| See also:
Earliest Fossils
Publications
External Links:
The origins of
life, sex and oil
(AGSO press release)
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Early life on Earth
Molecular Fossils
Scientists from the University of Sydney and the Australian Geological
Survey Organization have recently isolated molecular fossils of
biological lipids from 2.7 billion year old rocks in the Pilbara
region. The 'fossils' take the form of hydrocarbon materials which
result from the decay of materials in living cells. Such biomarkers
are well known from younger rocks, but have not previously been
found at ages greater than 1.7 billion years. The new results from
rocks in Western Australia push back the molecular fossil record
by 1 billion years.
One type of hydrocarbon biomarker found in these rocks indicates
the presence of cyanobacteria, showing that oxygenic photosynthesis
was established at least 2.7 billion years ago. Such bacteria provided
the source of oxygen which created our oxygen atmosphere and transformed
the planet's surface.
Another type of biomaker is typical of eukaryotic cells - cells
like those in animals and plants which include a separate nucleus.
This indicates that eukaryotes were present more than one billion
years earlier than previously known.
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