首次报道呼鲁斯太晚石炭世羊虎沟组的牙形刺４属９种。根据化石组合面貌，自上而下可建立两个组合，即：Ｓｔｒｅｐｔｏｇｎａｔｈｏｄｕｓ ｐａｒｖｕ－Ｉｄｉｏｇｎａｔｈｏｄｕｓ ｍａｇｎｉｆｉｃｕ组合和Ｎｅｏｇｎａｔｈｏｄｕｓ ｂａｓｓｌｅｒｉ－Ｉｄｉｏｇｎａｔｈｏｄｕｓ ｄｅｌｉｃａｔｕｓ组合，其时代为晚石炭世维斯发期和晚纳缪尔期。为本区石炭纪地层划分对比及盆地格局的研究提供了新的资料。

Abundant conodonts,first collected from the Upper Carboniferous Yanghugou Formation at the Hulustai Section of the Helanshan area in the west of the Ordos Basin,have been studied in this paper.They are described as 9 species of 4 genera: Streptognathodus parvus, S.expansus,S.oppletus, Idiognathodus acutus,I. delicatus,I. claviformis, I.magnificus,Synprioniodina microdenta, and Neognathodus bassleri. Two conodont assemblages could be primarily recognized (in descending order): Streptognathodus parvus Idiognathodus magnificu Assemblage and Neognathodus bassleri Idiognathodus delicatus Assemblage.They are Pennsylvanian and latest Namurian in age and could be entirely correlated with those contemporary conodont zones both at home and abroad.

Q915.2