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Triceratops horridus

Reptilia - Ceratopsidae

Taxonomy

Ceratops horridus was named by Marsh (1889). Its type specimen is YPM 1820, a skull, and it is a 3D body fossil. Its type locality is Buck Creek pens, Johnson Brothers Ranch, which is in a Maastrichtian fluvial-lacustrine sandstone/shale in the Lance Formation of Wyoming. It is the type species of Triceratops.

It was recombined as Triceratops horridus by Marsh (1889), Zittel (1890), Marsh (1896), Marsh (1897), Nopcsa (1901), Mansel-Pleydell (1902), Hay (1902), Hatcher et al. (1907), Knowlton (1909), Brown (1914), Huene (1914), Huene (1927), Perrier (1928), Hay (1930), Russell (1930), Johnson (1931), Schlaikjer (1935), Gray (1946), Lull and Gray (1949), Sternberg (1949), Tatarinov (1964), Kuhn (1964), Ostrom (1965), Charig (1967), Laub (1979), Breithaupt (1985), Sloan (1985), Ostrom and Wellnhofer (1986), Tokaryk (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990), Derstler (1994), Retallack (1994), Lehman (1996), Forster (1996), Breithaupt (1997), Currie and Padian (1997), Lehman (1998), Makovicky (2001), Buchholz (2002), Dodson et al. (2004), Chinnery (2004), Diem and Archibald (2005), Farke (2007), Currie et al. (2008), Butler et al. (2008), Hunt and Lehman (2008), Scannella and Horner (2010), Longrich (2010), Goodwin and Horner (2010), Scannella and Horner (2011), Farke (2011), Longrich and Field (2012), Armitage and Anderson (2013), Goodwin and Horner (2014), Longrich (2014), Erickson (2017) and D'Anastasio et al. (2022).

Synonyms

Triceratops calicornis was named by Marsh (1898). Its type specimen is USNM 4928, a skull, and it is a 3D body fossil. Its type locality is east of Lance Creek, which is in a Maastrichtian terrestrial horizon in the Lance Formation of Wyoming.

It was synonymized subjectively with Triceratops elatus by Lull (1910) and Sloan (1985); it was synonymized subjectively with Triceratops horridus by Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990), Lehman (1990), Forster (1996), Dodson et al. (2004) and Farke (2011).
Triceratops obtusus was named by Marsh (1898). Its type specimen is YPM, a skull, and it is a 3D body fossil. Its type locality is 2 miles southeast of U-L Ranch, Buck Creek, which is in a Maastrichtian terrestrial horizon in the Lance Formation of Wyoming.

It was synonymized subjectively with Triceratops horridus by Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990), Lehman (1990), Forster (1996) and Dodson et al. (2004).
Triceratops flabellatus was named by Marsh (1889). Its type specimen is YPM 1821, a skull, and it is a 3D body fossil. Its type locality is ridge between Buck Creek and Lance Creek, which is in a Maastrichtian terrestrial marl in the Lance Formation of Wyoming.

It was recombined as Sterrholophus flabellatus by Marsh (1891), Marsh (1896), Marsh (1897), Woodward (1898), Nopcsa (1901), Hay (1902) and Swinton (1934); it was synonymized subjectively with Triceratops horridus by Sloan (1985), Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990), Lehman (1990), Forster (1996), Dodson et al. (2004) and Farke (2011).
Triceratops serratus was named by Marsh (1890). Its type specimen is YPM 1823 (= Sk. 4), a skull, and it is a 3D body fossil. Its type locality is Middle Fork, Dry Creek, which is in a Maastrichtian terrestrial sandstone in the Lance Formation of Wyoming.

It was synonymized subjectively with Triceratops horridus by Sloan (1985), Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990), Forster (1996) and Dodson et al. (2004).
Triceratops elatus was named by Marsh (1891). Its type specimen is YPM 1201, a skull, and it is a 3D body fossil. Its type locality is Lance Creek, near mouth of Lightning Creek, which is in a Maastrichtian terrestrial shale in the Lance Formation of Wyoming.

