Cryptospores of Iapó formation: The first evidence of early land plants from Late Ordovician in Paraná Basin, Brazil.

Abstract

Assemblages of cryptospores were reported and detailed for the first time from the Upper Ordovician from Brazil. These assemblages were recovered from diamictites and shales with dropstones of the Iapó Formation, Rio Ivaí Group, Paraná Basin. The analyzed sequence represents the Hirnantian glacial deposits containing well-preserved palynomorphs with low thermal maturity and low total organic carbon. The cryptospore assemblages comprise monads, dyads, permanent tetrads, and polyads, naked or enclosed in an envelope, totalizing 17 species. The associated marine palynomorphs consist of 12 species of acritarchs and prasinophycean algae which are not discussed in detail herein. It is noticied the occurrence of Tortotubus protuberans and abundant black fragments at the lowermost portion of diamictites. The Late Ordovician cosmopolitan assemblages of cryptospores corroborate the early radiation of the land plants in western Gondwana. These results contribute to a better knowledge of Late Ordovician in Brazil and more generally in South America.