Article: Dinoflagellate cysts from the Bearpaw Formation (?Upper Campanian to Maastrichtian) of Montana

A dinoflagellate cyst assemblage is described from the Bearpaw Formation of Montana, U.S.A. Deflandrea montanaensis sp. nov. is described. Archeopyle formation in Senegalinium tricuspis (O. Wetzel) comb. nov. is demonstrated to be of the large intercalary type, and this, together with its basic cavate morphology, allows for the recombination of the species. Also recombined are S. magnifica (Stanley). ?S. albertii (Corradini), S. boloniensis (Riegel), S. gaditanum (Riegel), ?S. kozlowskii (Gorka), S. pannuceum (Stanley), S. pentagonalis (Corradini), and 5. subquadratum (Corradini). The Bearpaw Formation in Montana, on radiometric and on dinoflagellate cyst evidence is younger than that seen in southern Alberta, and may include strata encompassing the Campanian-Maastrichtian boundary.