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Class Mammalia
Order Perissodactyla
Family Equidae


Equidae—Family Equidae // Equidae sp.—Horses // Equus sp. (small)—Small Horse // Equus sp (large)—Large Horse // Equus calobatus—Stilt-legged Onager // Equus conversidens—Mexican Horse // Equus cumminsii—Cummings' Ass // Equus enormis—Enormous Horse // Equus fraternus—Fraternal Horse // Equus giganteus—Giant Horse // Equus occidentalis—Western Horse // Equus pacificus—Pacific Horse // Equus (Plesippus) sp.—American Zebra // Equus (Plesippus) francescana—Francescana Zebra // Equus (Plesippus) simplicidens—American Zebra // Equus Species A—Unidentified Equus // Haringtonhippus francisci—Harington's Stilt-legged Horse

Equus calobatus Troxell 1915—Troxell's Stilt-legged HorseRegional Pleistocene distribution of Equus calobatus

The position of this taxon in relation to E. francisci is unclear. Kurtén and Anderson (1980) cite E. calobatus as the largest of the stilt-legged horses, whereas Haringtonhippus francisci is said to be the smallest of the North American Pleistocene horses assuming Equus tau is a synonym (Dalquest 1979). Winans (1985) considered E. calobatus to be a junior synonym of E. francisci. Vanderhill (1986), in considering Blancan to Irvingtonian specimens from fossil beds revealed by the incision of the Rio Grande Valley, referred material to this taxon, retaining E. calobatus as valid.


Late Blancan: 111 Ranch (Morgan and White 2005: ?); La Union (Morgan and Lucas 2003: ?); Santo Domingo (Morgan and Lucas 2003: ?).

Early Irvingtonian: Adobe Ranch (Morgan and Lucas 2003: cf.).

Irvingtonian: El Paso (UTEP).


Dalquest 1979; Kurtén and Anderson 1980; Morgan and Lucas 2003; Morgan and White 2005; Vanderhill 1986; Winans 1985.


Last Update: 7 Jul 2018