The Neoproterozoic Record of the Origin of Eukaryotes and Biogeochemical Change

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The history of life is recorded in the fossil record. Because significant episodes of global-level environmental change have recurred in the earth's history, it is feasible to predict the effect of current levels of change on the earth's biota, by studying the fossil record before and after those important episodes. Three types of information are necessary to interpret this record effectively: (1) a sound systematic framework (that is, a consistent and biologically meaningful set of names and categories that are based on phylogenetic relationships) for discussing the fossils; (2) reliable stratigraphic placement (that is, a framework for ordering fossil occurrences in space and time); and (3) an independent record of environmental change that allows placement of the biological record in the context of a dynamic planet (lithosphere, atmosphere, hydrosphere, and biosphere). Although such data are routinely available for fossils deposited during the past 540 million years, there is at present no comparable framework for interpreting older fossils, which constitute about 90% of life's history. In this project, the PI proposes to provide detailed systematic, stratigraphic, and environmental data for the fossils of organisms that lived 900-540 million years before the present. This will almost double the period for which the life history of the planet can be studied in detail. More importantly, it is clear that the interval under consideration was a time of profound environmental change that had a major influence on the subsequent course of evolution and, hence, the diversity of life. The derived data will help refine our understanding of a critical period in the Earth's environmental and biological development. The research is also of practical value in that the establishment of a reliable stratigraphic and environmental framework will facilitate resource exploration in rocks containing under exploited petroleum and ore deposits.