SILICEOUS DINOFLAGELLATE THECAL FOSSILS FROM THE EOCENE OF BARBADOS

Detailed sampling of Palaeogene sediments from Barbados has resulted i n the rediscovery of the type locality of the rare siliceous dinoflage llate Peridinites. Electron microscopic examination has revealed that Peridinites can only be interpreted as the remains of dinoflagellate m otile thecate cells, rather than hypnozygotic cysts; it thus represent s the first unequivocal example of a fossil dinoflagellate theca. Dino flagellate cysts have also been found and identified as belonging to L ithoperidinium. Both Peridinites and Lithoperidinium are valid genera, and are interpreted as being primarily silicified. Peridinites is thu s the only known dinoflagellate capable of secreting siliceous thecal plates.