A bizarre sea beast with a round mouth full of serrated teeth sparked a prehistoric “ arms race ” as its eyes evolved, new research has revealed.
Radiodonts haunted the oceans more than 500 million years ago and are one of the earliest animal species to appear on Earth.
Now, a new study has revealed how their wide eyes gave them an edge when hunting for food, forced their prey to adapt or die, and triggered a wave of evolution.
While other animals at the time also had eyes, the radiodonts’ eyes were particularly sophisticated, giving them the edge in dimly lit areas of the ocean.
Radiodonta haunted the oceans more than 500 million years ago and is one of the earliest animal species to emerge on Earth
John Paterson of the University of New England, the study’s lead author, said it was this “arms race” that gave rise to the diversity of life we see today.
He said, ‘Radiodonts are really weird because they look like a mix of different animal parts stuck together.
The head has a pair of large spiny appendages for catching prey, a round mouth with serrated teeth and a pair of large eyes.
“The rest of the body resembles that of a squid, with a series of swim flaps along either side of the body.”
He continued: “They are some of the first animals to appear in the history of the planet.
Because they are so well equipped to hunt, especially with their excellent vision, they would have put their prey under heavy pressure, especially when it came to long-term survival.
So prey species had to adapt and evolve in response to this pressure or they would be in danger of extinction.
“This so-called” arms race “has been a constant evolutionary battle between predators and prey over time, with predators adapting better” weapons “and prey improving their defenses.”
He added: ‘It is possible that this arms race is largely responsible for the diversity of life we see today.
Dr. Paterson and his team came to their conclusions after examining fossils from Emu Bay Shale on Kangaroo Island, South Australia
“When animals started to eat each other more than 500 million years ago, it created a growing network of complex ecological interactions that undoubtedly resulted in new species that evolved over time.”
Dr. Paterson and his team came to their conclusions after examining fossils from Emu Bay Shale on Kangaroo Island, South Australia.
Until recently, relatively little was known about radiodontic eyes, but the discovery of larger, better eye samples paved the way for a breakthrough.
Their wide eyes gave them an edge when hunting for food, forcing their prey to adapt or die, feeding a wave of evolution
One eye sample had a whopping 28,000 lenses – a number that only rivaled insects like the dragonfly.
Dr. Paterson said, “We have shown that radiodonts have some of the largest and most complex eyes in the history of animal life.
Not only did they have sharp vision, but they were also able to see at different light levels in the ocean.
Radiodonts had some of the largest and most complex eyes in the history of animal life, allowing them to see sharply as well as see at different light levels in the ocean.
Some were over three feet long at a time when most life forms were aquatic plants and multicellular organisms
‘That also applies to the dark depths of the twilight zone – up to 1000 meters – where sunlight has virtually disappeared.’
He added, “Radiodonts represent some of the earliest and most primitive arthropods in existence.
‘Without them, we might not see the enormous diversity of arthropods that live today, including insects, spiders, crustaceans and centipedes.’
John Paterson of the University of New England, lead author of the study, said it was this “ arms race ” that gave rise to the diversity of life we see today
The oldest radiodont fossils date back to about 518 million years ago, and while it’s unclear exactly when they became extinct, the creatures appear to have survived up to 400 million years ago.
A diverse order of predators, they ranged in size from over six feet in length to just a few inches.
“Many types are now known and it has become quite clear that they had varied diets,” said Dr. Paterson.
Some would have been the great white sharks of their day – those are apex predators that ate large prey.
However, other species probably ate very small plankton.
Interestingly, the largest radiodonts in existence are the ones that would have eaten these tiny organisms, which is similar to the diet of some of today’s giant whales.
“Because they are quite large, it is possible that some may have had significant lifespans, maybe on the scale of decades, but that’s speculative.”
Dr. Paterson and his colleagues, Gregory Edgecombe and Diego García-Bellido, published their findings in the journal Science Advances.
WHAT WAS THE ‘CAMBRIAN EXPLOSION’?
Scientists have long speculated that a large peak of oxygen during the ‘Cambrian Explosion’ was key to the development of many animal species.
The Cambrian explosion, about 541 million years ago, was a time when a wide variety of animals erupted on the evolutionary scene.
Before about 580 million years ago, most organisms were simple and consisted of individual cells occasionally organized into colonies.
Over the next 70 or 80 million years, evolution accelerated and the diversity of life began to resemble that of today.
It ended with the extinction of the Cambrian Ordovician about 488 million years ago.
A recent study linked the historical rise in oxygen responsible for the formation of animal life on Earth to fossil fuels. Pictured: Formed 450 million years ago, this black shale contains trilobite fossils and organic matter that helped support it in oxygen