Folhas denteadas da formação Rio do Rasto (Bacia do Paraná, Permiano Superior) e seu possível significado paleoclimatico

Abstract

This paper describes Ilexoidephyllum permicum, a new genus and new species, based on specimes from six outcrops of the Upper Permian Rio do Rasto Formation (Passa Dois Group, Paraná Basin, Brazil). The new species exhibits glossopterid venation, but the leaf margin has spaced, cuspidate teeth not observed in other Late Permian leaf forms, and not in conformity with the diagnosis for the genus Glossopteris, which spiculates the presence of an entire margin. The peculiar margin of J. permicum plus other features also found in some Glossopteris leaves from the same formation, such as rounded or emarginate apex and spatulate shape, associated with the prevalence of small leaf dimensions, may represent xeromorphic adaptations. A tendency for arid conditions during the Late Permian in the region is also suggested by other evidence. Not all the fossil plants present in the Rio do Rasto Formation exhibit xeromorphic adaptations, however, these fossils may represent plants that lived in locally humid settings.