MACROSTRATIGRAPHY: A QUANTITATIVE FRAMEWORK FOR TESTING THE CAUSES AND CONSEQUENCES OF MASS EXTINCTIONS

Macrostratigraphy is based on the statistical analysis of hiatus-bound sedimentary rock packages. A number of studies have now linked macrostratigraphic quantities to patterns of extinction and extinction selectivity in the fossil record, including extinction and selectivity at the end-Ordovician, planktonic foraminiferal extinction in the open ocean, and Phanerozoic-scale extinction and extinction selectivity among marine animals. Recent work integrating the PaleoDB with the Macrostrat Database for North America has shown that fossil first and last occurrence datums are neither uniformly distributed within hiatus bound sedimentary packages nor are they concentrated at package boundaries in the way that is predicted by sequence stratigraphic models of fossil preservation. We hypothesize that this disconnect in the stratigraphic distribution of fossils at different scales of temporal resolution, and the relationship between macrostratigraphy and macroevolution generally, is related to two different phenomena: 1) biologically important shifts in the geomorphology and environmental heterogeneity of epicontinental seas during the evolution of “second order” (10s Myr) basin fill successions, and 2) an increasingly strong coupling between large-scale Earth systems evolution and patterns of sedimentation with increasing temporal and spatial scale. Recent work interrogating geochemical proxy data for long-term Earth systems evolution, macrostratigraphic data, and the fossil record suggests that Earth systems evolution is an important driver of both macrostratigraphy and macroevolution. Incorporating field-based geochemical data directly into the quantitative framework of macrostratigraphy is likely to provide powerful new tests of the hypothesis that Earth systems evolution is responsible for establishing the physical environmental boundary conditions that promoted perturbations to the ocean-atmosphere system, patterns of sedimentation, and biological turnover.