TUBULIDENTATA, Huxley, 1872

Lehmann, Thomas, Vignaud, Patrick, Likius, Andossa & Brunet, Michel, 2005, A new species of Orycteropodidae (Mammalia, Tubulidentata) in the Mio-Pliocene of northern Chad, Zoological Journal of the Linnean Society 143 (1), pp. 109-131 : 109-110

ORDER TUBULIDENTATA

The order Tubulidentata Huxley, 1872 consists of a single family: the Orycteropodidae Gray, 1821 . Following Patterson (1975, 1978), this family contains two subfamilies ( Orycteropodinae Gray, 1821 ; Plesiorycteropodinae Patterson, 1975) and four genera (three fossil), the affinities and validity of which are still debated ( Pickford, 1975).

The genus Plesiorycteropus Filhol, 1895 , from the Pleistocene of Madagascar, is the single member of the Plesiorycteropodinae. MacPhee (1994) shows evidence that this taxon does not belong to the Tubulidentata but represents a new order: Bibymalagasia . However, other authors continue to refer to the genus as a member of the Tubulidentata ( Milledge, 2003) . It is not the purpose of this paper to debate this issue. Two species of Plesiorycteropus are recognized: Plesiorycteropus madagascariensis Filhol, 1895 and Plesiorycteropus germainepetterae MacPhee, 1994 , both subfossils from different localities on Madagascar.

Among Orycteropodinae , two genera from Kenya have been described: Myorycteropus MacInnes, 1956 from the Lower Miocene and Leptorycteropus Patterson, 1975 from the Upper Miocene. Both are monospecific: Myorycteropus africanus MacInnes, 1956 from Rusinga and Mfwangano, and Leptorycteropus guilielmi Patterson, 1975 from Lothagam.

The fourth genus is Orycteropus Geoffroy, 1791 . The only living species of the order Tubulidentata , Orycteropus afer ( Pallas, 1766) (the aardvark), belongs to this genus. It is a nocturnal animal that burrows relatively deeply in the ground for shelter. The aardvark shows a very low degree of sexual dimorphism, such that zoo specimens are often ‘resexed’ after their death (M. Damen, pers. comm.). Its diet consists of ants, termites and larvae of some insects. The aardvark is easily able to break open termite mounds. From South Africa to sub-Saharan regions, 18 subspecies have been described since 1766 ( Shoshani, Goldman & Thewissen, 1988), but their taxonomic validity is uncertain.

Fossils representing this genus are found from the Lower Miocene until the present. Traditionally, it includes six Eurasian species: O. seni Tekkaya, 1993 from the Middle Miocene of Çandir ( Turkey); O. browni and O. pilgrimi Colbert, 1933 from the Middle and Upper Miocene of Nagri, Dhok Pathan and Chinji ( Pakistan) ( Pickford, 1978); O. pottieri Ozansoy, 1965 from the Vallesian of Sinap ( Turkey) and Pentalophos ( Greece) ( Bonis et al., 1994); Orycteropus gaudryi Major, 1888 from the Turolian of Samos ( Colbert, 1941), Italy ( Rook & Masini, 1994), Turkey ( Sen, 1994), Moldavia ( Pavlova, 1915) and Iran ( Major, 1893); and O. depereti ( Helbing, 1933) from the Pliocene of Perpignan ( France). In Africa, the genus comprises five species: O. minutus Pickford, 1975 from the Lower Miocene of Songhor, Mfwangano, Rusinga ( Kenya); O. chemeldoi Pickford, 1975 from the Middle and Upper Miocene of Ngorora and Fort Ternan ( Kenya); O. mauritanicus Arambourg, 1959 from the Upper Miocene of Bou Hanifia ( Algeria); O. crassidens MacInnes, 1956 from the Pleistocene of Rusinga and Kanjera ( Kenya); and O. afer , the extant and type species, recognized from the Late Pleistocene of Algeria ( Romer, 1938) onwards. Pickford (1975) considers Myorycteropus and Leptorycteropus as synonyms of Orycteropus .

Many Orycteropus fossils have not been attributed to any species in particular. An Orycteropus sp. is present in Lower Miocene deposits from East Africa ( MacInnes, 1956). Other specimens have been discovered in Middle Miocene deposits in Asia, notably in Pakistan ( Pickford, 1978), Georgia ( Gabunia, 1956) and Turkey ( Fortelius, 1990; Tekkaya, 1993; Sen, 1994). Upper Miocene specimens have been excavated in Greece ( Bonis et al., 1994), East Africa ( Patterson, 1975; Milledge, 2003) and South Africa ( Hendey, 1973). Pliocene specimens have been found in East Africa ( Dietrich, 1942; Pickford, 1975; Leakey, 1987) and South Africa ( Kitching, 1963; Lehmann, 2004). Pleistocene specimens are represented throughout Africa ( Leakey, 1931 1951; Clark, 1942; Lehmann, 2004).

The Upper Miocene is the period during which the Tubulidentata show their widest distribution and greatest diversity. Later, in the Pliocene, aardvarks are found mostly in Africa. The Pleistocene is the real beginning of the isolation of the order in Africa.