On chronostratigraphic calibration using Bryozoa: suggestions from two Paleogene case studies

Abstract

The bryozoan species present in each Paleocene and Eocene chronostratigraphic unit of the Atlantic and Gulf Coastal Plains in North America, and the Paris Basin in France are analysed. The comparison between species exclusive to each unit considered (EX), non-exclusive species, but appearing for the first (FA) or last time (LA), species existing before and after the unit considered (BA), and, finally, the total number of species present (T), shows the chronostratigraphic discriminating value of this fauna within the Paleogene. The same analysis was previously applied to bryozoan Paleocene and Eocene families and genera, according to the inormation. It is also interesting to note the significant renewal of bryozoan fauna in both basins during the Middle Eocene.