Paleobiogeografía y correlaciones bioestratigráficas intercontinentales con carofitas cretácicas y macroforaminíferos paleocenos

Abstract

Cretaceous charophytes and Palaeocene larger foraminifera are facies-linked microfossils used to perform biostratigraphic correlation between distant basins, in Eurasia (charophytes) or the whole Tethys (larger foraminifera). The capability of these organisms for dispersal and colonization is analysed and appears to be dependent both on palaeoecological and palaeobiological factors. During the Cretaceous of the Northern hemisphere, Clavatoracean charophytes include five cosmopolitan or subcosmopolitan species. They display a generalistic range of habitats (from fluvial siliciclastic to alkaline lacustrine and brackish) and conjoint gametangia (monoecious) allowing them to colonize effectively new sites and disperse. Palaeocene Tethyan larger foraminifera that show a large distribution live in the deeper parts of shallow platforms, a habitat where the taxonomic diversity within the group is low. Significant for the long range geographic expansion of larger foraminifera is the possibility to catch planktonic algae to establish the species-specific endosymbiosis that characterize the group. In spite of being so different, both case-studies suggest that there are common patterns of biogeographic behaviour of this kind of facies-linked microfossils, which could lead to propose a model of biogeographic constraints in long distance biostratigraphic correlation