It was synonymized subjectively with Triceratops horridus by Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990), Lehman (1990), Forster (1996) and Dodson et al. (2004).
Triceratops brevicornus was named by Hatcher and Lull (1905). Its type specimen is YPM 1834, a skull, and it is a 3D body fossil. Its type locality is Lance Creek, 1.5 miles south of Lightning Creek, which is in a Maastrichtian terrestrial sandstone in the Lance Formation of Wyoming.

It was synonymized subjectively with Triceratops prorsus by Sloan (1976), Sloan (1985) and Forster (1996); it was synonymized subjectively with Triceratops horridus by Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990), Lehman (1990) and Dodson et al. (2004).
Diceratops hatcheri was named by Lull (1905) [Lull vide Hatcher & Lull 1905; name also given as "gen. et sp. nov." in Hatcher et al. 1907]. Its type specimen is USNM 2412, a skull, and it is a 3D body fossil. Its type locality is 3 miles southwest of Lightning Creek, which is in a Maastrichtian terrestrial sandstone in the Lance Formation of Wyoming.

It was recombined as Triceratops hatcheri by Arldt (1930), Lull (1933), Schlaikjer (1935), Gray (1946), Sternberg (1949), Ostrom (1965), Breithaupt (1985) and Tokaryk (1986); it was synonymized subjectively with Triceratops obtusus by Sloan (1985); it was synonymized subjectively with Triceratops horridus by Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990), Lehman (1990) and Longrich and Field (2012); it was recombined as Diceratus hatcheri by Mateus (2008) and Hunt and Lehman (2008); it was recombined as Nedoceratops hatcheri by Ukrainsky (2007), Farke (2011) and Mallon et al. (2022).
Triceratops albertensis was named by Sternberg (1949). Its type specimen is NMC 8862, a skull, and it is not a trace fossil. Its type locality is T. albertensis type, Red Deer River (NMC), which is in a Maastrichtian terrestrial claystone/sandstone in the Scollard Formation of Canada.

It was synonymized subjectively with Triceratops elatus by Sloan (1985); it was considered a nomen dubium by Forster (1996); it was synonymized subjectively with Triceratops horridus by Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990) and Dodson et al. (2004).
Triceratops eurycephalus was named by Schlaikjer (1935). Its type specimen is MCZ 1102, a partial skeleton, and it is a 3D body fossil. Its type locality is 1.5 miles up Horse Creek (41 ft), which is in a Maastrichtian terrestrial sandstone/shale in the Lance Formation of Wyoming.

It was considered a nomen dubium by Forster (1996); it was synonymized subjectively with Triceratops horridus by Sloan (1985), Ostrom and Wellnhofer (1986), Dodson and Currie (1990), Ostrom and Wellnhofer (1990) and Dodson et al. (2004).

