Late Ediacaran life on land: desiccated microbial mats and large biofilm streamers

S. McMahon* (Corresponding Author), J.J Matthews, A. Brasier, J. Still

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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The Ediacaran period witnessed transformational change across the Earth–life system, but life on land during this interval is poorly understood. Non marine/transitional Ediacaran sediments preserve a variety of probable microbially induced sedimentary structures and fossil matgrounds, and the ecology, biogeochemistry and sedimentological impacts of the organisms responsible are now ripe for investigation. Here, we report well preserved fossils
from emergent siliciclastic depositional environments in the Ediacaran of Newfoundland, Canada. These include exquisite, mouldically preserved microbial mats with desiccation cracks and flip-overs, abundant Arumberia-type fossils and, most notably, assemblages of centimetre-to-metre-scale, subparallel, branching, overlapping, gently curving ribbon-like features preserved by aluminosilicate and phosphate minerals, with associated filamentous
microfossils. We present morphological, petrographic and taphonomic evidence that the ribbons are best interpreted as fossilised current-induced biofilm streamers, the earliest record of an important mode of life (macroscopic streamer formation) for terrestrial microbial ecosystems today. Their presence shows that late Ediacaran terrestrial environments could produce substantial biomass, and supports recent interpretations of Arumberia as a current-influenced microbial mat fossil, which we here suggest existed on a “streamer–arumberiamorph spectrum”. Finally, the absence of classic Ediacaran
macrobiota from these rocks despite evidently favorable conditions for soft tissue preservation upholds the consensus that those organisms were exclusively marine
Original languageEnglish
Article number20211875
Number of pages10
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1962
Early online date3 Nov 2021
Publication statusPublished - 10 Nov 2021

Bibliographical note

SM acknowledges support from the European Union’s Horizon 2020 Research and Innovation Programme under Marie Skłodowska-Curie grant agreement 747877, and from the NASA Astrobiology Institute NNA13AA90A, Foundations of Complex Life, Evolution, Preservation and Detection on Earth and Beyond. JJM recognised funding from Novas Consulting, through the Geological Society of London, as well as from the Government of Newfoundland and Labrador.

We thank B. Lynne and J. Poling for help in obtaining panels A, C and D of Figure 4. Discussions with D. McIlroy and P. Smith, and the comments of William McMahon (no relation to SM) and three anonymous reviewers, significantly improved this work. We thank the people of Ferryland for their continued support and hospitality. The early stages of this research benefited greatly from the guidance of M. D. Brasier.

Data Availability Statement

Electronic supplementary material is available online at


  • Ediacaran
  • Arumberia
  • streamers
  • matground
  • non-marine
  • terrestrial


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