EAR-PF: The Silicification of Soft-Bodied Biotas: Reconstructing the Preservation, Ecology and Environments of Earth's Earliest Animal Communities

Lidya Tarhan博士被授予美国国家科学基金会地球科学博士后奖学金，以在耶鲁大学和加州理工学院开展一项研究和扩大参与计划，重点关注复杂生命的多样化。她将采用多学科方法，采用新颖的地球化学、岩石学、古生物学和实验技术，研究生物地球化学过程，特别是早期硅化作用在地球最早动物群落化石中的作用。保存完好的软体动物化石组合为研究古代群落和环境的生物学、生态学和化学提供了独特的窗口。开发模型来解释这种特殊保存的化石路径对于重建生物多样化的初始步骤以及早期复杂生命辐射期间普遍存在的环境条件至关重要。此外，Tarhan博士将使用的许多新兴分析技术不仅有助于阐明砂岩中化石的特殊保存过程，而且还有助于阐明早期和晚期胶结作用在砂岩油藏孔隙度和渗透率发展中的作用。她的指导和推广工作将与耶鲁大学皮博迪博物馆的世界级收藏和教育和推广项目一起进行。例如，她将通过参加皮博迪的“进化”课外项目，以及指导本科生的地球科学研究项目，促进科学探究和批判性思维技能的发展，这些学生群体在科学领域的代表性不足。埃迪卡拉生物群（Ediacara Biota）是地球上最早的动物生态系统，保存在世界各地的埃迪卡拉末期（~ 5.8 - 5.41亿年）地层中。埃迪卡拉化石组合由保存异常完好的软体动物组成，它们的形态和亲和力都是谜一般的。大多数埃迪卡拉化石组合都以铸件和模具的形式保存在砂岩层中。然而，对于软体埃迪卡拉生物群和类似的砂岩寄主的年轻生物群是如何被保存下来的机制理解很少，这阻碍了重建这些种子群落的生物学和生态学的尝试。我们对这些生物的生态学知识——这些信息对于分析从埃迪卡拉生物群到显生宙（我们当前的地球历史时期）的动物群过渡以及解决埃迪卡拉-显生宙过渡的生态和生物地球化学特征至关重要——目前是不完整的。充分了解地球历史上这段时期特有的石化途径，对于重建这些早期动物生态系统的复杂性至关重要。这项工作将为埃迪卡拉纪和显生宙早期古生物学长期存在的问题提供线索，并阐明环境在地球上复杂生命的早期发育、辐射和保存中所起的作用。

Dr. Lidya Tarhan has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and broadening participation plan, focused on the diversification of complex life, at Yale University and the California Institute of Technology. Through a multidisciplinary approach, employing novel geochemical, petrographic, paleobiological and experimental techniques, she will investigate the biogeochemical processes and particularly the role of early-stage silicification in the fossilization of Earth's earliest animal communities. Exceptionally preserved soft-bodied fossil assemblages offer unique windows into the biology, ecology and chemistry of ancient communities and environments. Developing models to explain the fossilization pathways responsible for this exceptional preservation is essential to reconstructing the initial steps in biological diversification, as well as the environmental conditions that prevailed during the radiation of early complex life. Further, many of the emerging analytical techniques Dr. Tarhan will utilize may help to shed light not only on the processes responsible for the exceptional preservation of fossils in sandstones, but also the role played by early- and late-stage cementation in the development of porosity and permeability in sandstone petroleum reservoirs. Her mentoring and outreach efforts will be carried out in association with the world-class collections and educational and outreach programs of Yale University's Peabody Museum. For instance, she will foster the development of scientific inquiry and critical thinking skills of student groups underrepresented in the sciences through participation in the Peabody's EVOLUTIONS after-school program, as well as by mentoring undergraduate geoscience research projects.The Ediacara Biota, Earth's earliest animal ecosystem, is preserved in terminal Ediacaran (~580-541 million years old) strata worldwide. Ediacara fossil assemblages consist of exceptionally preserved soft-bodied forms of enigmatic morphology and affinity. The majority of Ediacara fossil assemblages are preserved in situ as casts and molds in sandstone beds. However, there is little mechanistic understanding of how the soft-bodied Ediacara Biota and similar sandstone-hosted younger biotas were preserved, hindering attempts to reconstruct the biology and ecology of these seminal communities. Our knowledge of the ecology of these organisms-information that is essential to analyzing the transition from the Ediacara Biota to the faunas of the Phanerozoic (our current eon of Earth history) and to resolve the ecological and biogeochemical character of the Ediacaran-Phanerozoic transition-is currently incomplete. A full understanding of the fossilization pathways unique to this interval in Earth history is essential to reconstruct the complexity of these early animal ecosystems. This work will shed light on long-standing issues in Ediacaran and early Phanerozoic paleobiology, and also illuminate the role played by environment in the early development, radiation and preservation of complex life on Earth.