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Merychippus (Protohippus)

Mammalia - Perissodactyla - Equidae

Synonyms
Synonymy list
YearName and author
1858Equus (Protohippus) Leidy p. 26
1869Protohippus Leidy
1881Protohippus Cope p. 399
1892Protohippus medius Cope p. 944
1893Protohippus medius Cope p. 25
1907Protohippus Gidley p. 867
1907Protohippus medius Merriam and Sinclair
1920Protohippus medius Matthew
1940Merychippus (Protohippus) Stirton p. 181
1955Protohippus Quinn p. 13
1955Eoequus Quinn p. 54
1988Protohippus Carroll
1988Protohippus Hulbert, Jr. p. 281
1989Protohippus Prothero and Schoch p. 532
1995Protohippus Kelly p. 25
1996Protohippus Prado and Alberdi p. 676
1998Protohippus MacFadden p. 549
1998Protohippus MacFadden and Dobie
2006Protohippus Hulbert and Whitmore p. 17

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
OlfactoresJefferies 1991
subphylumVertebrata
Gnathostomata()
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
subfamilyEquinaeSteinmann and Döderlein 1890
genusMerychippus
subgenusProtohippus()

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
R. C. Hulbert 1988Medium- to large-sized, hypsodont, tridactyl equids with toothrow lengths generally between 125 and 145 mm in mature individuals. Malar fossa absent. DPOF large, teardrop-shaped, relatively shallow; distinctly rimmed dorsally and posteriorly in earlier populations, often with a small posterior pocket; less distinct in later populations, without a pocket. Lacrimal bone large, included in posterior region of DPOF. Diastema short; rostrum broad, but not to the degree of advanced species of Calippus; incisors form typical equine rounded arcade. Upper cheekteeth with large, elongate-oval protocones that are isolated from the protoselene to varying degrees during early wear-stages (most prevalent on P34 and M3); moderately large, single pli caballins on P34 (smaller and less persistent with wear on molars); simple but relatively persistent fossette plications; hypoconal groove generally remains open until at least middle wear; prominent parastyles on P34. Large protostylids on permanent and deciduous lower cheekteeth. Variably developed ectostylids on dp2-dp4.