Comments on some important issues concerning the establishment of a GSSP for Cambrian Stage 5

In order to help facilitate stratigraphic correlation between south China and Siberia, trilobite zones of Guizhou, China, and the Molodo River area, Siberia, need to be better coordinated. The Wuliu-Zengjiayan section is a strong candidate for the Global Standard Stratotype Section and Point for Cambrian Stage 5, and the Molodo River section provides important supplemental information that helps expand the precision of correlation on a global scale. The Kaili Formation in the Wuliu-Zengjiayan section contains three trilobite zones over an interval of 214.20 m. We propose that the Ovatoryctocara granulata Zone, as used in Siberia, replace the Ovatoryctocara Zone. Equivalent strata in Guizhou extend more than 150 m stratigraphically, from the Protoryctocephalus wuxunensis Zone to the Bathynotus kueichouensis–O. cf. O. granulata Assemblage Zone. We also propose that the traditional Kounamkites Zone be supplemented or replaced by the Oryctocephalus reticulatus Zone, which outside Siberia contains Oryctocephalus indicus.