Climatic change has been a prominent cause of marine mass extinction, but areal restriction of seafloor during global regression has not. Late Eocene and Pliocene-Pleistocene cooling, for example, caused major extinctions, but profound global Oligocene and Pleistocene regressions had little or no direct effect on benthic diversity. Recurrent themes of pre-Cenozoic marine crises suggest that global temperature change also served as a major, and perhaps dominant, agent of extinction in these events: (1) Mass extinctions have frequently been concentrated in the tropics, which seem to have become a refrigerated trap from which there has been no escape; biotas previously occupying high latitudes have shifted equatorward, to replace disappearing tropical biotas. (2) Some crises were not instantaneous but followed protracted and pulsatile temporal patterns, as would be predicted for complex, global climatic crises. (3) Several mass extinctions coincided with recognized intervals of climatic cooling.

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