Early Archean planktonic mode of life

Implications from fluid dynamics of lenticular microfossils

Tomoki Kozawa, Kenichiro Sugitani, Dorothy Z. Oehler, Christopher H. House, Izumi Saito, Takeshi Watanabe, Toshiyuki Gotoh

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Lenticular, and commonly flanged, microfossils in 3.0–3.4 Ga sedimentary deposits in Western Australia and South Africa are unusually large (20–80 μm across), robust, and widespread in space and time. To gain insight into the ecology of these organisms, we performed simulations of fluid dynamics of virtual cells mimicking lenticular forms of variable sizes, oblateness, flange presence, and flange thickness. Results demonstrate that (a) the flange reduces sedimentation velocity, (b) this flange function works more effectively in larger cells, and (c) modest oblateness lowers sedimentation rate. These observations support interpretations that the lenticular microbes were planktonic—a lifestyle that could have been advantageous in an early Earth harsh environment including violent volcanic activities, repeated asteroid impacts, and relatively high UV-radiation. Although the robustness of these organisms could have provided additional protection on the early Earth, this architecture may have impeded a planktonic lifestyle by increasing cell density. However, our data suggest that this disadvantage could have been compensated by enlargement of cell volume, which could have enhanced the ability of the flange to slow sedimentation rate, especially if coupled with vacuolation. The results of this simulation study may help to explain the unique morphology and unusually large size of these Archean microfossils.

Original languageEnglish (US)
Pages (from-to)113-126
Number of pages14
JournalGeobiology
Volume17
Issue number2
DOIs
StatePublished - Mar 1 2019

Fingerprint

early Earth
microfossils
fluid dynamics
microfossil
lifestyle
sedimentation rate
Archean
fluid mechanics
asteroid
simulation
volcanic activity
organisms
sedimentation
cells
ecology
Western Australia
space and time
ultraviolet radiation
cell growth
South Africa

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

Cite this

Kozawa, T., Sugitani, K., Oehler, D. Z., House, C. H., Saito, I., Watanabe, T., & Gotoh, T. (2019). Early Archean planktonic mode of life: Implications from fluid dynamics of lenticular microfossils. Geobiology, 17(2), 113-126. https://doi.org/10.1111/gbi.12319
Kozawa, Tomoki ; Sugitani, Kenichiro ; Oehler, Dorothy Z. ; House, Christopher H. ; Saito, Izumi ; Watanabe, Takeshi ; Gotoh, Toshiyuki. / Early Archean planktonic mode of life : Implications from fluid dynamics of lenticular microfossils. In: Geobiology. 2019 ; Vol. 17, No. 2. pp. 113-126.
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Kozawa, T, Sugitani, K, Oehler, DZ, House, CH, Saito, I, Watanabe, T & Gotoh, T 2019, 'Early Archean planktonic mode of life: Implications from fluid dynamics of lenticular microfossils', Geobiology, vol. 17, no. 2, pp. 113-126. https://doi.org/10.1111/gbi.12319

Early Archean planktonic mode of life : Implications from fluid dynamics of lenticular microfossils. / Kozawa, Tomoki; Sugitani, Kenichiro; Oehler, Dorothy Z.; House, Christopher H.; Saito, Izumi; Watanabe, Takeshi; Gotoh, Toshiyuki.

In: Geobiology, Vol. 17, No. 2, 01.03.2019, p. 113-126.

Research output: Contribution to journalArticle

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