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Rock Star: Huge 500-Million-Year-Old Fossil Unearthed  

“Mind boggling” ocean predator found in sheet of half a billion-year-old coastal shale. 

When related animals were barely the length of a human pinky finger, Titanokory gainesi was at least 20 inches (500 centimeters) long and lived in the seas of the Cambrian Age.

Paleontologists at the Royal Ontario Museum discovered a fossil of the giant new species in rocks a half-a-billion years old of the Burgess Shale area in the Kootenay National Park, British Columbia, in the Canadian Rockies.

“The sheer size of this animal is absolutely mind-boggling. This is one of the biggest animals from the Cambrian Period ever found,” said Jean-Bernard Caron, the Royal Ontario Museum’s curator of invertebrate paleontology and the co-author of the study published on Sept. 8 in Royal Society Open Science.

“Titanokorys is part of a subgroup of radiodonts, called hurdiids, characterized by an incredibly long head covered by a three-part carapace that took on myriad shapes,” said co-author Joe Moysiuk, a PhD candidate at the University of Toronto. “The head is so long relative to the body that these animals are really little more than swimming heads.

View of Titanokorys gainesi from the front. (Illustration by Lars Fields, Royal Ontario Museum)
Fossil of Titanokorys gainesi carapace. (Photo by Jean-Bernard Caron, Royal Ontario Museum)

Titanokorys belongs to a group including the streamlined predator Anomalocaris that may have reached just more than 3 feet (one meter) in length. Like other radiodonts, Titanokorys had an exoskeleton, multifaceted eyes, a tooth-lined circular mouth, spiny claws below its head to capture prey and flaps on its body for swimming the shallow seas.

Some species in this group also featured large head carapaces. Titanokorys has one of the largest ever discovered.

The carapace of Titanokorys gainesi (lower) along with two symmetrical rigid plates (upper) that covered the head from the underside. All together they form a three-part set of armor that protected the head from all sides. (Jean-Bernard Caron, Royal Ontario Museum)

Why radiodonts such as Titanokorys evolved such a huge array of head carapace shapes and sizes is not understood entirely. However, the broad flattened carapace of Titanokorys suggests this species was adapted to life near the seafloor.

“These enigmatic animals certainly had a big impact on Cambrian seafloor ecosystems. Their limbs at the front looked like multiple stacked rakes and would have been very efficient at bringing anything they captured in their tiny spines towards the mouth. The huge dorsal carapace might have functioned like a plough,” said Caron, who teaches ecology and evolutionary biology and earth sciences at the University of Toronto.

High up in the mountains of Kootenay National Park, the ROM fieldwork crew extracts a shale slab containing a fossil of Titanokorys gainesi. (Jean-Bernard Caron, Royal Ontario Museum)
Jean-Bernard Caron, Richard M. Ivey Curator of Invertebrate Palaeontology, Royal Ontario Museum, seated above a fossil of Titanokorys gainesi at the quarry site located in Kootenay National Park. (Joseph Moysiuk)

The fossils in this study were collected around Marble Canyon in Kootenay National Park by successive Royal Ontario Museum expeditions. The canyon has been rich in discoveries of a variety of Burgess Shale animals dating back to the Cambrian Period. These include Cambroraster Falcatus, which was named for the resemblance of its head carapace to the Millennium Falcon of “Star Wars” fame. Caron and Moysiuk say they believe that it might have competed with its relative, Titanokorys, for similar bottom-dwelling prey.

The Cambrian Period lasted approximately 55 million years from about 541 million years ago, following the end of a preceding ice age, to 485 million years ago. It was characterized by rapid development of multicellular animals, most of which were aquatic. Plant life was single-celled.

Edited by Richard Pretorius and Kristen Butler

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