Palaeoenvironmental and palaeoecological reconstruction during Late Pleistocene-Early Holocene in Mesopotamian and Chacoan regions (Argentina): a mammalian stable isotope approach

SANZ-PÉREZ, DÁNAE; TOMASSINI, RODRIGO; ZURITA, ALFREDO; MONTALVO, CLAUDIA; HERNÁNDEZ FERNÁNDEZ, MANUEL; PÉREZ DE LOS RÍOS, MIRIAM; FIEDRICHS, JUAN; LUNA, CARLOS; DOMINGO, LAURA

Roma

Congreso; XXI Congress of the International Union for Quaternary Research ?Time for Change?; 2023

Sapienza University of Rome

Carbon and oxygen stable isotope composition analyses on fossil bioapatite of herbivore mammals allow inferring palaeoenvironmental, palaeoclimatic, and palaeoecological conditions. δ13C values are used to reconstruct the diets of extinct taxa and their preferential habitats, whereas changes in the δ18O values of obligate drinking animals reflect variations in δ18O of meteoric water, which is controlled by temperature and evaporation rate. With the aim to infer these conditions during the Late Pleistocene-Early Holocene in northeastern Argentina, we evaluated a total of 155 tooth enamel and bone samples of representatives from eight families of herbivores: Glyptodontidae, Pampatheriidae, Megatheriidae, Mylodontidae (Xenarthra), Toxodontidae (Notoungulata), Camelidae, Cervidae (Cetartiodactyla) and Gomphoteriidae (Proboscidea). Samples come from the Toropí/Yupoí Formation (Late Pleistocene, Corrientes Province, Mesopotamian Region) and Río Bermejo Formation (Late Pleistocene-Early Holocene, Formosa Province, Chacoan Region). δ13C values point to the existence of an open environment. Representatives of all families had a preference for mixed C3-C4 plant-based diets, including Cervidae that usually show a C3 plant-based diet. Some individuals of Toxodontidae and Gomphotheriidae retrieved data with a preference for an exclusively C4 diet, indicating the presence of grasslands in Corrientes and Formosa provinces landscapes. No significant differences have been detected for δ18O values between both Quaternary intervals considered, indicating that all the analysed obligate drinkers may have consumed water subjected to the same temperatures and hydrological conditions. It is remarkable that during the latest Pleistocene-earliest Holocene of Formosa province, Camelidae showed a higher δ18O value than the rest of the families, presenting significant differences particularly with Toxodontidae and Glyptodontidae. Considering that the Camelidae genera here included are Lama and Hemiauchenia (nonobligate drinkers), we interpret their δ18O values as a reflection of the evaporation conditions of the vegetation and not of the water bodies. These are the first results of isotope composition applied to mammal communities from the Quaternary of northeastern Argentina. This allows comparisons with other paleocommunities of southern South America to make interpretations on palaeoecological, palaeoenvironmental and palaeoclimatic conditions of the region.