Estudo taxonômico de fósseis de mamíferos (Mammalia) de médio e grande porte do depósito sedimentar Quaternário da Ravina das Araras, Apodi, Rio Grande do Norte

Abstract

The Lajedo de Soledade, located in the municipality of Apodi/RN, corresponds to a large karstic sidewalk formed by carbonate rocks belonging to the Jandaíra Formation. The uplift of the sedimentary rocks exposed the formation to erosion and leaching, which originated the structures currently found in the region, such as ravines and caves that, during the Quaternary period, were filled by sediments and vertebrate remains. Recent collections made by the UERJ Paleontology Laboratory team in the Quaternary deposit of Araras Gully, at Lajedo de Soledade, brought to light new vertebrate remains, especially a wide variety of mammalian forms. The collection was carried out with stratigraphic control, where three fossiliferous layers were identified. The taxonomic study identified seven mammal species, these are: Hippidion principale; Palaeolama major; Puma concolor; Panthera onca; Dasypus novemcinctus; Euphractus sexcinctus; Tolypeutes cf. tricinctus. The biostratigraphic distribution of the species showed that: in Layer A, more basal, with a majority occurrence of extinct animals (Hippidion principale and Palaeolama major) corresponds to an environment of open fields (savannas) associated with forested environments; Layer B, intermediate, with occurrence of extinct animals (Hippidion principale and Palaeolama major) and living animals (Puma concolor, Panthera onca, Dasypus novemcinctus, Euphractus sexcinctus and Tolypeutes cf. tricinctus) represents a moment of faunal and environmental transition, where the savanna environment, with forested areas (more humid) is gradually replaced by a Caatinga environment (drier); finally, Layer C, closer to the surface, has basically records of living animals (Puma concolor, Panthera onca, Dasypus novemcinctus, Euphractus sexcinctus, and Tolypeutes cf. tricinctus) showing an environment similar to the present one. The taxonomic study and its paleoenvironmental implications showed a moment of faunal and environmental transition during the Late Pleistocene and Holocene Groenlandian for the Lajedo de Soledade Region. However, geochronological and isotopic studies of the material studied, of material collected in other ravines and new collections are necessary for a more precise understanding of this environmental transition.