Half a billion years ago, the oceans were filled with life that looked more like underwater aliens than the marine animals we know today.
Now researchers have discovered a fossil of an unusual creature that was likely a giant compared to the tiny ocean life of 500 million years ago.
Radiodons, a group of primitive arthropods, spread after the Cambrian explosion 541 million years ago – a time when a multitude of organisms suddenly appeared on Earth, based on the fossil record.
The newly discovered fossil belonged to the species “Titanokorys gainesi”, a radiodon that can be up to half a meter long – which can be considered huge compared to other ocean creatures that were the size of a little finger at that time.
The fossil was found in Cambrian rocks in Kootenay National Park, located in the Rocky Mountains of Canada.
A detailed study on the fossil was published on Wednesday (8) in the scientific journal Royal Society Open Science.
“The size of this animal is absolutely mind-boggling, this is one of the largest animals from the Cambrian period ever found,” said study author Jean-Bernard Caron, curator of invertebrate paleontology at the Royal Ontario Museum.
The Titanokorys would have been a difficult animal to find. It had multifaceted eyes, a mouth shaped like a pineapple slice with aligned teeth, and spiny claws located below its head to capture prey.
The animal’s body was equipped with a series of flaps that helped it to swim. And the Titanokorys had a large carapace on their head, or a defensive covering, like the carapace of a crab or turtle.
“Titanokorys are part of a subgroup of radiodons, called hurdiids, characterized by an incredibly long head covered by a three-part carapace that assumed a myriad of shapes. The head is so long relative to the body that these animals are really little more than swimming heads,” said study co-author Joe Moysiuk, doctoral student in ecology and evolutionary biology at the Royal Ontario Museum at the University of Toronto, in a statement.
Researchers are still trying to understand why some radiodons had such a variety of carapaces on their heads, of all shapes and sizes.
It’s not clear what this formation protected them from, given their size compared to other marine life forms at the time.
In the case of Titanokorys, the wide, flat carapace suggests that it has adapted to living close to the bottom of the sea.
“These enigmatic animals have certainly had a major impact on the ecosystems of the Cambrian seabed. Its front limbs looked like several stacked rakes and would have been very efficient in bringing anything caught in its little thorns to its mouth. The huge dorsal carapace could have functioned like a plow,” said Caron.
Titanokorys fossils were found in Marble Canyon, located in the north of Kootenay National Park, which was the site of many fossil discoveries from the Cambrian period, dating back to 508 million years ago.
The site is part of the Burgess Shale, a well-preserved fossil deposit in the Canadian Rockies.
The Burgess Shale is a UNESCO World Heritage Site. One of the discoveries made at the site includes the Cambroraster falcatus radiodon, so named because its head shell is similar in shape to the Star Wars Millennium Falcon.
It is possible that these two species fought on the seabed in search of prey, the researchers say.
Titanokorys and other fossils collected from the Burgess Shale will be displayed in a new gallery at the Royal Ontario Museum starting in December.
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