New Evidence on the Equidae from the Late Miocene of As Sahabi (MN13; Libya, North Africa)

As Sahabi is a celebrated Libyan late Miocene vertebrate locality. The discovery of the site was made by Rome palaeontologist, Carlo Petrocchi, in the first half of the 20th century. The excavations and expeditions in the area have recovered over than 5500 fossil vertebrates from 94 vertebrate localities of the Late Miocene age (MN13; Boaz et al., 2008a). Among the Equidae, the latest report (Bernor et al., 2008) suggested the occurrence of four species of Hipparion: Sivahippus sp., Eurygnathohippus feibeli, Cremohipparion matthewi and Cremohipparion periafricanum (Bernor et al., 2008; Bernor et al., 2012). A recent study on the complete fossil collection housed in Laboratory of Evolutionary Biology, Howard University, Washington D.C. (USA) carried out a revised taxonomic identification of the fossil specimens, confirming and sharing new insights on the Sahabi Hipparion assemblage. A statistical analysis has verified that the large form is best referred to Sivalhippus sp., comparing most closely to Sivalhippus perimensis (Potwar Plateau, Pakstan) and Sivalhippus turkanensis (Lothagam, Kenya). The evidence of this last species supports the biogeographic connection between Sahabi and East Africa, as proposed by Bernor et al. (2012). Most of the sample has been identified as being referable to Eurygnathohippus feibeli, a medium size form represented by several dental and postcranial features on the fossil specimens: ectostylids occasionally on the lower cheek teeth accompanied by more common pli caballinid and the medium size of the postcranial specimens. A smaller species in the sample has been identified as best referable to Cremohipparion matthewi: the small, gracile morphology of several metapodials and other postcranial specimens confirm the presence of this species supported by a few isolated upper and lower teeth. Bernor et al. (2008) identified a few tiny Hipparion specimens as being referable to Cremohipparion periafricanum, suggesting a correlation between Sahabi and other Mediterranean latest Miocene localities, in particular Tizi N’Tadderht, Morocco (Cirilli et al., in review). These new data on the Sahabi Hipparion assemblage confirm the paleobiogeography linkage of Sahabi between the East Africa Lothagam (Kenya) and Middle Awash (Ethiopia), and the Mediterranean Late Miocene localities, replaced that Sahabi represent a true crossroads fauna between Europe and Africa.