A NEW RHINOCEROS FROM THE LATE MIOCENE OF LOPEROT, TURKANA DISTRICT, KENYA D. A. HOOIJER' CONTENTS Introduction and acknowledgments 339 Skull and dentition of Chilotheridium patter-soni gen. et sp. nov. 342 Chilotlicridiiim from East African sites other than Loperot 358 Postcranial skeleton of Chilotheridium patter-soni gen. et sp. nov. 365 Distinguishing characters of Chilotheriuvi, Chilotheridium, and Dieeratherium 387 Literature Cited 389 Appendix 390 Abstract. Chilotheridium pattersoni, a new genus and species of Rhinocerotidae from the late Miocene, Vindobonian, Turkana Grit Formation of northwestern Kenya, is described and compared with its close relatives Chilotherium and Dieera-therium. The species also occurs at Ngorora. Fragments of Chilotheridium sp. from Bukwa II, Rusinga and Kirimun, of Aceratherium sp. or Dicerorhinus sp. from Kirimun and Ngorora, and of Brachijpotherium sp. from Ngorora are re-corded. Phalanges of a hippopotamid were mingled with tlie rhinoceros remains from the Turkana Grit; these constitute the earliest record of the family. INTRODUCTION AND ACKNOWLEDGMENTS In a paper on Miocene rhinocerose.s of East Africa (Hooijer, 1966), a single last upper molar from the Turkana Grit For-mation near Loperot, Turkana District, Kenya, collected in 1948 and preserved in the National Museum Centre for Prehistory ^ Rijksmuseum van Natuurlijke Historic, Leiden, Netherlands. and Palaeontology in Nairobi, was referred to the genus Chilotherium Ringstrom. To the same genus, and likewise without spe-cific allocation, I referred two incomplete upper molars from Gumba and Wakondu on Rusinga Island. Teeth indistinguishable from those of Chilotherium have since been found at Bukwa II, Uganda (Walker, 1968), and at Ngorora, Kenya (collected by Dr. W. W. Bishop in 1968), early Miocene and early Pliocene, respectively. The Loperot rhinoceros has been cited as Chilotherium sp. by Leakey (1967: 15) and bv Maglio (1969: 2). In the years 1964 and 1965 Professor Bryan Patterson led field parties of the Harvard Museum of Comparative Zoology to the Loperot area, which is at latitude 02° 20' N, and longitude 35° 50^ E, or 50 miles SSE of Lodwar and 45 miles SW of Lake Rudolf. The rhinoceroses collected were generously offered to me for description. The Loperot area has been geologically mapped by Joubert (1966), and three Potassium/Argon dates are available for the lava overlying the fossil-bearing Turkana Grit, 17.5 ± 0.9 m.y. for a sample five feet above the contact \\'ith the Turkana Grit at the rhinoceros quarry, 16.7 ± 0.8 m.y. for a sample approximately 200 feet above the contact with the Tur-kana Grit in the Auwerwer Hills, and 15.8 ± 1.2 m.y. from a basalt boulder in the Turkana Grit at the base of the Auwerwer Bull. Mus. Comp. Zool, 142(3): 339-392, October, 1971 339
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