Fossils from the Corumbataí and Estrada Nova formations of the state of São Paulo: contributions to paleontology and biostratigraphy

Abstract

Constitution, local and regional ranges and stratigraphic position of fossils of the Corumbataí and Estrada Nova formations sponge spicules, ostracodes, ichthyoliths, coprolites, probable biogenic fragments, charophyte oogonia, stromatolites and bivalves are studied. Micropaleontological analyses allowed to: 1) classify sponge spicules as monaxonid oxeas characteristic of the class Demospongia of the Haploscherida Order; 2) identify, based on the external morphology of the carapace, 16 genera and 23 new species of ostracodes; 3) identify 10 morphotypes of ichthyoliths and 4 types of Paleoniscoidei scales; 4) describe, for the first time in Brazil, a charophyte oogonium occurrence in which the paleozoic specimens could be isolated from the rock matrix. The charophyte may eventually prove to be an index fossil as it has so far been registered only at the top of the Teresina Member of the Estrada Nova Formation; 5) identify two distinct groups of probable biogenic fragments. The study of bivalves was extended to the regions of Santa Cruz das Palmeiras, Tambaú, Porangaba, Angatuba, Guareí, Taguaí and Fartura; it is shown that the biostratigraphic zonation proposed for the Rio Claro region can be applied to other areas of the State. The biozones were widely distributed geographically, as for instance the Pinzonella neotropica-Jacquesia brasiliensis Zone, which extends from the northeast to the southwest of São Paulo State. The lithological and petrographic characteristics and the sedimentary structures associated with the taphonomic and paleoecological features of the bioclasts showed that the fossils of the Corumbataí and Estrada Nova formations do not, in general, correspond to in situ depositions, but were transported and redeposited during sucessive storm events.