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Miohippus obliquidens
Taxonomy
Mesohippus obliquidens was named by Osborn (1904). Its type specimen is AMNH 668, a skull (skull and jaws), and it is a 3D body fossil. Its type locality is Middle Oreodon Beds (1892 AMNH Collection), which is in an Orellan terrestrial horizon in the Brule Formation of South Dakota.
It was synonymized subjectively with Mesohippus bairdi by Sinclair (1924); it was recombined as Miohippus obliquidens by Prothero and Shubin (1989) and MacFadden (1998).
It was synonymized subjectively with Mesohippus bairdi by Sinclair (1924); it was recombined as Miohippus obliquidens by Prothero and Shubin (1989) and MacFadden (1998).
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1904 | Mesohippus brachystylus Osborn |
| 1904 | Mesohippus eulophus Osborn |
| 1904 | Mesohippus obliquidens Osborn |
| 1904 | Mesohippus eulophus Osborn p. 173 fig. 5 |
| 1904 | Mesohippus obliquidens Osborn p. 173 figs. fig. 4, Pl. v, C |
| 1904 | Mesohippus meteulophus Osborn p. 174 figs. figs. 1-8, Pl. v. pp. 174-5, Pl. v, D |
| 1904 | Mesohippus brachystylus Osborn p. 175 figs. fig. 6, Pl. v, E |
| 1908 | Mesohippus brachystylus Douglass p. 270 |
| 1908 | Mesohippus brachystylus Lambe |
| 1918 | Mesohippus obliquidens Osborn p. 48 figs. Plates 1.5, 2.7. Text Fig. 28 |
| 1918 | Mesohippus eulophus Osborn p. 49 figs. Plates 1.6, 2.8. Text Fig. 29 |
| 1918 | Miohippus meteulophus Osborn p. 51 figs. Plates 1.7, 3.1. Text Fig. 30 |
| 1918 | Miohippus brachystylus Osborn p. 53 figs. Plates 1.8, 3.2. Text Fig. 31 |
| 1920 | Mesohippus meteulophus Gregory |
| 1930 | Mesohippus meteulophus Hay |
| 1930 | Miohippus brachystylus Hay |
| 1935 | Pediohippus antiquus Schlaikjer p. 141 |
| 1935 | Pediohippus brachystylus Schlaikjer p. 144 |
| 1940 | Mesohippus antiquus Stirton p. 170 |
| 1940 | Mesohippus eulophus Stirton p. 170 |
| 1940 | Mesohippus obliquidens Stirton p. 170 |
| 1940 | Miohippus brachystylus Stirton p. 172 |
| 1940 | Miohippus metulophus Stirton p. 172 |
| 1941 | Mesohippus meteulophus Scott |
| 1941 | Pediohippus brachystylus Scott |
| 1951 | Mesohippus meteulophus Macdonald |
| 1974 | Miohippus antiquus Forsten |
| 1989 | Miohippus obliquidens Prothero and Shubin |
| 1992 | Mesohippus eulophus Macdonald p. 45 |
| 1998 | Miohippus obliquidens MacFadden p. 544 |
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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.
†Miohippus obliquidens Osborn 1904
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Invalid names: Mesohippus brachystylus Osborn 1904 [synonym], Mesohippus eulophus Osborn 1904 [synonym], Mesohippus meteulophus Osborn 1904 [synonym], Pediohippus antiquus Schlaikjer 1935 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| H. F. Osborn 1918 (Miohippus brachystylus) | (Osborn, 1904, 1917) The name refers (1) to the broad rounded para8tyle, readily distinguishable from the flattened angulate parastyle of Mesohippua eulophus, Miohippus meteulophus, and Hypohippus. This species is further distinguished by: (2) p2-4 exceeding ml-3 in length (the reverse Occurs in M. eulophus); (3) broadly .depressed proto- and metalophs; (4) protoloph interrupted, with large oval protocone and distinct protoconule uniting externally with parastyle as in M. bairdii; (5) ectoloph with broad, prominent, rounded parastyle and well defined mesostyle, para- and metacone ribs defined; (6) hypostyle connected with cingulum but giving off a strong outward spur. (7) A vertically broad, shallow lachrymo-malar fossa (as compared with the narrow fossa in M. meteulophus); (8) facial exceeds cranial length. | |
| H. F. Osborn 1918 (Mesohippus eulophus) | (Osborn, 1904) "Distinguished from M. bairdi[i] by (1) deep preorbital [lachrymal] fossa, which is deeper also than in M. hypostylus; (2) large size of m3 ; (3) protoloph with very faint protoconule, and strongly connected with parastyle, constituting a nearly perfect anterior crest; metaloph also continuous; (4) as in M. meteulophus M1-M3 exceed in linear measurement p2-p4; (5) p4 slightly narrower than m1; (6) series of grinding teeth, mLp2, narrowing anteriorly." | |
| H. F. Osborn 1918 (Miohippus meteulophus) | (Osborn, 1904, p. 174) "This species is a successor of M. eulophus,from which it is distinguished (1)by its decidedly more elongate or hypsodont molar crowns, the crests being .002 higher; (2) by its larger size; (3) unlike M. eulophua p4 is broader than m1, a progressive stage towards the equine condition; (4) it accents theM. eulophua char- acter of the heavy but continuous meta- and protolophs which are not distinctly interrupted by conules. In the ectoloph the parastyle, mesostyle, and ribs are sharply-defined but not prominent, in fact, the ectoloph is somewhat flattened. (5) Another feature is that the protoloph is more elongate transversely than the metaloph, causing these crests to be somewhat asymmetrical as in M. latidens."
Additional characters,- (Osborn, 1918) (6) P2-4 of less length than m1- 3, i.e. Pms. | |
| H. F. Osborn 1918 | (Osborn, 1904) "Distinguished from the other species of the Oreodon Beds by (1) large size of skull and teeth as compared with M. bairdii, (2) preorbital Oachrymal] fossa shallow or wanting, (3) but especially by the high crowns of upper and lower molars: ectoloph of m1 measures .0105 vertical as compared with .008 in an unworn m1 crown of M. bairdi[i], (4) metaloph elevated, metaconule not being clearly defined, (5) proto- and metalophs directed obliquely back ward at a sharp angle with ectoloph, to which fact the name M. obliquidens refers." This is one of the horses of relatively larger size from the Upper Oreodon zone, possessing also relatively long-crowned molar grinding teeth. |
Measurements
No measurements are available
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| Source: f = family, subc = subclass, c = class, subp = subphylum | |||||
| References: Nowak 1991, Lillegraven 1979, Carroll 1988, Ji et al. 2002, Hendy et al. 2009 | |||||
Age range: base of the Chadronian to the top of the Monroecreekian or 37.20000 to 24.80000 Ma
Collections (10 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Chadronian | USA (Montana) | Miohippus obliquidens (17041) | |
| Orellan | USA (South Dakota) | Miohippus obliquidens (type locality: 17142) | |
| Orellan | USA (Colorado) | Mesohippus eulophus (17081 17082) | |
| Orellan | USA (Wyoming) | Pediohippus antiquus (17117) | |
| Orellan | USA (Montana) | Miohippus obliquidens (17109) | |
| Whitneyan | USA (South Dakota) | Mesohippus meteulophus (17343) Miohippus obliquidens (17317) | |
| Whitneyan - Monroecreekian | USA (North Dakota) | Miohippus obliquidens (17330) | |
| Arikareean | USA (South Dakota) | Miohippus brachystylus (17520) |