Three-dimensional phosphatic preservation of giant acritarchs from the Terminal Proterozoic Doushantuo Formation in Guizhou and Hubei provinces, south China

During the last two decades, a diverse assemblage of multicellular algae, spherical microfossils, bacteria and cyanobacteria (the Weng'an Biota) has been reported from the Terminal Proterozoic Doushantuo phosphorite in south China, which provides an important window for evolutionary studies of multicellular life just before the Ediacaran animal radiation. In this paper we report on three-dimensionally preserved acritarchs from the Doushantuo phosphorites at Weng'an in Guizhou Province and, for the first time, from Baokang in Hubei Province. Our assemblage contains species of the genus Meghystrichosphaeridium Zhang, Yin, Xiao and Knoll, 1998 non Chen and Liu, 1986 including M. chadianensis (Chen and Liu) Zhang, Yin, Xiao and Knoll, emend. 1998, and M. reticulatum Xiao and Knoll, 1999; the genus Echinosphaeridium Knoll, 1992 including the species E. maximum (Yin) Knoll, 1992; the new genus Bacatisphaera including the new species B. baokangensis and the new genus Castaneasphaera including the new species C. speciosa. The latter shows a marked resemblance to similarly preserved phosphatized Palaeozoic acritarchs called 'mazuelloids', consistent with a phytoplanktonic mode of life for the global Doushantuo/Pertatataka microflora (DPM).