The Quaternary vertebrate fauna of the limestone cave Gruta do Ioio, northeastern Brazil

摘要

The present study reports the Quaternary vertebrate fauna of Gruta do Ioio, a partially submerged limestone cave located in central Bahia, northeastern Brazil. A semi-arid weather prevails nowadays in the area, which is mostly covered by a xeric low arboreal scrubland known as Caatinga. The identified taxa include: Rhamdia (Osteichtyes, Siluriformes), Caiman (Crocodyliformes, Caimaninae), Myocastor cf. Myocastor coypus (Rodentia, Myocastoridae), Holochilus sciureus (Rodentia, Sigmodontinae), Natalus cf. Natalus macrourus (Chiroptera, Natalidae), Tonatia bidens, Trachops cirrhosus (Chiroptera, Phyllostomi-dae), and Eira cf. Eira barbara (Carnivora, Mustelidae). Whereas Rhamdia and Caiman have scarce fossil records, the recovered mammals have already been reported from Quaternary localities of northeastern Brazil, although only two of them are present in the current local fauna. Taphonomic signatures and the nature of the fossiliferous site indicate that the vertebrates lived inside or nearby the cave, including the swamp by its main entrance. Radiocarbon dating of dental bioapatite yielded calibrated ages between 19,980 and 22,040 BP. This indicates that the accumulation started at least during the late Pleistocene, within the Last Glacial Maximum. In agreement with the mode of life of most taxa recognized here, previous studies indicated that this was a wetter period in the region.