Intra-tooth carbon (δ13C) and oxygen (δ18O) isotope records of Eremotherium laurillardi (Lund, 1842) and Toxodontinae from the Late Pleistocene of northeastern Brazil

During the Pleistocene, South America was inhabited by a diverse range of giant mammals, each with varied ecological and dietary patterns. Isotopic analysis has proven to be a valuable tool in studying the diets and environmental conditions of these extinct animals, providing insights into past ecosystems. The use of carbon ( δ 13 C) and oxygen ( δ 18 O) isotopes allows for the reconstruction of feeding habits and the understanding of climatic variations over time. This study analyzes the carbon ( δ 13 C) and oxygen ( δ 18 O) isotopic variations in three dental fragments: one from the extinct giant ground sloth Eremotherium laurillardi (Lund, 1842) and two teeth from two indeterminate Toxodontinae individuals, recovered from Serra do Medo (Caruaru, Pernambuco state, Brazil). Through serial sampling, we aim to reconstruct dietary habits over time, estimate ecological niche breadth ( B A ), and infer the environmental variations experienced by these animals. For E. laurillardi , δ 13 C values ranged from −3.7‰ to −1.4‰, indicating a mixed diet of C 3 and C 4 vegetation, while the niche breadth ( B A = 0.59 ± 0.11) suggests a generalist behavior. Among the Toxodontinae, distinct patterns were observed: one sample showed δ 13 C values ranging from −2.6‰ to −1.5‰, indicating a mixed diet with a predominance of C 4 plants and a narrower niche breadth ( B A = 0.48 ± 0.07), suggesting a more specialist diet. In contrast, the other sample presented δ 13 C values ranging from −7.9‰ to −3.2‰, which fall within the range expected for a mixed C 3 -C 4 diet, associated with more closed environments. The high niche breadth ( B A = 0.93 ± 0.07) indicates generalist behavior. δ 18 O values ranged from 30.1‰ to 32.0‰, suggesting dry and warm conditions. The results reveal a diversity of dietary strategies among the analyzed individuals, with both generalist and specialist behaviors. Intra-tooth variations in δ 13 C and δ 18 O values indicate changes through time during enamel formation, although the magnitude and significance of these variations were not formally assessed due the absence of direct datings. Moreover, the δ 18 O values observed were consistently higher than those reported for other localities in the Brazilian Intertropical Region, suggesting that these animals inhabited warmer and drier environments. These findings enhance our understanding of the adaptation and ecology of the Late Pleistocene megafauna in response to environmental changes during this period.