Isotopic paleoecology (δ13C, δ18O) of two megamammals assemblages from the late pleistocene of Brazilian intertropical region

Abstract

In the late Pleistocene of two localities of Brazilian Intertropical Region (one in Bahia state, and another in Piauí state) lived meso-megamammals herbivores belonging, at least, to three guilds: mixed-feeders (Eremotherium laurillardi, indetermined Equidae, Glyptotherium sp., and Holmesina paulacoutoi), grazers (Notiomastodon platensis, Glyptotherium sp., indetermined Cervidae, and Toxodon platensis) and omnivores (Pachyarmatherium brasiliense). The paleoecologial informations (datings, isotopic diet and niche breadth) were acquired through radiocarbon datings and ratio isotopic analysis of carbon (δ13C). The Notiomastodon platensis from Caetanos, Bahia presents a radiocarbon dating of 23,040 ± 55 14C years BP (25,604–25,203 Cal years BP) showing that it lived in the region in the late Pleistocene. We propose that Notiomastodon platensis (pi > 74%) and Glyptotherium sp. (pi > 76%) had preference for C4 plants, Equidae preferred to eat C3 plants (pi = 62%), while Cervidae and Toxodon platensis were specialists in C4 plants (pi = 100%). Eremotherium laurillardi had a genaralist diet, with preference for C3 plants in Piauí (pi = 66%), and in C4 plants in Bahia (pi = 68%). Holmesina paulacoutoi had a generalist diet, as well, prefering C4 plants (pi = 59%). Pachyarmatherium brasiliense was the unique omnivore in this study, and could explore savanna habitats, searching for food.The δ13O values in Caetanos, Bahia ranged from 27.2% to 29.5% and for São Raimundo Nonato, Piauí, from 29.5% to 32.7%. We suggest that the paleoenvironments in both localities was constitude by dry and open environments.