Fossils of strange sea creatures tell us more about a crucial turning point in the evolution of life on Earth

For four billion years, the world's oceans have been the domain of single-celled microbes. But suddenly that changed and all kinds of strange new life forms appeared. Australian researchers have finally discovered the cause of this crucial moment in evolution.

They have succeeded in very accurately dating some of the oldest fossils of complex, multicellular life – the so-called Ediacaran organisms. For this unique discovery, the researchers used successive layers of volcanic rocks as bookmarks in the book on the geological history of our planet, as it appears poetic.

Volcanic time capsule
Researcher Anthony Clark Tells how they worked. “The Coed Cohion quarry in Wales contains an abundance of fossils of shallow marine life from ancient times. We used the eruption of an ancient volcano, which covered the animals in dust and lava, as a time marker. “We succeeded in dating the age of the fossils to 565 million years, with an accuracy of To 0.1 percent.’” Similar Ediacaran fossils have also been found in the ground elsewhere in the world. We can now say with a great deal of certainty that they were part of a very ancient group of animal species that evolved in the world's oceans as the Earth slowly thawed after a long ice age.

strange creatures
The Ediacaran organisms seemed very distinctive. “These creatures were similar in some ways to modern marine species, such as jellyfish. But they were very strange creatures. Some were fern-like, others were shaped like cabbages or sea feathers,” the British geologist said.

The name of the fossils is easy to explain. “We can directly link fossils found on land in Wales to the famous Ediacara fossils in South Australia. The name comes from the Ediacara Hills, where the first fossils of Ediacara organisms were found. This led to the discovery of the first new geological period in more than a century », explains Australian Professor Chris Kirkland. «British fossils provide some of the oldest evidence of the extensive presence of multicellular organisms. They represent an important turning point in Earth's biological history and show that some geological processes, such as the melting of our planet after the Ice Age, are strongly linked to biology, or the transition to more complex, multicellular organisms.

The study shows how important it is to understand how ecosystems that are hundreds of millions of years old work. Only in this way can we uncover the secrets of the distant past of our planet and understand the evolution of life on Earth.