Isotopic paleoecology of the Pleistocene megamammals from the Brazilian Intertropical Region: Feeding ecology (δ13C), niche breadth and overlap

Abstract

The extinct megamammals Eremotherium laurillardi (weight 6550 kg), Notiomastodon platensis (w = 6000 kg), Toxodon platensis (w = 3090 kg), Valgipes bucklandi (w = 980 kg) and Equus (Amerhippus) neogaeus (w = 370 kg) are recorded for the late Pleistocene of the Brazilian Intertropical Region. In order to evaluate the isotopic paleoecology (feeding diet, niche breadth and overlap) of these species, 14C dates, δ13C and δ18O analyzes were performed. Our results suggest that E. laurillardi (μδ13C = −4.35 ± 2.87‰; μBA = 0.77 ± 0.25), T. platensis (μδ13C = −5.74 ± 4.80‰; μBA = 0.57 ± 0.40) and N. platensis (μδ13C = −1.17 ± 2.76‰; μBA = 0.56 ± 0.20) were mixed feeders with a wide niche breadth, while E. (A.) neogaeus (μδ13C = 0.73 ± 1.19‰; μBA = 0.38 ± 0.22) was a grazer, and V. bucklandi (δ13C = −10.17‰; BA = 0.13) was a specialist browser. A narrow niche overlap occurred between V. bucklandi and the species that fed principally on C4 plants (>70%; O = 0.24–0.43). In contrast, there was a high niche overlap between E. neogaeus and N. platensis (O = 0.75) and between E. laurillardi and T. platensis (O = 0.86). Therefore, E. laurillardi was probably a key species in this Pleistocene community due to its high body weight and wide niche breadth, suggesting that E. laurillardi was a great competitor for resources in the BIR.