For over a century it’s been recognized that Burgess Pass, located in Yoho National Park in the shadow of Mount Wapta and Mount Field, is home to one of the most important fossil deposits in the world.
This deposit, known as the Burgess Shale, is not the only locale in the world where paleontologists have found Cambrian-period fossils that document the first appearance of many of the life forms we know today, including arthropods and vertebrates.
Other such Cambrian fossils have been found in Utah, Australia and China. The Chengjiang fossil site in China, for example, is older than the Burgess Shale, at about 520 million years old. The Burgess Shale site, at 505 million years old, however, has always been unique as, since it was discovered in 1909, it has offered the greatest abundance and diversity of species of soft-bodied creatures, along with a remarkable level of preservation.
But a new Burgess Shale site discovered near Marble Canyon in Kootenay National Park during the summer of 2012 is being described in the current issue of the scientific journal Nature Communications as the most significant find of Cambrian fossils since the 1984 Chengjiang discovery.
It may in fact, according to a press release from Parks Canada and the Royal Ontario Museum (ROM), one day outstrip the Burgess Shale beds of Yoho National Park. Until that is proven, researchers with ROM, Pomona College in Claremont, California, the University of Toronto, the University of Saskatchewan and Uppsala University of Sweden are content with the 12 new species they found among 3,000 fossils (representing 55 species in all) collected over a 15-day period in the summer of 2012.
According to Robert Gaines, associate professor of geology at Pomona College, the Marble Canyon site is exciting as it offers a great diversity and abundance of species, new species (along with the promise of more) and the same incredible level of preservation found at the Walcott Quarry of Burgess Pass.
“The abundance is just off the charts,” Gaines said, “and you don’t see that in any place but the Walcott Quarry. I’ve never put my hammer into anything like that before. It’s amazing. I’ve worked in Utah and China and many other parts of the world. I’ve spent most of the my professional life looking at these type of fossil beds, but I’ve never seen anything like this and the only place it exists really is in the Walcott Quarry where you have fossils in this kind of abundance.”
The Marble Canyon fossil beds sit in the Stephen Formation, along a feature known as the Cathedral Escarpment. In the Canadian Rockies, Burgess Shale creatures are typically found at the base of the escarpment, at one time a 200-metre tall submarine cliff, and today, at least 12 sites have been discovered in this zone.
The Marble Canyon site, like the Burgess Pass site, formed some 500 million years ago when mudslides entombed the Cambrian creatures in a oxygen-low environment.
The mudslides would eventually form the shale of the Canadian Rockies.
Gaines and other researchers, as part of an expedition led by the Royal Ontario Museum in co-operation with Parks Canada, were following the Stephen Formation when they discovered the Marble Canyon site.
Marble Canyon fossils are slightly younger that the Walcott Quarry fossils, by 100,000 years, but that difference, Gaines said, is not significant on an evolutionary time scale.
“What was really surprising – because the Burgess Shale is probably the best studied Cambrian fossil assemblage in the world with approximately 200,000 specimens that have come out of the Burgess Shale – is that it was shocking that (Marble Canyon), so close in space and relatively close in time, turned out to have such important differences,” Gaines said.
One of the key differences from the nearby Walcott Quarry is that the Marble Canyon site offers creatures found so far only in the Chengjiang beds.
Included in the 12 new species discovered at Marble Canyon are a tiny shrimp-like arthropod, isoxyid, with its carapace that appears to sit over its body like a clamshell and a new species of leanchoiliid, or a great appendage arthropod, which offers some tantalizing clues about the development of the arthropod family.
“Just their shape, their organizations and the bodies of each new species tells us things about the arthropod family tree that people have been debating for decades based on living arthropods and how living arthropods are related to one another,” Gaines said.
“There have been a lot of hypotheses about the structure of the arthropod family tree in particular so these things are very informative. They tell us about the nature of early arthropods,” added Gaines, who had the good fortune of finding the leanchoiliid fossil.
The team will return this summer to continue their work over July and August, with high confidence that they’ll make more discoveries. Early estimates suggest the Marble Canyon site potentially offers a greater abundance of arthropods than either the Walcott Quarry or Chengjiang.
And, while researchers continue working to understand the Marble Canyon site and its animals, Parks Canada is considering offering guided hikes to the site, similar to the hikes offered to Walcott Quarry and the trilobite beds.
Alex Kolesch, Burgess Shale site co-ordinator for Parks Canada, said the Marble Canyon site carries the story of the Burgess Shale into Kootenay National Park.
“It gives us another great opportunity to tell the story of the Burgess Shale and to tell a slightly different story of how these aren’t just rocks hidden in the mountains. This is active research and (it) facilitates new information about how evolution works, and it is happening right here in this our backyard,” Kolesch said. “It makes you wonder if you keep looking, whether you’ll keep finding things.”
Kolesch added that given how new this site is and how important it is proving to be, many details have to be worked out before visitors can tour the site.
“(Marble Canyon) has the potential to be as significant, if not more significant (than the Walcott Quarry)s. When you think about the ability researchers have to understand how life evolves and the evolutionary process, let alone get a glimpse into what life looked like half a million years ago, before, they were restricted to three or four sites across the whole planet. That was the reality of their work and now there’s another one that may even provide more information. The scientific value can’t be understated,” Kolesch said.
