Planktonic foraminiferal stability in the Upper Maastrichtian and the catastrophic mass extinction at the Cretaceous-Tertiary (K/T) boundary at Caravaca (Spain).

The planktic foraminiferal quantitative and biostratigraphic study across t he K/T boundary at the Caravaca section provides proof of the stratigraphic al range continuity and the evolutive stability of species in the Upper Maa strichtian. In Caravaca, the planktic foraminiferal extinction pattern is a catastrophic mass extinction since 74% of the species went extinct in coin cidence with the K/T boundary and with the evidence of impact. This pattern can be similarly identified in other Tethyan sections and, for this reason , the authors consider that the supposed extinctions suggested by other aut hors in Caravaca could be caused by the Signor-Lipps effect. In this study, it was found that possibly 17 Cretaceous species survived the K/T event an d their relative abundance suddenly drops above the K/T boundary (ARECS cur ve). This decrease can be a consequence of the progressive decline in abund ance of the Cretaceous species that survived due to biological competition with the new Tertiary species or, simply, the decrease in the relative prop ortion of reworked specimens. Nevertheless, independently of the fact that some species survived the K/T event, the existence of a gradual extinction pattern in the lowermost part of the Danian does not refute the hypothesis of a catastrophic event in coincidence with the K/T boundary. The K/T plank tic foraminiferal catastrophic mass extinction of more than 70% is very com patible with the hypothesis of the impact of a large asteroid and its effec ts in the short, middle and long term.