The Chalicotheriidae (Mammalia, Perissodactyla) from the upper Miocene Nakali Formation, Kenya.

Two upper molars of the Chalicotheriidae (Mammalia, Perissodactyla) from the upper Miocene (ca. 10 Ma) Nakali Formation of Nakali, central Kenya, are described. One is identified as M2. The other is very fragmentary and is tentatively referred to the same species as the M2. The M2 specimen is assigned to the subfamily Schizotheriinae in having a crown longer than wide and higher than that of the Chalicotheriinae. It is morphologically similar to upper molars of late Miocene and Plio-Pleistocene species of the Schizotheriinae such as Ancylotherium pentelicum and Ancylotherium hennigi. Metrically, the M2 is within the range of A. pentelicum, resulting an identification as Ancylotherium cf. pentelicum. This result suggests that the fossil record of this genus in Africa dates back to ca. 10 Ma. Previous and present studies suggest that Miocene African Ancylotherium would have been in forest-dominated environments. African and Eurasian fossil records of Ancylotherium suggest that the dispersal of this genus from Eurasia into Africa would have occurred before ca. 10 Ma, although more African fossil records are needed to confirm this. [ABSTRACT FROM AUTHOR]