Mississippian Plants from the Parnaíba Basin

The Poti Formation Flora represents the unique record of Mississippian age in Brazil. However, it is not so diverse bearing ten taxa represented by a dwarf lycopsid, shrubby sphenopsids, a putative fern (i.e., Paulophyton sommeri, Paulophyton sp. 1), a microsporangiate fructification (i.e., Kegelidium lamegoi), a cupule, and mainly distinct pteridosperm foliages. Among the pteridosperm foliages, the presence of Diplothmema gothanica, Notorhacopteris cf. N. kellaybelenensis and Fedekurtzia cf. F. argentina is significant. The Poti Flora was considered as part of the warm-temperate Paraca floral realm, a wide belt (approximately 30° to 60° South) extending from the west (South America) up to the east of Gondwana (Australia) during late Mississippian times (late Visean-earliest Serpukhovian). This realm represents a frost-free climate zone that existed in a short warming (greenhouse) interval directly before the onset of the major episode of the Carboniferous (Pennsylvanian) glaciations. It is fundamental to understanding the floristic evolution of taxa in Western Gondwana and even in the world due to a mixture of elements of Euramerican and Gondwanan affinities are present. This flora offers us a rare chance to contribute to the knowledge of ferns with psilophytic habits and non-synangiate microsporangiate fructifications, as well as the first seeds of pteridosperm affinity and the process of terrestrialization in different groups of plants.