A new species of the genusAmphilagus(Lagomorpha, Mammalia) from the Middle Miocene of south-eastern Siberia

Amphilagus tomidai n. sp. is a new species of the genus Amphilagus (Lagomorpha, Mammalia) erected on the fossil materials from the deposits of Aya Cave (Middle Miocene, Aya Bay, mid-western coast of Baikal Lake, south-eastern Siberia), previously identified as Amphilagus cf. fontannesi (Erbajeva MA, Filippov AG. 1997. Miocene small mammalian faunas of the Baikalian region. In: Actes du Congrès BiochroM'97. Aguilar J-P, Legendre C, Michaux J, editors. 21. Mémoires et Travaux de L'Institut de Montpellier, E.P.H.E. p. 249–259). Amphilagustomidai n. sp. is the northernmost Eurasian record of the genus. It differs from the other Asian species of the genus by its larger size and slightly higher crown, by some peculiar advanced features of the upper teeth the evidence of which are: width of teeth became significantly larger with wear stage, hypostria became deeper, flexids on the occlusal surface of teeth covered by deep cement; in P3 both anterior folds filled with cement. The main trend in the evolutionary development of Amphilagus lineage probably is an enlargement of size and crown height, increasing hypsodonty, rather high developing of cement.