Bolboforma (Chrysophyta?) from the Western North Atlantic

Abstract

From 10 localities along the western margin of the North Atlantic Ocean, including Deep Sea Drilling Project (DSDP) Sites 106, 604, and 612, we have observed 11 species of presumed encysted calcareous algae assignable to the genus Bolboforma Daniels and Spiegler. These microfossils range stratigraphically from the upper Eocene to the Pliocene in this region and are found in inner sublittoral (30-50 m) to abyssal (4500 m) paleodepths. A transect from the Virginia Coastal Plain across the adjacent continental shelf to the abyssal plain indicates that bathyal sites contain the richest assemblages. Large populations from our samples reveal that variability in exterior morphology in conjunction with differential calcite dissolution may confuse taxonomic assignments and lead to false stratigraphic assumptions. We believe that careful analysis and comparison of large populations will lead to the widespread application of Bolboforma to interregional and global problems of biostratigraphy, paleoecology, and paleobiogeography.