PBDB Taxon

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Megacerops

Osteichthyes - Perissodactyla - Brontotheriidae

Taxonomy

Megacerops was named by Leidy (1870).

It was replaced with Megaceratops by Cope (1873); it was synonymized subjectively with Menodus by Scott and Osborn (1887), Clark and Beerbower (1967).

It was assigned to Proboscidea by Leidy (1873); to Brontotheriinae by Hay (1902); to Titanotheriidae by Lambe (1908); to Megaceropinae by Osborn (1914), Osborn (1929); to Telmatheriinae by Prothero and Schoch (1989); to Brontotheridae by Leidy (1870), Marsh (1875), Carroll (1988), Mader (1989), Mader (1998); and to Brontotheriita by Mihlbachler (2008).

Species

Allops crassicornus, Allops marshi, Brontops amplus, Brontops brachycephalus, Brontops dispar (syn. Brontops validus), Brontops robustus, Brontotherium dolichoceras, Brontotherium hypoceras, Brontotherium medium, Brontotherium ramosum, Brontotherium rumelicum, Brontotherium tichoceras, Diploclonus bicornutus, Diploclonus selwynianus, Diploclonus tyleri, Eotherium, Haplacodon, M. acer (syn. Symborodon altirostris), M. angustigenis, M. assiniboiensis, M. bucco, M. coloradensis (syn. Brontotherium ingens, Brontotherium gigas, Titanops elatus, Brontotherium hatcheri, Brontotherium platyceras, Brontotherium leidyi), M. copei, M. curtus (syn. Menodus peltoceras), M. kuwagatarhinus, M. osborni, M. riggsi, M. syceras, Menodus giganteus, Menodus heloceras, Menodus montanus, Menodus proutii, Menodus torvus, Menodus trigonoceras, Menodus varians, Menops bakeri, Menops crassicornis, Menops serotinus, Menops walcotti, Teleodus avus

Sister genera

Eotherium, Haplacodon

Entered

by J. Alroy on 2003-01-23; modified by M. Carrano on 2019-12-02

Synonyms

Palaeotherium (Menodus) was named by Pomel (1848) [named as a subgenus of Palaeotherium by Pomel 1849; raised to genus level]. Its type is Palaeotherium giganteum.

It was synonymized subjectively with Titanotherium by Marsh (1875); it was reranked as Menodus by Cope (1881), Scott and Osborn (1887), Cope (1891), Osborn (1929); it was considered a nomen dubium by Prothero and Schoch (1989), Mader (1989), Mader (1998); it was synonymized subjectively with Megacerops by Mihlbachler (2008).

It was assigned to Palaeotherium by Pomel (1848); to Menodontidae by Cope (1881), Scott and Osborn (1887); to Perissodactyla by Cope (1891); and to Menodontinae by Osborn (1929).
Anisacodon was named by Marsh (1875).

It was synonymized subjectively with Symborodon by Hay (1902).
Brontops was named by Marsh (1887).

It was synonymized subjectively with Titanotherium by Osborn and Wortman (1895); it was synonymized subjectively with Brontotherium by Hay (1902); it was synonymized subjectively with Menodus by Clark and Beerbower (1967); it was synonymized subjectively with Megacerops by Osborn (1902), Mihlbachler (2008).

It was assigned to Brontopinae by Osborn (1914), Osborn (1929), Ferrusquia-Villafranca (1969); to Telmatheriinae by Prothero and Schoch (1989); and to Brontotheridae by Marsh (1887), Marsh (1887), Carroll (1988), Mader (1989), Mader (1998).
Menops was named by Marsh (1887). It is not extant.

It was synonymized subjectively with Titanotherium by Hay (1902), Osborn (1902); it was synonymized subjectively with Menodus by Osborn (1929), Scott (1941), Clark and Beerbower (1967); it was synonymized subjectively with Megacerops by Mihlbachler (2008).

It was assigned to Telmatheriinae by Prothero and Schoch (1989); and to Brontotheridae by Marsh (1887), Mader (1989), Mader (1998).
Allops was named by Marsh (1887).

