Yukon News

The mystery of the three little bones

James Munson Friday March 20, 2009

Yukon Government/Yukon News

Dinosaur

Paleontologists from the Royal Ontario Museum, McGill University and Yukon search for fossils at the dinosaur fossil site on the Peel River in August 2008.

Some paleontologists hate dinosaurs.

The giant lizards tend to get all the media attention, making experts who work on other dead creatures jealous.

Grant Zazula, the Yukon’s paleontology officer, once held a grudge against the famous fossils.

“A lot of paleontologists find dinosaurs annoying,” said the 31-year-old Zuzula, who specializes on the last ice age. “I may have been one of them in the past.”

That all changed when David Evans, the dinosaur curator at the Royal Ontario Museum, called Zuzula in 2007.

Evans wanted to visit a little-known site in the Peel Watershed where the only dinosaur bones ever found in the Yukon had been discovered.

Zuzula, who moved up from Edmonton to study the ancient

Beringia land mass, changed his mind.

“Of course I jumped on the bandwagon and went along for the dinosaur project,” he said. “If you like paleontology, you’re going to like dinosaurs, even if you have some bitterness about them because they get all the press.”

The scientists visited the site, situated between the Wind and Bonnet Plume rivers, last summer.

It wasn’t a successful trip.

“For about seven of those eight days we had brutal flooding and rain,” said Zuzula. “It was kind of a disaster.”

The scientists found fossil impressions of giant redwood and ginkgo trees as well as other 65-million-year-old plants, but they didn’t find what they were really looking for: pieces of a duck-billed dinosaur.

In the late Cretaceous, hadrosaurs, or duck-billed dinosaurs, were one of the most abundant plant-eating dinosaurs on the planet.

“People often refer to them as the cows of the Cretaceous,” said Evans.

Duck-billed dinosaurs lived during the last 50 million years of the Cretaceous all over the northern hemisphere, which included Asia and North America.

“Four or five out of every 10 plant-eating dinosaurs would have been duck-billed dinosaur,” said Evans.

In the 1960s, geological surveyors mapping the Peel River discovered three small bones—a rib bone, a toe bone and a vertebrae.

“The three of them could fit in the palm of your hand,” said Zuzula.

The fossils were found protruding from an outcrop in the Smoking Hills, named after the fuming coal seams in the area.

The fossil discovery was noted in a paleontology journal, but was soon forgotten in the Yukon.

Yet it remained an object of mystery and intrigue in paleontology circles for years.

“Dinosaur paleontologists always refer to this crazy site up in the Yukon that they don’t know much about and have always been interested in doing more work,” said Zuzula.

Paleontology doesn’t lend itself easily to the permafrost-covered North, but discoveries on the Alaskan North Slope have renewed interests in this scientific frontier.

“They’re finding incredible dinosaurs up (on the North Slope,” said Zuzula. “It’s become a pretty famous site now. They’re finding duck-billed dinosaurs, triceratops and big carnivores.”

Those dinosaurs are of the same type and date as the ones found in the Yukon, he said.

The Arctic and sub-Arctic sites keep attracting scientists because they challenge accepted theories on how the dinosaurs survived, and subsequently went extinct.

During the Cretaceous, the continents were of vastly different shapes and locations from what they are today. The Peel site was believed to be even further north back then, around 70 degrees latitude.

“Even back then, during the Cretaceous at 70 degrees latitude, there was six months of darkness,” said Zuzula. “So how does a cold-blooded animal deal with six months of darkness when they need sun to sustain their warmth?”

“It’s this strange biological question about how dinosaurs could survive in the Arctic.”

There are competing theories that try to put the northern sites in line with accepted theories on dinosaur biology.

“Some people believe they may have migrated far south during the winter,” said Zuzula.

North America was once split in half by a vast ocean. The only land was a long strip where the Rockies stand today and an island made from the Appalachian range on the eastern side of the continent. That means duck-billed dinosaurs may have migrated along the eastern side of the Mackenzie Mountains, which would have been a coastline overlooking a shallow sea that covered the Northwest Territories.

Another theory is hibernation.

“But it seems kind of strange that dinosaurs would bury itself in a cave for the winter,” he said.

The cold climate sites pose some even more serious problems for extinction theories.

“It was really exciting when (the bones) were found because this (dig) site dates right to the terminal Cretaceous, right at the end of the Cretaceous, right when the dinosaurs went extinct,” said Zuzula.

“So this outcrop records the time of the extinction really well.”

The presence of dinosaurs at such a northern site is a “dilemma,”

said Evans.

“It looks like (the dinosaurs) were living in the Arctic year-round,” he said. “So it looks like these big dinosaurs were quite tolerant of cold climates and temperature extremes.”

This presents a challenge to the widely held notion that the dinosaurs died out because they couldn’t hack a changing climate.

“One of the theories about dinosaur extinction is that it was a changing climate, the climate getting colder,” he said. “Or that when the asteroid hit, it sort of brought on a nuclear winter.”

“But it looks like, from the evidence in the Arctic, that the dinosaurs were a lot more hardy.”

If dinosaurs could survive the cold extremes of the Arctic, they may have been able to survive both situations.

“There’s a bit of paradox there,”

said Evans.

The bones are so well-preserved that it’s very unlikely they are the only ones there.

“(Evan’s) suspicion is that (the bones) may have come from one animal, so there may be a skeleton in the bluff that we just haven’t seen,” said Zuzula.

The bluff is 50 metres high and the last expedition only made it half-way up the cliff.

Evans received news this week that he will receive funding from the Polar Continental Shelf Project to return to the Peel this summer.

“These guys found these bones in the ‘60s and, there’s got to be more,” said Evans. “You don’t just preserve three bones in a rock formation.”

“It’s just a matter of getting lucky and finding more,” he said.

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