MESOFOSSILS FROM THE DAKOTA FORMATION

Mesofossils are receiving increased attention by paleobotanists because of their good preservation and abundance in sediments. In the past few years, we collected mesofossils from Dakota Formation sediments (Cenomanian, Mid-Cretaceous) in Kansas and Nebraksa. These sediments yielded more than a hundred of various types of mesofossil plant. These consist of conifer leafy shoots, naked shoots, flowers, seeds, leaves and megaspores of plants including ferns, conifers and angiosperms. These fossils are usually thought to be produced by forest fires, because mesofossils consist of charcoal and are transported to a common depositonal site. Such charcoalified fossils usually preserve very detailed anatomical structures which can be useful to characterize the fossils. Based on our statistical primary data, we compare the frequencies of various fossils in different localities and different horizons in the same locality, and this comparison permits us to tell whether temporary or spatial ( environmental ) factors are major causes of the differences among assemblages of mesofossil floras. This provides us with a tool evaluate about the usefulness of mesofossils in stratigraphy and paleoenvironmental reconstruction.