Synonymy list

Year	Name and author
1889	Ceratops horridus Marsh pp. 173-174
1889	Triceratops horridus Marsh p. 173
1889	Triceratops flabellatus Marsh p. 174
1889	Ceratops horridus Marsh pp. 334-335
1890	Triceratops serratus Marsh p. 81
1890	Triceratops flabellatus Zittel p. 738
1890	Triceratops horridus Zittel p. 752
1890	Triceratops serratus Zittel p. 752
1891	Triceratops flabellatus Boule p. 16
1891	Triceratops elatus Marsh p. 265
1891	Sterrholophus flabellatus Marsh p. 340
1893	Triceratops flabellatus Winkler p. 109
1896	Sterrholophus flabellatus Marsh figs. Pl. 76:1
1896	Triceratops serratus Marsh figs. Pl. 77:4
1896	Triceratops horridus Marsh p. 208
1897	Sterrholophus flabellatus Marsh p. 511
1897	Triceratops serratus Marsh p. 512
1897	Triceratops horridus Marsh p. 527
1898	Triceratops flabellatus Gegenbaur p. 394
1898	Triceratops calicornis Marsh
1898	Triceratops obtusus Marsh
1898	Triceratops calicornis Marsh p. 92
1898	Triceratops obtusus Marsh p. 92
1898	Sterrholophus flabellatus Woodward p. 215
1900	Triceratops californis Walcott p. 23
1900	Triceratops obtusa Walcott p. 23
1901	Triceratops flabellatus Gadow p. 430
1901	Sterrholophus flabellatus Nopcsa p. 217
1901	Triceratops calcicornis Nopcsa p. 217
1901	Triceratops horridus Nopcsa p. 217
1901	Triceratops obtusus Nopcsa p. 217
1901	Triceratops serratus Nopcsa p. 217
1902	Triceratops calicornis Hay p. 498
1902	Triceratops elatus Hay p. 498
1902	Triceratops horridus Hay p. 498
1902	Sterrholophus flabellatus Hay p. 499
1902	Triceratops obtusus Hay p. 499
1902	Triceratops serratus Hay p. 499
1902	Triceratops serratus Lambe p. 69
1902	Triceratops flabellatus Mansel-Pleydell p. lxxxv
1902	Triceratops horridus Mansel-Pleydell p. lxxxv
1902	Triceratops serratus Mansel-Pleydell p. lxxxv
1903	Triceratops serratus Lull p. 685
1905	Triceratops brevicornus Hatcher and Lull pp. 413-416 figs. Pl. 12
1905	Diceratops hatcheri Hatcher and Lull p. 417
1905	Diceratops hatcheri Lull pp. 417-419 figs. Pl. 13
1907	Triceratops brevicornus Brown p. 842
1907	Triceratops serratus Brown p. 842
1907	Diceratops hatcheri Hatcher et al. pp. 149, 168
1907	Triceratops horridus Hatcher et al. p. 168
1907	Triceratops brevicornus Hatcher et al. p. 169
1907	Triceratops serratus Hatcher et al. p. 169
1907	Triceratops elatus Hatcher et al. p. 170
1907	Triceratops calicornis Hatcher et al. p. 171
1907	Triceratops flabellatus Hatcher et al. p. 171
1907	Triceratops obtusus Hatcher et al. p. 171
1909	Triceratops horridus Knowlton p. 202
1910	Diceratops hatcheri Lull p. 772
1910	Triceratops brevicornus Lull p. 775
1910	Triceratops elatus Lull p. 775
1911	Triceratops flabellatus Jaekel p. 161
1911	Triceratops flabellatus von Zittel p. 295 fig. 445
1911	Triceratops serratus von Zittel p. 296 fig. 446
1913	Triceratops flabellatus Tornier p. 375
1914	Triceratops brevicornus Brown p. 358
1914	Triceratops serratus Brown p. 358
1914	Triceratops horridus Brown p. 543
1914	Triceratops horridus Huene p. 583
1914	Triceratops flabellatus Huene p. 584
1914	Triceratops serratus Huene p. 584
1915	Triceratops elatus Lambe p. 24
1915	Triceratops flabellatus Lambe pp. 30, 36
1920	Diceratops hatcheri Pompeckj p. 114
1920	Triceratops calicornis Pompeckj p. 114
1920	Triceratops elatus Pompeckj p. 114
1920	Triceratops flabellatus Pompeckj p. 114
1920	Triceratops serratus Pompeckj p. 114
1925	Diceratops hatcheri Parks p. 5
1925	Triceratops brevicornis Parks p. 5
1925	Triceratops elatus Parks p. 5
1925	Triceratops flabellatus Parks p. 5
