Article Dans Une Revue Nature Ecology & Evolution Année : 2025

Marine snow fuels an opportunistic small food web in the Late Ordovician Soom Shale Lagerstätte

Résumé

Meiofauna are minute organisms that dominate the ‘small food web’—communities which, in modern sediments, play a key role in ecosystem functioning through benthic–pelagic coupling and carbon drawdown. Despite their importance today, the ecological contribution of such communities in ancient settings remains poorly understood, largely due to the sparse and fragmentary nature of their fossil record. Here we document trace fossils of a meiofaunal ecosystem that flourished in the immediate aftermath of the end-Ordovician extinction event, preserved in the Soom Shale Lagerstätte, South Africa. Micro computed tomography scanning reveals three-dimensionally preserved ichnofossils including two burrow/trail morphotypes and microcoprolites that are attributed to a low-diversity meiofaunal benthic community, dominated by nematodes and foraminifera. The ichnofossils consistently occur within fossilized marine-snow-bearing beds, where there is a clear pattern in their distribution and frequency of occurrence. This pattern mirrors behavioural responses of meiofauna to fluxes in delivery of organic matter to the sea floor recorded in modern oxygen-limited marine environments. The Soom Shale assemblage provides a remarkable insight into, not only one of the oldest meiofaunal trace-fossil records, but also the earliest account of an ancient behavioural response to episodic phytoplankton blooms.

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Dates et versions

hal-05526091 , version 1 (24-02-2026)

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Claire Browning, Sarah Gabbott, M. Gabriela Mángano, Luis Buatois, Abderrazak El Albani, et al.. Marine snow fuels an opportunistic small food web in the Late Ordovician Soom Shale Lagerstätte. Nature Ecology & Evolution, 2025, 10 (1), pp.34-43. ⟨10.1038/s41559-025-02923-0⟩. ⟨hal-05526091⟩
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