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Miohippus gidleyi

Mammalia - Perissodactyla - Equidae

Taxonomy
Mesohippus gidleyi was named by Osborn (1904). Its type specimen is AMNH 1192, a partial skeleton (partly broken skull of young individual, with complete unworn grinding teeth, cervical vertebrre associated), and it is a 3D body fossil. Its type locality is Indian Stronghold (Protoceras Channel), which is in a Whitneyan fluvial sandstone in the Brule Formation of South Dakota.

It was recombined as Pediohippus gidleyi by Schlaikjer (1935) and Scott (1941); it was recombined as Miohippus gidleyi by Matthew (1909), Osborn (1918), Hay (1930), Stirton (1940), Prothero and Shubin (1989) and MacFadden (1998).

Synonyms
Synonymy list
YearName and author
1894Mesohippus validus Osborn
1904Mesohippus gidleyi Osborn
1909Miohippus gidleyi Matthew
1909Miohippus validus Matthew
1918Miohippus validus Osborn p. 55 figs. Plates. 1.4, 3.5. Text Fig. 33
1918Miohippus gidleyi Osborn p. 56 figs. Plates 1.10, 3.4, 39.16,19, 51.8,12. Text Fig. 34
1925Mesohippus grallipes Sinclair p. 61
1930Miohippus gidleyi Hay
1933Miohippus validus Stock
1935Pediohippus gidleyi Schlaikjer p. 145
1940Miohippus gidleyi Stirton p. 172
1940Miohippus validus Stirton p. 172
1941Miohippus validus Scott
1941Pediohippus gidleyi Scott
1951Miohippus validus Macdonald
1989Miohippus gidleyi Prothero and Shubin
1998Miohippus gidleyi MacFadden p. 544

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
Cotylosauria()
Amniota
Synapsida()
Therapsida()
RankNameAuthor
infraorderCynodontia()
Epicynodontia
infraorderEucynodontia
Probainognathia
Mammaliamorpha
Mammaliaformes
classMammalia
subclassTribosphenida()
infraclassEutheria()
Placentalia
orderPerissodactyla()
suborderLophodontomorpha
infraorderEuperissodactyla
Hippomorpha
superfamilyEquoidea
familyEquidae
subfamilyAnchitheriinae()
genusMiohippus
speciesgidleyi()

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.

Diagnosis
ReferenceDiagnosis
H. F. Osborn 1918 (Osborn, 1904, p. 178, 1918) (1) An animal of somewhat larger size than the type of Miohippus inter-
mediWJ, which, however, it resembles in the presence of (2) a vertically deep lachrymo-malar fossa, and (3) in the sharpness of the metaloph crest of the molars. It is more primitive than Jf. intermediWJ in (4) the somewhat larger size
of p1• (5) Hypostyle and transverse crest still connected with posterior cingulum, a distinct pli hypostyle; (6) internal cingulum persisting, especially evident on the premolars; (7) ectoloph more elevated than metaloph. Other special characters which appear to be distinctive are (8) the crenulation of the enamel surface of the premolars, and (9) a rudi- mentary spur or crochet, pli crochet, on the metaloph of p3, m2 ; (10) external cingulum tending to cross base of parastyle; (11) protoloph longer than metaloph in the premolars.
H. F. Osborn 1918 (Miohippus validus)(Osborn, 1904, p. 177, 1917) PH apparently less than molars m1- 3 in length; (2) ectoloph elevated, height .013; (3) parastyle broad, paracone and metacone ribs distinct; (4) metaloph short or else separated from ecto- loph; (5) protoloph interrupted, protocone indented; (6) the hypostyle < shaped or triangular, connected with cingulum and with a strong outward spur. (7) Lachrymo-malar fossa relatively deep and vertically broad, subdivided by a low median ridge into anterior and posterior depressions; (8) cranial exceeds facial length. As compared with Mesohippus bairdii this animal is a relatively large horse, standing not less than twenty-eight inches at the withers.