Early Devonian graptolites from the Qinzhou–Yulin region, southeast Guangxi, China

Abstract

Early Devonian graptolites are widely distributed within the 30°N and 30°S parallels of paleolatitude, with only a few known locations outside the 30° parallel. Only three early Devonian graptolite locations, i.e., west Yunnan, southeast Guangxi (in low paleolatitude), and south Xizang (Tibet) (in middle-high paleolatitude), have been reported in China. An Early Devonian graptolite fauna of moderate diversity, including three genera and 14 species, is described from the Qinzhou–Yulin region in southeast Guangxi, China, including Uncinatograptus jadae sp. nov. and Neomonograptus aequabilis latus subsp. nov. Based on these taxa, four biozones, the Uncinatograptus uniformis Biozone, the tentative Uncinatograptus praehercynicus Biozone, the tentative Neomonograptus falcarius Biozone, and the Uncinatograptus yukonensis Biozone, are erected in ascending order. The Lower Devonian graptolite biozonation in Guangxi agrees with the global standard. However, the graptolite biodiversity below the Uncinatograptus yukonensis Biozone in the Qinzhou–Yulin region is lower than those of the other parts of the world. In the present study, the tentatively recognized Neomonograptus falcarius Biozone has only the index species. In the study region, the species Uncinatograptus hercynicus (Perner) is absent. Thus, we tentatively employ the Uncinatograptus praehercynicus Biozone as a possible substitute for the Uncinatograptus hercynicus Biozone.