EVOLUTION AND PALAEOGEOGRAPHIC DISTRIBUTION OF ORBITOLINIDS (LARGER FORAMINIFERA) IN THE URGONIAN CARBONATE PLATFORMS OF SW EUROPE. COMPARISONS WITH CARIBBEAN TETHYAN SPECIES

During the Hauterivian-Aptian interval, extensive carbonate platforms developed in wide areas of SW Europe (Urgonian facies). Stratigraphic calibration has been made possible by orbitolinid larger foraminifera, being excellent markers for correlating the different platforms and at the same time very useful for palaeogeographic reconstructions. Within the time interval Hauterivian-early Aptian four phyletic lineages have been reconstructed in the western Mediterranean area: 1. Praedictyorbitolina-Dictyorbitolina, 2. Valserina-Eygalierina, 3. Montseciella-Rectodictyoconus, 4. Eopalorbitolina-Palorbitolina. Shortly after his first occurrence in SW Europe (late Barremian), Palorbitolina lenticularis arrived at the American continent (Flemish Cap, NW Atlantic). This dating shows its spreading from E to W, favoured by Tethyan transoceanic currents, and may be related to the meroplanktonic stage of the megalospheric embryos, and a subsequent phase as epiphytic organisms. Orbitolinid fauna from late Aptian – Albian platform deposits of the Gulf of Mexico area are mainly characterized by representatives of the phylogenetic lineage Praeorbitolina-Mesorbitolina being wide-spread in the Tethyan realm. However, primitive orbitolinids of the same interval (Dictyoconus walnutensis, Paracoskinolina sunnilandensis) are limited to the Gulf region; records of these taxa in the European Tethyan realm are incorrect, thus excluding a migration from W to E.