Nova ocorrência de moluscos bivalves permianos em Itaiópolis, SC: taxonomia e implicações bioestratigráficas

Abstract

Permian fossil record of the Paraná Basin, Brazil, is widely represented by marine invertebrates, such as bivalves and gastropods mollusks, brachiopods and echinoderm. Rocks of the Guatá Group crop out in several localities in the south portion of the country, which were deposited in a post-glacial context during the Permian times. The present study aimed to the taxonomic analysis of a new fossil occurrence of bivalve mollusks of the Rio Bonito Formation, found in Itaiópolis, SC, and to verify if the species of this fauna belong to the same species of Taió, SC. In the taxonomic analysis, 345 samples were examined, in which 122 belong to the Paleontologial Center of the Contestado University, in the Mafra county, State of Santa Catarina and the other samples were collected in the field work. Fossils occur in rocks of the Itaiópolis county, State of Santa Catarina, in the Moema locality, in a rural property of the family Nietzkar. Fauna is represented by the bivalve’s families Heteropectinidae, Deltopectinidae and Pachydomidae, the first one by Heteropecten catharinae Reed (1930)the second by Deltopecten? sp. and the third by Myonia costata Rocha-Campos (1970) e Myonia tayoensis? Reed (1930). This fauna is majority (92,7%) represented by H. catharinae, which is represented by 99% of desarticulated valves, most of them (68,7%) are left valves. This shelly occurrence was deposited in a shallow marine environment, with a long exposition of the bioclasts in the substrate before the final burial. With the exception of Deltopecten? sp., the other species identified in this study also occur in the worldwide known fauna of Taió, in the Santa Catarina State, which occur 130 km from Itaiópolis. Therefore, this study suggests a biocorrelation between these sedimentary deposits, based on taxonomic atributes of faunistic elements, which corroborates stratigraphic and sedimentary data of previous studies.