The Utilization of Geographic Information Systems (GIS) for Inferring the Paleoenvironment of the Koanaka Hills

Many methods for reconstructing paleoenvironments from small mammal fossils are presently used including the analysis of isotopic ratios, dental micro-wear patterns, dental morphology and faunal turnover. Geographic Information Systems (GIS) based analyses are currently emerging as another powerful tool in paleoenvironmental reconstructions. GIS models, for example, allow for the prediction of past environments by analyzing the tolerances of modern taxa that have persisted relatively unchanged throughout the Plio-Pleistocene. These tolerance ranges are then applied to areas where these taxa are known to have occurred in the past. In order to better understand the past environment of the Koanaka Hills locality in northwestern Botswana, our analysis focuses on the modern distributions of southern African gerbils of the genus Tatera (Rodentia: Gerbillinae). The Koanaka Hills locality is a Plio-Pleistocene cave site with a large and diverse small mammal assemblage. Excavations at the site have produced at least two different members of the genus Tatera. Multiple taxa are still found in southern Africa today and are geo-referenced here along with their associated substrate type, mean annual precipitation and the annual temperature ranges. While their presence is often cited as evidence for an arid, savanna environment, these taxa show environmental tolerances that range from xeric to mesic and from desert to woodland habitats. The results of our analysis suggest that the Koanaka Hills environment of the Plio-Pleistocene could have differed greatly from the dry savanna environment known there today and which has been suggested as occurring during the late Pliocene. The environmental tolerances of the modern representatives of Tatera provide a baseline to which data from other taxa can be added to further refine our interpretations of this site's past environment.