1925	Triceratops serratus Parks p. 5
1925	Triceratops calicornis Parks p. 7
1927	Diceratops hatcheri Huene p. 261
1927	Triceratops brevicornis Huene p. 261
1927	Triceratops calicornis Huene p. 261
1927	Triceratops elatus Huene p. 261
1927	Triceratops flabellatus Huene p. 261
1927	Triceratops horridus Huene p. 261
1927	Triceratops obtusus Huene p. 261
1927	Triceratops serratus Huene p. 261
1928	Triceratops horridus Perrier p. 3088
1930	Triceratops brevicornus Arldt p. 702
1930	Triceratops elatus Arldt p. 702
1930	Triceratops hatcheri Arldt p. 702
1930	Diceratops hatcheri Hay p. 226
1930	Triceratops brevicornus Hay p. 228
1930	Triceratops calicornis Hay p. 228
1930	Triceratops elatus Hay p. 228
1930	Triceratops flabellatus Hay p. 228
1930	Triceratops horridus Hay p. 229
1930	Triceratops obtusus Hay p. 229
1930	Triceratops serratus Hay p. 230
1930	Diceratops hatcheri Russell p. 140
1930	Triceratops brevicornus Russell p. 140
1930	Triceratops calicornis Russell p. 140
1930	Triceratops elatus Russell p. 140
1930	Triceratops flabellatus Russell p. 140
1930	Triceratops horridus Russell p. 140
1930	Triceratops obtusus Russell p. 140
1930	Triceratops serratus Russell p. 140
1931	Triceratops elatus Huene p. 197
1931	Triceratops horridus Johnson p. 374
1933	Triceratops brevicornus Lull p. 119
1933	Triceratops serratus Lull p. 120
1933	Triceratops flabellatus Lull p. 121
1933	Triceratops elatus Lull p. 122
1933	Triceratops calicornis Lull p. 123
1933	Triceratops obtusus Lull p. 125
1933	Triceratops hatcheri Lull pp. 126-128
1934	Sterrholophus flabellatus Swinton p. 46
1935	Triceratops eurycephalus Schlaikjer p. 55
1935	Triceratops serratus Schlaikjer p. 58
1935	Triceratops elatus Schlaikjer p. 60
1935	Triceratops brevicornus Schlaikjer p. 62
1935	Triceratops calicornis Schlaikjer p. 62
1935	Triceratops flabellatus Schlaikjer p. 62
1935	Triceratops hatcheri Schlaikjer p. 62
1935	Triceratops horridus Schlaikjer p. 63
1935	Triceratops obtusus Schlaikjer p. 63
1940	Triceratops serratus Brown and Schlaikjer p. 3 figs. 2A-C
1940	Triceratops fabellatus Sternberg p. 479
1946	Triceratops brevicornus Gray p. 797
1946	Triceratops calicornis Gray p. 797
1946	Triceratops elatus Gray p. 797
1946	Triceratops hatcheri Gray p. 797
1946	Triceratops horridus Gray p. 797
1946	Triceratops serratus Gray p. 797
1946	Triceratops flabellatus Gray p. 798
1946	Triceratops obtusus Gray p. 798
1949	Triceratops horridus Lull and Gray p. 493
1949	Triceratops calicornis Lull and Gray p. 496
1949	Triceratops elatus Lull and Gray p. 496
1949	Triceratops albertensis Sternberg pp. 38-39 figs. Pl. 6
1949	Triceratops brevicornus Sternberg p. 42 fig. 1
1949	Triceratops calicornis Sternberg p. 42 fig. 1
1949	Triceratops elatus Sternberg p. 42 fig. 1
1949	Triceratops eurycephalus Sternberg p. 42 fig. 1
1949	Triceratops hatcheri Sternberg p. 42 fig. 1
1949	Triceratops horridus Sternberg p. 42 fig. 1
1949	Triceratops obtusus Sternberg p. 42 fig. 1
1950	Triceratops flabellatus Huene p. 350 fig. 3
1963	Triceratops elatus Anonymous p. 356
1964	Diceratops hatcheri Kuhn p. 56
1964	Triceratops albertensis Kuhn p. 59
1964	Triceratops calicornis Kuhn p. 59
1964	Triceratops eurycephalus Kuhn p. 59
1964	Triceratops horridus Kuhn p. 59
1964	Triceratops brevicornus Kuhn p. 60
1964	Triceratops elatus Kuhn p. 60
1964	Triceratops flabellatus Kuhn p. 60
1964	Triceratops obtusus Kuhn p. 60
1964	Triceratops serratus Kuhn p. 60
1964	Triceratops serratus Russell p. 17
1964	Triceratops albertensis Russell p. 19
