Figure 4.25   Size changes in planktic foraminiferans from high and low latitudes during the last 70 Ma, compared to temperature profi les generated from oxygen isotope data and Mg : Ca ratios. Three phases are recognized, a fi rst (6542 Ma) with dwarf taxa, a second (4212 Ma) with moderate-sized taxa, and a third (12 Ma to present) with large-sized taxa. Size increases are correlated with intervals of global cooling. (Courtesy of Daniela Schmidt.)

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