Scientists have found molecules of fat believed to be from the earliest confirmed animal that existed some 550 million years ago.
Australian National University researchers discovered a well-preserved Dickinsonia fossil, with the organic matter still intact, in a remote area northwest of Russia near the White Sea. They call the discovery a "game changer."
The findings were published in the journal Science.
Dickinsonia Mystery
The Dickinsonia, a jellyfish-like creature, has long been a puzzle for the scientific community. It was classified as Ediacaran biota, a now-extinct life form that emerged from the seas as early as 570 million years ago. The Ediacaran biota critters are also the earliest complex life on Earth.
However, scientists have always found it a problem to determine what exactly is the creature. It has been classified as either fungus, a protist, or an animal but no one knows for sure.
The First Animal
The latest discovery ends all debates. The Dickinsonia fossils recently unearthed by researchers contain a significant amount of cholesterol, a type of fat that is considered to be the "hallmark of animal life."
"The fossil fat now confirms Dickinsonia as the oldest known animal fossil, solving a decades-old mystery that has been the Holy Grail of paleontology," explained Jochen Brocks, an associate professor from ANU.
To study the fossil, the team of researchers developed a new approach to unlock the history that was coded into it. While paleontologists usually study the structure of a fossil, researchers from ANU extracted molecules inside the fossil to make the breakthrough.
"Most rocks containing these fossils such as those from the Ediacara Hills in Australia have endured a lot of heat, a lot of pressure, and then they were weathered after that," explained Ilya Bobrovskiy, a co-author of the study, "these are the rocks that paleontologists studied for many decades, which explained why they were stuck on the question of Dickinsonia's true identity."
Bobrovskiy also said that Dickinsonia and other Ediacaran biota fossils hold the key to understanding the time between the world dominated by bacteria and the emergence of large animals 540 million years ago called "Cambrian explosion." The Cambrian explosion happened when complex animals, as well as macroscopic organisms, began dominating the fossil record around the world.
The discovery pushes back the Cambrian explosion a couple of million years earlier than previously thought. Professor Brocks added that large animals have existed and were abundant 558 million years ago.
