XVI International Botanical Congess
Megafossil evidence of ferns in the Mesozoic is assessed and plotted on paleogeographic maps from early and late Triassic, early, middle and late Jurassic, and early, middle, late, and latest Cretaceous. Families emphasized are the Matoniaceae, Dipteridaceae, Gleicheniaceae, Dicksoniaceae, Osmundaceae, and Schizaeaceae because of the more definitive family assignments of the fossil material. Some of the more modern families will be noted as first occurrences during the Mesozoic, such as the aquatic ferns, Dryopteridaceae and Pteridaceae s.l. Distributions will be compared to continental positions, topographic features, atmospheric circulation and rainfall patterns. The last appears to provide the best fit for those patterns of distribution which can be well-documented.