Restudy of Ovatoryctocara Tchernysheva, 1962 from the Kaili Formation, Jianhe County, Guizhou, South China

Abstract

The First Appearance Datum (FAD) of the oryctocephalid trilobite Ovatoryctocara granulata Tchernysheva, 1962 is one of the candidates for establishing the base of the Cambrian Series 3, Stage 5. However some records of this taxon in China and elsewhere are doubtful and in need of review. Ovatoryctocara cf. granulata and Ovatoryctocara sp., previously described from the lower part of the Kaili Formation, China are transferred herein to Ovatoryctocara sinensis sp. nov., which shows significant morphological differences with type specimens of O. granulata. All Chinese specimens of Ovatoryctocara are therefore transferred to O. sinensis sp. nov. As consequence, the former trilobite Zone Bathynotus kueichouensis-Ovatoryctocara cf. guanulata is renamed the Bathynotus kueichouensis-Ovatoryctocara sinensis Assemblage Zone. O. granulata from Newfoundland also exhibits large differences in morphology with type specimens of O. granulata from Siberia. It is concluded that O. granulata does not occur in China but is restricted to Siberia and North Greenland. Hence, O. granulata is not suitable for defining the Cambrian Series 2–3 boundary, as previously suggested.