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article imageFossils found in Kootenay Natl. Park shed light on early origins

By Karen Graham     Jun 12, 2014 in Science
Paleontologists digging in British Columbia's Kootenay National Park in 2012 came across a most amazing "motherlode" of fossil specimens. The 44 fossils are of an ancient fish named Metaspriggina that swam in an ancient sea 500 million years ago.
University of Cambridge earth sciences professor Simon Conway Morris and Jean-Bernard Caron, a paleontologist at the Royal Ontario Museum and the University of Toronto published their findings in the journal Nature on Wednesday.
The tiny fish, about the size off a minnow, or no longer than a man's thumb, swam about in an ancient tropical sea around 505 million years ago in what is now the Canadian Rockies. The little creatures apparently were trapped in a mudslide, literally burying them alive. Their flattened remains were discovered in Marble Canyon, on a barren mountainside along the British Columbia-Alberta border within Kootenay National Park.
Tokumm Creek at Marble Canyon.
Marble Canyon is named for its carbonate rocks that belong to the Ca...
Tokumm Creek at Marble Canyon. Marble Canyon is named for its carbonate rocks that belong to the Cathedral Formation and that were deposited more than 500 million years ago. This particular canyon was initially carved by glaciers and further eroded by the Tokumm Creek.
Royal Ontario Museum
What makes this discovery so exciting is that these fish will provide a piece of the puzzle, perhaps even a missing link, to the earliest evolution of vertebrates, and in particular the "key feature" of vertebrates today, our jaws. Caron says the fossils are "a stunning find," adding, "We consider this fossil among the oldest fish known anywhere."
The exact location of the fossil site is being kept a secret to prevent anyone disturbing the fossil bed. "I am so thankful that the site was found in a national park," said Caron, referring to the way Parks Canada is controlling access to the site to prevent pillaging. The team is looking forward to a 10-week return to the site this summer.
Caron excitedly described the creatures named Metaspriggina. He is amazed at how well preserved they are, saying you can even see their muscles and nasal structures. Based on the structure of its muscles, it swam with a side-to-side motion. It also had a notochord, a primitive structure that later became a backbone in the vertebrates.
"In some ways, you can recognize yourself in there," Caron said in an interview with CBCNews.ca. "He has all the features that all vertebrates will eventually share."
Metaspriggina wasn't exactly like the goldfish swimming in the bowl in your child's bedroom. For one thing, it didn't have any bones and it didn't have jaws. This means it couldn't open or close its mouth. Instead, along its throat there are seven pairs of structures that look like rods or bars. They were made of cartilage and are called gill bars or pharyngeal bars. The creature had big eyes on the top of its head, and this has led researchers to believe it lived on the sea floor and was a filter feeder.
The bars appear to have helped the little fish to eat and breathe. And this discovery is of great importance to the scientists. In today's fish, the front-most of these bars has evolved into jaws and this one little change helped them to move past filter-feeding and grasp and swallow their food.
"The evolution of these bars in the first place had a profound impact into the evolution of vertebrates," Caron said. "As soon as you evolved jaws, vertebrates were able to explore new niches and diversify considerably." This competitive edge has given almost all vertebrates, from birds, reptiles, amphibians and mammals, the ability to diversify.
Marble Canyon fossil site in Kootenay National Park.
The Marble Canyon fossil site is located at the north end of Kootenay National Park, about 40 km from the Burgess Shale Sites, famous for its extraordinary preservation of the soft parts of fossils. Dating to 505 million years ago, this Middle Cambrian site is one of the world's earliest fossil sites with the imprints of the soft parts of animals.
Fossil of Marrella splendens (Marrellomorpha) found in British Columbia s Kootenay National Park. Th...
Fossil of Marrella splendens (Marrellomorpha) found in British Columbia's Kootenay National Park. The site of the find was not revealed so the fossil bed would not be disturbed.
Verisimilus
The Burgess Shale site dates back to the time when the Canadian Rockies were part of the sea near the Earth's equator. During that period, the seas teemed with arthropods, a group of creatures that include crabs, insects and spiders. The first two fossils of Metaspriggina ever found were part of a small number of vertebrates out of the 200,000 fossils found at the Burgess Shale in Yoho National Park in 1993.
Caron says that while the Marble Canyon and Burgess Shale sites are different, they do complement each other. Describing their environment in the tropical seas as "dynamic" Caron says, "These animals would have been trapped very quickly in mudflows that would have buried them alive." It was common for mudflows to occur, burying creatures, and over the thousands and thousands of years, the layers built up. It took eons, but the sea floor eventually rose up, forming the Canadian Rockies.
More about fish fossils, secret location, Canadian Rockies, Burgess Shale sites, British columbia
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