- Onager altidens was named by Quinn (1957) [several specimens listed as type, "all believed to belong to one individual, approximately three years old."]. Its type specimen is BEG 31186-3, -4, -7, -10, -24, -34, -35, -36, -37, a partial skeleton (Right maxillary, with worn D.P. 2-4, unerupted P.2-4, M.1-2 (B.E.G. no. 31186-35); right and left lower jaws with l.l, D.l.2, D.P.2-4, M.1-2, P.2-4 un- erupted ), and it is a 3D body fossil.
It was synonymized subjectively with Equus hemionus by Kurten and Anderson (1980); it was synonymized subjectively with Equus francisci by Winans (1989); it was synonymized subjectively with Equus pseudaltidens by Hulbert (1995).