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Eohippus angustidens

Mammalia - Perissodactyla - Equidae

Taxonomy
Orohippus angustidens was named by Cope (1875). Its type specimen is USNM 1079, a mandible (left mandible fragment with M1–M3), and it is a 3D body fossil.

It was recombined as Hyracotherium angustidens by Cope (1877), Cope (1884), Trouessart (1898), Kitts (1956) and MacFadden (1998); it was synonymized subjectively with Hyracotherium index by Wortman (1896), Matthew (1899), Gingerich (1989), Gingerich (1991) and Lillegraven (1994); it was synonymized subjectively with Eohippus index by Hay (1902); it was recombined as Eohippus angustidens by King (1878), Granger (1908), Stirton (1940), Froehlich (1999) and Froehlich (2002).

Synonyms
  • Eohippus validus was named by Marsh (1876) [genotype]. Its type specimen is YPM 11307 and is a 3D body fossil.

    It was synonymized subjectively with Hyracotherium vasacciense by Wortman (1896), Trouessart (1898), Matthew (1899) and Gingerich (1991); it was synonymized subjectively with Hyracotherium angustidens by Kitts (1956); it was synonymized subjectively with Eohippus angustidens by Froehlich (2002).
  • Hyracotherium seekinsi was named by Morris (1968). Its type locality is Lomas las Tetas de Cabra, which is in a Wasatchian fluvial-lacustrine sandstone/siltstone in the Las Tetas de Cabra Formation of Mexico.

    It was synonymized subjectively with Eohippus angustidens by Froehlich (2002).
  • Orohippus cuspidatus was named by Cope (1875). Its type specimen is USNM 1079, a mandible (left mandible fragment with M1–M3), and it is a 3D body fossil.

    It was recombined as Hyracotherium cuspidatum by Cope (1877) and Cope (1884); it was recombined as Eohippus cuspidatus by King (1878); it was synonymized subjectively with Hyracotherium index by Wortman (1896), Matthew (1899), Gingerich (1989) and Gingerich (1991); it was synonymized subjectively with Eohippus index by Hay (1902); it was synonymized subjectively with Eohippus angustidens by Granger (1908) and Froehlich (2002).
Synonymy list
YearName and author
1875Orohippus angustidens Cope p. 22
1875Orohippus cuspidatus Cope p. 22
1876Eohippus validus Marsh p. 401
1877Hyracotherium angustidens Cope
1877Hyracotherium cuspidatum Cope
1878Eohippus angustidens King
1878Eohippus cuspidatus King
1884Hyracotherium angustidens Cope
1884Hyracotherium cuspidatum Cope
1898Hyracotherium angustidens Trouessart
1902Eohippus validus Hay p. 610
1908Eohippus angustidens Granger
1908Eohippus validus Granger
1940Eohippus angustidens Stirton
1940Eohippus validus Stirton
1956Hyracotherium angustidens Kitts
1968Hyracotherium seekinsi Morris
1998Hyracotherium angustidens MacFadden p. 542
1998Hyracotherium seekinsi MacFadden p. 542
1999Eohippus angustidens Froehlich
2002Eohippus angustidens Froehlich p. 175–176

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RankNameAuthor
kingdomAnimalia()
—Bilateria
—EubilateriaAx 1987
—Deuterostomia
phylumChordataHaeckel 1874
subphylumVertebrata
superclassGnathostomata
—Osteichthyes()
subclassSarcopterygii()
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
—Tetrapoda
—Reptiliomorpha
—Anthracosauria
subclassAmphibiosauriaKuhn 1967
—Cotylosauria()
—Amniota
subclassSynapsida
—Therapsida()
infraorderCynodontia()
RankNameAuthor
—Mammaliamorpha
—Mammaliaformes
classMammalia
—Cladotheria
—Zatheria
subclassTribosphenida()
subclassTheria
—Eutheria()
—Placentalia
—Boreoeutheria
—Laurasiatheria
—Scrotifera
—Euungulata
—Panperissodactyla
superorderPerissodactylamorpha
orderPerissodactyla()
superfamilyEquoidea
familyEquidae
genusEohippus
speciesangustidens()

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.

†Eohippus angustidens Cope 1875
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Invalid names: Eohippus validus Marsh 1876 [synonym], Hyracotherium cuspidatum Cope 1875 [synonym], Hyracotherium seekinsi Morris 1968 [synonym]
Diagnosis
ReferenceDiagnosis
D. J. Froehlich 2002This taxon has no identified unambiguous autapomorphies in this analysis. It is diagnosed by the following characters of the clade that contains this taxon and all more-derived equids: basicranial foramina completely confluent (Character 12, 1 to 2), and upper molar parastyle moderate (Character 38, 0 to 1). The taxon lacks an upper molar ectoloph slightly W-shaped (Character 48, 0 to 1) and lower molar convergence angle <20° (Character 94, 1 to 2), the synapomorphies of the next more-derived equid clade.
Measurements
No measurements are available
Composition: phosphaticsubp
Environment: terrestrialsubc
Locomotion: actively mobilec
Life habit: ground dwellingf
Diet: browserf
Reproduction: viviparoussubc
Created: 2005-06-08 10:11:09
Modified: 2005-08-31 16:55:50
Source: f = family, subc = subclass, c = class, subp = subphylum
References: Ji et al. 2002, Carroll 1988, Lillegraven 1979, Hendy et al. 2009, Nowak 1991

Age range: Wasatchian or 55.80000 to 50.30000 Ma

Collections (5 total)


Time interval Ma Country or state Original ID and collection number
Wasatchian55.8 - 50.3Mexico (Baja California) Eohippus angustidens, Hyracotherium sp. (15671)
Wasatchian55.8 - 50.3USA (New Mexico) Hipposyus sp. (15430) Hyracotherium vasacciense (15663)
Wasatchian55.8 - 50.3USA (Colorado) Eohippus angustidens (15655) Hyracotherium vasacciense (15652)