THE MID-TERTIARY CTENODACTYLIDAE (RODENTIA, MAMMALIA) OF EASTERN AND CENTRAL ASIA

The mid-Tertiary Ctenodactylidae, a profusely ramified rodent of easte rn and central Asia, is thoroughly revised based on collections from t he Hsanda Gol Formation made in the 1920s by the Third Asiatic Expedit ion of the American Museum of Natural History, as well as on relativel y recently collected material from China. Leptotataromys, Muratkhanomy s, and Roborovskia are all synonyms of Tataromys. The species formerly referred to Tataromys are divided into four genera: Tataromys, Yindir temys, Bounomys, and Euryodontomys, new genus. Thus Tataromys in elude s only four species: T. plicidens, T. sigmodon, T. minor, and T. parvu s, new species. Some species referred to Tataromys [T. grangeri, T. de flexus, T. suni, T. gobiensis, T. cf. T. plicidens, T. cf. T. sigmodon of Bohlin (1946) and Zhai (1978), T. cf T. grangeri, and some Tatarom ys species] are assigned to Yindirtemys. T. bohlini (partim) and T. ul antatalensis are allotted to Bounomys. T. cf. T. sigmodon and T. bohli ni (partim) of Huang (1985) belong to a new genus, Euryodontomys. The mid-Tertiary Ctenodactylidae of Asia falls into four lineages, here co nsidered as four sub-families. Tataromyinae includes Tataromys, Yindir temys, and Bounomys; Karakoromys is considered not only a valid genus, but also the representative of a subfamily, Karakoromyinae, which is composed of Karakoromys and Euryodontomys; Ctenodactylinae includes Sa yimys, some other fossil genera from the Neogene and Pleistocene, and the living ctenodactylids. This subfamily is thought to be more closel y related to the Karakoromyinae than to the Tataromyinae. The family D istylomyidae is here reduced to subfamily rank, Distylomyinae, the sis ter group of the Ctenodactylinae. Among the four subfamilies, the Tata romyinae, which abruptly flourished during the mid-Tertiary, became ex tinct by the end of the middle Miocene. On the other hand, the Ctenoda ctylinae survived and migrated into southern Asia, the Mediterranean a rea, and North Africa. Now they still survive and live only in North a nd East Africa. Evolution, radiation, migration, and extinction of the Ctenodactylidae are discussed. The main influential factors are inter preted to be climatic and topographic changes within the Palearctic Re gion from Eocene through Miocene times.