A latest Maastrichtian global warming event, which began approximately 450 k.y. and ended about 22 k.y. prior to the K/T boundary, is associated with the pole-ward migration of the warm-water planktonic foraminifer Pseudotextularia elegans. The warming event was apparently inititated by greenhouse warming due to the main outpouring of the Deccan Traps in India and is now well documented in the North and South Atlantic Oceans and in North America by the poleward migration of warm-water planktonic foraminifera and subtropical vegetation.
A cooling trend ca 22 kyr prior to the K/T boundary caused marine δ18O values to return to climatic conditions recorded prior to the onset of warming and thus does not represent a significant change in long-term climate. Planktonic foraminifera responded by migration to the latest Maastrichtian global warming and cooling before their mass extinction at the K/T.