FROM MODERN ANALOGS TO THREE DIMENSIONS: LESSONS LEARNED FOR INTERPRETING THE STRATIGRAPHIC RECORD OF THE PROTEROZOIC–PHANEROZOIC TRANSITION

Recently, we took a step back from the crucial job of developing better resolved stratigraphic records of environmental and biological change across the Proterozoic-Phanerozoic transition. Shedding light on the causes and consequences of the radiation of early animals remains our goal, but we found ourselves asking two questions that we did not have good answers to: (1) how do carbonates record seawater chemistry and environmental change; and (2) what can the morphology of a fossil teach us about how early animals engineered structures that altered the physics and chemistry of the water column? To address question (1), we investigated the Great Bahama Bank as a modern environmental analog to many of the shallow water carbonates that host records of the Proterozoic-Phanerozoic transition. To explore question (2), we used a serial grinding and imaging approach to compare putative Ediacaran-Cambrian reef builders to modern calcifying animals in three dimensions. In both cases, these exercises challenged many of our assumptions about how to read the stratigraphic record, and helped us develop new strategies for quantifying uncertainty and building more robust interpretations of the past.