Phosphatization Through the Phanerozoic

Phosphatization of soft tissues and skeletal remains has varied temporally and taxonomically through the Phanerozoic. During the Cambrian through early Ordovician, microscopic arthropods and animal embryos were preferentially preserved. Phosphatization was uncommon during the rest of the Paleozoic, as recalcitrant tissues of a few taxa were preserved in hospitable microenvironments. The Cretaceous through Eocene saw another expansion of phosphatization, with a strong bias toward fish remains already enriched in apatite. Throughout its Phanerozoic history, phosphatization exhibited a taphonomic bias toward taxa with recalcitrant tissues that could resist the early stages of organic decay, taxa with organic structures already enriched in calcium phosphate, and, in many cases, taxa with small body sizes. The pulse of phosphatization during the Cambrian through Early Ordovician may have been facilitated by the generally lower levels of mixed layer development in the upper few centimeters of seafloor sediments during that time period, whereas the Cretaceous through Eocene increase in phosphatization was possibly related to the enlargement of euxinic epicontinental seaways.