EARLY MIDDLE JURASSIC OSTRACOD MIGRATION BETWEEN THE NORTHERN AND SOUTHERN HEMISPHERES - FURTHER EVIDENCE FOR A PROTO ATLANTIC CENTRAL-AMERICA CONNECTION

Early to Middle Jurassic marine ostracod assemblages from the southwes tern part of the British Isles, North African continental margin and S outh America have yielded taxa which are not known from other parts of Britain and Europe. We discuss the palaeogeographical and stratigraph ical distribution of these taxa, here arranged into ten informal ''gro ups'', from which we infer that benthonic podocopid Ostracoda successf ully migrated between Northwest Europe and the eastern part of Tethys during the Early and Middle Jurassic, not through the main Tethyan sea way but via a proto Atlantic-Central America route supporting previous observations based on macrofossil evidence (''Hispanic Corridor'' of Smith, 1983). Furthermore, the fact that these taxa are absent from co ntemporary European sequences suggests the existence of physical and/o r chemical barriers limiting benthonic faunal exchange between the wes tern part of the British Isles and the rest of north-western Europe, p articularly during the Late Pliensbachian through to Aalenian interval .