This terrifying ancient ‘ghost shark’ is YOUR distant relative and it’s got a family secret to pass on
Scientists analyse remains of long lost deep sea dweller in bid to solve the mystery of human evolution
A STUDY of the earliest type of shark that roamed the ocean 280 million years ago has shed light on the origins of humanity.
The extinct creature called Dwykaselachus oosthuizeni had huge eyes and was similar to today's 'ghost sharks' - allowing it to swim at incredibly deep depths.
Its remarkably preserved skull was dug up from rocks beneath South Africa's unforgiving Karoo desert.
From the outside it resembles that of prehistoric sharks known as symmoriiforms - notable for the male's large brush-like spine which may have been used as a form of sexual display.
But high definition scans shows telltale structures of the brain, major cranial nerves, nostrils and inner ear belonging to modern-day chimaeras - dead-eyed, wing-finned fish dubbed 'ghost sharks' because they are rarely seen by people.
Complete with exceptionally large orbits the results indicate chimaeroids are rooted within the order of symmoriiform sharks.
This discovery allows scientists to firmly anchor chimaeroids - the last major surviving vertebrate group to be properly situated on the tree of life - in evolutionary history.
The study, published in the journal Nature, offers insights into the early development of chimaeroids - a group of fish obscurely related to sharks and rays - as they diverged from their deep, shared ancestry.
Professor Michael Coates, of Chicago University, said: "Chimaeroids belong somewhere close to the sharks and rays but there's always been uncertainty when you search deeper in time for their evolutionary branching point.
"Chimaeras are unusual throughout the long span of their fossil record.
"Because of this it's been difficult to understand how they got to be the way they are in the first place.
"This discovery sheds new light not only on the early evolution of shark-like fishes but also on jawed vertebrates as a whole."
Analysis of the fossil reveals more similarities to chimaeroids than have previously been observed which helps clarify where these creatures fit in the fish family tree.
Chimaeroids - or ghost sharks - are members of the class of fish known as Chondrichthyes whose skeletons are made of cartilage rather than bone.
These include sharks and rays. But it had been difficult to see how closely linked they are because they look so different - distinguished by exceptionally large eyes with orbits so big they distort the shape of the brain.
Chimaeras include about 50 living species - known in various parts of the world as ratfish, rabbit fish, ghost sharks, St. Joseph sharks or elephant sharks.
They represent one of four fundamental divisions of modern vertebrate biodiversity. With large eyes and tooth plates adapted for grinding prey, these deep-water dwelling fish are far from the bloodthirsty killer sharks of Hollywood.
For more than 100 years the relationship between chimaeras - the earliest sharks - and other early jawed fishes in the fossil record - has fascinated palaeontologists.
Chimaeras - named for their similarities to a mythical creature described by Homer as "lion-fronted and snake behind, a goat in the middle" - are unusual.
Their anatomy comprises features reminiscent of sharks, ray-finned fishes and tetrapods, and their form is shaped by hardened bits of cartilage rather than bone.
Because they are found in deep water, they were long considered rare. But as scientists gained the technology to explore more of the ocean, they are now known to be widespread, but their numbers remain uncertain.
Of all living vertebrates with jaws, chimaeras seemed to offer the best promise of finding an archive of information about conditions close to the last common ancestor of humans and a Great White.
Cartilage rarely fossilizes so the Dwykaselachus find by farmer Roy Oosthuizen when he split open a nodule of rock on his farm in the 1980s was extraordinary.
It was carefully archived in the South African Museum in Cape Town until a state-of-the-art micro CT scanner allowed scientists to take a closer look.
At the surface 'Dwyka' seemed to be a symmoriid shark - a bizarre group more than 300 million years old known for their unusual dorsal fin spines resembling boom-like prongs and surreal ironing boards.
The skull was remarkably intact - one of a very few that had not been crushed during fossilisation. The scans also provided an unprecedented view of the interior of the brain case.
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Prof Coates said: "When I saw it for the first time I was stunned. The specimen is remarkable."
The brain case preserves details about the brain shape, the paths of major cranial nerves and the anatomy of the inner ear.
A large extinction of vertebrates at the end of the Devonian period - about 360 million years ago - gave rise to an explosion of cartilaginous fishes.
Prof Coates said instead of what became modern-day sharks revelations from this study indicate "much of this new biodiversity was, instead, early chimaeras."
Prof Coates said: "We can now say the first radiation of cartilaginous fishes after the end Devonian extinction was chimaeras - in abundance.
"It's the inverse of what we've got today - where sharks are far more common."
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