About a month ago, two young sisters from the Hay River Reserve discovered what appears to be a fossil of rib bones, possibly from a six-metre-long fish titled sauripterus.
The bones were discovered in the vicinity of Louise Falls by 12-year-old Ashley Lamalice and her 14-year-old sister Amber.
Ashley said they saw the fossilized bones in rock on the ground.
“They looked like ribs,” she said, adding she and her sister knew they were bones right away.
The discovery has attracted the interest of Donald Henderson, curator of dinosaurs at the Royal Tyrrell Museum of Paleontology in Drumheller, Alta.
Henderson was in the Alexandra Falls area last year to examine circular/oval impressions in the rock, about 2.5 kilometres up river from Louise Falls.
The impressions are also believed to have been caused by a sauripterus, which pushed itself along in shallow water by using its large fins.
“I’ve been wanting to come back here since last summer to do a proper job,” Henderson said on Oct. 1. “And then last week, we got the news of that interesting find at Louise Falls, and my boss and I looked at (the photos) and we both thought, ‘Wow. What is this?’ The rocks are the right age to be possibly one of these early amphibians.”
On Oct. 1, the Lamalice sisters showed Henderson where to find the fossil, and they helped as he cut out the rock surrounding the bones.
“It looks like ribs,” he said, adding there are what he believes to be three bones, about 10 or 12 centimetres long. “They’re about the size of my fingers, and they’re curved in the rock.”
The cross-section was grapefruit sized, or about 12 or 15 centimetres in diameter. Henderson said the sauripterus had very distinctive platy ribs.
When asked about the significance of the find when combined with the possible tracks, Henderson said, “That would be the icing on the cake, but unfortunately there are no limbs to go with these ribs. Ideally, we would want to find hands and feet.”
Still, he said the find would be a first for western North America, adding, “The only other example of these things in North America is a shoulder blade from Pennsylvania.”
Henderson said it is remarkable that the Lamalice sisters found the fossil, adding it was usually covered by algae, silt and mud, and there may have only been a window of a couple of months for someone to spot it.
“You just had to be there at the right time, but we can also tell at that overhang the erosion rate is really high,” he said. “There are no plants growing there. They can’t get established. So the rock is continually peeling away.”
The fossil will be taken to Alberta for study. If found to be a significant, it is undetermined where it will be permanently stored and perhaps displayed, but it would require controlled temperature and humidity.
Bruce Green, a director with the Hay River Museum Society, is hoping that at least an exact replica could be displayed at the Hay River Heritage Centre.
“They’re among the rarest bones that you can find,” he said. “Bones from this period are extremely rare.”
Green said the Lamalice sisters have to be commended for finding the fossil, and how they handled the discovery by telling the proper people and not trying to remove it.
“When you some find something as rare as that, you want the best people in the country working on it, and that’s what we have,” he said. “So I’m thrilled about that.”
The sisters are the daughters of Doug Lamalice, the operator of Twin Falls Gorge Territorial Park for the GNWT.
After removing the fossil near Louise Falls, Henderson went back to the impressions in the rock at Alexandra Falls, and plans to be there until Oct. 9, depending on what he finds and the weather.
Henderson and a colleague are using a jackhammer to remove part of a rocky shelf to hopefully find higher-quality impressions. They are working under a scientific research permit from the GNWT.
The uncovered area will be about 3.6 metres long by two metres wide.
“Right now we want to expose fresh tracks,” Henderson said. “The things that you can see here are being exposed to the wind, and the sun and the freeze-thaw, and the ice moving in spring breakup, and that just chews up this soft rock. So it would be much better if we could get fresh, uneroded tracks. And if they are here, we’ll get all sorts of details. I suspect we could probably see scale impressions from the limbs, maybe fin rays, maybe a body drag or a drag of a fin as it was being moved across the seabed.”
The researchers have latex rubber to paint on the impressions and make a record of them, if the temperature allows that to happen.
Twenty-five or more tracks have been spotted along the edge of the Hay River, but some have been noticeably damaged by erosion and ice, while some have disappeared completely.
Henderson said the only way to really protect the tracks would be to cut them out and get them indoors.
When the tracks were created, it is believed the rock was underwater near the shore of a shallow tropical sea. At that time, the land was near the equator, but over the last few hundred million years has moved north with the tectonic motion of the continents.
The tracks were spotted in 2009 by a visitor to Twin Falls Gorge Territorial Park, which is within the boundaries of the Hamlet of Enterprise.
The world’s only other example of such tracks by large lobe-finned fishes from the Devonian Period is in Poland.
— Paul Bickford