AGE OF THE FOSSIL CONCHOSTRACANS FROM DAOHUGOU OF NINGCHENG,INNER MONGOLIA
AGE OF THE FOSSIL CONCHOSTRACANS FROM DAOHUGOU OF NINGCHENG,INNER MONGOLIA
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发表时间：
2003
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通讯作者：
Shen Yan-bin
中科院分区：
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作者：
Shen Yan-bin
内蒙古宁城道虎沟村以出产种类繁多的化石群而闻名，尤其是丰富的甲壳类，保存完好，软体部分和幼虫期个体。甲壳小，圆形或椭圆形，网状纹饰小，包括1属4种：紫柳江螺属、海房沟螺属、靖远螺属和乱平真螺属。中国地区有两个中侏罗世甲壳动物群：下部(巴约西-中巴托世)的紫柳江真甲藻动物群(Euestheria Ziliujingens)和上部(巴吞世晚期-卡洛纪)的假石龙门动物群。在道虎沟村发现的紫柳江真水蚤、海房沟真水龙和靖远水龙是中侏罗世早期紫柳江水母动物群的重要组成部分。乱平真水蚤产于冀北九龙山组中下侏罗统，该种也保存有软体和幼虫期个体。因此，道虎沟的海螺化石组合应属于中侏罗世早期的紫柳江真海鞘动物群，并与九龙山组进行对比。它不同于中侏罗世晚期的伪氏动物群，后者具有中等的甲壳、复杂的瓣形雕刻和多样的属。它不同于辽西大北沟组上侏罗统的雀巢动物群和辽西义县组著名的Eosestheria动物群。
Daohugou village in Ningcheng, Inner Mongolia, is famous for yielding a variety of fossil groups, especially abundant conchostracans, which are very well preserved with soft parts and larval-stage individuals. The conchostracans are characterized by small carapaces, circleular or elliptical shapes, small reticulate ornamentation, including four species in one genus: E. ziliujingensis Chen, E. haifanggouensis Chen, E. jingyuanensis Chen, and Euestheria luanpingensis Shen et Niu. In China there are two conchostracan faunas of Middle Jurassic age, Euestheria ziliujingensis fauna in the lower part (Bajocian—middle Bathonian) and Pseudograpta fauna in the upper part (late Bathonian—Callovian). Euestheria ziliujingensis, E. haifanggouensis, and E. jingyuanensis found in Daohugou village are the important elements of the early Middle Jurassic Euestheria ziliujingensis fauna. Euestheria luanpingensis was known from the lower Middle Jurassic Jiulongshan Formation in northern Hebei where this species is also preserved with soft parts and larval-stage individuals. So the conchostracan assemblage from Daohugou should belong to the early Middle Jurassic Euestheria ziliujingensis fauna and are correlative with that in the Jiulongshan Formation. It is distinguished from the late Middle Jurassic Pseudograpta fauna by that the latter possesses mo- derate carapace, complex sculpture of the valve and diverse genera. It is quite different from the Upper Jurassic Nestoria fauna of the Dabeigou Formation and the famous Eosestheria fauna from the Yixian Formation, western Liaoning.