Protosterol biota

Group of fossilized protosteroid-producing microorganisms from 1,500–800 million years ago

The protosterol biota is a group of organisms found in fossilized fats that comprised aquatic protosterol-producing bacteria and ancient deep-branching stem-group eukaryotes from 1.6 to 0.8 billion years ago. These organisms were more complex than today's bacteria and they predate the last common ancestors of all modern eukaryotes. Perhaps they hunted their own species, since they were predators, as they fed on other bacteria. They were present in large numbers in the aquatic environments of the seas and seriously affected the Earth's ecosystem at the time. These microorganisms adapted to the much lower oxygen levels of the era and are also thought to have produced protosteroids.

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