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Abstract

The Late Cretaceous pathways of ocean circulation differ fundamentally from modern oceanographic settings and were constrained primarily by the paleogeographic continental constellation of the past. We have conducted a detailed biogeographic analysis of the global distribution of 25 of the most common genera of Late Cretaceous (Santonian–Maastrichtian) larger foraminifera from tropical and subtropical latitudes. We have established a global data base for Late Cretaceous larger symbiont-bearing foraminifera to compare the extent of biogeographic provinces, to analyze distributional patterns of genera and patterns of biodiversity, and to examine geological factors regulating shifts and pathways in the evolution of diversity through time. The analysis of distributional patterns in Cretaceous larger foraminifera (Santonian/Maastrichtian) exhibits prominent biogeographic patterns that reveal extents over regional, superregional, and circumtropical levels. The spatial patterns that emerge from these studies are used to highlight some of the environmental variables exerting control over the biogeographic distribution of larger foraminifera in time and space. The biogeographic patterns observed are strongly constrained by a complex and intriguing mixture of geological history, physical oceanography, and protistan biology. The latitudinal ranges of individual genera may provide clues to infer sea-surface temperature (SST) ranges and the heat transfer regulated by the major ocean current regimes. The longitudinal range of taxa is applied as a measure for dispersal capabilities as controlled by the prevailing currents and SST patterns. The biogeographic data compiled also allowed us to assess diversity patterns among assemblages of larger foraminifera from different localities in the Late Cretaceous oceans and to identify hotspots of diversity.

Presence–absence patterns and distributional extents of key taxa suggest the existence of four major biogeographic provinces: the Caribbean, the “European” Tethys, the North African Tethys, and the Indo-Asiatic provinces. The biogeographic provinces appear to be constrained mainly by the “circumglobal” Cretaceous current-system dynamics and the prevailing temperature gradient at the ocean surface. The biogeographic pattern of generic diversity of Late Cretaceous larger foraminifera correlates with the size and extent of shallow-water shelf and reefal areas present in the Cretaceous oceans. The Late Cretaceous hotspot of larger foraminiferal diversity is centered in shallow-water areas of the European Tethys, the largest reef and shelf region at this time.

Geologic Problem Solving with Microfossils: A Volume in Honor of Garry D. Jones

SEPM Special Publication No. 93, Copyright © 2009

SEPM (Society for Sedimentary Geology), ISBN 978-1-56576-137-7, p. 187–232.

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