This work is a renewal of support for NSf-sponsored research on the Lower Cambrian of the southwestern Great Basin. Previous research examined the taxonomy and paleoecology of faunas in the "pre-trilobite" and Fallotaspis and Nevadella Zones in the White- Inyo region of eastern California and western Nevada. The focus of future research is upon the expansion of this work to include the final portion of the Lower Cambrian, the Bonnia-Olenellus Zone. The research will involve detailed taxonomic, biostratigraphic and paleoenvironmental analyses of newly- discovered and previously known fossils from this stratigraphic interval. In conjunction with our previous studies, this research will provide: 1)new information about the temporal pattern of diversification during the Cambrian radiation event 2) improved and refined regional and interregional biostratigraphic correlations 3) data to aid in reconstruction of the phylogenetic relationships of the early metazoan taxa; and 4) documentation of the influence of changing paleoecologies on the actual nature of the radiation event as well as its apparent record. All of this information is critical to constraining the many hypotheses detailing the processes that might have controlled the diversification of Metazoa.
