The proposed research will attempt to demonstrate that information from modern mammalian communities and those preserved in the recent fossil record is pertinent to understanding mammalian community organization past and present. A model of community organization in relation to one of its important causes -- climatic conditions -- based on both modern and late Quaternary communities should be more powerful than a model based on modern communities and climates alone. The inclusion of late Quaternary mammalian faunas and climates broadens the information base and also adds communities and environments more similar to those of the Tertiary than any extant ones are. Previous studies of size distributions in mammalian communities as well as a pilot study presented here suggest that regularities are present in community structure under similar environmental conditions despite differences in location and taxonomic composition, but these regularities remain to be quantified. Quantification of the relationship between environmental parameters and the distribution of species' sizes and feeding habits will serve to clarify and measure the strength of this relationship. If this relationship is strong, then it can serve as the basis for a quantitative method for estimating paleoenvironmental conditions in older mammalian communities. In addition, this study will provide hypotheses of the adaptive significance of size-change during the Cenozoic record of changing mammalian faunas and environments.. These specific goal can also be generalized to allow analyses of environmental changes through time .
