Аннотация:A review of the proposed markers for the base of the Serpukhovian has shown that their
entries are not consistent in different sections, especially when they are not controlled by other fossil groups. The diagnosis and interspecific relations in the genus Lochriea of the conodont species L. ziegleri, the primary candidate marker, needs to be reassessed and it needs to be decided which morphotype is the best marker. The first occurrence levels of the marker
foraminiferal species, especially J. delicata and N. postrugosus, need to be agreed, and the taxa from the critical levels need to be illustrated before a decision can be made on the boundary choice.