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Scientists Find The Oldest Animal On Earth: Meet The Half-Billion-Year-Old Dickinsonia

Sep 24, 2018 10:22 PM EDT
Organically preserved Dickinsonia fossil from the White Sea in Russia. The breakthrough find led scientists to finally classify the mysterious organism as the oldest known animal on Earth.
(Photo : Ilya Bobrovskiy | Australian National University)

The mysterious Dickinsonia has baffled scientists and evaded classification for many decades, but now scientists are certain that it's an animal.

In fact, it's the oldest known animal on Earth at 558 million years old, proving that animals existed for longer than previously believed.

The Case Of The Dickinsonia

In the early days of the animal kingdom, many of the organisms that existed were just strange blobs of life. One such organism is Dickinsonia, an oval-shaped creature that stretched up to 4.6 feet (1.4 meters) long and featured rib-like segments on its body.

Live Science reports that its unconventional body without discernable limbs, organs, or even a head made the Dickinsonia difficult to classify on the tree of life.

The Dickinsonia and other similarly odd creatures lived during the Ediacaran Biota around 635 million to 541 million years ago. This period was followed with the Cambrian explosion, which was when more modern animal life began to appear on the fossil record.

With the classification of Dickinsonia, scientists can now confirm that animals populated the planet in abundance 20 million years prior to the Cambrian explosion.

Solving The Mystery

In the new study published in the journal Science, researchers from the Australian National University are finally able to definitively identify the Dickinsonia as the oldest known animal on the planet.

To do this, the team analyzed an ancient fossil from a remote region near the White Sea in Russia. When Ilya Bobrovskiy, an ANU PhD scholar, unearthed the remnants of the long-extinct organism, it was so well-preserved that it still contained molecules of cholesterol fat, which is a hallmark of animal biology, according to ANU.

Dated 558 million years ago, the presence of the fat molecules confirmed to the scientists that they were looking at an animal that existed in abundance millions of years earlier than previously believed.

"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," Jochen Brocks, lead senior researcher and an associate professor from the ANU Research School of Earth Sciences, explains.

"The fossil fat now confirms Dickinsonia as the oldest known animal fossil, solving a decades-old mystery that has been the Holy Grail of palaeontology," he concludes.

One of the reasons that the mystery of the Dickinsonia took so long to solve is the challenge of finding quality fossils that still retained organic matter. To make the breakthrough, Bobrovskiy had to take a helicopter to a remote part of the White Sea in Russia, hang off the edges of cliffs, and dig out the ancient rocks to get to the fossil.

The effort pays off now with the definitive identification of the creature as the world's oldest known animal.

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