Dietary and Paleoenvironmental Reconstruction Using Stable Isotopes of Herbivore Tooth Enamel From Middle Pliocene Dikika, Ethiopia: Implications for Australopithecus afarensis Habitat and Food Resources

Authors

Zelalem K. Bedaso, University of South Florida
Jonathan G. Wynn, University of South FloridaFollow
Zeresenay Alemseged, California Academy of SciencesFollow
Denis Geraads, CNRS-UPR 2147

Document Type

Article

Publication Date

1-2013

Keywords

Dikika, Ethiopia, Stable isotope, Tooth enamel, Middle Pliocene, Australopithecus afarensis

Digital Object Identifier (DOI)

https://doi.org/10.1016/j.jhevol.2012.05.015

Abstract

Carbon and oxygen isotopes of mammalian tooth enamel were used to reconstruct paleoenvironments of Australopithecus afarensis from the middle Pliocene locality of Dikika, Ethiopia. Isotopic analyses were conducted on 210 mammalian herbivore teeth from 15 different taxa collected from the Basal Member (∼3.8–3.42 Ma) and Sidi Hakoma Member (3.42–3.24 Ma) of the Hadar Formation. The isotopic analyses aim specifically at reconstructing shifts in the relative abundance of C₄ grasses in mammalian diets, and more generally at paleoclimate factors such as aridity and seasonality, as well as habitat structure. Carbon isotopic data suggest a wide range of foraging strategies, characterized by mixed C₃/C₄ to C₄-dominated diets in wooded grasslands to open woodlands. Weighted average C₄ dietary proportions range between 60% and 86% in the Basal Member and 49% and 74% in the Sidi Hakoma Member. Paleoclimatic conditions based on the reconstructed mean annual water deficit from the δ¹⁸O_enamel values indicate a wetter climate as compared to either the early Pliocene or the Pleistocene nearby. The middle Pliocene habitat structure at Dikika could be as diverse as open grassland and wooded grassland, and woodland to forest in the Sidi Hakoma Member while wooded grassland, woodland to grassland are evident in the Basal Member. All habitats except closed woodland and forest are persistent through both members; however, the relative proportion of individual habitats changed through time. These changes could have put the fauna in competition for preferred habitats and food resources, which could have forced migration, adaptation to other resources and/or extinction. Thus, the existence of A. afarensis throughout the middle Pliocene indicates either this species might have adapted to a wide range of habitats, or its preferred habitat was not affected by the observed environmental changes.

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Yes

Citation / Publisher Attribution

Journal of Human Evolution, v. 64, issue 1, p. 21-38

Scholar Commons Citation

Bedaso, Zelalem K.; Wynn, Jonathan G.; Alemseged, Zeresenay; and Geraads, Denis, "Dietary and Paleoenvironmental Reconstruction Using Stable Isotopes of Herbivore Tooth Enamel From Middle Pliocene Dikika, Ethiopia: Implications for Australopithecus afarensis Habitat and Food Resources" (2013). School of Geosciences Faculty and Staff Publications. 210.
https://digitalcommons.usf.edu/geo_facpub/210