甘肃广河地区中中新世哺乳动物化石的发现及其地层学意义

DISCOVERY OF THE MIDDLE MIOCENE FOSSIL MAMMALS IN GUANGHE DISTRICT, GANSU AND THEIR STRATIGRAPHIC SIGNIFICANCE

本文记述了采自甘肃广河石那奴中中新世地层的哺乳动物化石6目10科12属16种类(以小化石为主),其中新种两个:Alloptox guangheensis sp. nov., Pseudaelurus guangheensis sp. nov.。通过对动物群性质的研究及与其它地区的详细对比,认为下化石层的时代应为中中新世早期,上化石层应为中中新世晚期。二者分别与山旺期、通古尔期大体相当。 广河地区中中新世早期车头沟组和中中新世晚期咸水河组的建立,表示该地区存在着中中新世两个时期的不同环境沉积。

<ABSTRACT> The fossils discoverd in Shinanu, Guanghe, Gansu, are discribed in detail in this paper. It consists of at least 16 species, including two new species: Alloptox guangheensis, Pseudaelurus guangheensis,belonging to 6 orders. They are Collected from two layers: the upper (fossil-bearing bed II) and the lower ( fossil-bearing bed I). Compared to the other Neogene mammalian faunas, especialy on the basis of Megacricetodon and other micromammals, the fossils found in the lower layers show close affinities to the early middle Miocene elements of Europe, and they are much closer to the mammals found in Danshuilu located in Xining basin, Qinghai, an early middle Miocene Mammalian locality. Therefore, an early middle Miocene age is assumed to them . The mammals found in the upper layers demonstrate apparent advanced characteristics, and they are typical representatives of late middle Miocene. The features of the fossil mammals of Shinanu indicate that the late Tertiary fossiliferous sediments in the district contain three fossil levels. They may be reasonably divided into three formations: the early middle Miocene Chetougou Fm., containing the fossil mammal combination-egacricetodon sinensis, Sayimys cf. obliquidens, Alloptox minor, Pseudaelurus guanheensis sp. nov. ect.$ the late middle Miocene Xianshuihe Fm., the combination optox guangheensis sp. nov., Platybelodon tongxinensis, Gomphotherium sp., Anchitherium guangheensis ect; and the late Miocene-Pliocene Linsia fm., containing Hipparion sp. ect.. In addition, based on the mammal fossils and the other data of the test, a preliminary discussion on paleoenvironment and paleogeography is made .