Billion-Year-Old Fossil May Provide a Major ‘Missing Link’ | IGN

A billion-year-old fossil discovered in the Scottish Highlands may provide the “missing link” in how animals evolved.

That “missing link” is the bridge between the transition of a single-celled organism and multicellular animals, according to the Current Biology study published about the discovery. This billion-year-old fossil “shows an organism which lies somewhere between single cell and multicellular animal,” according to a press release published by The University of Sheffield.

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“The origins of complex multicellularity and the origin of animals are considered two of the most important events in the history of life on Earth (and) our discovery sheds new light on both of these,” University of Sheffield’s Department of Animal and Plant Sciences investigative lead Charles Wellman said. “We have found a primitive spherical organism made up of an arrangement of two distinct cell types, the first step towards a complex multicellular structure, something which has never been described before in the fossil record.”

Wellman continued on to say that the evolution of multicellular animals occurred at least one billion years ago and “that early events prior to the evolution of animals may have occurred in freshwater like lakes rather than oceans.”

Another researcher on the team, Paul Strother from Boston College, said it’s long been speculated that the origin of animals included the repurposing of genes from already-evolved “unicellular organisms,” but that what’s seen in Bicellum Brasieri, which is the formal name of the fossil discovered in Scotland, is an actual example of such an occurrence.

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“What we see in Bicellum is an example of such a genetic system, involving cell-cell adhesion and cell differentiation that may have been incorporated into the animal genome half a billion years later,” Strother said.

The fossil, which was discovered at Loch Torridon in the Northwest Scottish Highlands, was in a state of “exceptional preservation,” according to the press release, which made analyzing its cellular and sub-cellular levels possible. The team expects to find even more fossils from the Torridonian deposits that could lead to additional revelations about the evolution of multicellular animals.

For more about fossils, check out this story about a dinosaur fossil discovered that may reveal the largest animal to ever walk on Earth and then read about this Tyrannosaurus rex fossil that recently sold for $31.8 million. Check out this story about a T.rex and Triceratops locked in the same fossil after that, then read about evidence found by researchers that suggests a microevolution in humans.

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Wesley LeBlanc is a freelance news writer and guide maker for IGN. You can follow him on Twitter @LeBlancWes
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