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通过对广西六景地区谷闭组下部的牙形石Ancyrodella类群的早期个体分析 ,识别出Ancyrodellabino dosa→Ancyrodellarotundiloba→Ancyrodellaalata→Ancyrodellagigas的演化谱系。以中 上泥盆统界线层型剖面为准 ,由Ancyrodellarotundilobaearlyform的首次出现为标志 ,将六景地区中 上泥盆统界线置于谷闭组底界之上1 .80m处 ,这条处于Ancyrodella早期演化系中间的界线是一条可靠的和高分辨率的界线 ,能与层型点进行精确对比
Through the early individual analysis of the Ancyrodella conodont in the lower part of the Gu closure group in the Liujing area, Guangxi, the evolutionary lineage of Ancyrodellabino dosa → Ancyrodellarotundiloba → Ancyrodellalata → Ancyrodellagigas was identified. Based on the Middle-Upper Devonian stratigraphic profile and the first occurrence of Ancyrodellarotundilobaearlyform, the boundary of the Upper-Middle Devonian in the Liujing area is located at 1.80m above the bottom of the Gu- The boundary between evolutionary systems is a credible and high-resolution boundary that can be precisely compared with layer-type points