Author	Dörhöfer, G. and Davies, E.H.
Year	1980
Journal	Life Sciences Misc., Publ. Royal Ontario Museum pp.91 figs.40
Title	Evolution of archaeopyle and tabulation in Rhaetogonyaulacinean dinoflagellate cysts

Abstract D÷rh÷fer, G. and Davies, E.H., 1980; Evolution of archaeopyle and tabulation in Rhaetogonyaulacinean dinoflagellate cysts. Life Sciences Misc., Publ. Royal Ontario Museum pp.91 figs.40 Abstract Jurassic to Lower Cretaceous dinoflagellate cysts from Arctic Canada and Germany demonstrate evolutionary lineages from a Triassic ancestral stock (Rhaetogonyaulax-type). These lineages are based on archeopyle formation, tabulation, and horn development. The evolution of archeopyles can be interpreted as an overlap scheme (imbrication) of plate boundaries. Initial archeopyle formation tends to remain stable through time in the preferred mid-dorsal keystone position. Earliest cyst genera formed disintegration archeopyles which later genera stabilized into fused opercular pieces of definite position, representing all major archeopyle types. A lineage within the Suborder Rhaetogonyaulacineae was developed from the Triassic ancestral stock through the Early to Middle Jurassic phallocystacean cysts, then through the pareodiniacean cysts of the Middle Jurassic to Early Cretaceous times through to the pseudoceratiacean cysts of the Late Jurassic to Early Late Cretaceous. The Pseudoceratiaceae have two intercalary plates within the operculum resulting in the asymmetrical archeopyle suture. Relevant genera of the Rhaetogonyaulacineae are reviewed and reinvestigated using scanning electron and interference contrast microscopy. The families Pseudoceratiaceae, Rhaetogonyaulacaceae, and Pareodiniaceae are emended. The families Phallocystaceae and Baticasphaeraceae are proposed. The first four families together constitute the suborder Rhaetogonyaulacineae. Three new genera are proposed: Dodekovia, Phallocysta, and Susadinium. Nine genera are emended: Aptea, Batiacasphaera, Canningia, Cyclonephelium, Dapcodinium, Imbatodinium, Noricysta, Paragonyaulacysta, and Pseudoceratium. Five new species are proposed: Comparodinium aquilonium, Dodekovia syzygia, Paragonyaulacysta retiphragmata, Phallocysta eumekes, and Susadinium scrofoides.