Paleoecology and evolutionary response of planktonic foraminifera to the Plio-Pleistocene Intensification of Northern Hemisphere Glaciations

Abstract. The Plio-Pleistocene is associated with many important climatic and paleoceanographic changes which have shaped the biotic and abiotic nature of the modern world. The closure of the Central American Seaway and the development and intensification of northern hemisphere icesheets had profound global impacts on the latitudinal and vertical structure of the oceans triggering the extinction and radiation of many marine groups. In particular, marine calcifying planktonic foraminifera, that are sensitive to water column structure, exhibited a series of extinctions as global temperatures fell. By analyzing high-resolution (~5 kyr) sedimentary records from the Eastern Equatorial Pacific Ocean, complimented with global records from the novel Triton dataset, we document the biotic changes in this microfossil group, within which three species displayed isochronous co-extinction, and species with cold-water affinity increase in dominance. We suggest that these changes are associated with the terminal stages of the closure of the Central American Seaway and mark the initiation of a world in which cold- and deep-dwelling species became increasingly more successful.