Isotopic insights into the Early Acheulean (1.95 Ma-1.66 Ma) high-elevation paleoenvironments at Melka Kunture (Upper Awash, Ethiopia)

Abstract

Abstract In this paper, we present carbon and oxygen stable isotope analysis of fauna tooth enamel from Garba IVD (~1.95 Ma) and Gombore IB (~1.66 Ma), two Early Acheulean sites of Melka Kunture (Upper Awash, Ethiopia) and discuss faunal taxonomy and fossil pollen. Our aim is to infer the diet, habitat, and environment at both sites and provide a broader paleoecological reconstruction. During the Pleistocene, the vegetation of the highlands of Ethiopia belonged to the “Dry evergreen Afromontane Forest and grassland complex”, distinct from the savanna of lower elevations in East Africa. Our carbon isotopic results indicate that all the analyzed faunal taxa were grazers, consuming C4 grasses, while oxygen isotopic results clearly discriminate the taxa according to their semi-aquatic or terrestrial habitats. These results are consistent with the analysis of the faunal assemblages and the palynological results, suggesting extended mountain grasslands in the landscape at Garba IVD. In contrast, the carbon isotopic results do not totally agree with the pollen paleoenvironmental reconstruction at Gombore IB, where the open vegetation was interrupted by forests and bushy vegetation. Stable isotopes and pollen data provide different outcomes (feeding strategies vs. nearby plants) and have different temporal and spatial resolutions. This is relevant when reconstructing past environments by exclusively using independent proxies. Furthermore, isotopic comparisons with other East African archaeological sites of the Lower Pleistocene age indicate that all the analyzed taxa fed on C4 grasses, and that their dietary strategies were not affected by differences linked to various elevations.