Mammalia - Perissodactyla - Equidae

Alternative combinations: Merychippus placidus, Protohippus placidus

Synonyms: Calippus optimus Quinn 1955, Pseudhipparion optimum Quinn 1955

Belongs to Calippus according to M. R. Voorhies 1990

Sister taxa: Calippus castilli, Calippus cerasinus, Calippus circulus, Calippus elachistus, Calippus hondurensis, Calippus maccartyi, Calippus martini, Calippus proplacidus, Calippus regulus

Average measurements (in mm): P3 17.0 x 17.9, P4 17.0 x 17.9, M1 16.1 x 16.0, p3 17.4 x 9.6, p4 17.4 x 9.6, m1 16.5 x 8.7