The high resolution sampling across the Cretaceous/Tertiary (K/T) boundary of the most expanded and continuous sections located in Spain and Tunisia allows us to test and elucidate the extinction model of Cretaceous planktic foraminifera in subtropical and temperate latitudes. The planktic foraminiferal extinction occurred over a short period, with 5% of the species disappearing in the late Maastrichtian, 70% of the species became extinct at the K/T boundary and about 25% of the species are ranging into the early Danian. The species that became extinct at the K/T boundary were large, complex tropical and subtropical forms that dwelled in deep and intermediate water depths. Their disappearance constitutes the largest and most sudden extinction event in the history of planktic foraminifera. Nevertheless, the small cosmopolitan surface dwellers with simple morphologies appear to have survived and the last of them gradually disappeared in the early Danian. The planktic foraminiferal extinction model can be interpreted as a catastrophic mass extinction that was centred at the K/T boundary, and was superimposed on a less evident and controversial gradual mass extinction which apparently began in the late Maastrichtian and continued into the early Danian. The catastrophic pattern of extinction of 70% of the species at the K/T boundary is very compatible with the effect of a large asteroid impact.

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