Approaches to the analysis of faunal change during the East African Pliocene

Abstract

Vertebrate faunas provide important evidence for the ecological context of evolving hominins over a wide range of scales, from site-specific analysis of taxa directly associated with hominin fossils to faunal trends indicating longterm environmental change that could have affected human evolution. The foundation for all such paleoecological interpretations consists of fossil specimens in their original geological context. Study of fossils in context generates a body of “first-order” evidence consisting of taxonomic identifications of specimens and placement of these taxa in a time/space continuum. Analysis of first-order faunal data in light of additional evidence about taphonomy, sedimentology, geochemistry, and ecomorphology generates a body of “second-order” interpretations. These require additional assumptions and result in evidence for the ecological attributes of a taxon, its habitat, and its temporal and spatial relationships to other taxa. Both first- and second-order data sets can be examined for larger-scale patterns across space and through time. The validity of inferences relating faunal evidence to the ecology of a hominin species requires an additional step, i.e., careful consideration of exactly how the faunal information relates spatially and temporally to hominin remains and archeological sites. Examples of different approaches to using faunal information to infer paleoenvironmental contexts, paleoecological relationships, and long-term ecological trends highlight major issues in faunal analysis and how these relate to understanding the ecological context of human evolution.