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Minippus index

Mammalia - Perissodactyla - Equidae

Taxonomy

Orotherium index was named by Cope (1873). Its type specimen is AMNH 4680, a mandible, and it is a 3D body fossil.

It was synonymized subjectively with Orotherium uintanum by Cope (1875); it was recombined as Hyracotherium index by Cope (1877), Cope (1884), Wortman (1896), Matthew (1899), Gazin (1952), Gingerich (1989), Gingerich (1991) and MacFadden (1998); it was recombined as Eohippus index by King (1878), Hay (1902), Granger (1908), Hay (1930) and Stirton (1940); it was synonymized subjectively with Pliolophus uintanus by Cope (1886); it was synonymized subjectively with Hyracotherium angustidens by Lydekker (1886), Pavlow (1888) and Kitts (1956); it was synonymized subjectively with Hyracotherium vasacciense by Kitts (1956) and Gazin (1962); it was recombined as Minippus index by Froehlich (2002).

Synonyms

Hyracotherium sulcatus was named by Gingerich (1989) [correct form is actually sulcatum].

It was synonymized subjectively with Hyracotherium index by Gingerich (1989) and Gingerich (1991).
Orotherium loevii was named by Cope (1877).

It was recombined as Pliolophus loevii by Cope (1884); it was synonymized subjectively with Hyracotherium cristonense by Wortman (1896); it was synonymized subjectively with Pliolophus cristonensis by Hay (1902); it was synonymized subjectively with Eohippus cristonensis by Granger (1908); it was synonymized subjectively with Hyracotherium index by Gingerich (1989) and Gingerich (1991).

Synonymy list

Year	Name and author
1873	Orotherium index Cope p. 4
1877	Hyracotherium index Cope
1877	Orotherium loevii Cope
1878	Eohippus index King
1884	Hyracotherium index Cope
1884	Pliolophus loevii Cope
1896	Hyracotherium index Wortman pp. 9, 10
1899	Hyracotherium index Matthew
1902	Eohippus index Hay p. 609
1908	Eohippus index Granger
1930	Eohippus index Hay
1940	Eohippus index Stirton
1952	Hyracotherium index Gazin
1989	Hyracotherium index Gingerich
1989	Hyracotherium sulcatus Gingerich
1991	Hyracotherium index Gingerich
1998	Hyracotherium index MacFadden p. 542
2002	Minippus index Froehlich pp. 162-163

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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
subclass	Synapsida
—	Therapsida	()
infraorder	Cynodontia	()
—	Mammaliamorpha
—	Mammaliaformes

Rank	Name	Author
class	Mammalia
—	Theriamorpha	(Rowe 1993)
—	Theriiformes	()
—	Trechnotheria
—	Cladotheria
—	Zatheria
subclass	Tribosphenida	()
subclass	Theria
—	Eutheria	()
—	Placentalia
—	Boreoeutheria
—	Laurasiatheria
—	Scrotifera
—	Euungulata
—	Panperissodactyla
superorder	Perissodactylamorpha
order	Perissodactyla	()
superfamily	Equoidea
family	Equidae
genus	Minippus
species	index	()

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.

†Minippus index Cope 1873

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Invalid names: Hyracotherium sulcatus Gingerich 1989 [synonym], Orotherium loevii Cope 1877 [synonym]

Diagnosis

Reference	Diagnosis
D. J. Froehlich 2002	Small equids with a lower preultimate molar hypoconulid closely appressed against hypolophid (Character 95, 0 to 1), a buccal molar postcristid (Character 97, 1 to 0) and a strong pre-M3 hypoconulid (Character 98, 1 to 0). The group lacks the characters of the next more-derived equid clade, P4 posterior ridge moderate (Character 76, 0 to 1), lower premolar paralophid complex very short (Character 79, 1 to 0), and a rounded lower molar paracristid bend (Character 88, 1 to 0).