TAPHONOMY AND BIOLOGICAL AFFINITY OF THREE-DIMENSIONALLY PHOSPHATIZED BROMALITES FROM THE MIDDLE ORDOVICIAN WINNESHIEK LAGERSTÄTTE, NORTHEASTERN IOWA, USA

A review of the processes required for exceptional preservation of soft-bodied fossils demonstrates that anoxia does not significantly inhibit decay and emphasizes the importance of early diagenetic mineralization. Early diagenesis is the principal factor amongst the complex processes leading to soft-part preservation. The development of a particular preservational mineral is controlled by rate of burial, amount of organic detritus, and salinity. A new causative classification of soft-bodied fossil biotas is presented based upon fossil mineralogy and mineral paragenesis.