A few molecules of fat was all it took to rewrite the history books. With those molecules, scientists at Australian National University (ANU) were able to confirm that the earliest confirmed animal in the geological record was in fact an animal. Known as Dickinsonia, the creature lived 558 million years ago.
Living as the first animal wasn't very exciting. Dickinsonia lived in the late Ediacaran period at the bottom of the ocean. With an oval-like shape that could grow up to 4.5 feet (1.4 meters) in length, it's been interesting to scientists in large part because they have struggled to figure out what, exactly, it was. From time to time, arguments saying it was a polychaete, turbellarian or annelid worm, jellyfish, polyp, xenophyophoran protist, lichen or even an early mushroom.
The breakthrough came with a new fossil. ANU Ph.D. scholar Ilya Bobrovskiy found an extraordinarily well-preserved fossil in near remote near the White Sea, an inlet along the northwestern coast of Russia. Because of their truly remote location in a cliff, Bobrovskiy and his fellow scientists had to climb down the cliff with ropes and dig through large blocks of sandstone.
"I took a helicopter to reach this very remote part of the world—home to bears and mosquitoes—where I could find Dickinsonia fossils with organic matter still intact. These fossils were located in the middle of cliffs of the White Sea that are 60 to 100 metres (196 feet to 328 feet) high," Bobrovskiy recalls in a . "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."
Though difficult to locate in the midst of bears and a thicket of mosquitos, the find was worth it. Bobrovskiy's fossil was preserved to the extent that is still contained molecules of cholesterol.
Cholesterol, beyond dieting and eating habits, is an organic molecule. It's a crucial component of all animal cell membranes that allows animal cells to survive without cell walls. Around 30 percent of all animal cell membranes are cholesterol, it's one of the defining molecules of animal existence.
The fossil fat molecules that we've found prove that animals were large and abundant 558 million years ago, millions of years earlier than previously thought," says Jochen Brocks, an associate professor from the ANU Research School of Earth Sciences.
"Scientists have been fighting for more than 75 years over what Dickinsonia and other bizarre fossils of the Edicaran Biota were: giant single-celled amoeba, lichen, failed experiments of evolution or the earliest animals on Earth. 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."
Bobrovskiy is the lead author of a discussing his discovery.
In other oldest news, earlier this year archaeologists found the world's oldest bread.