A team of researchers led by Curtin University has taken a significant step forward in understanding the evolution of life on Earth. For the first time, the team has accurately dated some of the world's oldest fossils of complex multicellular life.
The study illuminates a pivotal moment in Earth's history, when diverse life forms emerged in the oceans after four billion years of harboring only single-celled microbes.
The Ediacaran period
“The Ediacaran period represents a crucial period in the evolution of life, containing the first clear fossil evidence of large multicellular organisms, including the first animals,” the study authors write.
“The Ediacaran biota exhibits examples of heterotrophy, locomotion, sexual reproduction, and organization in complex ecosystems. »
Dating fossils
The study's lead author, Anthony Clarke, a PhD student in the Timescales of Mineral Systems group at Curtin, explained the innovative method for determining the age of ancient fossils. Using layers of volcanic ash as time markers in the geological sequence, the team was able to date the fossils with remarkable precision.
“Located at Coed Cochion Quarry in Wales, which contains the richest deposit of shallow marine life in Britain, we used the outflow from an ancient volcano that covered the animals as a time marker to precisely date the fossils to 565 million years old Accuracy of 565 million years. 0.1 percent,” Clarke said.
“Similar Ediacaran fossils found in locations around the world, including Australia, can be identified based on the dating of the fossils as part of an ancient community that evolved as the Earth thawed after a global ice age.” »
“These creatures would resemble modern sea creatures like jellyfish in some ways, but in others they would be bizarre and unknown.” Some look like ferns, others like cabbages, and still others look like sea feathers.
New geological period
Study co-author Professor Chris Kirkland said the fossils were named after the Ediacaran Hills in the Flinders Ranges of South Australia where they were first discovered, leading to the first new geological period in over a century.
“These Welsh fossils appear to be directly comparable to the famous Ediacaran fossils in South Australia,” Professor Kirkland said. “Fossils, including creatures like the disc-shaped Aspidella terranovica, represent some of the first evidence of large multicellular organisms and mark a transformative moment in Earth's biological history. »
“Ediacaran fossils document life's response to the thaw of global glaciation and reveal the deep connection between geological processes and biology. »
“Our study highlights the importance of understanding these ancient ecosystems to unlock the mysteries of Earth’s past and shape our understanding of the evolution of life. »
The study was published in the Journal of the Geological Society.
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