甘肃临夏盆地牙沟地区椒子沟组底部的小哺乳动物化石  

Micromammal fossils from the basal part of the Jiaozigou Formation in Yagou area,Linxia Basin,Gansu Province

作　　者：王伴月[1] 邱占祥[1] WANG Ban-Yue;QIU Zhan-Xiang(Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences,Beijing 100044)

机构地区：[1]中国科学院古脊椎动物与古人类研究所,北京100044

出　　处：《古脊椎动物学报（中英文）》2023年第4期284-316,共33页Vertebrata Palasiatica

基　　金：中国科学院前沿科学重点研究项目(编号:QYZDY-SSW-DQC022)资助。

摘　　要：记述了中国科学院古脊椎动物与古人类研究所一野外队于2003年在甘肃临夏盆地牙沟附近的椒子沟组底部发现的小哺乳动物化石,计3目13科17个属。这个小哺乳动物化石群是中亚和东亚典型的渐新世组合。其中的14属(约为总数的82%)是亚洲渐新世所共有的,4个属(Ordolagus,Tataromys,Tsagonomys和Bagacricetodon)和Eucricetodon属的4个种的时代分布仅限于渐新世,Bagacricetodon属限于晚渐新世,Glis和Eomyodon两属在晚渐新世时首次出现。根据小哺乳动物化石组合,牙沟地区椒子沟组底部的时代可能为晚渐新世,这与根据大哺乳动物化石得出的结论一致。与中亚和东亚地区其他已知的晚渐新世哺乳动物群比较,由于该动物群中具有两个原仅在始新世出现的属(Anatolechinos和Gobiomys)和缺少较进步的属,其时代比内蒙古乌兰塔塔尔带III和蒙古湖谷地区的生物带C稍早。这与现在对毛沟剖面的古地磁解释大致一致,即椒子沟组的下界可能与Chron C10r(~29 Ma)相当。牙沟动物群包含有大量喜欢干旱的zapodines,ctenodactylids,cricetids,lagomorphs和穴居的Tsaganomys化石,而且产化石地层的岩性主要是由含有石膏的褐红色泥岩组成,这些都倾向于表明牙沟地区在晚渐新世时主要为半干旱的林地-灌木林地环境。在晚渐新世时,在亚洲和欧洲之间共有4属小哺乳动物,而在亚洲和北美洲只共有一属动物,这表明在晚渐新世时,欧亚之间动物群的交流要比亚洲与北美之间的多,这可能与土尔盖海峡在晚渐新世时消失有关。Renewed fieldwork in 2003 produced a rich micromammal assemblage from the basal part of the Jiaozigou Formation in the Yagou area of Linxia Basin.17 genera distributed among 13 families of three orders were recovered.The micromammal fauna is a typical Oligocene assemblage for Central and Eastern Asia.14 genera(~82%of the fauna)are common in the Oligocene of Asia.Of them four genera and four species of Eucricetodon are restricted to the Oligocene,one genus(Bagacricetodon)is restricted to Late Oligocene and Glis and Eomyodon made their first appearances in the Late Oligocene.Based on this micromammal composition,the basal part of the Jiaozigou Formation in the Yagou area could be mainly of Late Oligocene in age,which is in accordance with the conclusion based on large mammal fossils.In comparison with the other Late Oligocene micromammal faunas in Central and East Asia,the Yagou Fauna is slightly older than the Ulan III biozone of Nei Mongol and biozone C of Mongolia,because it has two Eocene genera and lacks more advanced genera.This is roughly in accordance with the recent palaeomagnetic interpretation for the Maogou section,where the lower boundary of the Jiaozigou Formation was correlated with Chron C10r(~29 Ma).The presence of large number of xerophilous zapodines,ctenodactylids,cricetids and lagomorphs combined with fossorial Tsaganomys and the lithology of the fossil-bearing deposits,composed of gypsiferous reddish brown mudstone,tend to show a semiarid woodland-shrubland habitat during the Late Oligocene in Yagou area.In Late Oligocene more frequent faunal interchange might have occurred between Asia and Europe(4 genera commonly shared)rather than between Asia and America(only 1 genus shared),partly because of the disappearance of the Turgai Strait.

关 键 词：甘肃临夏牙沟 晚渐新世 椒子沟组 小哺乳动物化石 

分 类 号：Q915.873[天文地球—古生物学与地层学]