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Old 24-12-2017, 10:46 AM
gary
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Life on Earth started at least 3.465 billion years ago - West Australia fossils

In a Dec 21 2017 article at Astronomy magazine, Jake Parks reports on
a study published December 18 in the Proceedings of the National
Academy of Sciences.

Quote:
Originally Posted by Jake Parks
Scientists confirmed that the oldest fossils ever discovered — found in a nearly 3.5-billion-year-old rock from western Australia — contain 11 complex microbes that are members of five distinct species.
Full story here :-
http://astronomy.com/news/2017/12/ol...sil-ever-found

Story also at phys.org including photo of part of the Apex Chert, a rock
formation in western Australia that is among the oldest and best-preserved rock deposits in the world :-
https://phys.org/news/2017-12-oldest...rth-began.html

Quote:
Originally Posted by University of Wisconsin-Madison, phys.org
The study, published today in the Proceedings of the National Academy of Sciences, was led by J. William Schopf, professor of paleobiology at UCLA, and John W. Valley, professor of geoscience at the University of Wisconsin-Madison. The research relied on new technology and scientific expertise developed by researchers in the UW-Madison WiscSIMS Laboratory.

The study describes 11 microbial specimens from five separate taxa, linking their morphologies to chemical signatures that are characteristic of life. Some represent now-extinct bacteria and microbes from a domain of life called Archaea, while others are similar to microbial species still found today. The findings also suggest how each may have survived on an oxygen-free planet.

The microfossils—so called because they are not evident to the naked eye—were first described in the journal Science in 1993 by Schopf and his team, which identified them based largely on the fossils' unique, cylindrical and filamentous shapes. Schopf, director of UCLA's Center for the Study of Evolution and the Origin of Life, published further supporting evidence of their biological identities in 2002.

He collected the rock in which the fossils were found in 1982 from the Apex chert deposit of Western Australia, one of the few places on the planet where geological evidence of early Earth has been preserved, largely because it has not been subjected to geological processes that would have altered it, like burial and extreme heating due to plate-tectonic activity.

But Schopf's earlier interpretations have been disputed. Critics argued they are just odd minerals that only look like biological specimens. However, Valley says, the new findings put these doubts to rest; the microfossils are indeed biological.

"I think it's settled," he says.
Paper here by Schopf et. al. (requires subscription) :-
http://www.pnas.org/content/early/2017/12/12/1718063115

Quote:
Originally Posted by Schopf et. al, PNAS
"SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions"

Significance

Although the existence of the Archaea (one of three all-encompassing domains of life) in the Archean Eon (4,000 to 2,500 million years ago) has been inferred from carbon isotopes in bulk samples of ancient rocks, their cellular fossils have been unknown. We here present carbon isotope analyses of 11 microbial fossils from the ∼3,465-million-year-old Western Australian Apex chert from which we infer that two of the five species studied were primitive photosynthesizers, one was an Archaeal methane producer, and two others were methane consumers. This discovery of Archaea in the Archean is consistent with the rRNA “tree of life,” confirms the earlier disputed biogenicity of the Apex fossils, and suggests that methane-cycling methanogen−methanotroph communities were a significant component of Earth’s early biosphere.
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Old 24-12-2017, 01:35 PM
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Thanks for that Gary, very interesting indeed.

Leon
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Old 24-12-2017, 02:47 PM
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multiweb (Marc)
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Fascinating to discover how old life can be and even more amazing to have these rocks in our backyard undisturbed for so long. A real time capsule on an ever changing earth.
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