It was synonymized subjectively with Menodus by Clark and Beerbower (1967); it was synonymized subjectively with Menops by Prothero and Schoch (1989), Mader (1989), Mader (1998); it was synonymized subjectively with Megacerops by Hay (1902), Mihlbachler (2008).

It was assigned to Brontotheridae by Marsh (1887); and to Menodontinae by Osborn (1929).
Ateleodon was named by Schlaikjer (1935). Its type is Ateleodon osborni.

It was synonymized subjectively with Megacerops by Kihm (1987), Mihlbachler (2008).
Brontotherium was named by Marsh (1873). Its type is Brontotherium gigas. It is the type genus of Brontotherioidea.

It was synonymized subjectively with Menodus by Scott and Osborn (1887), Clark and Beerbower (1967); it was considered a nomen dubium by Mader (1989), Mader and Alexander (1995), Mader (1998); it was synonymized subjectively with Megacerops by Prothero and Schoch (1989), Mihlbachler (2008).

It was assigned to Brontotheridae by Marsh (1873), Marsh (1875); and to Brontotheriinae by Hay (1902), Osborn (1914), Osborn (1929).
Diconodon was named by Marsh (1876) [replacement for "Anisacodon" Marsh 1875].

It was synonymized subjectively with Menodus by Scott and Osborn (1887), Osborn (1929), Scott (1941); it was synonymized subjectively with Symborodon by Osborn (1902); it was considered a nomen dubium by Mader (1989), Mader (1998).
Diploclonus was named by Marsh (1890) [also, but incorrectly said to be 1887].

It was synonymized subjectively with Allops by Osborn (1902); it was synonymized subjectively with Brontops by Scott (1941), Prothero and Schoch (1989), Mader (1989), Mader and Alexander (1995), Mader (1998); it was synonymized subjectively with Menodus by Clark and Beerbower (1967); it was synonymized subjectively with Megacerops by Mihlbachler (2008).

It was assigned to Brontopinae by Osborn (1914), Osborn (1929).
Eotherium was named by Leidy (1853).

It was considered a nomen dubium by Osborn (1929); it was synonymized subjectively with Archaeotherium by Scott (1940).

It was assigned to Mammalia by Leidy (1853); and to Titanotheriidae by Palmer (1904).
Haplacodon was named by Cope (1889).

It was synonymized subjectively with Megacerops by Hay (1902), Osborn (1902); it was considered a nomen dubium by Osborn (1929).

It was assigned to Perissodactyla by Cope (1889).
Megaceratops was named by Cope (1873).

It was synonymized subjectively with Megacerops by Leidy (1873), Marsh (1875), Osborn (1929), Scott (1941), Galbreath (1953), Mader (1989); it was synonymized subjectively with Symborodon by Cope (1902); it was synonymized subjectively with Brontops by Osborn (1914); it was considered a nomen dubium by Mader (1998).

It was assigned to Dinocerata by Cope (1873).
Palaeotherium giganteum was named by Pomel (1849) [from the Badlands and not European; later "named" by Leidy 1853 based on different material; made type of subgenus Menodus]. It is the type species of Palaeotherium (Menodus).

It was synonymized subjectively with Titanotherium proutii by Leidy (1857); it was recombined as Menodus giganteus by Osborn (1929); it was considered a nomen dubium by Mader (1989), Mader (1998), Mihlbachler et al. (2004).
Symborodon was named by Cope (1873).

It was synonymized subjectively with Menodus by Scott and Osborn (1887), Osborn (1929), Clark and Beerbower (1967); it was considered a nomen dubium by Mader (1989), Mader (1998); it was synonymized subjectively with Megacerops by Osborn (1914), Mihlbachler (2008).

It was assigned to Menodontidae by Cope (1881); to Brontotheriinae by Hay (1902); and to Brontotheridae by Prothero and Schoch (1989).
Teleodus was named by Marsh (1890) [virtually all "Teleodus" is actually Duchesneodus: Lucas and Schoch 1982]. Its type is Teleodus avus.

