Technical procedure to collect and preserve fossils in mudstones: application in levels with plant remains from the Upper Triassic of Paraná Basin, Brazil

Abstract

This work deals with the possibility of conservation and prevent the loss of plant fossils in pelitic rocks marked by thin lamination. The São Luiz outcrop, in the Rio Grande do Sul state, South Brazil, an exclusive Upper Triassic exposition in Paraná Basin succession, was used as place of testing by its richness and the variety of fossils preserved (animals and plants). The paleofloristic composition is unique to this sector of the Gondwana, with conifers from the Pagiophyllum-Brachyphyllum-Cyparissidium Complex and other gymnosperms preserved in distinct taphonomic ways. The mudstones characterize the middle portion of the profile and indicates a lake deposition influenced by deltas. The friable character of the lithology and its rapid drying after being exposed prevent the getting of complete rests, since their collect to their storage and study, leading to a loss of diagnostic elements. The technique suggested here indicates that their conservation in PVC film and subsequent inclusion in paraffin wax blocks proved to be adequate for the period analyzed.

Key words: technique, conservation, shale, paleobotany, Triassic, Paraná Basin.