22 Aug 11 – Examining thin slices of rock under the microscope, a team of Australian and British geologists have discovered fossilized, single-cell organisms that are possibly the oldest known fossils on earth.
The scientists say their microscopic discovery is convincing evidence that cells and bacteria were able to thrive – without oxygen – more than 3.4 billion years ago.
Their studies suggest that early life lived off and metabolized sulphur rather than oxygen for energy, thus supporting the idea that similar life forms could exist on other planets where oxygen levels are low or non-existent.
The new fossils are described in the latest issue of Nature Geoscience by a team led by David Wacey of the University of Western Australia and Martin D. Brasier, a professor in the department of earth sciences at Oxford University.
“Could these sorts of things exist on Mars? It’s just about conceivable. This evidence is certainly encouraging and lack of oxygen on Mars is not a problem,” said Brasier.
The fossils were found in some of the oldest sedimentary rocks ever discovered preserved between quartz sand grains at the base of the Strelley Pool rock formation in Western Australia, the oldest shoreline known on Earth.
Earth at this time was apparently a hot, murky, violent place where there was a high and constant threat of volcanic eruptions and meteor strikes, and the oceans would have been around 40-50 degrees Celsius — the temperature of a hot bath.
“It’s a rather hellish picture,” said Brasier. “But for bacteria, all of this was wonderful. In fact, if you were to invent a place where you wanted life to emerge, the early Earth is exactly right.”
See fossil photos here:
Thanks to Steven Woodcock for these links