Changes in the patterns of phosphatic preservation across the Proterozoic-Cambrian transition

Using both well known and new examples, the changing nature of phosphatic preservation is here outlined from c. 1000 Ma to c. 450 Ma. The first significant change observed through this interval is the departure from high-fidelity cellular (and possibly sub-cellular) preservation observed in the Precambrian, towards the low-quality preservation of organic materials that is generally seen in the Phanerozoic. Secondly, the locus of phosphatisation is also observed to change between the Precambrian and post-Cambrian times; from near-shore towards outer shelf environments, and from the sediment-water interface towards greater depths below the surface of the sediment. Lastly, we draw attention to the significance of the change from the phosphatisation of possible photoautotrophic organisms towards the preservation of faecal matter and heterotrophic remains. A model is put forward to link these observed patterns to major biological innovations, notably the emergence of deep bioturbation and grazing (including zooplankton), as well to episodic increases in mixing and oxygenation of the oceans and sediment through much of the Phanerozoic.