Massive new animal species discovered in half-billion-year-old Burgess Shale

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University of Toronto paleontologists based at the Royal Ontario Museum (ROM) have discovered the remains of a huge new fossil species belonging to a group of extinct animals in Cambrian rocks half a billion years old. years of Kootenay National Park in the Canadian Rockies.

Named Titanokorys gainesi and described in a study published in Royal Society Open Science earlier this month, the new species is notable for its size. With an estimated total length of half a meter, Titanokorys was a giant compared to most of the animals that lived in the seas at that time – most of which barely reached the size of a pinky finger.

Jean-Bernard Caron sits above a Titanokorys gainesi fossil at the quarry in Kootenay National Park (photo by Joe Moysiuk)

“The size of this animal is absolutely mind-boggling – it is one of the largest animals from the Cambrian period ever found,” explains Jean-Bernard Caron, Associate Professor in the Departments of Earth Sciences and Ecology and Evolutionary Biology (EEB) in the Faculty of Arts and Sciences at the University of Toronto and Richard M. Ivey Curator of Invertebrate Paleontology at ROM .

Evolutionarily, Titanokorys belong to a group of primitive arthropods called radioodonts. The most iconic representative of this group is the profiled predator Anomalocaris, which itself may have approached a meter in length. Like all radiodons, the Titanokorys had multifaceted eyes, a pineapple slice-shaped mouth, edged with teeth, a pair of thorny claws under its head for capturing its prey, and a body with a series of flaps for swimming. . Within this group, some species also had large conspicuous head shells, Titanokorys being one of the largest ever known.

“Titanokorys are part of a subgroup of radiodons, called hurdiids, characterized by an incredibly long head covered with a three-part shell that has taken on a myriad of shapes. The head is so long in relation to the body that these animals are in reality little more than swimming heads ”, added Joe Moysiuk, co-author of the study, and doctoral student in EEB based at ROM.

Jean-Bernard Caron and Joe Moysiuk in the ROM’s paleontology lab room examining Titanokorys gainesi and Cambroraster falcatus (photo by Andrew Gregg / © Red Trillium)

The reason why some radioodonts developed such a bewildering array of head shell shapes and sizes is still poorly understood and was likely due to various factors, but the large, flattened shell shape of Titanokorys suggests that this species was adapted to life near the seabed.

“These enigmatic animals certainly had a significant impact on the ecosystems of the Cambrian seabed. Their limbs at the front looked like multiple rakes stacked up and would have been very effective in bringing whatever they caught in their tiny thorns back to their mouths. The huge dorsal shell could have functioned like a plow, ”added Caron, who is Moysiuk’s doctoral director.

All study fossils were collected around Marble Canyon in northern Kootenay National Park by successive ROM expeditions. Discovered less than a decade ago, this area has yielded a wide variety of Burgess Shale animals dating back to the Cambrian period, including a smaller and more abundant parent of Titanokorys named Cambroraster falcatus in reference to its shell of head in the shape of a millennial falcon. According to the authors, the two species could have competed for similar prey living on the bottom.

These and other specimens from the Burgess Shale will be on display in a new gallery at the ROM, the Willner Madge Gallery, Dawn of Life, which will open in December 2021.

The Burgess Shale fossil sites are located in Yoho National Park and Kootenay National Park and are managed by Parks Canada. Parks Canada works with leading scientific researchers to deepen knowledge and understanding of this key period in Earth’s history and to share these sites with the world through award-winning guided hikes. The Burgess Shale was designated a UNESCO World Heritage Site in 1980 for its Outstanding Universal Value and is now part of the largest World Heritage Site in the Canadian Rocky Mountain Parks.

Research support came from a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada in Caron and a Vanier Canada Graduate Scholarship in Moysiuk. Additional support for research and fieldwork came from the Polk Milstein family, ROM, National Geographic Society, Swedish Research Council, National Science Foundation and Pomona College.


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