The fat of 558 million years ago reveals the earliest known animal

This is a Dickinsonia fossil. Credit: Australian National University (ANU)

Scientists from the Australian National University (ANU) and elsewhere have discovered fat molecules in an ancient fossil to reveal the oldest confirmed animal in the geological record that lived on Earth 558 million years ago .

The strange creature called Dickinsonia, which was 1.4 meters long and oval in shape, had rib-shaped segments that were part of the Ediacara biocide that lived on Earth 20 million years before the Cambrian explosion of modern animal life.

Ilya Bobrovskiy, PhD researcher at ANU, discovered a Dickinsonia Fossil so well preserved in a remote area near the White Sea, north-west of Russia, that the tissue still contained cholesterol molecules, a type of fat characteristic of animal life.

Jochen Brocks, Senior Research Associate, said the Cambrian explosion was the fact that complex animals and other macroscopic organisms – such as molluscs, worms, arthropods and sponges – were beginning to dominate the fossil record.

"The fossil fat molecules we found prove that animals were large and abundant 558 million years ago, millions of years earlier than expected," said ANU Associate Professor Jochen Brocks.

"Scientists have been fighting for over 75 years on what Dickinsonia and other strange fossils of Edicaran biota were: the giant unicellular amoeba, lichen, failed evolutionary experiments or the first animals on Earth. Fossil fat now confirms Dickinsonia as the oldest known animal fossil, solving a decades-old mystery that has been the holy grail of paleontology.

Mr. Bobrovskiy stated that the team had developed a new approach to study Dickinsonia the fossils, which hold the key between the old world dominated by bacteria and the world of large animals, appeared 540 million years ago during the Cambrian explosion.

"The problem we had to overcome was to find Dickinsonia fossils that have retained organic matter, "said Dr. Bobrovskiy of the ANU School of Earth Sciences Research.

"Most of the rocks containing these fossils, like those in the Ediacara Hills in Australia, have been subjected to a lot of heat, a lot of pressure, and they have been altered – the rocks that paleontologists have studied for decades. explains to them were stuck on the issue of Dickinsonia"True identity".

Paleontologists normally study the structure of fossils, but Mr. Bobrovskiy extracted and analyzed molecules Dickinsonia fossil found in ancient rocks in Russia to make the revolutionary discovery.

"I took a helicopter to reach this very remote region of the world – where bears and mosquitoes live – where I could find Dickinsonia fossils with organic matter still intact, "said Bobrovskiy.

"These fossils were located in the middle of the cliffs of the White Sea, which are between 60 and 100 meters high. I had to hang the edge of a cliff on ropes and dig huge blocks of sandstone, throw them to the ground, wash the sandstone and repeat this process until I found the fossils I was looking for.

Associate Professor Brocks said that studying molecules from these ancient organisms was a game of chance.

"When Ilya showed me the results, I could not believe it," he said. "But I also immediately saw the meaning."

The ANU led the research in collaboration with scientists from the Russian Academy of Sciences and the Max Planck Institute of Biogeochemistry and the University of Bremen in Germany.

The research is published in Science.