Paleoecology and Taphonomy of Ediacaran macrofossils from the Khatyspyt Formation, Olenek Uplift, Siberia

Abstract

The Ediacaran Period (635 – 541 Ma) is a critical transition in the history of the Earth and life. It is marked by the appearance of enigmatic Ediacara-like fossils and macroalgae, which had existed since the early Proterozoic, but started to diversify morphologically and ecologically during this geological period. Nevertheless, paleontologists have been studying Ediacaran fossils for more than a century, the key questions about these fossils remain unanswered, including their phylogenetic affinities, taphonomic history, ecology, and paleoenvironmental distribution. Thus, new ways of investigation need to be employed to unveil enigmas of Ediacaran organisms. As well as, scientists need to engage other representatives of Ediacaran assemblages, such as macroalgae, to fully understand how those communities operated in the past.

The chapters of this original research in this dissertation demonstrate innovative approaches and methods for studying the paleoecology and taphonomy of Ediacaran macrofossils. The second chapter presents the results of a geochemical analysis to resolve taphonomic and paleoecological questions about the Ediacara-like discoidal holdfast fossil Aspidella. Stable isotope data of organic carbon, carbonate carbon/oxygen, and pyrite sulfur were integrated with iron speciation data to reconstruct the taphonomy, paleoecology, and paleoenvironments of Aspidella fossils. The third chapter presents results from a comprehensive analysis of macroalgae from Proterozoic to early Paleozoic. In this study, a database of macroalgal fossil was updated and analyzed in order to gain insights into the big-picture evolutionary patterns of macroalgal morphology and ecology through time. These methods and approaches offer new opportunities to test major paleobiologic and geobiologic hypotheses, thus improving our understanding of the history of the biosphere and the Earth system.