CENOMANIAN ANGIOSPERM LEAF MEGAFOSSILS, DAKOTA FORMATION, HOISINGTON III LOCALITY, BARTON COUNTY, KANSAS

A new assemblage of early angiosperm leaf megafossils from the Dakota Formation of Kansas is reported. Approximately 850 specimens examined and 27 species of angiosperm leaves are recognized. Most of them possess combined features of two or more modern families and are only assignable to modern orders. No modern genus is recognized from this locality. Comparisons with other angiosperm leaf megafossil assemblages, e.g., the Rose Creek Locality of Nebraska (Upchurch and Dilcher, 1990), Courtland Locality of Minnesota (Dilcher et. al., in prep.), Braun locality of Kansas (Wang and Dilcher, in prep.) indicate that this assemblage represents the most diverse flora known from the Dakota Formation. Inter-locality comparisons show that there is about 25% or less species overlap between any two localities within the Dakota Formation. Diversity analysis also confirms that the early angiosperm diversity was environmentally controlled.