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Life on Earth started 2.2 billion years ago

Last Updated: Tuesday, July 23, 2013 - 15:07

Washington: A new study suggests that life on land is four times as old, pushing the date back to 2.2 billion years ago than earlier believed - almost half way back to the inception of the planet.

That evidence involves fossils the size of match heads and connected into bunches by threads in the surface of an ancient soil from South Africa.

They have been named Diskagma buttonii, meaning "disc-shaped fragments of Andy Button," but it is unsure what the fossils were, the authors say.

"They certainly were not plants or animals, but something rather more simple," lead researcher Gregory J. Retallack, professor of geological sciences and co-director of paleontological collections at the University of Oregon`s Museum of Natural and Cultural History, said.

The fossils, he added, most resemble modern soil organisms called Geosiphon, a fungus with a central cavity filled with symbiotic cyanobacteria.

"There is independent evidence for cyanobacteria, but not fungi, of the same geological age, and these new fossils set a new and earlier benchmark for the greening of the land," he said.

"This gains added significance because fossil soils hosting the fossils have long been taken as evidence for a marked rise in the amount of oxygen in the atmosphere at about 2.4 billion to 2.2 billion years ago, widely called the Great Oxidation Event," he added.

The research is published in the journal Precambrian Research.


First Published: Tuesday, July 23, 2013 - 15:07
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