Evolutionary significance and botanical relationships of cretaceous angiosperm pollen in the western Canadian interior

Abstract

A sequence of angiosperm pollen from the subsurface of southeastern Alberta can be grouped into six distinct palynofloral suites that span Albian to Campanian age strata. These angiosperm pollen species were a part of a terrestrial flora that often was dominated by pteridophyte and gymnosperm taxa. Marine phytoplankton is abundant throughout most of the interval studied, and it provides accurate dating of certain evolutionary or migrational events of the terrestrial flora. The proposed botanical relationships suggest that at least 60% of the total angiosperm flora is represented by taxa whose extant counterparts are distributed in tropical to subtropical regions of the world. Certain evolutionary trends, including aperture type and major exine morphology, suggest that by Middle Campanian time, angiosperm pollen had evolved most of the principal aperture configurations and surface features presently observed in extant angiosperm pollen. These two trends are consistent and distinct enough to establish an evolutionary sequence of pollen morphology for western Canadian Cretaceous sediments.