Paleolimnological inferences based on Oligocene ostracods (Crustacea: Ostracoda) from Tremembé Formation, Southeast Brazil.

Cristianini T Bergue,Gerson Fauth,Maria Da Saudade A.S Maranhão

doi:10.1590/0001-3765201520140366

Cristianini T Bergue, Gerson Fauth + Show 1 more

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https://doi.org/10.1590/0001-3765201520140366

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Abstract

Non-marine Oligocene ostracods from Tremembé Formation (Taubaté Basin, Southeast Brazil) are studied for the first time. The study reveals rich assemblages which are probably composed of many new taxa, two of which are described here. The sixteen ostracod species registered are classified in the generaCypretta Vávra, Strandesia Stuhlmann,Potamocypris Brady, Heterocypris Claus,Eucypris Vávra, Herpetocypris Brady and Norman, Cytheridella Daday and LimnocythereBrady. Two new species of the latter are herein proposed: L. mandubi sp. nov. and L. katu sp. nov. The succession of ostracod assemblages along the studied core changes conspicuously in composition, abundance and preservation, and are characterized by the following associations: Herpetocypris-Cytheridella (lower), Limnocythere-Cypretta (middle) andPotamocypris-Heterocypris (upper). It is assumed that these associations represent different ecological phases of the paleolake Taubaté which is in accordance to previous stratigraphic and paleontological studies in the basin. The results from this pioneering taxonomic and paleoecological study on ostracods from Tremembé Formation reinforce the potential of these fossils for paleolimnological researches in Brazilian Cenozoic deposits.

Highlights

The study of fossil non-marine ostracods in Brazil began in a wide research project set out by Pinto and Sanguinetti (1958) aiming at improving the knowledge and comparative analysis of Early Cretaceous assemblages
The main objectives of this work are to study the taxonomy of ostracods, to interpret the paleoecology of the assemblages and the taphonomy of some specimens
In an attempt to overcome this restraint, the fossil record of nonmarine ostracods in South America was taken into account. This reasoning is based on the assumption that Paleogene non-marine ostracods followed a pattern similar to that of the living ones, i.e., approximately 90% of species and 60% of genera restricted to certain zoogeographical regions (Martens et al 2008)

Summary

Introduction

The study of fossil non-marine ostracods in Brazil began in a wide research project set out by Pinto and Sanguinetti (1958) aiming at improving the knowledge and comparative analysis of Early Cretaceous assemblages. The studies went deep in basins with economic potential, the same did not occur in younger (i.e., Cenozoic) deposits, which data available are scarcer and mostly restricted to the Neogene mixohaline assemblages. The Oligocene non-marine deposits of Tremembé Formation (Taubaté Basin) preserve a vast array of fossils, such as mammals, birds, fishes and plants (Mezzalira 1989). In spite of the abundance of ostracods, there are no published studies describing the assemblages and their paleoecology. The main objectives of this work are to study the taxonomy of ostracods, to interpret the paleoecology of the assemblages and the taphonomy of some specimens.

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