PUBLISHED: 09:25, Thu, Sep 10, 2020 | UPDATED: 09:29, Thu, Sep 10, 2020
A 410 million-year-old fossil of an armoured fish skull is expected to turn accepted ideas of sharks' evolutionary history on its head. Unlike modern-day sharks, the Minjinia turgenensis fish had a skeleton made of bone.
Shark skeletons, with the exception of their teeth, are made entirely out of a softer material called cartilage.
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It was a very unexpected discovery
Dr Martin Brazeau
Dr Martin Brazeau of Imperial College London, the study's lead author, said: “It was a very unexpected discovery.
"Conventional wisdom says a bony inner skeleton was a unique innovation of the lineage that split from the ancestor of sharks more than 400 million years ago, but here is clear evidence of bony inner skeleton in a cousin of both sharks and, ultimately, us.”
This ancestor to modern-day sharks is likely to have been even larger than today's apex predator, the great white.
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Shark news: An ancient 'armoured' fish may re-write evolution of sharks (Image: Getty)
Shark news: Inset shows raw scan data showing the spongy endochondral bone inside (Image: Imperial College London)
Some descendants of the placoderm (jawed fish) species may have grown to 30ft (10m) or more in length.
However, Minjinia turgenensis is believed to have been significantly smaller, at only a mere one foot (30cm) in length, although it is thought to have made an enormous impact.
The researchers believe this suggests sharks once had bone and then evolved to lose it.
As well as having a bony skeleton, the shark had bony plates over its head and shoulders acting as shields.
Shark news: Virtual three-dimensional model of the braincase of Minjinia turgenensis generated from CT scan (Image: Imperial College London)sonos sonos One (Gen 2) - Voice Controlled Smart Speaker with Amazon Alexa Built-in - Black read more