Early Hominin Paleoecology

1. Faunal Approaches in Early Hominin Paleoecology

3 1 Faunal Approaches in Early Hominin Paleoecology Kaye E. Reed, Lillian M. Spencer, and Amy L. Rector The paleoecology of early hominin species is more than simply reconstructing the habitats in which they existed. Ultimately we would like to know the ecological context before and after speciation and extinction events, and about the interactions of hominins with their environment, including other species. A first step toward this goal is to discover as much information as possible regarding the climate, geomorphology, vegetation physiognomy (habitat structure), and the faunal community. These factors build on one another such that climate, soil properties, and geomorphology are responsible for the vegetation, which, in turn, plays a fundamental role in controlling what other life forms can be supported. An understanding of extant African habitats is necessary to reconstruct ancient vegetation physiognomy for early Pliocene hominins. An appreciation of living mammals is also important in interpreting Pliocene environments when using faunal techniques.The most common data recovered with early hominins are other mammalian fossils, and these are targeted here for explaining how reconstructions of habitat and community ecology can be approached. Faunal analyses can be compared with other types of research such as palynology, fossil botanical studies, and isotopic analyses of soils and teeth to arrive at a better understanding of hominin paleoecology. Fossil mammals found within the same deposits as early hominins can be used to answer a variety of questions relating to evolutionary paleoecology. First, fossil DOI: 10.5876/9781607322252:c01 kaye e. reed, lillian m. spencer, and amy l. rector 4 mammals have been used as indicators of habitats since early paleontological studies (e.g., Ewer 1958; Brain 1967; Leakey and Harris 1987). More recent work on this topic has emphasized the importance of determining taphonomic histories before reconstructions are attempted (e.g., Behrensmeyer and Hill 1980; Brain 1981; Behrensmeyer 1991; Soligo and Andrews 2005; Andrews 2006), but this caveat is still only rarely addressed. The majority of African hominin paleoecological work falls into the category of using faunal analyses for reconstructing ancient habitats, and forms the bulk of the work reviewed here. Second, studies of contemporaneous fauna are critical for investigating aspects of community ecology, such as guild structure. This avenue of research can be also used to determine possible differences between ancient Plio-Pleistocene and extant communities (e.g., Janis et al. 2004). Third, faunal studies can give insights into how hominins might have interacted with specific members of their shared community. For example, study of the members of the carnivoran guild (Marean 1989; Lewis 1997) can lead to hypotheses about how hominins might have avoided predation or competed with predators for access to meat. Finally,faunal studies can be used to answer questions of patterns and processes in the evolution of both hominins and other mammalian lineages (e.g., Vrba 1988, 1995; Behrensmeyer et al. 1997; Potts 1998; Bonnefille et al. 2004). Faunal approaches in hominin paleoecology can be assigned to two types of studies. The first is analyzing individual fossil species of mammals and other fauna found at particular localities.This information can be used to reconstruct habitats and to look at species interactions with hominins. It is also a critical precursor for community studies.The second type of study examines communities as a whole,which is necessary for studies of community ecology and also for investigating evolutionary patterns in hominin lineages. A second dichotomy exists between the taxonomic and ecological/functional approaches to faunal research. In taxonomic analyses, phylogeny plays an important role. Taxonomic methodologies are used occasionally to reconstruct environments (e.g., Vrba 1980), but the usual focus using these methods is to examine biogeographic and species-turnover patterns (Behrensmeyer et al. 1997; Bobe and Eck 2001). The second approach is often referred to as taxon free because species diversity, ecological diversity, or the results of functional studies are ecological representations of each species. Damuth (1992) has argued that results derived from these types of taxon-free data transform species-specific fauna, and by extension assemblages or communities, into parameters to be incorporated into ecological patterns that can then be compared with any other faunal community in space and time since the parameters used are not taxon specific. For example, it might be difficult to compare an faunal approaches in early hominin paleoecology 5 Australian Macropoda (kangaroo) to an African Damaliscus (topi) on a phylogenetic level, but to compare them as terrestrial grazers of similar...