Abstract Several lacustrine species of Pleistocene and Recent peridiniacean cysts form archeopyles by means of a single transapical suture, with or without accessory sutures. Previously published records of closely similar structures in marine Cretaceous peridiniacean cysts are documented and reinterpreted, and a further type is described from the Albian of Oklahoma. These bipesioid cysts appear to represent a lineage that diverged from the marine peridiniacean stock in the Early Cretaceous and invaded freshwater environments during the Tertiary, completely abandoning marine environments by the Quaternary.