Fossil mammals from Lajedo de Soledade, Quaternary of Rio Grande do Norte, Brazil

Abstract

The Lajedo de Soledade site, located in the municipality of Apodi, State of Rio Grande do Norte, is a vast karstic platform formed by carbonate rocks belonging to the Jandaíra Formation (Upper Cretaceous of the Potiguar Basin). The uplift of sedimentary rocks has exposed the formation to processes of erosion and leaching, leading to the creation of ravines and caves. These geological features, during the Quaternary Period, became repositories of sediments containing vertebrate remains. Recent collections conducted by the research team at the Paleontology Laboratory of the Universidade do Estado do Rio de Janeiro in the Araras Ravine and a new analysis of the fossil accumulation in the Leon Ravine have revealed new vertebrate taxa, especially mammals. The taxonomic study of these faunal accumulations identified at least thirteen different mammal taxa: Cerdocyon thous, Leopardus tigrinus, Puma concolor, Panthera onca, Mazama sp., Palaeolama major, Hippidion principale, Cuniculus sp., Euphractus sexcinctus, Glyptotherium sp., Tolypeutes cf. T. tricinctus, Dasypus novemcinctus, and Megalonychidae indet. The mammal taxa discovered in the layers of the Araras Ravine indicate the presence of at least two distinct environments in the Lajedo de Soledade Region: an open environment associated with denser areas resembling the Cerrado Bioma, and a drier environment akin to the current Caatinga Bioma. In the faunal assemblage of the Leon Ravine, four additional mammal taxa were identified: P. onca, Mazama sp., Cuniculus sp., and Megalonychidae indet. The occurrence of Cuniculus sp. serves as a significant historical record for the genus within the state, further reinforcing the hypothesis that the paleoenvironment of the region comprised open areas intertwined with forested environments, potentially featuring small bodies of water. To gain a deeper understanding of the relationship between the ravines and any potential environmental transitions, geochronological, isotopic studies, and other data collections are crucial. Keywords: Pleistocene, Holocene, small-sized mammals, megafauna, paleoenvironment.