The most primitive Elasmotherium (Perissodactyla, Rhinocerotidae) from the Late Miocene of northern China

The origin of Elasmotherium has been a puzzle for many years. Herein, we report the earliest representative of Elasmotherium, based on a Late Miocene skull from Dingbian County in Shaanxi, northwestern China. The skull bears a unique mosaic of primitive and derived features different from all hitherto known elasmotheres, henceforth demarcated as holotype of Elasmotherium primigenium sp. nov. Dental characters of E. primigenium are more primitive than any other known species of Elasmotherium, e.g. relatively incipient enamel folding, fairly weak lingual groove on the base of the protocone, relatively weaker crista, small and closed posterior valley and straight ectoloph. E. primigenium is evidently more primitive than all the known species of Elasmotherium, yet appreciably more derived than Sinotherium, thereby marking an important transitional species between Sinotherium and further species of the genus Elasmotherium.