1300 – 1200 million years ago

Year thirty-four
Life on the land

Life on the land?

It is very likely that the first organisms to try to leave the protection of the ocean and live on the land were bacteria. But when did this happen? It is not possible to say for certain.

Some of the earliest organisms lived in Western Australia, where there is a fossil soil that has been dated to about Earth's 26th birthday (about 2000 million years ago). The chemistry of this fossil soil suggests that bacteria may have been living in small pools of fresh water and not on the land. This was a precarious existence because the pools periodically dried up.

They lived at a time when there was so little ozone in the air that harmful ultraviolet rays would have killed organisms that tried to live on the land. Perhaps there was enough protection in the pond water and in the soil that the bacteria were protected.

The earliest fossils of land-dwelling bacteria are much younger. They are found in fossil soils in Arizona (USA) that date to about the Earth's 34th birthday (about 1200 million years ago).

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