1964	Triceratops brevicornis Tatarinov p. 579 fig. 635
1964	Triceratops serratus Tatarinov p. 579 fig. 635
1964	Triceratops flabellatus Tatarinov p. 581 fig. 637
1964	Triceratops horridus Tatarinov p. 583
1965	Triceratops brevicornus Ostrom p. 39
1965	Triceratops calicornis Ostrom p. 39
1965	Triceratops elatus Ostrom p. 39
1965	Triceratops flabellatus Ostrom p. 39
1965	Triceratops hatcheri Ostrom p. 39
1965	Triceratops horridus Ostrom p. 39
1965	Triceratops obtusus Ostrom p. 39
1965	Triceratops serratus Ostrom p. 39
1966	Triceratops albertensis Russell p. 25
1967	Triceratops horridus Charig p. 717
1969	Triceratops brevicornis Schuyf p. 68
1970	Triceratops serratus Swinton p. 103
1975	Triceratops flabellatus Langston p. 1585
1979	Triceratops horridus Laub p. 4
1979	Triceratops serratus Laub p. 6
1979	Triceratops elatus Laub p. 15
1981	Triceratops brevicornus McIntosh p. 41
1982	Triceratops brevicornus McGinnis p. 104
1985	Triceratops flabellatus Breithaupt p. 167
1985	Triceratops brevicornus Breithaupt p. 170
1985	Triceratops calicornis Breithaupt p. 170
1985	Triceratops elatus Breithaupt p. 170
1985	Triceratops eurycephalus Breithaupt p. 170
1985	Triceratops hatcheri Breithaupt p. 170
1985	Triceratops horridus Breithaupt p. 170
1985	Triceratops obtusus Breithaupt p. 170
1985	Triceratops serratus Breithaupt p. 170
1985	Triceratops elatus Sloan p. 265
1985	Triceratops horridus Sloan p. 265
1985	Triceratops obtusus Sloan p. 265
1986	Triceratops horridus Ostrom and Wellnhofer p. 156
1986	Triceratops albertensis Tokaryk p. 194
1986	Triceratops brevicornus Tokaryk p. 194
1986	Triceratops horridus Tokaryk p. 194
1986	Triceratops hatcheri Tokaryk p. 195
1990	Triceratops horridus Dodson and Currie p. 612
1990	Triceratops horridus Ostrom and Wellnhofer p. 247
1994	Triceratops horridus Derstler p. 131
1994	Triceratops horridus Retallack p. 1385
1996	Diceratops hatcheri Forster p. 260
1996	Triceratops horridus Forster p. 268
1996	Triceratops horridus Lehman p. 505 fig. 10
1997	Triceratops horridus Breithaupt p. 394
1997	Triceratops horridus Currie and Padian p. 369
1997	Triceratops albertensis Eberth p. 202
1998	Triceratops horridus Lehman p. 903
2001	Triceratops albertensis Eberth et al. p. 66
2001	Triceratops horridus Makovicky p. 254 fig. 18.3
2002	Triceratops horridus Buchholz p. 19
2004	Triceratops horridus Chinnery p. 584
2004	Diceratops hatcheri Dodson et al. p. 496
2004	Triceratops horridus Dodson et al. p. 496
2005	Triceratops horridus Diem and Archibald p. 251
2007	Diceratops hatcheri Farke p. 249
2007	Triceratops horridus Farke p. 249
2007	Nedoceratops hatcheri Ukrainsky p. 292
2008	Triceratops horridus Butler et al. p. 8
2008	Triceratops horridus Currie et al. p. 84
2008	Triceratops horridus Hunt and Lehman p. 1129
2008	Diceratus hatcheri Hunt and Lehman p. 1135
2008	Diceratus hatcheri Mateus p. 423
2010	Triceratops horridus Goodwin and Horner p. 552
2010	Triceratops horridus Longrich p. 691
2010	Triceratops horridus Scannella and Horner p. 1166
2011	Triceratops horridus Farke p. 1
2011	Nedoceratops hatcheri Farke p. 4
2011	Triceratops horridus Scannella and Horner p. 1
2012	Triceratops horridus Longrich and Field p. 9
2013	Triceratops horridus Armitage and Anderson p. 603
2014	Triceratops horridus Goodwin and Horner p. 334
2014	Triceratops horridus Longrich p. 303
2017	Triceratops horridus Erickson p. 14
2022	Triceratops horridus D'Anastasio et al. p. 1
2022	Nedoceratops hatcheri Mallon et al. p. 162

