Leptotragulus medius was named by Peterson (1919). Its type specimen is CM 2986, a partial skeleton (fragmentary skull and portion of mandible with M3 present; fragments of femur; distal end of calcaneum and astragalus), and it is a 3D body fossil. Its type locality is Myton Pocket, which is in an Uintan terrestrial horizon in the Uinta Formation of Utah.