Evolutionary Stages of the Earliest Skeletal Fauna and Division and Correlation of the Precambrian-Cambrian Boundary Strata

Through an analysis of the earliest fossils in the Precambrian-Cambrian boundary beds in various parts ofthe world, especially in the Yangtze and Siberia platforms, the author has found that the evolution of the ea-rliest skeletal animals may be divided from older to younger into three stages. The first stage (theAnabarites-Protohertzina fauna) is represented by the Anabarites-Protohertzina zone of the Meishucunian Stagein the Yangtze platform and the A. trisulcatus and P. cristata zones of the Manykayn Stage in Siberia. The sec-ond stage (the earliest orthothecimorphid and mollusc fauna) is represented by the Paragloborilus-Siphogonuchites zone of the Meishucunian Stage and the Aldanocyathus sunnaginicus zone of the TommotianStage. The third stage (the earliest hyolithimorphid and lapworthellid fauna) is represented by the Sinosachiteszone of the Meishucunian Stage and the D.regularis and D.lenaicus zones of the Tommotian Stage. The threeevolutionary stages can be used as a criterion for worldwide correlation.

Evolutionary Stages of the Earliest Skeletal Fauna and Division and Correlation of the Precambrian-Cambrian Boundary Strata

Abstract Through an analysis of the earliest fossils in the Precambrian-Cambrian boundary beds in various parts of the world, especially in the Yangtze and Siberia platforms, the author has found that the evolution of the earliest skeletal animals may be divided from older to younger into three stages. The first stage (the Anabarites-Protohertzina fauna) is represented by the Anabarites-Protohertzina zone of the Meishucunian Stage in the Yangtze platform and the A. trisulcatus and P. cristata zones of the Manykayn Stage in Siberia. The second stage (the earliest orthothecimorphid and mollusc fauna) is represented by the Paragloborilus-Siphogonuchites zone of the Meishucunian Stage and the Aldanocyathus sunnaginicus zone of the Tommotian Stage. The third stage (the earliest hyolithimorphid and lapworthellid fauna) is represented by the Sinosachites zone of the Meishucunian Stage and the D.regularis and D.lenaicus zones of the Tommotian Stage. The three evolutionary stages can be used as a criterion for worldwide correlation.