Fossils capture pivotal shifts in Earth's evolutionary history

As no one was present to give an account of how life started on , all we can bank on are theories from scientists who have tried to provide the best plausible meaning to certain factors relating to life itself. While there is a consensus that the evolution of life on planet Earth spans over three billion years, some scientists have gathered evidence that it began earlier than that.

Over the years, scientists have come up with several theories, like life on Earth beginning deep in the oceans, while some have credited it to Earth being crashed by asteroids or comets containing elements necessary for life. All in all, the reality is the complete narrative of life's origins remains — and is likely to remain — elusive.

Now, a Curtin led research team has, for the first time, precisely dated some of the oldest fossils of complex multicellular life in the world, showing a determining point in evolution when the oceans began teaming with new lifeforms. The Earth is filled with mysteries, and it is important to understand the ancient ecosystems in order to unravel these mysteries and comprehend the evolution process properly.

This was the reason that drove the Curtis led team to this study. Lead author Ph.D. student Anthony Clarke, from the Timescales of Mineral Systems Group within Curtin's School of Earth and Planetary Sciences, noted that the researchers made use of volcanic ash layers from an outfall from an ancient volcano in the Coed Cochion Quarry in Wales to determine the age of the fossils.

"Dating the fossils identifies them as being part of an ancient living community that developed as Earth thawed out from a global ice age," said Dr. Clarke in a . The volcanic ash layers used for this study are known to contain the richest occurrence of shallow marine life in Britain. Used as a time marer, it helped to date the fossils to 565 million years, accurate down to 0.1 percent, according to Mr Clarke.

The study noted a striking semblance between the Welsh fossils and the famous fossils of Ediacara in South Australia. These included creatures like the disc shaped Aspidella Terranovica — the first fossil ever identified from the Ediacaran period and one of the earliest evidence of large scale multicellular organisms recorded on the planet.

Study co author Professor Chris Kirkland, also from the Timescales of Mineral Systems Group at Curtin, found that these fossils "record the response of life to the thaw out from a global glaciation, which shows the deep connection between geological processes and biology. The complete study was published in the on January 15 and can be found ..