Les Rhinocerotidae (Mammalia, Perissodactyla) miocènes et pliocènes des Tugen Hills (Kénya)

More than 70 determinable and usable rhinoceros remains belonging to nine species were yielded by 26 Miocene and Pliocene sites from the Tugen Hills (Kenya), namely Cheboit, Kapsomin, Kipsaraman and Tabarin. Such a material allows a better knowledge of the anatomy of these species. It is now possible to distinguish the postcranial skeleton of Aceratherium acutirostratum from that of Dicerorhinus leakeyi . The cranial and dental anatomy of Paradiceros mukirii is better known. The temporal extension of Chilotheridium pattersoni and Paradiceros mukirii are increased. Ceratotherium praecox is the most frequent rhino from the Uppermost Miocene onwards. Diceros bicornis is known since 6 My, about at the same time the first C. praecox. Diceros cf. pachygnathus is identified in the Lukeino and Mabaget Formations, and the geographical extension of this group of species is much increased. The Hominid Orrorin tugenensis is associated with rhinoceroses in four sites of the Lukeino Formation; Ceratotherium praecox is present in three of them, alone in Kapcheberek, associated one time (Tabarin) with D. bicornis and in another one (Cheboit) with Brachypotherium lewisi ; at Aragai the sole rhino is Diceros cf. pachygnathus . All these rhinos contribute to assign to Orrorin a variable but mostly open and rather wet palaeoenvironment.