The world's oldest fossils: Researchers claim bacteria existed on Earth before OXYGEN
- The fossils found in north-west Australia are thought to be 3.5bn years old
- Not actual petrified remains, they are rather traces of organic processes
- Researchers claim the discovery could help the search for life on Mars
Fossils of bacteria found in Australia are the oldest yet discovered anywhere on Earth and predate the formation of oxygen on our planet, new research claims.
The fossils found in north-west Australia's Pilbara region are thought to be nearly 3.5billion years old and caused by bacteria which existed just one billion years after the Earth formed.
Now Old Dominion University's Nora Noffke, one of the researchers who worked on the project, says the discovery could help inform Mars rover Curiosity's searches for traces of life on the Red Planet.
A boulder trapped in the Knox Gorge, Pilbara: Researchers examining sedimentary rocks in this region of Western Australia claim they have found the world's oldest fossils which date back 3.5billion years
She told the Washington Post the bacteria traces 'are the oldest fossils ever described. Those are our oldest ancestors.'
The fossils are spider web-like imprints on the surfaces of sandstone which are thought to have been sculpted by once-living organisms interacting with sediment.
In a process that still takes place in some parts of the world today, thick mats of bacteria are thought to have trapped and glued together sand particles beneath them and protected them from erosion.
Sand stuck in this way gradually turned into rock with its particular texture shaped by the living organism that once covered it.
The ancient rocks in Western Australia's Pilbara region are some of the oldest anywhere on earth. Once shoreline, the sedimentary rocks in the area piled up billions of years ago and are now exposed for examination.
Scientists have discovered older rocks, but Professor Noffke told U.S. News that those rocks have eroded to the point traces of life are all but impossible to find.
'I can confidently say the structures we're working on cannot be found on older rocks — until now, there has been bothing that is this well preserved,' she said.
'There are some that are much older, but they experience metamorphosis - anything that's on them has been overprinted and it's difficult to reconstruct what was there.'
THE WORLD'S OLDEST DINOSAUR?
The first dinosaur to have walked on Earth may have been found by scientists.
Nyasasaurus parringtoni would have been alive 10 to 15 million years before any previously known dinosaurs - and more than 150million years before the mighty Tyrannosaurus Rex.
The size of a Labrador and slight of build, Nyasasaurus had a five foot-long tail and likely walked upright on two legs.
With only a few ribs and arm bones to go on, the scientists can't be sure what the world's oldest dinosaur ate.
However, it is likely it had a similar diet to other early dinosaurs of small prey, insects and plants.
The remains do allow for its size to be estimated.
Nyasasaurus is believed to have been 6.5 to 10ft from nose to tail, with its tail accounting for half of that.
Its slight build means it would have lived 'in the shadow' of other much larger reptiles alive at the time.
The patterns found by Professor Noffke and her colleagues are ridges which criss-cross the rocks like strands in a spider's web, hinting that primitive bacteria linked up in sprawling networks.
Like many such bacterial colonies which still exist today, they may have lived in the equivalent of microbial cities hosting different kinds of bacteria all communicating via chemical signals, the Washington Post reports.
It is thought the ancient microbes fed on sulphur, as many still do today.
The textures seen in the Australian rocks are similar to those already seen in 2.9billion-year-old rocks from South Africa which Professor Noffke and colleagues reported on in 2007.
However, old Australian rocks have deceived researchers in the past. Rippling layers found in some from the Strelley Pool, also in Western Australia, were claimed in 1980 to be the work of bacteria, but subsequent research showed the patterns could be formed by natural non-organic processes.
In an effort to corroborate their most recent findings, Professor Noffke and her colleagues measured the carbon that made up the textured rocks.
They found the tell-tale signatures of 'organic' carbon-13 that usually comes from living beings.
'It’s always nice to have a number of different lines of evidence, and you definitely want to see organic carbon,' said Dr John Stolz, a geomicrobiologist at Duquesne University, Pittsburgh.
The discovery could now help inform further searches for life on Mars, where such remnants of life may be even better preserved thanks to a lack of geological processes shaking things up like on Earth.
Nasa's Curiosity rover is equipped with instruments able to detect similar fossils, Professor Noffke told U.S. News.
'Our structure is one of the structures the rover is looking for—if we've found sedimentary structures like that on Earth's most well-preserved rocks, could they be on rocks of similar ages on Mars?' she added.
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