J. Zool., Lond. zyxwvuts (1976) zyxwvu 178, 57-75 Cranial and dental remains of Deinotherium bozasi (Mammalia zyx : Proboscidea) from East Rudolf, Kenya JOHN M. HARRIS Department zyxwvu of Palaeontologq,, National Museum of Kenya, Nairobi, E. Ajrica (Accepted 13 May 1975) (With 2 plates in the text) A skull, three immature mandibles and a number of isolated teeth belonging to Deinotherium bozasi have been collected from Plio-Pleistocene sediments to the east of Lake Rudolf, Kenya. D. zyxwvutsrq bozasi is the youngest representative of the family Deinotheriidae and the skull is the most complete yet found of this taxon. The East Rudolf specimens are contrasted with comparable specimens of Prodeinotherium hobleyi from East and North Africa and of Deinotherium giganteum from Europe. The size and morphology of the cranial vault of the East Rudolf skull confirms allocation to the genus Deinotherium but other dental and cranial evidence confirms taxonomic differentiation from D. giganteum and direct descent from P. hobleyi. Although the postcranial elements of D. bozasi are poorly known it is considered unlikely that this species developed the cursorial adaptations of D. giganteum. The extinction of D. bozasi is attributable to major changes in ecologic conditions towards the end of the early Pleistocene. Contents . . . . Introduction.. . . . . . . . . African Plio-Pleistocene Deinotheres . . .... Genus Deinotherium Kaup 1829 . . . . . . Deinotherium bozasi Arambourg zyxwvu 1934 .... Deinofherium bozasi from East Rudolf . . . . . . Skull . . . . . . . . . . . . . . Mandible . . . . . . . . . . .. Dentition .... . . . . . . . . Discussion . . . . . . . . . . .... Summary . . . . . . .... .... References . . . . . . . . . . . . .. *. .. .. .. .. .. .. .. .. .. b .... .... .... .... .... .. .. .... .. .. .. .. .... .... Page .. 57 . . zyx 58 .. 58 . . 59 . . 60 . . 60 . . 66 . . 69 .. 72 .. 14 .. 74 Introduction From 1968 the Plio-Pleistocene sediments on the northeast shore of Lake Rudolf, a region colloquially known as East Rudolf, have been a major source of important new specimens and information concerning African Plio-Pleistocene faunas and hominid evolution (Coppens, Howell & Isaac, in press). Representatives of the family Deino- theriidae have been collected from the lower portions of the East Rudolf sedimentary sequence, ranging in age from about 4.5 to 1.5 my. Deinotheres are less common at East Rudolf than other proboscideans, less than a score of specimens having been collected, but the remains include the youngest skull yet collected (1.5-2.6 my) which provides important information about the cranial anatomy of the last representatives of this extremely specialized and enigmatic family. 51