Platyspermic seeds from the Early Permian of Parana Basin, Brazil

Abstract

This paper results from a taxonomic study of platyspermic seeds from taphofloristic assemblage of the "Toca do Indio Ranch", belonging to the upper portion of the Itarare Subgroup, Municipality of Cerquilho (SP) and a revision of material collected by Millan (1977) from the same area which is deposited in the National Museum of Rio de Janeiro. The assemblage comprises the Transitional Taphoflora (A-B) or the Gangamopteris-Rubidgea-Stephanophyllites association from the type-locality of Northeastern Parana Basin. This taphoflora is Early Permian (Asselian- Early Sakmarian) in age and records the beginning of the colonization of the Parana Basin by the proto-glossopterid and gangamopterid elements of the Glossopteris flora. It is, probably, correlated to the Argentinean "Lubeckense A" Floristic Stage or even a little older. The platyspermic seeds are assigned to the genera Samaropsis and Cordaicarpus. The assemblage is diversified and includes the taxa Cordaicarpus brasilianus n. sp., Samaropsis dolianitii Millan, S. rigbyi Millan, S. tietensis Millan, S cerquilhensis (Millan) comb. nov., S moreirana (White) Millan, S. goraiensis Surange & Lele, S. rugata sp. nov. and S rohnii sp.nov. The record of S. moreirana (White) Millan in the present study is the oldest from the Parana Basin and S. goraiensis Surange & Lele is recognized for the first time outside India. The wide variety of detached seeds reflect the diversification of the gymnosperms in this assemblage, putatively related to the last interglacial event of the Lower Gondwana glaciation in the Parana Basin. Biostratigraphic correlation based on seeds is not possible due to apparent endemic nature of the assemblage and further work in this field is required.