内蒙古韩家营玄武岩夹层中三趾马动物群化石

An Upper Miocene“Hipparion fauna”locality sandwiched by basalt in Hanjiaying,Nei Mongol

内蒙古乌兰察布市集宁区韩家营村附近发现了一处夹在两层玄武岩之间的三趾马动物群化石地点。通过K-Ar同位素测年,确定了上、下两层玄武岩的年代分别为6.8和7.2Ma。与中国北方其他三趾马动物群相比,韩家营三趾马动物群与山西保德、内蒙古四子王旗以及甘肃临夏盆地的三趾马动物群非常相似。保德第43、44、49地点与韩家营的动物群组成类似,表明这几个地点的时代约为7.0 Ma而不是5.5 Ma。内蒙古四子王旗乌兰花地点与韩家营的化石类群也十分相像,证实了该动物群年龄约为7 Ma。对比甘肃临夏盆地的动物群,柳树组上部的杨家山三趾马动物群与韩家营的更接近。韩家营动物群的组成和牙齿结构表明其属于中国晚中新世的西部生物区系Gazella dorcadoides动物群。

Here we report a Hipparion fauna locality discovered in between two basalt layers near Hanjiaying Village,Jining District,Wulanchabu City,Nei Mongol.K-Ar isotopic dating of the lower and upper level of the basalt constrains the age of the fauna from 7.2 to 6.8 Ma.Compared with classical Hipparion fauna from northern China,the Hanjiaying fauna is closer to those from Baode of Shanxi,Siziwang Banner of Nei Mongol and the Linxia Basin of Gansu.It is similar to the Loc.43,44 and 49 from Baode by faunal composition,confirming their age to be~7.0 Ma rather than 5.5 Ma.The high similarity with the fossils from Wulanhua,Siziwang Banner,Nei Mongol,verified the age of Wulanhua fauna at about 7 Ma.Compared with faunas from the Linxia Basin,Gansu,it is more similar to those from the upper part of the Liushu Formation,especially the Yangjiashan fauna.Based on the faunal composition and their tooth morphology,