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5 results on '"Barlow, Erica"'

1. Community Report from the Biosignatures Standards of Evidence Workshop

Author

Meadows, Victoria, Graham, Heather, Abrahamsson, Victor, Adam, Zach, Amador-French, Elena, Arney, Giada, Barge, Laurie, Barlow, Erica, Berea, Anamaria, Bose, Maitrayee, Bower, Dina, Chan, Marjorie, Cleaves, Jim, Corpolongo, Andrea, Currie, Miles, Domagal-Goldman, Shawn, Dong, Chuanfei, Eigenbrode, Jennifer, Enright, Allison, Fauchez, Thomas J., Fisk, Martin, Fricke, Matthew, Fujii, Yuka, Gangidine, Andrew, Gezer, Eftal, Glavin, Daniel, Grenfell, Lee, Harman, Sonny, Hatzenpichler, Roland, Hausrath, Libby, Henderson, Bryana, Johnson, Sarah Stewart, Jones, Andrea, Hamilton, Trinity, Hickman-Lewis, Keyron, Jahnke, Linda, Kacar, Betul, Kopparapu, Ravi, Kempes, Christopher, Kish, Adrienne, Krissansen-Totton, Joshua, Leavitt, Wil, Komatsu, Yu, Lichtenberg, Tim, Lindsay, Melody, Maggiori, Catherine, Marais, David Des, Mathis, Cole, Morono, Yuki, Neveu, Marc, Ni, Grace, Nixon, Conor, Olson, Stephanie, Parenteau, Niki, Perl, Scott, Quinn, Richard, Raj, Chinmayee, Rodriguez, Laura, Rutter, Lindsay, Sandora, McCullen, Schmidt, Britney, Schwieterman, Eddie, Segura, Antigona, Sekerci, Fatih, Seyler, Lauren, Smith, Harrison, Soares, Georgia, Som, Sanjoy, Suzuki, Shino, Teece, Bonnie, Weber, Jessica, Wolfe-Simon, Felisa, Wong, Michael, Yano, Hajime, and Young, Liza

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Quantitative Biology - Populations and Evolution
Abstract

The search for life beyond the Earth is the overarching goal of the NASA Astrobiology Program, and it underpins the science of missions that explore the environments of Solar System planets and exoplanets. However, the detection of extraterrestrial life, in our Solar System and beyond, is sufficiently challenging that it is likely that multiple measurements and approaches, spanning disciplines and missions, will be needed to make a convincing claim. Life detection will therefore not be an instantaneous process, and it is unlikely to be unambiguous-yet it is a high-stakes scientific achievement that will garner an enormous amount of public interest. Current and upcoming research efforts and missions aimed at detecting past and extant life could be supported by a consensus framework to plan for, assess and discuss life detection claims (c.f. Green et al., 2021). Such a framework could help increase the robustness of biosignature detection and interpretation, and improve communication with the scientific community and the public. In response to this need, and the call to the community to develop a confidence scale for standards of evidence for biosignature detection (Green et al., 2021), a community-organized workshop was held on July 19-22, 2021. The meeting was designed in a fully virtual (flipped) format. Preparatory materials including readings, instructional videos and activities were made available prior to the workshop, allowing the workshop schedule to be fully dedicated to active community discussion and prompted writing sessions. To maximize global interaction, the discussion components of the workshop were held during business hours in three different time zones, Asia/Pacific, European and US, with daily information hand-off between group organizers., Comment: 86 pages, 14 figures, workshop report

Published
2022

2. Distinctive microfossil supports early Paleoproterozoic rise in complex cellular organisation.

Author

Barlow, Erica V., House, Christopher H., Liu, Ming‐Chang, Wetherington, Maxwell T., and Van Kranendonk, Martin J.

Subjects
*FOSSIL microorganisms, *GREAT Oxidation Event, *SURFACE of the earth, *FOSSILS, *CARBON isotopes, *ISOTOPIC analysis
Abstract

The great oxidation event (GOE), ~2.4 billion years ago, caused fundamental changes to the chemistry of Earth's surface environments. However, the effect of these changes on the biosphere is unknown, due to a worldwide lack of well‐preserved fossils from this time. Here, we investigate exceptionally preserved, large spherical aggregate (SA) microfossils permineralised in chert from the c. 2.4 Ga Turee Creek Group in Western Australia. Field and petrographic observations, Raman spectroscopic mapping, and in situ carbon isotopic analyses uncover insights into the morphology, habitat, reproduction and metabolism of this unusual form, whose distinctive, SA morphology has no known counterpart in the fossil record. Comparative analysis with microfossils from before the GOE reveals the large SA microfossils represent a step‐up in cellular organisation. Morphological comparison to extant micro‐organisms indicates the SAs have more in common with coenobial algae than coccoidal bacteria, emphasising the complexity of this microfossil form. The remarkable preservation here provides a unique window into the biosphere, revealing an increase in the complexity of life coinciding with the GOE. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Diversification of early life: Microfossils of the c. 2.45-2.21 Ga Turee Creek Group, Western Australia

Author

Barlow, Erica V

Subjects
GOE, Gunflint, Eukaryote, Microfossil, Carbon isotopes, Great Oxidation Event, Black chert, Sulfur isotopes, Turee Creek Group
Abstract

The Great Oxidation Event (GOE), ~2.45-2.3 Ga, witnessed a significant increase in atmospheric oxygen that irreversibly changed the Earth. However, the actual effect that this revolutionary change had on life is unknown, due to a lack of well-preserved fossiliferous rocks from this time. An ancient, shallow-water dolomite reef complex has recently been found within the c. 2.45-2.21 Ga Turee Creek Group (TCG) in Western Australia. This reef complex contains stromatolites (macroscopic fossils) that show an increase in morphological complexity compared to Archean (pre-GOE) stromatolites. A suite of microfossils (cellularly-preserved remains of microorganisms) is described here from nodular black chert (NBC) and bedded black chert (BBC) units that were deposited in the deeper-water part of the TCG reef complex. This suite comprises 19 different microfossil morphotypes, including large spheroidal microfossils and large, complexly-branching, filamentous rosettes that are both unknown from the geological record and are presented as new microfossil forms. Identified here are four distinct microfossil assemblages, representing separate communities that inhabited different parts of the TCG environment: 1) A benthic, deep-water community of tangled filamentous and unicellular microfossils that may have cycled sulfur, or possibly iron (NBC texture 1). 2) A separate, benthic, deep-water assemblage contains long filamentous microfossils that were likely sulfate-reducing bacteria (NBC texture 2). 3) A planktonic, likely phototrophic, assemblage (NBC texture 3) contains large (< 140 um) spheroidal microfossils, which are considered eukaryotic based on comparison with extant cyanobacterial colonies and algal coenobia. This pushes the record of eukaryotic microfossils back by at least 540 – and possibly by as much as 800 – million years. 4) A shallow-water, likely phototrophic, community preserved within grainstone clasts of BBC, transported from shallow-water into the deeper-water setting. Part of this community is comparable to the shallow-water Gunflint-type microbiota, pushing back the known occurrence of these microfossils by ~100-350 Ma. Combined, these four microfossil communities span shallow to deeper-water environments, creating an unprecedented snapshot of an early Paleoproterozoic ecosystem. The TCG microfossils provide a new benchmark within the sparse fossil record surrounding the GOE, highlighting that life from this time was both diverse and complex.

Published
2019
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