Siliceous dinoflagellate thecal fossils from the Eocene of Barbados

Detailed sampling of Palaeogene sediments from Barbados has resulted in the rediscovery of the type locality of the rare siliceous dinoflagellate Peridinites. Electron macroscopic examination has revealed that Peridinites can only be interpreted as the remains of dinoflagellate motile thecate cells, rather than hypnozygotic cysts; it thus represents the first unequivocal example of a fossil dinoflagellate theca. Dinoflagellate cysts have also been found and identified as belonging to Lithoperidinium. Both Peridinites and Lithoperidinium are valid genera, and are interpreted as being primarily silicified. Peridinites is thus the only known dinoflagellate capable of secreting siliceous thecal plates. -Authors