Fossilised fat reveals mysterious Dickinsonia blobs to be earliest known animal, dating back 558 million years

Molecules of cholesterol appear to have solved the puzzle surrounding the strange organisms

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This undated image courtesy of The Australian National University shows a Dickinsonia fossil from the White Sea area of Russia. Photo: Agence France-Presse

Published: 2:43pm, 21 Sep 2018Updated: 2:43pm, 21 Sep 2018

A strange fossil that looks a bit like a giant leaf, or a fingerprint the size of a coffee table, has puzzled scientists for decades.

Thousands of the blobby fossils have been found over the past seven decades, revealing that it lived at the bottom of the ocean, without a mouth, intestines or anus, half a billion years ago.

Was it a mossy plant? A giant single-celled amoeba? A failed experiment of evolution? Or the earliest animal on Earth?

After digging one of these fossils off a cliff in Russia and analysing its contents, researchers discovered molecules of cholesterol, a type of fat.

This photo provided by Ilya Bobrovskiy in September 2018 shows a fragment from a Dickinsonia fossil. Photo: AP

And they found their answer. The creature, known as Dickinsonia, is the Earth’s earliest known animal.

“Scientists have been fighting for more than 75 years” over the nature of these “bizarre fossils,” said associate professor Jochen Brocks from the Australian National University Research School of Earth Sciences.

“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.”