Fossil planktic foraminifera (an overview)

Planktic foraminifera are unicellular marine organisms able to produce calcareous tests, which can be fossilized and, therefore, can give important information about the geologic record. In this overview a summary of the present knowledge of fossil planktic foraminifera together with the gradual steps from the earliest and pioneering to the more recent studies on this microfossil group, is given. In particular, the criteria at the base of the classification of these organisms from the earlier studies until the present, are described and summarized. An overview of the biostratigraphic schemes based on species first and last occurrences and assemblages from different latitudes and different regions is also given. The evolution and the response of planktic foraminifera to changing environmental condition are summarized from the more primitiveGlobigerina-like Jurassic forms, to the specialized and diversified Cretaceous species, until their dramatic crisis across the Cretaceous/Tertiary boundary, their successive recovery in the Paleocene and their evolution toward modern organisms. Finally, an overview is given of the use of planktic foraminifera to reconstruct paleoenvironments from the more simple methods to those implying more sophisticated and recent techniques.