Plant Diversity of The Mid Silurian (Lower Wenlock, Sheinwoodian) Terrestrial Vegetation Preserved in Marine Sediments from The Barrandian Area, The Czech Republic

Abstract Plant mega- and microfossils are described from the middle Sheinwoodian of the Barrandian area. The material comes from the Loděnice locality and the same horizon as the earliest unequivocal land plant, Cooksonia barrandei LIBERTÍN, J.KVAČEK, BEK, ŽÁRSKÝ et ŠTORCH. Its age (432 Myr) is inferred from the associated graptolite fauna, including the zonal index graptolite Monograptus belophorus. Megafossils have clear similarity with Cooksonia, due to their dichotomised axes with slightly widened subtending axes bearing putative sporangia. They document some of the plant diversity that was in place when the first proven representative of the genus Cooksonia appeared, and together with dispersed spores they provide strong and important evidence that a diversified terrestrial ecosystem had developed on the Barrandian volcanic archipelago in the peri-Gondwanan realm by the end of the Sheinwoodian Stage of the Silurian Period.