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Key Moment Revealed in Ancient Fossils

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Key Moment Revealed in Ancient Fossils

Ancient Fossil Evolution Art Concept

Researchers have precisely dated ancient multicellular fossils to 565 million years ago, using volcanic ash layers as time markers. These findings, based on fossils from Wales and similar sites worldwide, shed light on a significant period in Earth’s history, when complex life began flourishing after a global ice age. (Artist’s concept.) Credit: SciTechDaily.com

A new study precisely dates ancient multicellular fossils, uncovering key moments in Earth’s history and the evolution of complex life after a global ice age.

Research led by Curtin University has for the first time precisely dated some of the oldest fossils of complex multicellular life in the world, helping to track a pivotal moment in the history of Earth when the seas began teeming with new lifeforms – after four billion years of containing only single-celled microbes.

Lead author PhD student Anthony Clarke, from the Timescales of Mineral Systems Group within Curtin’s School of Earth and Planetary Sciences, said to determine the age of the fossils, researchers used volcanic ash layers like bookmarks in the geological sequence.

“Located in the Coed Cochion Quarry in Wales, which contains the richest occurrence of shallow marine life in Britain, 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 percent,” Mr. Clarke said.

“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.

“These creatures would in some ways resemble modern-day marine species such as jellyfish, yet in other ways be bizarre and unfamiliar. Some appear fern-like, others like cabbages, whereas others resembled sea pens.”

Welsh Countryside Near Coed Cochion Quarry

The Welsh countryside near the Coed Cochion Quarry, where the fossils were found. Credit: Curtin University

Study co-author Professor Chris Kirkland, also from the Timescales of Mineral Systems Group at Curtin, said the fossils are named after the Ediacara Hills in South Australia’s Flinders Ranges, where they were first discovered, leading to the first new geological period established in over a century.

“These Welsh fossils appear directly comparable to the famous fossils of Ediacara in South Australia,” Professor Kirkland said.

“The fossils, including creatures like the disc-shaped Aspidella terranovica, showcase some of the earliest evidence of large-scale multicellular organisms, marking a transformative moment in Earth’s biological history.

“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.

“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.”

Reference: “U–Pb zircon–rutile dating of the Llangynog Inlier, Wales: constraints on an Ediacaran shallow-marine fossil assemblage from East Avalonia” by Anthony J. I. Clarke, Christopher L. Kirkland, Latha R. Menon, Daniel J. Condon, John C. W. Cope, Richard E. Bevins and Stijn Glorie, 15 January 2024, Journal of the Geological Society.
DOI: 10.1144/jgs2023-081

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