New Fossil Bed Discovery by Royal Ontario Museum/Pomona College Team Challenges Assumptions About Famous Fossil Site
Team member Jean-Bernard Caron (Royal Ontario Museum) extracts a new specimen of Stanleycaris hirpex from the Stephen Formation at Stanley Glacier, Kootenay National Park, British Columbia.
Robert Gaines, professor of geology at Pomona College, is part of an exploration team that discovered a new fossil deposit whose existence challenges long-held assumptions about the Burgess Shale, which is famous for its exceptional preservation of soft-bodied fossils of the Cambrian-era, during the dawn of animal life.
The discovery, “A new Burgess Shale-type assemblage from the ‘thin’ Stephen Formation of the southern Canadian Rockies,” was reported in the September 2010 issue of Geology.
“The classic Burgess Shale deposits,” explains Gaines, “are found at the base of a large underwater cliff. What is preserved there is extraordinary: We find eyes, antennae, guts and other soft body parts that normally stand no chance of fossilization. The cliff was thought to be important in producing mudslides that transported the organisms from their living environment to a habitat that was hostile but great for preservation. The new locality challenges that assumption.”
The classic deposits are in an area known as the “thick” Stephen Formation. The “thin” layer of the Stephen Formation was deposited in shallower water and has not been extensively studied.
The discovery of these fossils in the thin Stephen Formation is important because it suggests that paleontologists should be able to find fossils of soft-bodied organisms throughout the thin Stephen Formation, which is widely distributed throughout the Southern Canadian Rockies but poorly explored by paleontologists.
Among the more than 1,000 fossils collected by the team were eight new species of soft-bodied animals, including the anomalocaridid Stanleycaris hirpex, a new genus and new species.
“’Stan’ is part of the group that were largest predators at the time,” says Gaines. “It was greater than a meter in length with large frontal claws to grasp prey. Other organisms at the time range from a few centimeters to 20 centimeters. It was the terror of the Cambrian seas.”
Other finds include a crustacean, Tuzoia, preserved with appendages for the first time as well as eyes, and two new arthropods.
The 2008 exploration trip, on steep mountain slopes near Stanley Glacier in Kootenay National Park (British Columbia), was funded by the Royal Ontario Museum and Pomona College. Because of the steep terrain, they used helicopter support for team transportation, dropping nets of excavation gear and flying out fossils.
“We knew there was some interesting material coming from the talus,” says Gaines. “My job as the geologist was to determine what layers the fossils were coming out of and us that to determine the ancient environment and the relationship to the stratigraphy in the classical localities 40 kilometers away.”
“The Burgess Shale is the holy grail of paleontology. I was climbing around the large, fierce slope, and boom! This thing was exposed on a nice surface, and I knew that we had found it--a spot with enormous potential for new creatures.
“Being there, putting my hands on the rocks, and figuring it out was amazing, not only in terms of being able to work on this fossil locality, which is arguably the most important fossil deposit in the world, but being able to find new things and challenge the way people think about this deposit is thrilling.”
This past summer, the team explored three areas in the Southern Canadian Rockies covering both the thick and thin portions of the Stephen formation with tremendous results, reports Gaines.
Gaines’ interest and adventure began when he was just five, and his parents gave him his first fossil, a trilobite, Elrathia kingii.
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Geology Article: http://geology.geoscienceworld.org/cgi/content/full/38/9/811