The graptolite fauna across the Lower and Middle Ordovician boundary at the Huanghuachang GSSP section, Yichang and the Jianyangping section, Xingshan County is described. The taxonomy of the pendent didymograptids, the graptolite zonations across the base of Middle Ordovician and their correlations are discussed in this paper. The two revised graptolite zones, the Didymograptellus bifidus Zone and the Azygograptus suecicus Zone, can be well correlated to their equivalents elsewhere in the world.
WANG ChuanshangWANG XiaofengCHEN XiaohongLI Zhihong
