Eocene Perissodactyla from the Shinzhaly River, eastern Kazakhstan

A fossil mammal locality on the eastern bank of the Shinzhaly River, eastern Kazakhstan, is a bone bed in the Kolpak Formation that has produced three taxa of ceratomorph perissodactyls, the hyracodontid Forstercooperia minuta Lucas, Schoch, and Manning, the deperetellid Teleolophus beliajevae Biryukov (which we consider to be a junior subjective synonym of T. medius Matthew and Granger and the lophialetid Eoletes gracilis Biryukov. Eoletes is dentally indistinguishable from Lophialetes, but cranial features, especially the shallow nasal incision (only to above the upper canine) and large supraorbital bar of Eoletes, allow the two genera to be distinguished. Simplaletes Qi is a junior subjective synonym of Schlosseria Matthew and Granger, and we reassign Simplaletes xianensis Zhang and Qi, from the middle Eocene? of Shaanxi, China to Eoletes as E. xianensis. A re-evaluation of some character states used in a previous cladistic analysis suggests that Eoletes, Lophialetes, and Schlosseria form an unresolved trichtomy, so we recommend abandonment of the term Eoletidae Schoch. Because Eoletes and Lophialetes are impossible to distinguish solely on the basis of teeth, Eoletes may be represented by some Mongolian and Chinese dentitions referred customarily to Lophialetes but that lack associated diagnostic cranial material. This possibility, and the presence of F. minuta and T. medius at Shinzhaly, support the middle Eocene (Irdinmanhan) age of the Kolpak Formation bone bed.