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Distinctive microfossil supports early Paleoproterozoic rise in complex cellular organisation
Erica V Barlow1,2,3, Christopher H House3, Ming-Chang Liu4,5
1Australian Centre for Astrobiology, School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales, Australia.
Geobiology
|October 7, 2023
Summary
Exceptionally preserved microfossils from Western Australia reveal life
Area of Science:
- Paleobiology
- Geochemistry
- Astrobiology
Background:
- The Great Oxidation Event (GOE) fundamentally altered Earth's surface chemistry approximately 2.4 billion years ago.
- The impact of the GOE on early life remains poorly understood due to a scarcity of well-preserved fossils from this period.
Purpose of the Study:
- To investigate the morphology, habitat, reproduction, and metabolism of exceptionally preserved microfossils.
- To understand the evolutionary step-up in cellular organization during the GOE.
- To compare early life forms with extant microorganisms.
Main Methods:
- Field and petrographic observations of permineralised microfossils in chert.
- Raman spectroscopic mapping for chemical and structural analysis.
- In situ carbon isotopic analyses to infer metabolic processes.
Main Results:
- Discovery of unusually large spherical aggregate (SA) microfossils with no known fossil record counterparts.
- SA microfossils exhibit a higher level of cellular organization compared to pre-GOE microfossils.
- Morphological similarities suggest SAs are more akin to coenobial algae than coccoidal bacteria.
Conclusions:
- The study provides a unique glimpse into the biosphere during the GOE.
- An increase in biological complexity coincided with the Great Oxidation Event.
- These findings highlight the significant evolutionary advancements in early life.
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