The Middle Pleistocene mammalian fauna from Tam Hang karstic deposit, northern Laos: New data and evolutionary hypothesis

New fossil material was recovered at Tam Hang during the second fieldwork season conducted in 2007, by a Lao-French-American team. The Tam Hang site is located in northern Laos, in the Hua Pan province, about 260 km from Vientiane. The breccias of the Tam Hang South locality produced 404 new fossil specimens which complete the previous material recovered in 2003. The fossiliferous deposits are described geologically. In terms of palaeontology, the mammalian fauna is essentially composed of isolated teeth of middle- to large-sized mammals (Artiodactyla, Perissodactyla, Proboscidea, Carnivora, Rodentia, Primates). The overall fauna is compared to the six well-documented Middle to Late Pleistocene faunas from the Indochinese province (Yenchingkuo, Phnom Loang, Thum Wiman Nakin, Lang Trang, Duoi U’Oi, Ma U’Oi). On the basis of the faunal composition and evolutionary stages of the species, a biochronological framework at the transition between the Middle Pleistocene and the Late Pleistocene is proposed.