Dantas, M. A. | bioRxiv Science

bioRxiv2022

An attempt at restoring original radiocarbon ages in collagen from bioapatite

In the literature there is a consensus that radiocarbon dating performed in bioapatite presents younger datings than those performed in collagen, thus, we propose a general regression that could be used to convert the radiocarbon dating performed in bioapatite to the original ones in collagen in fossil samples all of the world. This general regression presents several good indexes of quality, high correlation (R2 = 0.98), lower values of percent predicted error (%PE = 0.01), and the standard error of the estimate (%SEE = 25), showing that is a good tool, as the predicted values are similar to those observed. Using this regression we converted the radiocarbon datings in bioapatite to collagen made for several taxa from the Brazilian Intertropical Region, and suggest that these datings could be 1-7 Cal BP kyr older than previously thought.

paleontology↗

bioRxiv2018

Integrative isotopic Paleoecology (δ13C, δ18O) of a Late Pleistocene vertebrate community from Sergipe, NE Brazil

Isotopes are one of the best tools to reconstruct the Paleoecology of extinct taxa, yielding insights about their diet (through carbon; C3 and C4 plants), niche breadth (BA) and the environment in which they lived. In the present work we go deeper in the use of isotopes and explore a mathematical mixing model with the stable isotopes of two elements (carbon and oxygen) to (1) suggest the relative contribution of four types of food resources (leaves, fruits, roots and C4 grass) for meso- and megaherbivores (weight > 100 kg) that lived in the Late Pleistocene of Poco Redondo, Sergipe, Brasil, and (2) evaluate which of these herbivores could be the potential prey for the carnivores Smilodon populator and Caiman latirostris. To explore the intra/interspecific competition of these fauna, we generate weight estimation, standardized niche breadth (BA) for the meso-megamammals from Sergipe and compare with data from the meso-megaherbivores from Africa, concluding that Eremotherium laurillardi and Toxodon platensis were the best resource competitors in the Late Pleistocene of Sergipe, and reinforcing their importance as key species in this extinct community. Finally, we reconstructed the paleoenvironment in which the vertebrate community of Sergipe lived, estimating Mean Annual Temperature ({degrees}C), Mean Annual Precipitation, Biomass and Energy Expendidure, noting that environments in the Late Pleistocene of Sergipe were similar to those of Africa nowadays, but hotter and with more energy expenditure for these meso-megamammals.

paleontology↗