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Eohippus angustidens
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), MacFadden (1998); it was synonymized subjectively with Hyracotherium index by Wortman (1896), Matthew (1899), Gingerich (1989), Gingerich (1991), 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), Froehlich (2002).
It was recombined as Hyracotherium angustidens by Cope (1877), Cope (1884), Trouessart (1898), Kitts (1956), MacFadden (1998); it was synonymized subjectively with Hyracotherium index by Wortman (1896), Matthew (1899), Gingerich (1989), Gingerich (1991), 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), Froehlich (2002).
Subspecies
Entered
by J. Alroy on 2003-01-23; modified by J. Marcot on 2026-04-17
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1875 | Orohippus angustidens Cope p. 22 |
| 1875 | Orohippus cuspidatus Cope p. 22 |
| 1876 | Eohippus validus Marsh p. 401 |
| 1877 | Hyracotherium angustidens Cope |
| 1877 | Hyracotherium cuspidatum Cope |
| 1878 | Eohippus angustidens King |
| 1878 | Eohippus cuspidatus King |
| 1884 | Hyracotherium angustidens Cope |
| 1884 | Hyracotherium cuspidatum Cope |
| 1898 | Hyracotherium angustidens Trouessart |
| 1902 | Eohippus validus Hay p. 610 |
| 1908 | Eohippus angustidens Granger |
| 1908 | Eohippus validus Granger |
| 1940 | Eohippus angustidens Stirton |
| 1940 | Eohippus validus Stirton |
| 1956 | Hyracotherium angustidens Kitts p. 35 |
| 1968 | Hyracotherium seekinsi Morris |
| 1998 | Hyracotherium angustidens MacFadden p. 542 |
| 1998 | Hyracotherium seekinsi MacFadden p. 542 |
| 1999 | Eohippus angustidens Froehlich |
| 2002 | Eohippus angustidens Froehlich p. 175–176 |
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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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†Hyracotherium angustidens angustidens Cope 1875
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Invalid names: Orotherium cristonense Cope 1877 [synonym]
†Hyracotherium angustidens grangeri Kitts 1956
Invalid names: Eohippus validus Marsh 1876 [synonym], Hyracotherium cuspidatum Cope 1875 [synonym], Hyracotherium seekinsi Morris 1968 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| D. B. Kitts 1956 | Size medium to large ; P3 and P4 triangular in shape with no apparent tendency towards molarization; heel of m3 uaually broad and short; diastema between P1 and P2 shorter than P1; diastema between p1 and p2 shorter than p1; femorotibial index about 110, reduced fifth metatarsal present. | |
| D. J. Froehlich 2002 | This 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
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| Source: f = family, subc = subclass, c = class, subp = subphylum | |||||
| References: Hendy et al. 2009, Ji et al. 2002, Carroll 1988, Lillegraven 1979, Nowak 1991 | |||||
Age range: Wasatchian or 56.00000 to 51.10000 Ma
Collections (5 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Wasatchian | USA (Colorado) | Eohippus angustidens (15655) Hyracotherium vasacciense (15652) | |
| Wasatchian | Mexico (Baja California) | Eohippus angustidens, Hyracotherium sp. (15671) | |
| Wasatchian | USA (New Mexico) | Hipposyus sp. (15430) Hyracotherium vasacciense (15663) |