Ferns from the Permian of the Paraná Basin and Paleoecological Interpretations

Abstract

This chapter presents the Permian ferns and fern-like taxa of the Paraná Basin. They often occur associated with glossopterid leaves, sphenophyte shoots, and some other elements of the Glossopteris Flora. In dozens of outcrops at the eastern border of the basin, the ferns are mostly preserved as pinnae adpressions. Sterile leaves that are assumed to be ferns can be classified as Pecopteris and more rarely as Sphenopteris. Fertile leaf species belong to Asterotheca, Dizeugotheca, Ponsotheca, and “Buritiranopteris-like” ferns. There are also a few petrified stem fragments of Tietea and Psaronius. All taxa are briefly described, exemplified by new illustrations, and commented on its classification. The ferns of several stratigraphic levels provide evidence about the changing paleoecology from early Permian humid-temperate paleoclimates to mid- and late-Permian semiarid-warm conditions. Some ancestors lived in humid tropical regions, as Asterotheca and Psaronius, reached the Paraná Basin after the Permo-Carboniferous glaciation. Dizeugotheca is a still poorly defined genus of Southwest Gondwana. The petrified stems and the Buritiranopteris-like leaves of the Paraná Basin apparently are the only plants shared with the Parnaíba Basin, not necessarily of the same age. Concerning particularly Tietea singularis, its wide translatitudinal dispersal and, in contrast, its endemism to both basins may be related to a relatively high drought-tolerance and increasing aridity in western Gondwana.