The critical role of accurate fossil identification: the case of the ostracods of the Codó Formation, NE Brazil

Abstract

The Class Ostracoda comprises bivalve microcrustaceans with great diversity and abundance in the Lower Cretaceous paleolakes of Brazil and the world. With species generally well-preserved and of relatively short biochrons, it has provided high-resolution biostratigraphic frameworks that permit long-distance correlations. In this context, the Lower Cretaceous biozones of the NE Brazilian basins have allowed the establishment of correlations between coeval geological sections not only in this region but also with those of the Brazilian marginal basins, including the rocks of the pre-salt deposits, as well as with West African basins. In addition to biostratigraphy, these microfossils have proved indispensable in paleoenvironmental and paleogeographical analyses, including studies on the opening of the South Atlantic Ocean. However, some publications have emerged that, regrettably, exhibit errors in species identification and/or the accurate interpretation of biostratigraphic works. These mistakes have led to proposed modifications in both the biochron and geographic distribution of index taxa and taxonomic synonymizations that are incongruent with the current state of knowledge of the species. Consequently, these inaccuracies have given rise to erroneous biochronostratigraphic correlations and paleoenvironmental inferences. In this context, we meticulously examine the current understanding of the taxonomy of ostracods from the Codó Formation (NE Brazil), which is essential for the debate on the use of Lower Cretaceous ostracods in stratigraphy. Keywords: biostratigraphy, paleoecology, microfossils, Lower Cretaceous, Brazil.