Precambrian animal diversity: Putative phosphatized embryos from the Doushantuo formation of China

Putative fossil embryos and larvae from the Precambrian phosphorite rocks o f the Doushantuo Formation in Southwest China have been examined in thin se ction by bright field and polarized light microscopy. Although we cannot co mpletely exclude a nonbiological or nonmetazoan origin, we identified what appear to be modern cnidarian developmental stages, including both anthozoa n planula larvae and hydrozoan embryos. Most importantly, the sections cont ain a variety of small (less than or equal to 200 Gem) structures that grea tly resemble gastrula stage embryos of modern bilaterian forms.