It was a time of spaceships but not the NASA kind.
Scientists at the Royal Ontario Museum in Toronto have unveiled a previously unknown family of extinct animals – nicknamed “spaceships” because of their science fiction appearance – that lived off the coast of what would eventually become North America about 506 million years ago.
This was during the Cambrian Period, when the continents were barren but the oceans were teeming with all manner of bizarre creatures that collectively represent the first great flowering of animal life on Earth.
Trapped by mudslides and preserved for the ages, many of those species are now coming to light in the Canadian Rockies, where ROM researchers are exploring new fossil sites similar to the renowned Burgess Shale deposits in British Columbia’s Yoho National Park.
The latest to be unveiled is Cambroraster falactus, a football-shaped arthropod that motored along the seafloor, presumably using its comb-like claws to scoop up worms and other tiny critters wriggling in the mud.
“You can imagine it almost like a fishing trawler, raking the bottom,” said Jean-Bernard Caron, the museum’s curator of invertebrate paleontology.
Dr. Caron and his team came across Cambroraster last year during their first detailed exploration of a fossil-rich area called Tokumm Creek, not far from the Burgess Shale. They found dozens of examples of the creature’s distinctive carapace, which likely helped protect it from predators, somewhat like a turtle’s shell. Two notches on either side of the carapace provided openings through which Cambroraster could peer upward and backward, watching for danger, while it moved blindly forward.
Fossil remains of Cambroraster reveal a circular mouth on its bottom side. This puts it in the same broad animal group as Anomalocaris, a larger, swimming carnivore that was the Cambrian’s top predator. The entire line died out at the end of Cambrian.
The find is an exciting one because Cambroraster is so large – roughly palm-sized – whereas many Cambrian fauna never grew longer than a few centimetres.
An even larger spaceship-like species has also turned up at Tokumm Creek. The dinner-plate-sized big brother to Cambroraster is still being analyzed. Together, the new finds are a strong indication that scientists have not yet sampled the full diversity of life that was present during the Cambrian Period.
Cambroraster received its scientific debut Tuesday with a detailed description in the Proceedings of the Royal Society B. It is one of many newly discovered species that are to be featured in the downtown Toronto museum’s new permanent gallery, scheduled to open in 2021. The gallery will showcase Canadian fossils and focus on the dawn and early development of animal life, Dr. Caron said.
The Globe and Mail, July 30, 2019