We will gain new information regarding the marine environmental conditions and the organic food sources that sustained the enigmatic fauna called the ediacaran biota; which were the first macroscopic,…

This is a $336,967.00 grant awarded by the Shared Services Center, a civilian agency, to the Regents of the University of California at Riverside (UC Riverside) to conduct research related to the Ediacaran biota - the first macroscopic, multicellular organisms that evolved on Earth. The research aims to gain new information about the marine environmental conditions and organic food sources that sustained the Ediacaran fauna. The project will involve detailed geochemical analyses of samples from multiple cores across Russia and Ukraine to map Ediacaran biomarker assemblages and assess microbial community structures and primary productivity modes during this important period of early animal evolution. This research directly supports the NASA Exobiology goal of understanding the biological and environmental factors leading to the origin and diversification of eukaryotes and the development of multicellularity. The grant has an ultimate completion date of June 10, 2023 and does not have a set-aside designation.

We will gain new information regarding the marine environmental conditions and the organic food sources that sustained the enigmatic fauna called the ediacaran biota; which were the first macroscopic, multicellular organisms that evolved on our planet. Exceptionally preserved biomarker lipids in thermally immature sedimentary organic matter in 560-540 million-year-old marine rocks from baltica, together with stable isotopic (c and n) stratigraphic records, will allow US to assess marine microbial communities and modes of primary productivity (bacterial versus algal) in the shallow-marine settings where early animals flourished during an important period with dramatic fluctuations in climatic and environmental conditions. Ediacaran oceans likely maintained strong heterogeneity in chemical conditions including nutrient-poor (oligotrophic) environments that fostered early metazoan evolution, so IT is important to consider appropriate rock targets from these settings as well as the more commonly studied eutrophic (productive) basins. Our study will be based around detailed geochemical analyses of samples from multiple cores from locations across russia and ukraine. Mapping of the ediacaran biomarker assemblages across hundreds of kilometers of epicontinental seaways of baltica will allow new insights into the responses of biological communities in shallow-marine environments to changes in the redox and nutrient budget. Detailed organic biomarker analysis will be performed on rock extracts and kerogen pyrolysates using sophisticated multiple reaction monitoring-gas chromatography-mass spectrometry (MRM-GC-MS). This selective and highly sensitive methodology opens up the possibility of monitoring for a large suite of biomarker compounds for assessing biogenic inputs and facilitating more accurate paleoenvironmental reconstructions. This includes quantification of any ancient animal steroids detectable in our baltica sedimentary rocks using the latest biomarker analysis methods developed in-house, comprising established targets as well as new sponge biomarkers. Various marine depositional settings are represented in our sample selection, including shallow-marine shelves and epicontinental basins. A lipid biomarker scoping study has been performed on samples from a selection of drill cores from russia and ukraine. These confirm excellent preservation and syngenicity of organic biomarkers as gauged from the hydrocarbon distributions and the very immature stereochemical signatures, consistent with the mild thermal history of the rocks. Strikingly, the biomarker assemblages encompass an exceptionally wide range of hopane/sterane ratios (1.6 to 119), which is a broad measure of bacterial/ eukaryotic source organism contribution. These include some high hopane/sterane ratios (22-119), particularly during the peak in diversity and abundance of ediacaran fauna, and reveal ancient microbial communities rich in bacteria. A high contribution of bacterial productivity may have bolstered a microbial loop sustaining dissolved organic matter as a viable feeding strategy for late ediacaran benthic multicellular organisms. The exceptional preservation of these proterozoic strata, as confirmed by multiple organic and inorganic proxies, highlights the previously unrecognized and thus untapped potential of preserving organic biological signatures of oligotropic settings under low thermal stresses despite long burial times. This program of work is highly relevant to a stated research emphasis of the NASA exobiology goal, namely evolution of advanced life, which seeks to determine the biological and environmental factors leading to the origin and diversification of eukaryotes and the development of multicellularity on earth. Additionally, our investigation will expand the existing repertoire of robust chemical biosignatures for primitive animals, through the identification of novel steroid biomarkers for sponges.