【作者】 刘淑文； 范国清；

【Author】 Liu Shuwen (Institute of Geology,Chinese Academy of Geological Sciences) Fan Guoqing (Liaoning Institute of Geology and Mineral Resources)

【机构】 中国地质科学院地质研究所； 辽宁省地质矿产研究所；

【摘要】 <正>华北本溪组一般为海陆交互相沉积,含有丰富的动植物化石,而辽宁凌源地区的“本溪组”却系一套陆相沉积,平行不整合在奥陶纪马家沟组之上。其上与太原组为整合接触。由于岩性和辽东太子河地区的本溪组层型剖面不同,故冠以引号引用。更多还原

【Abstract】 The Benxi(Penki)Formation is considered to be Carboniferous in age in northern China.There are more than 20 Conchostracan genera,which have been found from the Carboniferous system in the world. Based on the features of shell,Carboniferous Conchostracan fossils can be divided into four types:1.Family Leaiidae:Carapace with some radial carina,represented by Leaia, Hemicycloleaia and Paraleaia;2.Family Vertexiidae:With a node on the umbo,for ex- ample Pemphicyclus,Protomonocarina and Pemphilimnadiopsis;3.Family Palaeolimna- diopseidae:Having growth lines recurred at dorsal margin,including Anomalonema and Palaeolimnadiopsis;4.Family Euestheriidae;Dorsal margia being straight,possessing numerous genera,such as Asmussia,Cycladestheria,Euesyheria,Pseudestheria, Concherisma,Sphaerestheria and so on. This paper describes a new genus——Retrofractus which could be considered as a new type:The dorsal margin is long,but is not straight,and it bends down at anterior 1/2, thus forming an angle of about 25°.It is the primitive and important character thar leads it to be distinguished from all known Conchostracan genera.更多还原