It was synonymized subjectively with Titanotherium by Osborn (1896) and Hatcher (1983); it was considered a nomen dubium by Lucas and Schoch (1982); it was considered a nomen dubium by Lucas and Schoch (1989); it was synonymized subjectively with Megacerops by Osborn (1902), Mihlbachler (2008).

It was assigned to Brontotheriinae by Hay (1902); to Brontopinae by Osborn (1929); to Brontotheridae by Bjork (1967); and to Telmatheriinae by Prothero and Schoch (1989).
Titanops was named by Marsh (1887).

It was synonymized subjectively with Brontotherium by Hay (1902), Osborn (1902), Osborn (1929), Scott (1941); it was synonymized subjectively with Megacerops by Prothero and Schoch (1989), Mader (1989), Mader and Alexander (1995), Mader (1998), Mihlbachler (2008).

It was assigned to Brontotheridae by Marsh (1887).
Titanotherium was named by Leidy (1852).

It was synonymized subjectively with Menodus by Scott and Osborn (1887), Cope (1889), Osborn (1914), Osborn (1929), Scott (1941), Simpson (1945), Toohey (1959), Clark and Beerbower (1967); it was considered a nomen dubium by Mader (1989), Mader (1998); it was synonymized subjectively with Megacerops by Mihlbachler (2008).

It was assigned to Pachydermata by Leidy (1856); to Brontotheriinae by Hay (1902); to Titanotheriidae by Osborn and Wortman (1895), Scott (1913); and to Brontotheridae by Marsh (1873), Marsh (1875), Prothero and Schoch (1989).

Synonymy list

Year	Name and author
1848	Palaeotherium (Menodus) Pomel
1849	Palaeotherium giganteum Pomel
1852	Titanotherium Leidy
1853	Eotherium Leidy p. 392
1856	Titanotherium Leidy p. 92
1870	Megacerops Leidy p. 2
1873	Megaceratops Cope
1873	Symborodon Cope pp. 2 - 3
1873	Megaceratops Cope p. 5
1873	Megacerops Leidy p. 335
1873	Brontotherium Marsh p. 486
1873	Titanotherium Marsh p. 486
1875	Anisacodon Marsh
1875	Brontotherium Marsh
1875	Megacerops Marsh
1875	Titanotherium Marsh
1876	Diconodon Marsh
1881	Menodus Cope p. 397
1881	Symborodon Cope p. 397
1886	Menodus Cope
1887	Allops Marsh
1887	Brontops Marsh
1887	Menops Marsh
1887	Titanops Marsh
1887	Brontops Marsh p. 326
1887	Menops Marsh p. 328 figs. 9-10
1887	Titanops Marsh p. 330 fig. 11
1887	Allops Marsh p. 331
1887	Menodus Scott and Osborn p. 157
1889	Haplacodon Cope p. 153
1890	Diploclonus Marsh
1890	Teleodus Marsh p. 524
1891	Menodus Cope p. 8
1895	Titanotherium Osborn and Wortman p. 346
1902	Megacerops Hay p. 633
1902	Brontotherium Hay p. 634
1902	Titanotherium Hay p. 635
1902	Symborodon Hay p. 637
1902	Teleodus Hay p. 638
1904	Eotherium Palmer p. 265
1908	Megacerops Lambe
1913	Titanotherium Scott p. 291
1914	Brontops Osborn p. 405
1914	Brontotherium Osborn p. 405
1914	Diploclonus Osborn p. 405
1914	Megacerops Osborn p. 405
1929	Allops Osborn p. 247
1929	Brontotherium Osborn p. 247
1929	Diploclonus Osborn p. 247
1929	Megacerops Osborn p. 247
1929	Menodus Osborn p. 247
1929	Teleodus Osborn p. 247
1929	Brontops Osborn p. 482 figs. Plates XVIII, XX, XXI, XXIII, XXIV, XXXIII-XXXVI, XLIII, XLVII, LXXXII-CIII, CLIII, CLX, CXCV- CCXXI
1929	Menodus giganteus Osborn p. 530 figs. Plates XVIII, XX, XXIV, XLVII, XLIX, CXXXIII, CXXXV-CXLI; text figures 24, 159, 227, 228, 375, 3 1,
1935	Ateleodon Schlaikjer
1945	Teleodus Scott
1967	Teleodus Bjork p. 231
1969	Brontops Ferrusquia-Villafranca
1988	Brontops Carroll
1988	Megacerops Carroll
1989	Brontops Mader
1989	Megacerops Mader
1989	Menops Mader
1989	Brontops Prothero and Schoch p. 537
1989	Megacerops Prothero and Schoch p. 537
1989	Menops Prothero and Schoch p. 537
1989	Symborodon Prothero and Schoch p. 537
1989	Teleodus Prothero and Schoch p. 537
1989	Titanotherium Prothero and Schoch p. 537
1998	Brontops Mader
1998	Megacerops Mader
1998	Menops Mader
2008	Megacerops Mihlbachler p. 413

