Name: Doushantuo Formation Location: South China Age: 550-590 million years old (latest Precambrian)

4. Taphonomy

The process of fossils in the preservation of the Doushantuo Formation was phosphatization. Phosphatization is the process that occurs when substances originally made up of other material are converted to phosphate substances, which have a higher preservation potential. Phosphatization as a process is still not completely understood.

Plate movements and sea-level rises may have led to phosphorus-rich bottom waters rising, and forming phosphorite (phosphorus-rich rock) deposits on continental margins (Zhang and Yuan, 1992); or phosphorus in organisms themselves may have caused the phosphorite deposits (Xiao et al., 1998b). Phosphate precipitation would have been aided by low sedimentation rates, a lack of disturbance from organisms, and extensive cover by microbes and algae (Yuan and Hoffmann, 1998).

Reworking of material could have occurred: " Globular microfossils were probably phosphatized soon after they were deposited, resuspended by storms, transported for a short distance, and then redeposited and cemented in place." (Shen et al., 2000, p. 779).