They have discovered microscopic fossils, about 3.43 billion years old, in the remote Pilbara region of Western Australia, the Age reported
Until the new discovery, the oldest uncontroversial microbial fossils were 3.2 billion years old, as reported last year from South Africa by Emmanuelle Javaux of Belgium’s Liege University.
‘‘Our discovery pushes back the microbial fossil record by around 200 million years,’’ said team leader David Wacey, a postdoctoral research fellow at the University of Western Australia in Perth.
‘‘It was like searching for a very small needle in a very large haystack. The microfossils are minute and the Pilbara is several hundred kilometres across,” he stated.
In 2006, the team concentrated on these black, carbon-rich and metal-rich sandstones and struck gold with two samples containing microstructures that resembled microfossils. In 2007, they found more examples.
For three years, the samples were subjected to state-of-the-art techniques to confirm their microfossil status.
The reason the microfossils had survived the ravages of time was that there was precious little or no free oxygen in the atmosphere 3.4 billion years ago.
This was because neither plants nor algae were present at that time to photosynthesise and produce oxygen.
‘‘Our microfossils were sulphur-based, living off and metabolising compounds containing sulphur rather than oxygen for energy and growth,’’ Dr Wacey explained.
The findings were reported in the respected British journal Nature Geoscience.