A bizarre sea beast with a circular mouth full of jagged teeth triggered a prehistoric “arms race” as its eyes evolved, new research has revealed.
Radiodonts hid the oceans more than 500 million years ago and are one of the first types of animals to appear on planet Earth.
Now, a new study has revealed how their large eyes gave them an advantage when hunting for food, forcing their prey to adapt or die and fueling an increase in evolution.
While other animals of the time also had eyes, the eyes of the radiodoners were particularly sophisticated, giving them an edge in the dimly lit areas of the ocean.
Radiodonta followed the oceans more than 500 million years ago and is one of the first types of animals to appear on planet Earth.
John Paterson of the University of New England, lead author of the study, said that this “arms race” has given birth to the diversity of life we see today.
He said: “Radiodonts are really weird because they look like a mixture of various parts of animals glued together.
“The head has a pair of large, prickly appendages for capturing prey, a circular mouth with jagged teeth and a large pair of eyes.
“The rest of the body looks like a squid, with a series of swimming flaps along both sides of the body.”
He continued: “These are some of the first animals to appear in the history of the planet.
“Because they are so well equipped for hunting, especially with their excellent vision, they would have put a lot of pressure on their prey, especially when it comes to long-term survival.
So, prey species needed to adapt and evolve in response to this pressure, otherwise they would have faced extinction.
“This so-called ‘arms race’ has been a constant evolutionary struggle 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 reach their conclusions after examining fossils from the Emu Bay Shale on Kangaroo Island, South Australia
“Once animals began eating each other more than 500 million years ago, it triggered an expanding network of complex ecological interactions that undoubtedly led to the development of new species over time.”
Dr. Paterson and his team came to their conclusions after examining fossils from the Emu Bay shale on Kangaroo Island, South Australia.
Until recently, relatively little was known about radiodontic eyes, but the discovery of larger, better eye specimens paved the way for a discovery.
Their large eyes gave them an advantage when hunting for food, forcing their prey to adapt or die and fueling an increase in evolution.
One eye sample had 28,000 jaw-dropping lenses – a number rivaled only by dragonfly-like insects.
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 able to see at different levels of light in the ocean.
Radiodonts have had some of the largest and most complex eyes in the history of animal life, which have given them clear vision and the ability to see at different levels of light in the ocean.
Some reached a length of over a meter at a time when most life forms were aquatic plants and multicellular organisms.
“This includes in the dark depths of the twilight zone – up to 1,000 meters – where sunlight has almost completely disappeared.”
He added: “Radiodonts are some of the earliest and most primitive arthropods in existence.
“Perhaps without them, we would not currently see a huge diversity of arthropods, including insects, spiders, crustaceans and centipedes.”
John Paterson of the University of New England, the study’s lead author, said that this “arms race” has given birth to the diversity of life we see today.
The oldest radiodont fossils date back to about 518 million years ago and – although it is not clear exactly when they disappeared – the creatures appear to have survived 400 million years ago.
A diverse order of predators, they ranged in size from more than two meters long to just a few centimeters.
“There are many known species and it has become quite clear that they have varied diets,” said Dr. Paterson.
“Some would have been the Great White Sharks of their time – that is, top predators that ate large prey.
However, other species probably ate small plankton.
“Interestingly, the largest existing radiodonts are those who ate these small organisms, which is similar to the diet of some of today’s giant whales.
“Being quite large, it is possible for some to have a considerable lifespan, perhaps on a scale of decades, but this is speculative.”
Dr. Paterson and 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 increase in oxygen during the “Cambodian explosion” was the 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 broke out on the evolutionary stage.
Before about 580 million years ago, most organisms were simple, composed of individual cells occasionally organized in colonies.
Over the next 70 or 80 million years, the rate of evolution accelerated and the diversity of life began to resemble that of today.
It ended with the Cambrian-Ordovician extinction event, about 488 million years ago.
A recent study linked the historic increase in oxygen responsible for the formation of animal life on Earth to fossil fuels. Pictured: This black shale, formed 450 million years ago, contains fossils of trilobites and organic materials that helped support them in oxygen.