Lower and Middle Ordovician conodont diversity of the Yichang Region, Hubei Province, Central China

A survey on the (palaeo-) diversity of the Lower and Middle Ordovician conodont faunas from the Yichang Region, Hubei Province, Central China is presented. Analysis of the number of species through time shows the species richness is cyclical developed in the succession - varying from low to high. One major conodont diversity peak is recorded in the mid to late Floian Stage (Oepikodus evae Zone, stage slice FI 2, Lower Ordovician), where 33 species are recorded in the lower unit of the Dawan Formation. A smaller but second high diversity is found in the Darriwilian Stage (Lenodus variabilis Zone; stage slice Da 2, Middle Ordovician) with a maximum of 23 species. Secondary, smaller diversification maxima are present in the early Tremadocian, late Tremadocian, early Dapingian and late Darriwilian stages. Current information on acritarchs, brachiopods, and trilobites shows that the highest diversity maximum of conodonts corresponds to a similar high in brachiopod diversity, whereas acritarch and trilobite maximum diversity appear after the conodonts/brachiopods in the region.