Early fossil eukaryotes were benthic aerobes

All complex life on Earth is descended from a single-celled eukaryotic ancestor that lived more than a billion years ago. Although the timing and environmental context of eukaryogenesis, the prolonged origin and evolution of the eukaryotic cell, are poorly constrained, the geological record offers considerable insight. Through integrated paleontological, sedimentological, and geochemical analyses, we reconstruct the habitats of the oldest known (ca. 1.75–1.4 billion-year-old; Ga) fossil eukaryotes. These data show that although eukaryote microfossils are found in samples deposited in a range of marine environments from coastal to offshore, they are almost entirely restricted to settings with oxygenated bottom waters. This distribution suggests that these organisms were aerobic and, given their size and morphological complexity, likely possessed mitochondria by this time. Further, the absence of eukaryotes from otherwise fossiliferous samples that record bottom water anoxia suggests a be..., , # Early fossil eukaryotes were benthic aerobes Dataset DOI: [10.5061/dryad.1vhhmgr8n](https://doi.org/10.5061/dryad.1vhhmgr8n) ## Description of the data and file structure Table 1 includes occurrence data for organic-walled microfossils recovered from fine grained siliciclastic rocks of the Paleoproterozoic-Mesoproterozoic units in the McArthur and Birrindudu basins of northern Australia. Rock samples were collected from eight drillcores stored by the Northern Territory Geological Survey in Darwin, NT. The table indicates the drillcore name, sample depth, group and formation names, the occurrences of organic walled microfossil species, subdivided as likely to have been eukaryotic or not, and redox, trace element and depositional setting data. Additional tabs in the workbook sort fossil occurrences according to redox state and species or group occurrences. Table 2 provides descriptions of species characters, whether those species are considered eukaryotic or not and references to p..., ,