Fossilized fat depicts 550 million-year-old sea creatures that may have been the first animals in the world

A bizarre sea creature whose fossils look like a cross between a leaf and a fingerprint is perhaps the oldest known animal on Earth, dating back 558 million years.

According to New Scientist, researchers from the Australian National University (ANU) have found a happy discovery in a remote region of Russia: Dickinsonia a fossil with fat molecules still bound. These unusual oval-shaped creatures were soft-bodied, had ribbed structures that ran down their sides, and were about 4.5 feet long. They were “weird like life on another planet,” the researchers wrote in a summary of a new paper published in the journal Science.

Although Dickinsonia fossils were first discovered in South Australia in 1946, researchers lacked the organic matter needed to classify this creature. “Scientists have been fighting for more than 75 years Dickinsonia and other bizarre fossils of the Edicaran biota were: giant unicellular amoebae, lichens, failed evolutionary experiments, or the earliest animals on Earth, ”said senior author Jochen Brocks, an associate professor at ANU.

By discovering cholesterol molecules – found in almost all animals but not in other organisms like bacteria and amoebae – scientists can say that Dickinsonia were animals. The creatures swam the seas during the Ediacaran period, 635 million to 542 million years ago. More complex organisms such as mollusks, worms and sponges appeared only 20 million years later.

A fossil with fat molecules was found on cliffs near the White Sea in an area of ​​northwestern Russia that was so far away that researchers had to go by helicopter to get there. Collecting samples is also a feat that causes death.

“I had to hang over the edge of a cliff on ropes and dig up huge blocks of sandstone, throw them down, wash the sandstone and repeat this process until I found the fossils I was looking for,” said lead author Ilya Bobrovskiy of ANU. . Given that this discovery could change our understanding of the earliest life forms on Earth, the risk seems to have paid off.

[h/t New Scientist]