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古老的地球上的生命的证据在370亿年发现的化石

2018-09-25 08:25

The stromalites trapped in layered rocks from Greenland。 Credit: ALLEN NUTMAN

The stromatolites trapped in layered rocks from Greenland。 Credit: ALLEN NUTMAN

Locked in Greenland rocks dated from 3。7 billion years ago, scientists discovered the oldest physical evidence of life on the planet。 What the researchers found was not fossilized life, but rather telltale structures carved in the rock by bacteria called stromatolites, sort of like a footprint。

Pushing ancient life farther in time than ever before

If the findings are confirmed by other independent researchers, these stromatolites would be 220 million years older than the previous record-holder, also stromatolites but found in Western Australia。 These structures are made by microbial communities which trap and bind sediment or attract carbonate from surrounding water。 The algae or bacteria that build these thin layers can’;t be found, but their presence can be marked for billion of years onward*******>We don’;t know which kind of bacteria or the type of organism, for that matter, that formed the stromatolites。 What we know for sure is that these ancient organisms, perhaps the earliest we can infer so far, were water-based since it would be impossible for the sediments to form otherwise。

These were unearthed from the Isua supracrustal belt in southwest Greenland by a team of Australian and US researchers。 The site is home to some of the oldest rocks ever, some ext***ing up to 4。2 billion years。

Isua rocks are metamorphic —; sedimentary rocks subjected to extreme temperature and pressure。 Typically, these c***itions deform the original rock so everyone was very surprised to find stromatolites etched inside them。 At the same time, critics are concerned that the metamorphic c***itions have altered the fossil too。

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