There is a great diversity of works on tanks in Bahia that deal with taxonomic aspects, while taphonomic studies are still scarce. The study of taphonomic signatures allows a better understanding of them and enhances the paleoenvironment reconstructions. Therefore, this work aimed to describe and interpret taphonomic signatures in fossils from the Lagoa Escura tank in the municipality of Santaluz, Bahia, in order to improve the understanding of the preservation of fossils in natural tanks and infer paleoenvironmental aspects of northeastern Brazil during the Quaternary. The fossiliferous accumulation of Lagoa Escura is taxonomically diverse, recording seven taxa of fossil mammals. The abundance of Eremotherium laurillardi in the accumulation may be a result of the great abundance that this species had in the paleocommunity and the resistance of its bones. The Lagoa Escura thanatocenosis is a peripheral assemblage, which at times experienced a short period of subaerial exposure, before burial and short-distance transport, probably through floods. We observed that the fossils with the coloration with strong shades of black, brown and red have as the most frequent minerals iron oxide and manganese oxide. Permineralization and substitution are the main fossildiagenetic processes present in fossil of the Lagoa Escura tank.