Biostratigraphic and isotopic studies of planktic foraminifera suggest that early to middle Pliocene closure of the Central American Seaway caused vicariant speciation among previously cosmopolitan menardellid foraminifera. New morphospecies were restricted to the tropical Atlantic. Isotopic data suggest that newly evolved Atlantic menardellids were adapted to more oligotrophic conditions, living higher in the water column than ancestral forms and perhaps harboring photosymbionts. In the late Pliocene, all but one menardellid morphospecies became extinct. These extinctions coincided with a progressive increase in the amplitude of periodic climatic change and the end of isolated tropical Atlantic surface circulation as Northern Hemisphere glaciation intensified.

West: -43.2922 East: -43.2920 North: 4.1216 South: 4.1215

Expedition: 154

Site: 154-925

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=10.1130/G19834.1 (c.f. for more detailed metadata)

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