The flat, oval creature with many rib-like segments along the length of its body ranged in size up to about 1.4m, and scientists have debated what the fossils actually were for decades. One of these Dickinsonia was found 72 years ago, in the Flinders Ranges of South Australia, but it was eroded and poorly preserved, which encouraged wild speculation for decades. Some experts thought it could be a lichen or fungus, others believed it was a huge single-celled amoeba-type organism, yet others theorised it was some kind of evolutionary dead end.
“It doesn’t have the symmetry of an animal,” said associate professor Jochen Brocks from the ANU Research School of Earth Sciences. “That’s why people were fighting over it for a very long time.”
Finally, an ANU doctoral student, Ilya Bobrovskiy, found a well-preserved fossil of Dickinsonia in cliffs in a geographically stable region near the White Sea in northwest Russia.
Molecules of cholesterol, or fat, found in this specimen have confirmed Dickinsonia was indeed an animal, the earliest proved to have existed in the world.
ANU led the research in collaboration with scientists from the Russian Academy of Science and the Max Planck Institute for Biogeochemistry, and the University of Bremen in Germany; the research is published in Science.
Professor Brocks’s student, Mr Bobrovskiy, had the “crazy idea” to venture to the area where the fossils were “incredibly well-preserved”.
“(The fossil) was more or less mummified and contained the original animal fat,” Professor Brocks said. “The fossil fat molecules we’ve found prove that animals were large and abundant 558 million years ago, millions of years earlier than previously thought.”
Mr Bobrovskiy took a helicopter to a remote region with cliffs 60 to 100m high. “I had to hang over the edge of a cliff on ropes and dig out huge blocks of sandstone, throw them down, wash the sandstone and repeat this process until I found the fossils I was after.”