CAREER: Investigating Controls of Exceptional Fossil Preservation

我们的生命历史图景有差距，因为贝壳和骨质材料更有可能作为化石保存下来，而不是软组织。这项研究将重点关注一些最壮观的软组织化石保存实例，即伯吉斯页岩类型，以了解这些稀有化石是如何形成的。伯吉斯页岩型化石是在生物史上已知的最大和最早的多样化事件之一寒武纪大爆发(约5.4亿年前)之后保存下来的。该项目将使用对化石的微观分析、保存在沉积物中的化学信号以及基于实验室的衰变实验，以更好地了解伯吉斯页岩型化石的形成，并了解我们一些最早的动物祖先的生物学。这项工作的一个关键组成部分将是制定一项旨在跨越STEM管道的早期动物生命教育计划。它将包括基础教育的组成部分，向公众推广科学，以及对本科生的地球科学教育做出贡献，后者将在本奖项有效期结束后继续塑造未来几代早期STEM学习者。软组织石化的每一个案例都可以被视为破坏性腐烂和建设性矿化过程之间的一场竞赛。通过利用实验室衰变实验与传统的野外和化石方法相结合，这项职业奖研究将为Burgess页岩类型窗口不同假设(和观察到的)条件下腐烂导致的生物信息丢失和石化必备矿化的时间和进程提供必要的约束。除了久经考验的沉积学、地球化学和挖掘学方法外，这项职业奖项研究还将利用定制设计的扫描电子显微镜(由美国国家科学基金会EAR IF授予Pi Schiffbauer的1636643号赠款支持)，以显著改进化石和衰变实验产品的微观化学。具体地说，这台仪器配备了双面共面能量色散光谱仪和微斑点X射线荧光系统，再加上几个高清晰度成像探测器，可以提供无与伦比的全面定量和无阴影的多种样品类型的微量化学分析。化石分析和沉积地球化学将侧重于四个北美、古生代、伯吉斯页岩型软组织化石沉积，这将更好地勾勒出可能促进这种挖掘表达的一级化石过程和古环境背景。这项研究的最终目标是提供对伯吉斯页岩型保存如何发生的精细理解，这反过来将有助于更好地理解保存下来的生物化石的生物保真度，并有助于更清晰地描绘动物进化的最早阶段。

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.