PALEOECOLOGY OF THE EARLIEST CAMBRIAN BIOMINERALIZING ORGANISMS IN WESTERN NORTH AMERICA

The first biomineralizing metazoans appear in Precambrian-Lower Cambrian strata, and these shelly organisms have yet to be placed into a context that accurately reflects the non-actualistic paleoecological conditions of latest Ediacaran and earliest Cambrian seafloors. This research uses morphological, sedimentological and geochemical analyses to test the hypothesis that this radiation of biomineralizers was strongly affected, at least in part, by a shift in seafloor conditions during the Precambrian-Cambrian transition. Typically there have been two approaches which have been used in investigations of the earliest shelly fauna: 1) a paleobiological approach that focuses on the small shelly fossils without significant emphasis on their environment and how it may have affected their evolution; and 2) a sedimentological approach which investigates the paleoenvironmental factors that affected marine communities during the Precambrian-Cambrian transition without significant emphasis on biological dynamics. The paleobiological approach involves analysis of a variety of skeletal materials which are typically dissolved from calcareous strata with weak acid. The sedimentological approach includes data collection pertaining to geochemical, paleoenvironmental and paleogeographical influences on these benthic marine communities. Samples collected from measured sections of the Deep Spring Formation from the White-Inyo Mountains in eastern California were used for this research. The majority of related previous research has taken only one of the aforementioned approaches, while the importance of this invistigation is that it is the first step in effectively combining fossil analysis with the rock data to form a cohesive paleoecological context for this early window of rapid evolution for biomineralizing metazoans.