The bone is only a fragment, no longer than a thumb, tawny and weathered. To the untrained eye, it looks like a piece of wood. But Natalia Rybczynski knew it was something more when she picked it up during an expedition to Ellesmere Island in 2006. Yet even she didn't imagine just how interesting the find would turn out to be.

Now a team led by Dr. Rybczynski, who is a paleobiologist with the Canadian Museum of Nature in Ottawa, has determined the bone's owner was a camel. It is the first evidence that the ancestors of today's archetypal desert dwellers roamed the Canadian High Arctic at least 3.4 million years ago.

The discovery is likely to cause some double-takes among evolutionary biologists.

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While it's known that camels originated in North America about 45 million years ago and then crossed over into Asia by way of the Bering land bridge, the northern sojourn could – until now – be imagined as a fleeting affair for a species adapted to warmer climate. Dr. Rybczynski and her colleagues have shown otherwise. The ancestors of today's Asian and African camels apparently occupied the Canadian North for millions of years and may have emerged there.

"I think what's neat about this is it changes the story," Dr. Rybczynski said.

The find carries implications for climate science. While the planet was only two or three degrees warmer during that period, the camel bone along with fossilized plants from the same period show that average temperatures in the Far North were a whopping 14 to 22 degrees warmer than today.

But while Ellesmere Island may have been warmer then, its high latitude means that Arctic camels still endured months of continuous darkness through the winter.

In a paper published Tuesday in the journal Nature Communications, Dr. Rybczynski and her co-authors speculate that some of the defining features of the camel, particularly its fat-storing hump, were adaptations for coping with the long polar night.

"When people think of camels they think of Lawrence of Arabia. We should be thinking North America," said Grant Zazula, the Yukon government's paleontologist, based in Whitehorse. Dr. Zazula, who was not involved in the new find, has previously worked with two sets of camel bones that have turned up in the Yukon. He says the appearance of a camel specimen on Ellesmere Island raised the possibility that the Arctic environment was a driver of camel evolution and not just a stopover on the way to Asia.

Although the find amounts to only part of a single leg bone, the researchers are confident in their claim because a molecular signature left by the collagen in the bone is specific to camels.

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Dr. Rybczynski said she and her colleagues are trying to better characterize the epoch during which the Arctic camel lived, known as the mid-Pliocene warm period. The work is of interest to climate scientists because the Arctic may be making a rapid return to its pre-ice age state due to global warming.

For paleontologists, climate change in the region is a double-edged sword. Receding ice is exposing new finds while increased erosion is obliterating others. While a bounty of new discoveries is undoubtedly lying in wait, the high cost of working in the North means that much of what is now being exposed will ultimately be lost.

"In satellite images we can see new gullies opening up and steeper slopes," says John Gosse, a geochronologist at Dalhousie University in Halifax and a co-author fn the paper. "The problem is, where am I going to get $90,000 to bring four of us up north next summer."

PICTURING THE PLIOCENE

Environment

About 3.4 million years ago, the Strathcona fjord would have looked like a northern forest. Depicted in autumn, it's chilly enough for snowfall and the sun will soon disappear for months. Scientists estimate average temperatures were 14 to 22 degrees warmer than today.

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Camels

In anticipation of the polar darkness, the camels are well fed and growing winter coats. Standing three metres tall at the hump, they are 30 per cent larger than modern camels. Large eyes may have helped them see in low light while flat feet aided walking in snow.

Flora and fauna

Larch trees are turning yellow and losing their needles, a portent of the diminishing food supply during the winter darkness. Evidence of birch suggests the region was once warm enough for some deciduous species.

Other species

Scaup ducks are based on a fossil found nearby that dates to the same period as the camel bone. Other fossils suggest beaver lived nearby. Although the camel bone was found inland, a higher sea level means the shoreline was closer at that time.