Hypocystal archeopyles in the dinoflagellate cyst genus caligodinium drugg

Abstract

The unique archeopyle in the dinoflagellate cyst (dinocyst) genus Caligodinium Drugg has previously been regarded as apical gonyaulacalean with the operculum consisting of three partially or completely separated pieces, despite there being a problem with determination of the paraplate relationships. A more logical interpretation would be to regard the opercular pieces as representing the three fundital plates in a peridinialean tabulation, making the archeopyle hypocystal. The apparent stratigraphic range of the Caligodinium type of archeopyle is Albian to Early Miocene, although there is some uncertainty over the archeopyle morphology in the Cretaceous forms.