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Pliohippus spectans

Mammalia - Perissodactyla - Equidae

Taxonomy
Hippidium spectans was named by Cope (1880). Its type specimen is AMNH 8183, a set of teeth (a left superior molar, M2, and an associated or referred upper premolar, P2), and it is a 3D body fossil.

It was recombined as Hippidion spectans by Trouessart (1892), Trouessart (1898) and Hay (1902); it was recombined as Protohippus spectans by Matthew (1909); it was recombined as Pliohippus (Pliohippus) spectans by Stirton (1940); it was recombined as Dinohippus spectans by Creely et al. (1982), Kelly and Lander (1988), Hulbert (1989), Kelly (1995) and Kelly (1998); it was considered a nomen dubium by Macdonald (1992); it was recombined as Pliohippus spectans by Zittel (1893), Roger (1896), Matthew (1899), Trouessart (1905), Gidley (1907), Merriam and Sinclair (1907), Cope and Matthew (1915), Merriam (1917), Osborn (1918), Merriam et al. (1925), Hay (1930), Quinn (1955), Macdonald (1959), Shotwell (1963) and MacFadden (1998).

Synonymy list
YearName and author
1880Hippidium spectans Cope
1892Hippidion spectans Trouessart
1893Hippidium spectans Cope p. 43
1893Pliohippus spectans Zittel
1896Pliohippus spectans Roger
1898Hippidion spectans Trouessart
1899Pliohippus spectans Matthew
1902Hippidion spectans Hay
1905Pliohippus spectans Trouessart
1907Pliohippus spectans Gidley p. 898
1907Pliohippus spectans Merriam and Sinclair
1909Protohippus spectans Matthew
1915Pliohippus spectans Cope and Matthew pp. Plate CXLVIIIa
1917Pliohippus spectans Merriam p. 428
1918Pliohippus spectans Osborn p. 165 figs. Plate 28.2. Text Fig. 132
1925Pliohippus spectans Merriam et al.
1930Pliohippus spectans Hay
1940Pliohippus (Pliohippus) spectans Stirton p. 192
1955Pliohippus spectans Quinn p. 17
1959Pliohippus spectans Macdonald
1963Pliohippus spectans Shotwell p. 75
1982Dinohippus spectans Creely et al.
1988Dinohippus spectans Kelly and Lander
1989Dinohippus spectans Hulbert, Jr.
1995Dinohippus spectans Kelly p. 14
1998Dinohippus spectans Kelly
1998Pliohippus spectans MacFadden p. 550

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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
tribeEquini
genusPliohippus
speciesspectans()

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(Cope, 1880) (1) Molar teeth of larger size than those of.any of the extinct American horses excepting
Equus excelsus, about equalling those of Hippidium neogceum Lund; (2) crowns very long, slightly curved; (3) roots short; (4) internal columns [protocone, hypocone] relatively small, subequal in size, flattened in outline; (5) fossettes of great transverse width, equal to the anteroposterior diameters; (6) crescents [pa, me, pl, ml] correspondingly narrow; (7) enamel borders of fossettes simple, there being only a few notches on the adjacent faces; (8) one loop [pli caballin] projecting from inner enamel border almost reaching anterior inner column [protocone]; (9) cement abundant; (10) a crochet fold projecting into prefossette.