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Pseudhipparion gratum

Mammalia - Perissodactyla - Equidae

Taxonomy
Hipparion gratum was named by Leidy (1869) [also said to be 1868]. Its type specimen is USNM 587, a set of teeth (A right upper premolar, p2, associated with two others, ?m2 and m3), and it is a 3D body fossil.

It was recombined as Hippotherium gratum by Lydekker (1882) and Cope (1889); it was synonymized subjectively with Protohippus placidus by Leidy (1885), Cope (1893) and Matthew (1899); it was synonymized subjectively with Hipparion ingenuum by Leidy (1889), Leidy (1892) and Roger (1896); it was recombined as Neohipparion gratum by Gidley (1906), Gidley (1907), Matthew (1909), Hay (1917), Hay (1930) and Hibbard (1941); it was recombined as Nannippus gratus by McGrew (1936), Johnston (1938), Stirton (1940), Gregory (1942), Lance (1950), Macdonald (1960) and Dalquest and Hughes (1966); it was recombined as Griphippus gratus by Quinn (1955) and Skinner (1972); it was considered a nomen dubium by Macdonald (1992); it was recombined as Pseudhipparion gratum by Webb (1969), Webb and Hulbert (1986), Kelly and Lander (1988), Voorhies (1990), Dalquest et al. (1996) and MacFadden (1998).

Synonyms
Synonymy list
YearName and author
1869Hipparion gratum Leidy
1882Hippotherium gratum Lydekker
1889Hippotherium gratum Cope p. 445
1906Neohipparion gratum Gidley
1906Neohipparion niobrarense Gidley
1907Neohipparion gratum Gidley p. 888
1907Neohipparion niobrarense Gidley p. 927
1909Neohipparion gratum Matthew
1917Neohipparion gratum Hay
1918Protohippus niobrariensis Osborn p. 136 figs. Plate 21.2. Text Fig. 108
1918Hipparion gratum Osborn p. 179 figs. Plate 32.3. Text Figs. 142, 143.
1930Neohipparion gratum Hay
1930Protohippus niobrariensis Hay
1936Nannippus gratus McGrew
1938Nannippus gratus Johnston p. 246
1938Nannippus niobrarensis McGrew and Meade p. 201
1940Nannippus gratus Stirton p. 186
1940Nannippus niobrarensis Stirton p. 186
1941Neohipparion gratum Hibbard
1942Nannippus gratus Gregory
1950Nannippus gratus Lance
1955Griphippus gratus Quinn p. 42
1960Nannippus gratus Macdonald
1966Nannippus gratus Dalquest and Hughes
1969Pseudhipparion gratum Webb
1972Griphippus gratus Skinner p. 117
1986Pseudhipparion gratum Webb and Hulbert, Jr.
1988Pseudhipparion gratum Kelly and Lander
1990Pseudhipparion gratum Voorhies
1996Pseudhipparion gratum Dalquest et al.
1998Pseudhipparion gratum MacFadden p. 548

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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
tribeHipparionini
genusPseudhipparionAmeghino 1904
speciesgratum(Leidy 1869)

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(Leidy, 1869) (1) Second superior (fig. 25, pl. XVIII) closely resembles that of
Protokippua placidua in size, form, and proportions; (2) fossettes less gaping than in P. placidua; (3) enamel more plicate. Type and neotype. (Gidley, 1907) (4) Protocone usually small, elliptical in cross section, separate from protoconule to base of crown; (5) anterior border of prefossette plicated in the premolars, a character not in Protokippua. (6) Lachrymal and malar fossre moderately deep, limited in area; (7) anterior palatal foramina opening backward into long, narrow slits, as in the modem horse; (8) palate strongly concave, especially anteriorly; (9) nasals short-tipped, but very · broad where they join the premaxillaries; (10)-lower jaws short and deep as in P. placidua, but symphysis long and exten- sion beyond premolars comparatively shorter; (11) angle of jaw proportionately smaller, lower border of ramus more curved and bowed.
H. F. Osborn 1918 (Protohippus niobrariensis)(Gidley, 1906, p. 152, 1907, p. 927) Gidley separates this species from Hipparion (Neohipparion) gratum as follows: (1) The skull, especially in the nasal and premaxillary region, is longer and narrower; (2) the palate is narrow and more arched; (3) the anterior palatine foramina are more open but do not extend as far backward as in H. gratum; the posterior palatal notch apparently extends as far forward as the middle of m1; (4) the malar fossa is wanting; (5) the lachrymal fossa is lll.l"ger, extends farther backward, and has a rather sharply defined posterior border; (6) the symphysis of the lower jaw is longer and narrower than in H. gratum but is not so extreme in proportions as in H. dolichops; and (7) the ramus is bowed as in H. gratum but has a less vertical depth.