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

Rank	Name	Author
—	Mammaliaformes
class	Mammalia
—	Cladotheria
—	Zatheria
subclass	Tribosphenida	()
subclass	Theria
—	Eutheria	()
—	Placentalia
—	Boreoeutheria
—	Laurasiatheria
—	Scrotifera
—	Euungulata
—	Panperissodactyla
superorder	Perissodactylamorpha
order	Perissodactyla	()
family	Brontotheriidae	()
subfamily	Brontotheriinae	Marsh 1873
tribe	Brontotheriini	Marsh 1873
subtribe	Brontotheriina	Marsh 1873
—	Brontotheriita	Marsh 1873
genus	Megacerops

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.

G. †Megacerops Leidy 1870

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†Megacerops acer Cope 1873

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Invalid names: Symborodon altirostris Cope 1873 [synonym]

†Megacerops angustigenis Cope 1886

†Megacerops assiniboiensis Lambe 1908

†Megacerops bucco Cope 1873

†Megacerops coloradensis Leidy 1870

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Invalid names: Brontotherium gigas Marsh 1873 [synonym], Brontotherium hatcheri Osborn 1908 [synonym], Brontotherium ingens Marsh 1874 [synonym], Brontotherium leidyi Osborn 1902 [synonym], Brontotherium platyceras Scott and Osborn 1887 [synonym]

†Megacerops copei Osborn 1908

†Megacerops curtus Marsh 1887

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Invalid names: Menodus peltoceras Cope 1891 [synonym]

†Megacerops kuwagatarhinus Mader and Alexander 1995

†Megacerops osborni Schlaikjer 1935

†Megacerops riggsi Osborn 1916

†Megacerops syceras Cope 1889

Invalid names: Allops Marsh 1887 [synonym], Ateleodon Schlaikjer 1935 [synonym], Brontops Marsh 1887 [synonym], Brontotherium Marsh 1873 [synonym], Diploclonus Marsh 1890 [synonym], Megaceratops Cope 1873 [synonym], Menodus Pomel 1848 [synonym], Menops Marsh 1887 [synonym], Symborodon Cope 1873 [synonym], Teleodus Marsh 1890 [synonym], Titanops Marsh 1887 [synonym], Titanotherium Leidy 1852 [synonym]

Diagnosis

Reference	Diagnosis
W. B. Scott and H. F. Osborn 1887 (Menodus)	Dentition : I. 2/2 (variable), C. 1/1, Pm. 4/3, M. 3/3. The incisors are small and variable in number. The upper and lower median incisors are usually wanting. Molars and premolars alike, resembling those of Chalicotherium in pattern. A stout pair of transversely placed horns developed from the frontals and nasals.
H. F. Osborn 1929 (Brontops)	Upper and lower incisors 2-1. Canines pointed, becoming obtuse. Premolars cingulate; tetartocones retarded. Horns of an elongate to transverse oval section, shifting forward. Skulls progressively brachycephalic.