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Cormohipparion sphenodus

Mammalia - Perissodactyla - Equidae

Taxonomy
Hippotherium sphenodus was named by Cope (1889). Its type specimen is AMNH 8281, a tooth (Crown of the second upper premolar, p2 of the right side), and it is a 3D body fossil.

It was recombined as Hipparion sphenodus by Trouessart (1898), Matthew (1899) and Hay (1902); it was recombined as Neohipparion sphenodus by Trouessart (1905); it was recombined as Merychippus sphenodus by Gidley (1907), Matthew (1909), Cope and Matthew (1915), Osborn (1918), Hay (1930), Galbreath (1953) and Woodburne (1996); it was recombined as Merychippus (Merychippus) sphenodus by Stirton (1940); it was considered a nomen dubium by Macdonald (1992); it was recombined as Cormohipparion sphenodus by Woodburne et al. (1981), MacFadden (1984) and MacFadden (1998).

Synonymy list
YearName and author
1889Hippotherium sphenodus Cope p. 449
1898Hipparion sphenodus Trouessart
1899Hipparion sphenodus Matthew
1902Hipparion sphenodus Hay p. 621
1905Neohipparion sphenodus Trouessart
1907Merychippus sphenodus Gidley
1909Merychippus sphenodus Matthew
1915Merychippus sphenodus Cope and Matthew pp. Plate CXLVII
1918Merychippus sphenodus Osborn p. 112 figs. Plates 10.2, 12, 15.1,2,3, 18.4, 43.1, 47.2, 48.3, 53.1. Text Fig. 87
1930Merychippus sphenodus Hay
1940Merychippus (Merychippus) sphenodus Stirton p. 181
1953Merychippus sphenodus Galbreath
1981Cormohipparion sphenodus Woodburne and et al.
1984Cormohipparion sphenodus MacFadden p. 156 figs. 8, 21, 22, 23, 117-120, 124-130, 149,150
1996Merychippus sphenodus Woodburne
1998Cormohipparion sphenodus MacFadden p. 549

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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()
—Mammaliamorpha
RankNameAuthor
—Mammaliaformes
classMammalia
—Cladotheria
—Zatheria
subclassTribosphenida()
subclassTheria
—Eutheria()
—Placentalia
—Boreoeutheria
—Laurasiatheria
—Scrotifera
—Euungulata
—Panperissodactyla
superorderPerissodactylamorpha
orderPerissodactyla()
superfamilyEquoidea
familyEquidae
subfamilyEquinae
tribeHipparionini
genusCormohipparion
speciessphenodus()

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.

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Diagnosis
ReferenceDiagnosis
H. F. Osborn 1918(Osborn, 1918) (1) Type premolars with measurements as cited by Gidley above; (2) crowns of inter- mediate length, hypsodont; (3) protocones relatively narrow, suboval, with a spur tending toward protoloph; (4) enamel plications of protoconule consisting of two double folds in the crochet region; (5) enamel plications of metaloph and of hypostyle region complex.
B. J. MacFadden 1984Same as for genus with the following specific characters: Medium- sized and moderately hypsodont hipparion. Mean TRL 126.48mm. Unworn or little-worn MlMSTHT ca. 30-35mm. DPOF moderately pocketed (ca.5mm or less). Protocones oval and moderately complex. Protostylids moderately developed and sometimes isolated. Pli caballinids moderately developed in premolars and poorly developed in molars. Ectofiexids moderate in premolars and deep in molars. Cormohipparion sphenodus differs from all other horse genera in the generic characters. Cormohipparion sphenodus differs from C. goorisi in increased size and crown height, shallower posterior pocket of the DPOF, more elongated protocone lacking rudimentary anterior spur, slightly more complex enamel plications on fossette borders, shallower ectoflexids and better developed pli caballinids (particularly in premolars), and more expanded metaconids, metastylids, entoconids, and hypoconulids. Cormohipparion sphenodus differs from C. occidentale in being smaller in size and having shorter crown height, less elongated protocones with more rounded borders, significantly simpler enamel plications on fossette borders, and less expanded and angular metaconids, metastylids, entoconids, and hypoconulids.
Measurements
No measurements are available
Composition: phosphaticsubp
Environment: terrestrialsubc
Locomotion: actively mobilec
Life habit: ground dwellingsubf
Diet: grazerg
Diet 2: browserg
Reproduction: viviparoussubc
Created: 2009-01-04 10:23:13
Modified: 2009-01-04 12:58:34
Source: g = genus, subf = subfamily, subc = subclass, c = class, subp = subphylum
References: MacFadden and Cerling 1996, Hendy et al. 2009, Lillegraven 1979, Ji et al. 2002, MacFadden 1998, Carroll 1988

Age range: base of the Barstovian to the top of the Hemingfordian or 16.30000 to 15.97000 Ma

Collections (3 total)


Time interval Ma Country or state Original ID and collection number
Hemingfordian20.43 - 15.97USA (Colorado) Merychippus sphenodus (17908)
Barstovian16.3 - 12.5USA (Florida) Cormohipparion sphenodus (18583)
Barstovian16.3 - 12.5USA (Colorado) Merychippus sphenodus (18203)