Leptosporangiate ferns

Osmundaceae can be traced back to the Upper Carboniferous. Earlier known reports of leptosporangiate ferns are in the Lower Carboniferous. Subsequent major filicalean radiations during the early Mesozoic resulted in several families with extant representatives, but it was obviously not until the Upper Cretaceous that much of the extant diversity has appeared [365]. Based on coevolution, the Urediniomycetes and Ustilagjonmycetes appeared as distinct lineages at least since the Carboniferous. 

Skog, l.E. (2001). Biogeography of Mesozoic leptosporangiate ferns related to extant ferns. Brittonia 53,236-269. 

Pryer, K.M., Schuettpelz, E., Wolf, P.G. et al. (2004). Phylogeny and evolution of ferns (monilophytes) with a focus on the early leptosporangiate divergences. American Journal of Botany 91,1582-1598. 

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