DEEP-SEA MACROSTRATIGRAPHY AND THE MACROEVOLUTION OF PLANKTIC FORAMINIFERA

Planktic foraminifera (PF) are abundant in the global ocean and play an important role in earth history, but relatively little is know about the factors that have governed their macroevolution. Here we compare diversity and rates of extinction/origination in a new global compilation of PF species/genus ranges to spatiotemporal patterns of sedimentation in the Atlantic Ocean basin. Data on the lithology, thickness, and temporal distribution of deep-sea sediments were recovered from published ODP/DSDP/IODP scientific reports. Hiatuses in sedimentation at each site were identified wherever one or more nannofossil zones were missing or not represented by a measurable thickness of sediment. A total of 249 gap-bound sediment packages composed of 3,692 lithological units were recognized from 73 suitably drilled Atlantic sites.

First differences in PF diversity are significantly positively correlated with changes in the number of deep-sea sediment packages. The correlations persist when the mutual correlation imposed by variable interval durations is removed by partial correlation. The only systematic departure from this relationship occurs during the Eocene-Oligocene, which represents the most dramatic climate transition in the past 200 m.y. First differences in PF per-capita species/genus extinction rates are strongly and significantly positively correlated with first differences in rates of sediment package truncation. Rates of PF species/genus origination, by contrast, are significantly but less strongly positively correlated with rates of package initiation. Thus, similarities between changes in PF diversity and changes in the number of sediment packages reflect primarily congruence in rates of sediment truncation and lineage extinction. These results indicate that the macroevolutionary history of the PF is intimately linked to the oceanographic factors that govern spatiotemporal patterns of sedimentation in the deep sea, such as ocean circulation and global climate.