Evrim Yazgin
Cosmos science journalist
Complex, multicellular life emerged on Earth 600-700 million years ago. For the first time, scientists have accurately dated some of the oldest examples of complex life.
For about 3.5 billion years, life on Earth was made of simple, single-celled organisms.
That all changed about 700 million years ago when, for the first time, large, complex, multicellular organisms evolved in Earth’s ancient oceans.
Some of the oldest examples of these mysterious, ancient creatures were found in Coed Cochion Quarry in southern Wales. Strange, jellyfish-like organisms, comparable to the Ediacaran organisms found in South Australia’s remote Flinders Ranges, were discovered at the site in the 1970s and 1980s.
A team led by researchers at Curtin University in Western Australia has accurately dated these fossils for the first time in research published in the Journal of the Geological Society.
“We used outfall from an ancient volcano that blanketed the animals as a time marker to accurately date the fossils to 565 million years, accurate down to 0.1%,” says lead author and PhD student at Curtin University Anthony Clarke.
“With similar Ediacaran fossils found at sites around the world including in Australia, dating the fossils identifies them as being part of an ancient living community that developed as Earth thawed out from a global ice age,” Clarke explains. “These creatures would in some ways resemble modern day marine species such as jellyfish. Yet in other ways they’re bizarre and unfamiliar. Some appear fern-like, others like cabbages, whereas others resembled sea pens.”
The Ediacaran period (635-541 million years ago) marks the first time in Earth’s history that life got “big.”
All the so-called Ediacaran fauna went extinct by the time of the Cambrian explosion about 540 million years ago, which saw the emergence of the major body plans that would come to dominate animal life on our planet, including the first vertebrates and arthropods – ancient relatives of today’s insects, spiders and crabs.
“Ediacaran fossils record the response of life to the thaw out from a global glaciation, which shows the deep connection between geological processes and biology,” says co-author Professor Chris Kirkland, also from Curtin University. “Our study underscores the importance of understanding these ancient ecosystems in order to unravel the mysteries of Earth’s past and shape our comprehension of life’s evolution.”
