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The World’s Oldest Fishes

Artist’s reconstruction of Metaspriggina walcotti. Credit: Maryanne Collins

Artist’s reconstruction of Metaspriggina walcotti. Credit: Maryanne Collins

By John Long

Just 6 cm long and lacking fins and bone, the world’s oldest fish looked more like a worm yet it was the most advanced creature on Earth about 518 million years ago.

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The first fossil fishes are known from scant and often ambiguous fossil remains, but new research published in Nature is giving us the first clear picture of what these earliest fishes were really like. The new finding takes the record for the oldest known definite fish to date – 520 million years – and looks more like the worm on an angler’s hook than any living fish we might recognise today.

Metaspriggina walcotti was discovered from the famous Cambrian Burgess Shale sites in British Columbia, Canada, and is dated at around 518 million years old. It was about 6 cm long and had an elongated body and a pair of large protruding eyes. The fossil reveals impressions of small paired nasal capsules, but breathed through seven pairs of external gills. These are different from the internal gill arches we see in living lampreys, and are more like those in jawed fishes.

The stout rod supporting its spine (notochord) enabled strong W-shaped muscle bands to develop along its entire body – a feature found in all vertebrates. Its ability to swim fast was no doubt a key factor in its success while living in precarious seas inhabited by huge predators such as the 1 metre-long Anomalocaris.

Metaspriggina was first discovered and named in 1993 as it was thought to be related to the 560-million-year-old Spriggina from the Ediacaran fauna of Australia (Spriggina was...

The full text of this article can be purchased from Informit.