“Settled science” has had it that life on land dates from about 500 million years ago. But fossils of something rather simpler than plants or animals found in South Africa provide evidence that life on land could be 2.2 billion years old.
Gregory J. Retallack, Evelyn S. Krull, Glenn D. Thackray, Dula Parkinson. Problematic urn-shaped fossils from a Paleoproterozoic (2.2Ga) paleosol in South Africa. Precambrian Research, 2013; 235: 71
DOI:10.1016/j.precamres.2013.05.015
Conventional scientific wisdom has it that plants and other creatures have only lived on land for about 500 million years, and that landscapes of the early Earth were as barren as Mars.
A new study, led by geologist Gregory J. Retallack of the University of Oregon, now has presented evidence for life on land that is four times as old — at 2.2 billion years ago and almost half way back to the inception of the planet.
That evidence, which is detailed in the September issue of the journal Precambrian Research, 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,” said Retallack, professor of geological sciences and co-director of paleontological collections at the UO’s Museum of Natural and Cultural History. 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.”
By modern standards, in which Earth’s air is now 21 percent oxygen, this early rise was modest, to about 5 percent oxygen, but it represented a rise from vanishingly low oxygen levels earlier in geological time. …
Tags: Diskagma buttonii, fossils, Great Oxygenation Event, Gregory J. Retallack
The k2p blog 
July 25, 2013 at 12:30 pm
wow that kind mind-boggling 2.2 billion years old. It makes sense it would be found in South Africa, that is where all the oldest fossils are found