Diversity of cnidarians and cycloneuralians in the Fortunian (early Cambrian) Kuanchuanpu Formation at Zhangjiagou, South China

The latest discovery of microfossils from lower Cambrian (Fortunian Stage) Zhangjiagou Lagerstätte in South China are presented. This lagerstätte is rich in exceptionally preserved microfossils, including embryos of Olivooides multisulcatus, Olivooides mirabilis, and Pseudooides prima, hatched stages of O. multisulcatus, O. mirabilis, Hexaconularia sichuanensis and Quadrapyrgites quadratacris, and cycloneuralians represented by Eopriapulites sphinx and a new form. The largest known fragment of O. mirabilis implies that its adults length can be more than 9.0 mm with at least 50 annuli, and the longest known specimen of Q. quadratacris has at least 18 annuli. These unusually large specimens refute the non-feeding larvae hypothesis for Olivooides and Quadrapyrgites. New material documented here includes two new types of fossil embryos, one with hexaradial symmetry and the other with octaradial symmetry, as well as a new cycloneuralian with two tail spines. Based on the current material, it...