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The oldest known animal in the geological record has been identified, in a discovery that scientists call "the holy grail of paleontology".
The fat molecules discovered on the fossil of a mysterious creature called Dickinsonia confirmed that he lived 558 million years ago, making him the first known member of the animal kingdom.
The discoveries place its existence 20 million years before the Cambrian explosion event, when important animals began to appear on the fossil record.
The fossil was discovered for the first time by Australian scientists on an isolated Russian cliff on the shores of the White Sea in 1947. The study, released Friday, ends a decades-long debate to identify what it was.
"The fossil fat molecules we found prove that animals were large and abundant 558 million years ago, millions of years earlier than expected," said Jochen Brocks, a member of the # 39; team of the ANU. research.
The symmetrical oval shaped body was about 1.4 meters long and had rib-like features all over the body.
His fossil was so well preserved that scientists found cholesterol, which they called "the hallmark" of animal life.
"Scientists have been fighting for over 75 years on what Dickinsonia and other strange fossils of Ediacaran biota were: unicellular giant amoebae, lichens, failed evolutionary experiments or the first animals on Earth" said Brocks.
"The fossil fat now confirms Dickinsonia as the oldest known animal fossil."
A new approach leads to a breakthrough
Scientists had been intrigued by the fossil for so long because rocks containing fossils had been altered by heat and pressure, according to the ANU.
But the team made the breakthrough discovery after extracting molecules from inside the fossil rather than studying its structure as scientists usually do.
"I took a helicopter to reach this very remote part of the world – where bears and mosquitoes live – where I could find Dickinsonia fossils whose organic matter was still intact," said Ilya Bobrovskiy, the newspaper's main author. .
"I had to hang ropes at the edge of a cliff and dig enormous blocks of sandstone, throw them away, wash the sandstone and repeat this process until I found the fossils I was looking for", a- he added.
Dickinsonia contained a "striking abundance" of cholesterol – 93%, compared with only 10.6% and 11.9% in deposits immediately above and below the fossil.
The team worked alongside researchers from the Russian Academy of Sciences, the Max Planck Institute for Biogeochemistry and the University of Bremen, both in Germany.
Earlier this year, scientists discovered the world's oldest known human fossil outside Africa, dating from 177,000 to 194,000 years ago.
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