EXPERIMENTAL SIMULATION OF TAPHONOMY OF MODERN FISH EMBRYOS: INSIGHT INTO EARLY FOSSIL EMBRYOS

Phosphate fossil embryos were found in the Ediacaran Doushantuo Formation and Early Cambrian Kuanchuanpu Formation in the Guizhou and Shaanxi provinces of South China respectively. The structure of the fossils is delicate and artistic. Although there has been some work done to date to identify the nature of these fossil embryos, their identification and characterization still are controversial. Therefore, we used experimental taphonomy approach to provide insight into the origin of these structures. Previous studies confirmed that delicate, perishable structures could be retained by mineralization, but the experiments about the early morphological changes are few. Research about the sequencing of embryonic structure during the mineralization process is an important direction. The experimental taphonomy in this study simulated the chemical conditions (pH and Eh) of the sediment environment to observe the morphological changes of Bluntnose black bream embryos (Megalobrama amblycephala). We assume that silicate mineralization is similar to phosphate mineralization, and that silicified fossil embryos are comparable to fossil embryos preserved by phosphate. In the experiment, a silicate solution was used instead of a phosphate solution. The result shows that the preservation of the embryos is affected by the environment. Silicification is a very rapid process, taking place over 15 days. Different forms and part of embryos are preserved entirely. The results also show that the substitution reaction occurs within the structure of embryo rather than just as a coating. Experimental taphonomy provides a good way to explore the origin and preservation of Early Cambrian fossil embryos.