Fossil microbes discovered in Australia could be Earth's oldest known life form
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Posted 25 August 2011 - 10:53 AM
Credit: David Wacey/AFP/Getty Images
Fossils date to 3.4bn years ago, when landmasses first began to emerge from the oceans in an oxygen-free atmosphere. The fossilised remains of microbes that lived beside the sea in the earliest chapter of life on Earth have been discovered in a slab of rock in Western Australia.
Researchers found the tiny fossils in rock formations that date to 3.4bn years ago, making them strong candidates to be the oldest microbes found. Some clung to grains of sand that had gathered on one of the first known stretches of beach.
The findings paint a vivid picture of life arising when the first land masses began to emerge in fragmentary fashion from the oceans. At the time, volcanic eruptions spewed gas and lava, while a blanket of thick cloud greyed the skies. The moon – much closer than it is today – pulled the oceans into vast tidal surges. There was no breathable oxygen.
"To us it would have seemed like a hellish place to live," said Prof Martin Brasier at Oxford University, who co-authored a report on the fossils in the journal Nature Geoscience. "To early life, this was paradise. A true Eden."
Brasier worked with a team led by Dr David Wacey at the University of Western Australia, who found the fossils in the region's Strelley Pool formation, one of the oldest outcrops of sedimentary rock on Earth.
High-magnification images showed the fossils were spherical, oval and tubular, much like modern microbes, and were of a similar size, between 0.01mm and 0.02mm across.
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