2023-11-07 ペンシルベニア州立大学(PennState)
◆これらの微化石は、従来の微生物とは異なり、藻類に似た特徴を持ち、真核生物の存在を示唆しています。これは、地球上で複雑な生命が形成された時間枠を再評価し、他の場所での生命の存在を考える上で重要な示唆を提供します。
＜関連情報＞
- https://www.psu.edu/news/research/story/window-past-new-microfossils-suggest-earlier-rise-complex-life/
- https://onlinelibrary.wiley.com/doi/full/10.1111/gbi.12576
古生代初期に複雑な細胞組織が出現したことを、特徴的な微化石が裏付ける Distinctive microfossil supports early Paleoproterozoic rise in complex cellular organisation
Erica V. Barlow, Christopher H. House, Ming-Chang Liu, Maxwell T. Wetherington, Martin J. Van Kranendonk
Geobiology Published: 06 October 2023
DOI:https://doi.org/10.1111/gbi.12576
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.
