Scientists find 3.7 billion-year-old fossil

Discussion in 'Earth Science' started by paddoboy, Aug 31, 2016.

  1. paddoboy Valued Senior Member

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    Scientists find 3.7 billion-year-old fossil, oldest yet
    August 31, 2016 by Seth Borenstein

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    In this photo provided by Laure Gauthiez, taken in July 2012, a field team examine rocks in Greenland. Scientists have found what they think is the oldest fossil on Earth, a remnant of life from 3.7 billion years ago when Earth's skies were orange and its oceans green. In a newly melted part of Greenland, Australian scientists found the leftover structure from a community of microbes that lived on an ancient seafloor, according to a study in Wednesday, Aug. 31, 2016 journal Nature. (Laure Gauthiez/The Australian National University via AP)
    Scientists have found what they think is the oldest fossil on Earth, a remnant of life from 3.7 billion years ago when Earth's skies were orange and its oceans green.


    In a newly melted part of Greenland, Australian scientists found the leftover structure from a community of microbes that lived on an ancient seafloor, according to a study in Wednesday's journal Nature .

    The discovery shows life may have formed quicker and easier than once thought, about half a billion years after Earth formed . And that may also give hope for life forming elsewhere, such as Mars, said study co-author Martin VanKranendonk of the University of New South Wales and director of the Australian Center for Astrobiology.

    "It gives us an idea how our planet evolved and how life gained a foothold," VanKranendonk said.



    Read more at: http://phys.org/news/2016-08-scientists-billion-year-old-fossil-oldest.html#jCp
     
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  3. paddoboy Valued Senior Member

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    http://www.nature.com/nature/journal/vaop/ncurrent/full/nature19355.html

    Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures


    Biological activity is a major factor in Earth’s chemical cycles, including facilitating CO2sequestration and providing climate feedbacks. Thus a key question in Earth’s evolution is when did life arise and impact hydrosphere–atmosphere–lithosphere chemical cycles? Until now, evidence for the oldest life on Earth focused on debated stable isotopic signatures of 3,800–3,700 million year (Myr)-old metamorphosed sedimentary rocks and minerals1, 3700-Ma sea-floor sedimentary rocks from west greenland. Science 283, 674–676 (1999)" id="ref-link-6" style="color: rgb(92, 121, 150);">2 from the Isua supracrustal belt (ISB), southwest Greenland3. Here we report evidence for ancient life from a newly exposed outcrop of 3,700-Myr-old metacarbonate rocks in the ISB that contain 1–4-cm-high stromatolites—macroscopically layered structures produced by microbial communities. The ISB stromatolites grew in a shallow marine environment, as indicated by seawater-like rare-earth element plus yttrium trace element signatures of the metacarbonates, and by interlayered detrital sedimentary rocks with cross-lamination and storm-wave generated breccias. The ISB stromatolites predate by 220 Myr the previous most convincing and generally accepted multidisciplinary evidence for oldest life remains in the 3,480-Myr-old Dresser Formation of the Pilbara Craton, Australia4, 5. The presence of the ISB stromatolites demonstrates the establishment of shallow marine carbonate production with biotic CO2sequestration by 3,700 million years ago (Ma), near the start of Earth’s sedimentary record. A sophistication of life by 3,700 Ma is in accord with genetic molecular clock studies placing life’s origin in the Hadean eon (>4,000 Ma)6.
     
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  5. sculptor Valued Senior Member

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    Were stromatolites likely to have been the first lifeforms?
     
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