Buried alive: extracellular polymeric substances promote clay mineral templating of live eukaryotic algae

The Proterozoic fossil record of early eukaryotes is a crucial archive for major events in the early evolution of life, yet it is composed almost entirely of non-biomineralized organisms which required special environmental conditions to be preserved. Emerging work has shown that clay minerals can enhance preservation, and fossils of early eukaryotes are closely associated with clay minerals. Thus, understanding the role of clay minerals in organic preservation directly affects our interpretation of the early eukaryotic fossil record. Here, we perform taphonomic experiments using green algae and clay mineral substrates to investigate how clay minerals ‘template’ protist-grade organisms and enhance their preservation potential. We show that clay mineral templating occurs on geologically instantaneous timescales (days-weeks)—while organisms are still alive—via interactions with extracellular polymeric substances. Furthermore, we show that the extent and rate of templating is affected both by both the presence or absence of light and mineralogy. These results point towards a secular bias, which in turn likely influences our view of evolution during the Proterozoic. This dataset contains (3) spreadsheets from SEM, ICP-MS, and pH data, and one zip file with (6) .csv files containing relative abundances of cell types (healthy/clay-coated healthy/clay-coated unhealthy). Files and variables File: SEMdata_raw.xlsx Description: This spreadsheet contains data from SEM-EDS point counts of elemental abundances, shown in Figure S3. File: ICPMS.xlsx Description: This spreadsheet contains data from ICP-MS measurements of cation concentrations, shown in Figure 8. File: pH.xlsx Description: This spreadsheet contains a replicate list and pH measurements from each sampling interval, shown in Figure 8. File: Image_analysis.zip Description: This zip folder contains (6) .csv files which contain relative abundances of cell types (healthy/clay-coated healthy/clay-coated unhealthy), shown in Figure 4.