What he didn’t expect to find were a set of gigantic rib bones, sticking out of the riverbank.
"I was a little surprised because of the size of them," he says. "It was kind of exciting to see something like that. I knew they were larger than what I would say a standard cow is."
Van Megen took some pictures and got in touch with Francois Therrien, a paleontologist at the Royal Tyrrell Museum in Drumheller, east of Calgary, that is home to 140,000 fossil specimens.
Therrien told him the bones were unlikely to be from a dinosaur, because the rock in the Calgary area is too young. But the discovery could still be significant — potentially signalling an early bison fossil — and a team will be heading out in August to have a look.
Therrien predicts a call like Van Megen's will likely be the first of many this summer.
The paleontologist and other scientists are urging the public to keep their eyes peeled, saying erosion from June's widespread floods could spur significant discoveries of fossils and artifacts.
"The general public plays a big role in helping paleontologists with finding new fossils, especially in remote areas," says Therrien.
"So when people find fossils along riverbanks we always appreciate them contacting us and letting us know about any new discoveries that have been made."
While amateur explorers can discover Alberta’s buried treasures, however, they’re not permitted to collect them without a permit. Fossils and artifacts are protected under provincial law and even when in private hands, they remain the property of the province.
But for those motivated by the thrill of discovery, the chances of finding something unearthed by erosion from the floods is high, says Therrien.
Alberta, especially the arid Badlands region in the province’s east, is an incredibly dino-rich area, ranking alongside Mongolia’s Gobi Desert for one of the top fossil spots in the world.
But Therrien says the current opportunity lies largely in the flood-stricken foothills to the west of Calgary.
While the rock there is old enough to contain dinosaurs, thick vegetation in the region means fossils are often only spotted along exposed rocks on rivers and banks.
"All of southern Alberta is dinosaur galore, there is potential to find fossils pretty much anywhere," he says. "So it's going to be a matter of just trying to select the areas where there's more exposure and where there's more potential."
Caution while exploring is urged as high floodwaters do, however, mean many potential sites are still soggy and even unsafe. But Therrien says he plans to bring a crew to look at certain areas within a few weeks.
Other teams will be waiting until late August or the autumn to check on existing sites and look for new ones.
Possible discoveries after Alberta's flooding aren't limited to fossils.
Darryl Bereziuk of the Archaeological Survey of Alberta says the potential for finding artifacts – including bison bone beds, tool collections and rock drawings – is also high.
The 45,000 archaeological sites listed in the province are “just the tip of the iceberg”, he says, noting his group “continually” receives calls about new discoveries.
"The great majority of archaeological sites out there have not been recorded yet, which is why we need the help of the public to let us know when they see some of these things."
But while scientists are excited to see what the dramatic erosion could turn up, archeological crews still have to deal with damaged sites and delayed digs.
Newly exposed specimens also run the risk of being damaged or washed away before they can be discovered or collected, says Bereziuk.
Increased rainfall and flooding year after year also pose another, long-term challenge, adds Therrien.
While erosion can reveal fossils in less explored regions, it also means more vegetation appears on the dry, exposed rock. And more vegetation means fossils are far harder to find.
Meanwhile, although the sheer amount of fossils and artifacts in the province makes collecting many of them unfeasible, the pressure is on make sure experts don’t miss anything new or important.
"We're racing against erosion and vegetation," says Therrien. "You have to find all the good fossils before they're lost."