Ediacaran-age siliciclastic deposits preserve some of the earliest known complex macroscopic lifeforms, with the fossils typically preserved as three-dimensional moulds and clasts. Silvina Slagter at Yale University, USA, and colleagues use an experimental approach to determine the types of conditions that may have led to the remarkable preservation of Ediacara-style fossils, which include soft tissues and animal embryos.
The team use laboratory experiments to simulate silica precipitation under conditions similar to those expected for Precambrian seawater. They found that biofilms and mat-forming microorganisms play a vital role in enabling the fossilisation of such vulnerable specimens. Microbial mats and biofilms are dynamic and complex assemblies of bacterial cells that are kept together by protein and sugar to form a sticky, sturdy fibre, in some ways similar to dental plaque. They can accumulate as a fine layer over the microorganisms, protecting the specimen and acting as loci for the precipitation of silica during burial and diagenesis.
The results imply that the preservation window for Ediacaran-style fossils was influenced by the occurrence of biofilms and microbial mats. It is interesting to see the mechanisms that enabled preservation of Earth’s earliest lifeforms come to light from beneath a vale of uncertainty.
Amelia Jane Piper
Scientific Reports 12, 8631 (2022); doi.org/10.1038/s41598-022-12473-1