The holotype of Equus conversidens, a partial palate, was unearthed in Pleistocene deposits northeast of Mexico City, Mexico. In January 1963, a partial skeleton was found in the city of Canyon, Texas in a white clay bed during the excavation of a basement, and was referred to E. conversidens by Dalquest and Hughes (1965), who interpreted the species as medium to small-sized, and added additional records of the species from Texas (including a skeleton from Slaton), Arizona, New Mexico, Oklahoma, Kansas and Florida, synonymizing Equus francisci, Equus tau, E. littoralis, E. achates, and E. barcenaei with E. conversidens.[1] However, Winans (1985) and MacFadden (1992) challenged the validity of E. conversidens due to its minimal diagnostic value, and treated E. francisci as valid.[2][3] Subsequent study confirmed the nomen dubium status of E. conversidens because the holotype was undiagnostic besides its small size.[4]
↑Winans, M.C. 1985. Revision of North American fossil species of the genus Equus (Mammalia:Perissodactyla:Equidae). Unpublished PhD dissertation. Austin: University ofTexas, Austin, Texas. 264 pp.
↑MacFadden, B.J. 1992. Fossil horses: systematics, paleobiology, and evolution of the family Equidae. Cambridge: Cambridge University Press. 369 p.
↑Heintzman, Peter D; Zazula, Grant D; MacPhee, Ross DE; Scott, Eric; Cahill, James A; McHorse, Brianna K; Kapp, Joshua D; et al. (2017). "A new genus of horse from Pleistocene North America". eLife. 6. doi:10.7554/eLife.29944 .
