Article: Preservation of fish in the Cretaceous Santana Formation of Brazil

Early diagenesis of calcareous concretions in the Santana Formation (Cretaceous) of north-east Brazil has allowed some fishes killed in mass mortality events to be preserved three dimensionally. Fluctuating salinities may have been responsible for the mass deaths of the dominantly marine fish fauna. Early phosphatization, brought about by bacterial activity, has allowed a variety of soft tissues to be preserved within the body cavity of a variety of fish taxa. Both high and low pH micro-environments existing within the body cavity of the fishes allowed the precipitation of microcrystalline francolite within the partly decomposing soft tissues, while early non-ferroan calcite was produced within the coelomic cavity.