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
subclass	Eureptilia	()
—	Romeriida

Rank	Name	Author
—	Diapsida	()
—	Archosauromorpha	(Huene 1946)
—	Crocopoda
—	Archosauriformes	Gauthier 1986
—	Eucrocopoda
—	Archosauria	()
informal	Avemetatarsalia
—	Ornithodira
—	Dinosauromorpha
—	Dinosauriformes
—	Dinosauria	()
—	Ornithischia	()
—	Genasauria
—	Cerapoda
—	Marginocephalia
—	Ceratopsia	()
family	Ceratopsidae
subfamily	Chasmosaurinae
—	Triceratopsini
genus	Triceratops
species	horridus	()

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.

†Triceratops horridus Marsh 1889

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Invalid names: Nedoceratops hatcheri Lull 1905 [synonym], Triceratops albertensis Sternberg 1949 [synonym], Triceratops brevicornus Hatcher and Lull 1905 [synonym], Triceratops calicornis Marsh 1898 [synonym], Triceratops elatus Marsh 1891 [synonym], Triceratops eurycephalus Schlaikjer 1935 [synonym], Triceratops flabellatus Marsh 1889 [synonym], Triceratops obtusus Marsh 1898 [synonym], Triceratops serratus Marsh 1890 [synonym]

Diagnosis

Reference	Diagnosis
E. M. Schlaikjer 1935 (Triceratops eurycephalus)	1. Crest greatly expanded inproportion to the length of the skull. 2. Facial region abbreviated and broadly triangular in outline when seen from above. 3. Orbit elevated so that almost two-thirds of its area is above the posterior of the nasal. 4. Anterio-inferior corner of the squamosal extended forward, giving a straight anterior border to the squamosal. 5. Dentary short and proportionately deep with high coronoid which distally is little antero-posteriorly expanded. 6. Brow-horns proportionately very long and relatively slender. 7. Nasal horn greatly diminished. 8. Olfactory nerves separate and diverge laterally immediately in front of the cerebrum.
J. H. Ostrom and P. Wellnhofer 1986	Same as for the genus.
J. B. Scannella and J. R. Horner 2010	Diagnosis same as for genus.
A. A. Farke 2011 (Nedoceratops hatcheri)	Diagnosis. Chasmosaurine ceratopsid with the following autapomorphies: nasal horncore nearly completely undifferen- tiated from the nasal bone; greater portion of procurved postorbital horncores forms a 90 degree angle with tooth row; and parietal fenestrae extremely small (occupying less than five percent of the total surface area of the parietal). Nedoceratops hatcheri is distinguished from Triceratops spp. in the the position of the ventral extremity of the squamosal well above the alveolar process of the maxilla, and in the presence of parietal fenestrae, which are lacking in all Triceratops species. Nedoceratops hatcheri is distinguished from Torosaurus latus in squamosal shape (particularly the reduced jugal notch and lack of a thickened medial margin in N. hatcheri), and that N. hatcheri has extremely reduced parietal fenestrae and a low number of episquamosals in N. hatcheri compared to T. latus.