When the Arctic was too hot for muskoxen

A herd of thick-coated, shaggy muskoxen graze on bits of vegetation poking up through the frozen earth on central Ellesmere Island. Their small curved horns can be used to break through the ice to get to the grasses. This animal, with its long hair and squat stature is well adapted to the high Arctic, where it is dark for four months of the year and the temperature can dip to -65 C.

Fifty-five million years ago, a muskox in the same area would have had to shed many layers of hair to be comfortable. At the time, what is called the Eocene period, the Arctic was warm and swampy. Alligators, turtles and snakes slithered and crept on the same ground now beset by permafrost.

This summer, a group of scientists will be crawling over parts of southern Ellesmere Island looking for fossilized bones of these warm-weather creatures.

Paleontologist Dr. Jaelyn Eberle and three fellow researchers left last Wednesday for the two-and-a-half-week expedition. They will travel to four parts of the island — Stenkul, Baumann and Sör Fiords, as well as the Swinnerton Peninsula.

“The Arctic Eocene 55 million years ago was just a very different place,” Eberle explains in a phone interview from the Canadian Museum of Nature in Ottawa, where she is an ancient mammal expert.

“I picture what I see in the Arctic in the Eocene as very much like today’s southeastern United States including eastern Texas — cypress swamps filled with alligators, all sorts of turtles, these red-eared sliders sitting along the edge of the bayou. This is the kind of environment I see — a nice, wet, humid swamp.”

This is the second summer Eberle has done fieldwork on Ellesmere. Last year she was part of a fossil-hunting expedition in the central part of the island.

“Last summer we got more fossil mammals, including a lot of fossils of a guy called coryphodon,” she says. Coryphodon was a hippo-like mammal, she explains. “He’s probably kind of round and hung out in the swamps. Up in the Arctic, we get mainly teeth and jaws, so you can’t really say a lot about their bodies.”

Teeth are the hardest part in the body, she says, so if anything’s going to fossilize there’s a good chance it will be a tooth. Jaws are also often well preserved in the Arctic, probably because they contain teeth and because they are solid bones — especially in mammals.

“We do get body parts, like leg bones, or parts of them, but they’re not as well preserved and can be difficult to link up with the head unless you’ve got something to associate with it,” she says. “As the permafrost does its thing, the stuff gets churned up and broken up.”

Scientists have found some partial skulls, including one from a tapir, an animal now found living in South America, as well as fossilized pieces of creatures related to today’s flying lemurs, and other rodent relatives that were most likely tree-climbers.

Yes, Eberle says, the Arctic was forested 55 million years ago.

“We’re dealing with an environment that probably didn’t dip below freezing very often — if at all.” That means there was no ice. “We find trees. I’ve actually got pictures of [fossilized] trees up there.”

Scientists have also found pieces of brontotheres, which are big rhino-like mammals that lived throughout North America.

“We find chunks of their teeth up North, which is kind of cool,” she says. “These are big guys, too, and would have been walking around munching on plants.”

But aside from the fun of finding these ancient treasures on the surface of the Eureka Sound Group rocks, research on this period is important to understanding today’s environment.

“What we can say is 55 million years ago was about the warmest time. It would have been the height of climate warming in the last 65 millions years,” she says. “Today, with our overall concern of global warming, I think it’s really neat to start looking at past global warming events, including this one, which was the height of it, just to get an idea of what goes on and what sort of organisms occur where.”

Warm-weather animals lived in the Arctic but still survived on minimal amounts of light, Eberle says. Researchers are looking at these animals’ descendants to see if there is anything in their biology or physiology that might allow them to flourish in a dark, warm world.

Eberle says scientists have learned that a lot of animals appear rather suddenly in North America at the very beginning of the Eocene era. Some scientists suggest these animals may have come out of Asia, possibly through the Arctic, across the Bering Strait, and over some sort of land bridge.

“The Arctic to me is a very important bridge between mid-latitude North America and both Asia and Europe,” she says.

Eberle’s expedition received US$23,250 in funding from the National Geographic Society Committee for Research and Exploration, and will get logistics support from the Polar Continental Shelf Project of Natural Resources Canada.

Two pioneers of fossil research on the Arctic, Dr. Mary Dawson of the Carnegie Museum of Natural History, and Dr. Howard Hutchison of the University of California at Berkley, will join Eberle in the field. University of Calgary geology professor Dr. Cindy Reidiger will also travel to Ellesmere with the team to study and date the rocks in which the fossils are found.

Eberle says a final report of their findings will be submitted to the government of Nunavut and the fossils, although property of the territory, will go to the Museum of Nature for study.