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

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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.