New observations of the ornamented Doushantuo embryo fossils from the Ediacaran Weng’an Biota, South China

摘要

Phosphatized Weng’an embryo fossils from the Ediacaran Doushantuo Formation in Guizhou, South China are dominated by various ornamented spheroidal fossils, with one internal body or several blastomeres enclosed within a single or multiple layered envelope, which have been interpreted as the resting eggs or diapause embryos of metazoans. Based on the microstructure of the envelope, we separated these ornamented spheroidal fossils into two groups: 1) group one, represented by typical Megasphaera ornata and characterized by an envelope consisting of at least two thick capsules with various surface ornaments and a single internal body, which can be interpreted as resting eggs; 2) another group, exhibiting an envelope consisting of a thin capsule with cell-like surface structure and internal blastomeres (amount is equal to 2n, n = 0, 1, 2, 3…), which are probably not diapause embryos but developing blastulae at various holoblastic cleavage stages.