ZOOGEOGRAPHY OF THE EARLY OLIGOCENE BASINS OF WEST EURASIA BASED ON BIVALVE MOLLUSKS

As in the Eocene, the boundary between the Tethyan and North Europe du ring the early Oligocene remained the main zoogeographical boundary of West Eurasia, although it was considerably displaced southward. The T ethys was still a tropical region, but its fauna, which was mainly inh erited from the Eocene, became impoverished. The North European mollus can fauna was considerably renewed and acquired a boreal-subtropical a spect. The German and East Paratethyan provinces were distinguished wi thin this realm. A uniform endemic brackish-water fauna appeared in th e Paratethys after its closing during the late Rupelian.