Quantitative biogeography of Cretaceous planktonic foraminifera from the North Atlantic and circum-Mediterranean

Upper Albian and Cenomanian planktonic foraminiferal faunas from seven circ um-European open ocean sections and one southern hemisphere high-latitude s ection were studied quantitatively, and biogeographic patterns were compare d to those in the Maastrichtian. Lower Cenomanian biogeographic contrasts a r-e weak, but middle and upper Cenomanian sections show distinct provinces. By that time, North Atlantic faunas were distinct from circum-Mediterranea n faunas, a biogeographic pattern that is similar to that in the Maastricht ian. Upper Albian geographic coverage is too limited to determine biogeogra phic patterns. Mid-Cretaceous planktonic foraminifera as a group were less diverse globall y than during the Maastrichtian, but still, biogeographic contrasts between regions as well as latitudinal gradients in relative diversity were more o r less similar in both periods. Presumably, surface water circulation patte rns, which are mostly determined by physical processes and basin geometry, were more important for the geographic distribution of Cretaceous faunal pr ovinces than actual the climatic conditions. which changed considerably fro m mid-Cretaceous to Maastrichtian times.