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详细描述我国新疆塔克拉玛干沙漠东北部轮南探区50井的中-上奥陶统界线附近的牙形刺动物群,包括Pygodus anserinus,P.serra,P.xinjiangensis,Ansella jemtlandica,Cornuodus longibasis,Periodon aculeatus,Protopanderodus calceatus,P.cooperi,P.varicostatus,Scabbardella altipes,Spinodus spinatus和Cahabagnathus sweeti等,由上而下可划分Pygodus anserinus,P.serra和P.xinjiangensis等3个牙形刺带,并以Pygodus anserinus带的底界稍偏上处视为中-上奥陶统界线。尤为重要的是,本文对Pygodus xinjiangensis的有效性、Pygodus属的演化趋势及其3个种的区别进行详细讨论,同时说明Pygodus anserinus由P.serra演化而来。
A detailed description of the conodont fauna near the mid-upper Ordovician boundary in Well Lunnan Block 50 in the northeastern Taklimakan Desert, Xinjiang, China, includes Pygodus anserinus, P. serra, P. xinjiangensis, Ansella jemtlandica, Cornuodus longibasis, Periodon aculeatus , Protopanderodus calceatus, P.cooperi, P.varicostatus, Scabbardella altipes, Spinodus spinatus and Cahabagnathus sweeti etc. The topographies of Pygodus anserinus, P.serra and P.xinjiangensis can be divided into three types. Slightly offset at the bottom of the belt as the Middle - Upper Ordovician boundaries. More importantly, the paper discusses in detail the effectiveness of Pygodus xinjiangensis, the evolutionary trend of the genus Pygodus, and the differences between the three species. It also shows that Pygodus anserinus evolved from P.serra.