The Volyn biota (Ukraine) – indications of 1.5 Gyr old eukaryotes in 3D preservation, a spotlight on the “boring billion”
<p>The Volyn biota, fossilized organisms with a minimum age of 1.5 Ga, were found in cavities in granitic pegmatites from the Korosten Pluton, NW Ukrainian shield. Fossilization was due to an influx of hydrothermal fluorine-rich waters, which silicified the outermost part of the organisms, thu...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-05-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/1901/2023/bg-20-1901-2023.pdf |
| Summary: | <p>The Volyn biota, fossilized organisms with a minimum age of 1.5 Ga, were
found in cavities in granitic pegmatites from the Korosten Pluton, NW
Ukrainian shield. Fossilization was due to an influx of hydrothermal
fluorine-rich waters, which silicified the outermost part of the organisms,
thus preserving the 3D morphology. Details of the morphology (investigated
by scanning electron microscopy) show that the majority of the specimens are
filamentous, of a large variety with diameters ranging from <span class="inline-formula">∼</span> 10 to <span class="inline-formula">∼</span> 200 <span class="inline-formula">µ</span>m, thin filaments with typical
branching and thick filaments with ball-shaped outgrowths and dented surface.
Filaments can be straight or conical, curvilinear, or strongly curved, up to
millimeters in length, some with a central channel. Some filaments show indications
of segmentation and are grown as sessile organisms onto substrate; others show
both intact ends, indicating a non-sessile, free-living lifestyle. Objects
with flaky morphology and agglutinating filaments are interpreted as fossil
biofilms. Other objects are hollow and show a large variety of forms;
spherical objects are scarce. Infrared spectroscopy indicates the presence
of chitosan in one filament type, electron microprobe analysis of nanometer-sized
inclusions in filaments identified the presence of Bi(Te,S) minerals, and
both observations are compatible with the interpretation as fungi-like
organisms. Stable C- and N-isotope data of bulk samples are in the range of
<span class="inline-formula">−</span>31 ‰ to <span class="inline-formula">−</span>47 ‰ <span class="inline-formula"><i>δ</i><sup>13</sup></span>C and of <span class="inline-formula">+</span>3 ‰ to <span class="inline-formula">+</span>10 ‰ <span class="inline-formula"><i>δ</i><sup>15</sup></span>N, indicating possible methanogens as
part of the subsurface microecosystem. The Volyn biota indicate that at 1.5 Ga complex forms of life existed in the continental deep biosphere, well
above the microscopic level, including fungi-like organisms resembling
eukaryotes.</p> |
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| ISSN: | 1726-4170 1726-4189 |