August 31, 2016 by Seth
Borenstein
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.
Scientists had thought it would
take at least half a billion years for life to form after the molten Earth
started to cool a bit, but this shows it could have happened quicker, he said.
That's because the newly found fossil is far too complex to have developed soon
after the planet's first life
forms, he said.
In an outcrop of rocks that used
to be covered with ice and snow which melted after an exceptionally warm
spring, the Australian team found stromatolites, which are intricately layered
microscopic layered structures that are often produced by a community of
microbes. The stromatolites were about .4 to 1.6 inches high (1 to 4
centimeters).
It "is like the house left
behind made by the microbes," VanKranendonk said.
Scientists used the layers of ash
from volcanoes and tiny zircon with uranium and lead to date this back 3.7
billion years ago, using a standard dating method, VanKranendonk said.
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