What had thorny claws sticking out of his mouth, had a toilet brush-shaped body, and looked like he had slipped off the cover of a sci-fi novel? An oceanic predator of the Cambrian period known as Stanleycaris hirpex. The strange fossil’s recent fossils are exceptionally complete, preserving the brain, nervous system, and a third eye.
Researchers at the Royal Ontario Museum (ROM) in Toronto recently announced the discovery of fossils belonging to this strange animal as part of an “amazing” fossil treasure dating back 506 million years, according to a statement (opens in a new tab).
Paleontologists found these ancient treasures in the Burgess Shale, a formation in the Canadian Rockies of British Columbia that is known for its abundant and well-preserved fossilized animal remains, and among the half-million-year-old fossils were numerous marine specimens. predator S. hirpex.
“What makes this finding so remarkable is that we have dozens of specimens showing the remains of the brain and other elements of the nervous system, and they are incredibly well preserved and show very fine detail,” said Joseph Moysiuk, lead author of ‘a study describing fossils and a doctoral candidate from the University of Toronto in ecology and evolutionary biology.
“Before that, there had only been a few other fossilized brain finds, especially from the Cambrian period, but that’s still a pretty rare thing, and it’s only something that’s been observed in the last 10 years or so.” , said Moysiuk. Living Science. “In most species where we have seen fossilized brains there are only one or two specimens available.”
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Despite being small, measuring less than 20 inches long, S. hirpex was probably an imposing sight for its even smaller prey.
“He had this really fierce apparatus of prickly claws and round mouth that made him look absolutely fierce,” Moysiuk said. “It also had long, rake-like spines to comb the seabed to hunt down any buried organism, side flaps to help it slide through the water, and trident-shaped spines projecting one toward the other. ‘another from the opposite appendix which we believe he used as a jaw to crush his prey.’
A pair of fossil specimens of Stanleycaris hirpex, specimen ROMIP 65674.1-2. (Image credit: Royal Ontario Museum / Photo by Jean-Bernard Caron) (opens in a new tab)
The fossils show that S. hirpex’s brain was divided into two segments: the protocerebrum, which connected with his eyes, and the deutocerebrum, which connected with the frontal claws. This brain structure differs from the three-lobe structure of modern arthropods that are distant relatives of S. hirpex, such as insects. The brains of these modern relatives, on the other hand, comprise a protocerebrum, a deutocerebrum, and a tritocerebrum, which connects the brain to the labrum of an insect, or upper lip, among other parts of the body.
“Preserving the brain in these animals gives us a direct view of the evolution of the nervous system from the perspective of the fossil record,” Moysiuk said.
Radiodonta, an extinct branch of the arthropod evolutionary tree that includes Stanleycaris, “is an important group to know, as it offers us a better understanding of the evolution of modern arthropods.” said Moysiuk.
Another interesting aspect of S. hirpex was its third large medium eye, a feature first observed in a radiodont. Although the study authors are not sure how the ancient arthropod used this eye, it may have helped the animal track its prey, Moysiuk suggested.
“Finding the third eye was a shock to us because we were starting to think we understood the radiodonts and what they looked pretty good about,” he said. “For the first time, we were able to recognize this giant medium eye in addition to the pair of eyes we already knew in radiodonts.”
Although some modern arthropods, such as dragonflies and wasps, also have medium eyes, they are usually more sensitive than the other two eyes, and yet they do not focus as well. “We can only speculate, but we believe that this third eye helped guide an animal, and it is especially important for a predator like Stanleycaris to move quickly and accurately through the environment,” Moysiuk said.
Three of the S. hirpex fossils that were excavated during the excavation are now on permanent display at the Royal Ontario Museum in its Willner Madge Gallery, Dawn of Life.
The findings were published in the journal on July 8 Current biology (opens in a new tab).
Originally published in Live Science.