The Global Stratotype Section and Point (GSSP) for the boundary between the Capitanian and Wuchiapingian stages, also the boundary between the Guadalupian and Lopingian Series is defined at the First Appearance Datum (FAD) of the conodont Clarkina postbitteri postbitteri at the base of Bed 6k in the Penglaitan Section along the Hongshui River in Guangxi Province, South China.