Expressipollis striatus n.sp. to anacolosidites striaius n.sp. an upper cretaceous example of suggested pollen aperture evolution

Abstract

Expressipollis striatus and Anacolosidites striatus are new Upper Cretaceous (Campanian) pollen species described from arctic Alaska. E. striatus appears to evolve into A. striatus in less than 100 feet of stratigraphic section, and this change is noted by the apparent modification of a syndemicolpate pollen aperture to a hexaporate pollen aperture in successive outcrop samples.