Fats recovered from Ediacaran fossil, 558 mya, shows that animals then were “large,” “abundant”

Yes, you read that right and our physics color commentator Rob Sheldon explains why it was possible below.

From ScienceDaily:

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

The strange creature called Dickinsonia, which grew up to 1.4 metres in length and was oval shaped with rib-like segments running along its body, was part of the Ediacara Biota that lived on Earth 20 million years prior to the ‘Cambrian explosion’ of modern animal life.

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“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,” said Associate Professor Jochen Brocks 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 palaeontology.”

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Palaeontologists normally study the structure of fossils, but Mr Bobrovskiy extracted and analysed molecules from inside the Dickinsonia fossil found in ancient rocks in Russia to make the breakthrough discovery. Paper. (paywall) – Ilya Bobrovskiy, Janet M. Hope, Andrey Ivantsov, Benjamin J. Nettersheim, Christian Hallmann, Jochen J. Brocks. Ancient steroids establish the Ediacaran fossil Dickinsonia as one of the earliest animals. Science, 2018; 361 (6408): 1246 DOI: 10.1126/science.aat7228 More.

A reader wrote us to ask, how is this possible? Fats survive for over half a billion years?

Rob Sheldon offers some thoughts in response:

Both straight-chain fats (crude oil), and cyclic hydrocarbons (coal) survive for millennia in the ground. It isn’t too surprising if cholesterol (4 rings, 5-carbon chain) can survive. The principle way oils degrade is through oxidation, and buried in the mud is a good way to avoid oxygen.

The other degradation process is heat. But oils are pretty resistant to heat, which is why we use them to lubricate engines and make fried chicken.

But most significantly, water has very little effect on them. Proteins, on the other hand, are susceptible to oxygen, heat and water, which is why they don’t last as long in fossils as oils.

But how did the chemical bonds survive?

Most fossils have been cooked, high temperature and high pressure, so that the oils are all gone. This particular fossil came from an “uncooked” sandstone in Siberia–which minimizes the effect of heat over the past few million years. And then the article goes on to say that he doesn’t find cholesterol, what he finds is degradation products “sterols” that have a molecular fingerprint different from the sterols from plants. Having built mass spectrometers for part of my career, it doesn’t surprise me at all that the fingerprint for plant sterols is quite distinct from the fingerprint of animal sterols.

From The Scientist:

Dickinsonia and other Ediacara fossils are found all over the world, but in the majority of locations, the rock in which they reside has “been cooked,” says Brocks, meaning the preserved remains have been buried, heated, and compressed by tectonic activity such that “apart from the impression in the sandstone, there is nothing left of the fossil.”

In the White Sea cliffs, the sediments have escaped deep burial and geological baking. “The fossils there are so incredibly well preserved that Dickinsonia still consists of a film of organic matter,” says Brocks. Ruth Williams, “Fossilized Lipids Confirm Dickinsonia as One of the Earliest Animals” at The Scientist

Doubtless, the far reaches of the planet hold many similar surprises.

Rob Sheldon is author of Genesis: The Long Ascent

See also: Researchers: First Ediacaran animal identified (Dickinsonia)