Lower Cambrian phosphatized Punctatus from southern Shaanxi and their ontogeny sequence

Abstract

Phosphatized and three-dimensionally preserved embryos and spherical fossils of metazoan recovered from the Kuanchuanpu Member, Dengying Formation in southern Shaanxi, China provide nice developmental sequence for the studies of origination, taxonomy, phylogenic evolution and developmental biology of early animals. Ontogeny of these larva fossils has not been systemically studied mainly due to their poor preservation and limited identification. The Kuanchuanpu Member, predominated by phosphorites and cherts, yields phosphatized animal embryos, particularly those of Olivooides and Punctatus which have high resolution in fine structures and different ontogeny developmental stages. An ontogenetic sequence of the Punctatus is established mainly base on its developmental transitions from body part to oral one, which is perfectly consistent with the embryonic ontogeny sequence proposed by Bengtson and Yue (1997). Furthermore, a new genus Quadrapyrgites gen. nov is erected to receive a larva with tetraradial body plan.