The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Community dynamics through space and time in the Hadar and Turkana Basins, Ethiopia and Kenya


1Anthropology, George Washington University, 2Paleobiology, Smithsonian Museum of Natural History

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The Australopithecus afarensis fossil record spans nearly 700,000 years with little observed morphological change. To understand the context of evolutionary stability, this project explores the community structure and species similarities among A. afarensis localities through time in different paleobasins. Mammalian taxa (>1 kg) from A. afarensis localities were categorized into guilds based on dietary, locomotor, and size classes (defined in the Evolution of Terrestrial Ecosystems Database). To compare guild structure across space, the proportion of guilds from the upper Sidi Hakoma Member in the Hadar Formation, Ethiopia, (n=31 taxa) were compared to guilds in the Tulu Bor Member of the Koobi Fora Formation (n=19 taxa) in East Turkana, Kenya, both dated to ~3.4 Ma. Guild structure was compared between all geological members of the Hadar Formation (the Basal (n=31), Sidi Hakoma (n=94), Denen Dora (n=105) and Kada Hadar Members (n=83)) to examine change through time (3.45–2.95 Ma). Using chi squared tests, no significant differences were found between geological members at Hadar, despite a trend toward the environment becoming more arid and seasonal. Significant differences were found across space, however, between the lower Sidi Hakoma Member and lower Tulu Bor Member (p < 0.05). Further, there is no significant correlation between the Jaccard Similarity index and temporal separation between sub members of the Hadar Formation (r2=0.0061). These findings show that community structure within the Hadar Formation remained stable through time despite environmental change and species turnover, suggesting overall stasis in mammalian community composition throughout the Hadar Formation.

This material is based upon work supported by the National Science Foundation Graduate Research Fellowship and The Ford Foundation Predoctoral Fellowship. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors(s) and do not necessarily reflect the views of the National Science Foundation or the Ford Foundation.

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