Graptolite biostratigraphy of the Dapingian GSSP and its global correlation

The graptolite fauna of the Dapingian Global Stratotype Section and Point (GSSP) at Huanghuachang is relatively poorly preserved and difficult to correlate with the graptolite record of other regions. A few tie points have been identified, indicating that the base of the Dapingian lies above the base of the regional Azygograptus suecicus Biozone of South China. The base of this graptolite zone, however, represents the first appearance datum (FAD) of the genus Azygograptus instead of the species, as the species Azygograptus suecicus is considerably younger. The Azygograptus suecicus Biozone can be correlated indirectly with Scandinavia through the presence of isograptids associated with Azygograptus specimens in Sweden and Norway. The correlation of the upper Dapingian is uncertain, even though the top of the Dawan Formation with Levisograptus austrodentatus at the base of the Darriwilian indicates a correlation of the upper Dapingian with the Australasian upper Castlemainian and Yapeenian.