal-squamosal frill relatively short, broad, and fan-like (compared to other chasmosaurine genera). Fenestrated and expanded in mature individuals. Strong undulating midline parietal ridge throughout early ontogeny becomes a broad parietal bar in mature specimens; fenestrae are ovate to nearly circular. Pronounced squamosal bars alongside parietal-squamosal contacts in mature specimens. Epiparietals and episquamosals ornament posterior and lateral margins of the parietal-squamosal frill. Epijugals on the jugal flange fuse the jugal-quadratojugal complex (modified from Ostrom and Wellnhofer, 1986, and Forster, 1996).
R. M. Sullivan and S. G. Lucas 2010 (Ojoceratops)As for the type and only known species.
C. J. Ott and P. L. Larson 2010 (Tatankaceratops)As for type species, by monotypy.
A. A. Farke 2011 (Nedoceratops)As for the type and only species.