Ancient Metaspriggina fish fossils reveal ‘first steps’ taken toward evolution of jaws 500 million years ago

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“I am so thankful that the site was found in a national park, “ says Caron, referring to the way Parks Canada is controlling access to the site to prevent pillaging.

Metaspriggina lived 505 million years ago when life was exploding in new directions. It swam in a world then dominated by small, strange looking creatures, many of which resemble today’s shrimps and crabs, says Caron.

Metasprigina from Marble Canyon.

Metaspriggina was tiny. “They are no longer than my thumb,” he says of the fossils.

But some are so well preserved their muscles and nasal structures are visible.

“Even the eyes are beautifully preserved and clearly evident,” says Simon Conway Morris at the University of Cambridge, co-author of a report on Metaspriggina published Wednesday in the journal Nature.

The scientists say the fish had “unambiguous vertebrate features” and striking “branchial arches” on either side of its body.

The arches likely helped the primitive fish eat and breathe, and appears to be the one of the first steps toward the evolution of jaws. “It’s the first stage of a series of transformations that led to the jaws,” says Caron.

A photo Illustration of Metaspriggina.
Marianne Collins, Conway Morris

The “stunning” fossils, as Conway Morris describes them, enabled the scientists to classify Metaspriggina as one of the first primitive fishes that they say was common in the ancient seas.

The Kootenay fossil bed, which Caron and his colleagues discovered in 2012, is about 40 kilometres from the more famed Burgess Shale sites, discovered more than a century ago and long considered among the richest fossil beds in the world. They all formed during the Cambrian explosion when many forms and new branches of life emerged. Some died out while others evolved into animals seen today.

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