Article: A problematical dinoflagellate from the Tertiary of Virginia and Maryland

Inversidinium exilimurum, gen. et sp. nov., a problematical dinoflagellate recovered from the Aquia Formation (Upper Paleocene) of the Virginia-Maryland Coastal Plain, displays an atypical peridinioid outline characterized by a truncated antapex which ruptures to form a hitherto unreported type of antapical excystment apparatus; antapical archeopyles are exceedingly rare among the dinoflagellates.