CAREER: Investigating Controls of Exceptional Fossil Preservation

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Our picture of the history of life has gaps because shelly and boney materials are more likely to be preserved as fossils than soft tissues. This study will focus on some of the most spectacular examples of soft-tissue fossil preservation, known as Burgess Shale type, to understand how these rare fossils form. The Burgess Shale type fossils were preserved after one of the largest and earliest diversification events known in the history of life, the Cambrian Explosion (about 540 million years ago). This project will use micro-scale analyses of fossils, chemical signals preserved in sediments, and laboratory-based decay experiments to provide a better understanding of how Burgess Shale-type fossils form, and to understand the biology of some of our earliest animal ancestors. A key component of this work will be the development of an early animal life education plan designed to reach across the STEM pipeline. It will include components for elementary education, promotion of science to the general public, and contributions to geoscience education at the undergraduate level, the latter of which will continue to shape future generations of early STEM learners beyond the duration of this award. Each case of soft-tissue fossilization can be viewed as a race between destructive decay and constructive mineralization processes. By utilizing laboratory-based decay experimentation in concert with traditional field- and fossil-based approaches, this CAREER award research will provide necessary constraints on the timing and progression of decay-induced loss of biological information and fossilization-imperative mineralization within differing hypothesized (and observed) conditions for the Burgess Shale-type window. In addition to tried-and-true sedimentological, geochemical, and taphonomic approaches, this CAREER award research will utilize a custom-designed scanning electron microscope (supported by NSF EAR IF grant #1636643 to PI Schiffbauer) for significant improvements in fossil and decay-experiment-product microchemistry. Specifically, this instrument has been configured with dual, co-planar energy dispersive spectrometers and a microspot X-ray fluorescence system, coupled with several high-definition imaging detectors, to provide unparalleled fully quantitative and shadow-free microchemical analyses of a wide array of sample types. Fossil analyses and sedimentary geochemistry will focus on four North American, Paleozoic, Burgess Shale-type soft-tissue fossil deposits, which will better frame first-order fossilization processes and paleoenvironmental contexts that may have facilitated this taphonomic expression. This end goal of this study is to provide a refined understanding of how Burgess Shale-type preservation occurs, which in turn will deliver improved comprehension of biological fidelity of the fossil organisms preserved and contribute to a clearer picture of the earliest stages of animal evolution.