内蒙古阿拉善左旗克克阿木中渐新世早期哺乳动物化石的发现

本文简要报道了在内蒙古阿左旗克克阿木地点发现的哺乳动物化石,计4目10科11属12种.动物群的时代可能为中渐新世早期.

DISCOVERY OF EARLY MEDIAL OLIGOCENE MAMMALIAN FAUNA FROM KEKEAMU, ALXA LEFT BANNER, NEI MONGOL.

Kekeamu, a small branch of Ulantatal valley, is situated about 40 Km. north of Bayan Hot, the centre of the Alxa Left Banner, Nei Mongol (105°34′10″east longitude and 39°11′45″north latitude). Tertiary beds consisting of the upper Miocene Huhehaolai Formation and the lower red beds of Oligocene are exposed on the cliffs along Kekeamu gully. In 1988 and 1989 a joint team of Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica, and Hydrological Unit, Lanzhou Military Area, PLA, worked there twice. As a result, a small fauna of early medial Oligocene mammals was discovered in the lower red beds in the Kekeamu area, which is equivalent to the basal part of Ulantatal Formation. The Kekeamu fauna includes 11 genera 12 species representing 10 families of 4 Orders. The list is as follows: Insectivora Cylindrodontidae Erinaceidae Ardynomys sp. ? Tupaiodon sp. Aplodontidae Lagomorpha Prosciurus sp. Ochotonidae Cricetidae Desmatolagus sp. Eucricetodon spp. Perissodactyla Cricetidae gen. et sp. nov. Chalicotheriidae Zapodidae Schizotherium cf. avitum Heosminthus sp. Hyracodontidae Ctenodactylidae Ardynia cf. mongoliensis Karakoromys cf. decessus Rodentia ? Ctenodactyloidea gen. et sp. nov According to the above listed forms the Kekeamu fauna seems to be of media1 Oligocene. In comparison with other medial Oligocene faunas known in Asia, such as Hsanda Gol, Wulanbulage, Ulantatal and Saint Jacques faunas the Kekeamu fauna shows the following features: 1. the Kekeamu fauna includes the genus Heosminthus which is so far only recorded from lower Oligocene in Yunnan. In all the known medial Oligocene faunas Heosminthus has never been found. Instead, an advanced genus Parasminthus appeared there. 2. Kekeamu has a good number of Karakoromys. teeth, but lacks Tataromys, which is abundant in the typical medial Oligocene fauna so far known. Karakoromys is possibly more primitive than Tataromys, made its first appearance earlier than Tataromys and was replaced by the later genus gradually. 3. There are Schizotherium of. avitum and Ardynia of. mongoliensis similar to early Oligocene forms. All these features show that the Kekeamu fauna may be a little older than those medial Oligocene faunas mentioned above. In other words the Kekeamu fauna may be of early medial Oligocene.