NEW FOSSIL ORYCTEROPODIDAE (MAMMALIA, TUBULIDENTATA) FROM EAST AFRICA. ORYCTEROPUS MINUTUS SP. NOV. AND ORYCTEROPUS CHEMELDOI SP. NOV.

by

MARTIN PICKFORD (Queen Mary College,University of London)

SUMMARY Two new species of Orycteropusare described from Miocene deposits of Kenya. O. minutus, sp.nov. the smallest known orycteropodid is recorded from the lower Miocene of Songhor, Rusinga and Mfwangano. O. chemeldoisp.nov. is known from the mid-Miocene of Ngorora and Fort Ternan. Additional material of O. africanus (MacInnes) is described and parts of three specimens of O. afercrassidens (MacInnes) are described from the lower Pleistocene of East Rudolf. A review of fossil Orycteropodidae is given, and maps and diagrams presented which show all the recorded localities which have yielded Orycteropus.The Eurasian species are considered to form a closely related group which lived there from about 9 million until about 5 million years ago, in which case they may represent a good key group for stratigraphic purposes.

INTRODUCTION

Recent geological work in East Africa has resulted in the discovery of many fossiliferous sedimentary deposits ranging in age from lower Miocene to Pleistocene. Among these deposits have been recovered a series of fossils belonging to the family Orycteropodidae which form the basis of this report. Two new species, one from the lower Miocene and one from the Mid-Miocene deposits of the East African Rift System are described, and other indeterminate specimens are men- tioned. Additional material of well established species is included. A review of fossil Orycteropodidae is presented.

HISTORICAL REVIEW

The taxonomic history of the antbear or aardvark is one of progressive isolation. It began its classificatory journey as a new species of the genus Myrmecophaga in 1766, but since then has been separated generically, then as a family, then subordinally, ordinally in the Superorder 58

Edentata, and finally as an independant order, the Tubulidentata (after SIMPSON, 1945). The antbear was first scientifically described by PALLAS (1766) who referred it to the genus Myrmecophaga as the new species M. afra Pallas. In 1795, GEOFFROY realised that it was gen- erically different from the Central and South American anteater, but kept it within the same family calling it Orycteropus Geoffroy. There it remained until 1821, when GRAY erected a new family Orycteropidae for the genus. This was changed to Orycteropodidae in 1852 by BONAPARTE, but it was still grouped with the other families containing the sloths, armodillos and pangolins until 1872 when HUXLEY erected the separate order Tubulidentata. This view was not generally ac- cepted until about 1926/27 after the publication of SONNTAG, WooL- LARD & LE GROS CLARK (1925-26). The first fossil Orycteropus was described from the upper Miocene of Samos by FORSYTH MAJOR (1888) who called it 0. gaudryi F. Major. He extended its geographic range by announcing the discovery of a tooth of 0. gaudryi in the upper Miocene of Maragha in Iran. The following year FILHOL (1894) described a fossil humerus from the Phosphorites de Quercy ascribing it to the new genus Palaeorycteropus. In 1895, FILHOL described sub-fossil remains from Madagascar and erected the new genus Plesiorycteropus Filhol. In 1896 ANDREWS described a complete skull of Orycteropus gaudryi from the island of Samos. In 1925-26, SONNTAG et al. published a monograph on Orycteropus afer. In 1933, COLBERT increased the ge- ographic range of the genus Orycteropus with his descriptions of fossils from the Siwalik deposits of the Indian Subcontinent. He erected two new species 0. browni and 0. pilgrimi on fragmentary fossils. The same year HELBING (1933) described a complete Orycteropus skull from Perpignan and concluded that it belonged to a new species 0. depereti Helbing. In 1938, LEwis described a complete skull from the Dhok Pathan Formation of the Swalik Series, referring it to 0. pilgrimi Colbert. In 1942, LAMBERTON published a monograph on the Madagascan subfossil remains of Plesiogcteropus madagascariensis Filhol. In 1956, MACINNEs described relatively complete remains of a small oryctero- podid from the Lower Miocene of Rusinga and Mfwangano in Kenya. He erected a new genus Myorycteropus africanus MacInnes, and in the same publication erected a new species Orycteropus crissidens MacInnes on associated skeletal parts of a Lower Pleistocene fossil from Rusinga. In 1959, ARAMBOURG described the new species 0. mauritanicus Aram- bourg, from the Mid-Miocene of Oued el Hammam in Algeria. In recent years numerous minor references to Orycteropus have ap- peared in the literature, reports which increase our knowledge of the