By Canadian Press

Fossils reveal proof of early hibernating bears in Canada’s Arctic

Dec 19, 2017 | 3:15 PM

VANCOUVER — The discovery of rare fossilized remains in Canada’s Arctic has allowed experts to piece together an evolutionary tree for the descendant of North American bears.

A report published in the journal Scientific Reports this week says the skeletons from 3 1/2 million years ago reveal a bear that likely hibernated for long periods with a diet so full of berries that it had cavities.

Xiaoming Wang, a specialist in fossilized carnivores at the Natural History Museum in Los Angeles, said they were puzzled by the cavities on the chewing surface of one set of teeth. The damage was similar to what a child would experience after sucking on lollipops for hours on end over many days, he said.

“That allowed us to further infer this particular Canadian bear probably ate a fair amount of a sugar-rich diet and fairly frequently,” Wang said in a telephone interview Tuesday.

The Arctic bears would have had to endure six months of dark winters and that assumption, coupled with the cavities, led researchers to infer the ancient bears were preparing to hibernate when they bulked up on the berries.

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The remains of two bears were found on Ellesmere Island. The younger bear had the cavities, Wang said.

The species, named Protarctos abstrusus, was smaller than the average black bear and had a flattened forehead.

Before the discovery in Northern Canada only pieces of the same bear species had been found in Idaho and China, so experts believed it was related to the black bear. But Wang said the bear is now believed to be the grandfather of most bear species.

“They probably all inherited from their ancestors a habit of being able to winter in harsh environment in such a way they can minimize the burning of their fat and energy in the spring to survive the harsh winter.”

The remains were found in the so-called Beaver Pond fossil site in the High Arctic, an area that he said has evidence of Eurasian and North American plant and animal life deposited before the Bering Land Bridge disappeared many thousands of years ago.

Natalia Rybczynski, a research associate at the Canadian Museum of Nature in Ottawa, has worked at the site several times and said the preservation is incredible, partly due to the ice and a layer of peat where the bones have been found. 

“Even though it’s millions of years old, if I brought you to the site and I showed you, for example, pieces of tree, wood, leaves from the site, they’re not petrified, they look like they just came out of the forest.”

Many other fossils have been found besides the bear skeletons, including ancient varieties of beaver, a three-toed horse, a giant camel, a frog and a fish.

“A lot of the mammals that we see there are actually more closely related to animals from China than North American forms,” said Rybczynski.

The Arctic was much warmer millions of years ago, with temperatures around 20 Celsius, she said.

The researchers also have a list of over 100 plants that were found at the site, including four berry bushes — blueberries, raspberries, crowberries and lingonberries — that may have contributed to the bear’s trouble with their teeth, said Rybczynski.

“This gives us the source of the sugar that we can blame the cavities on. You can only get the cavities if you’re eating sugar and we actually have evidence that there would have been fruits there.”

The Canadian Press

Note to readers: This is a corrected story. A previous version said the Bering Land Bridge disappeared millions of years ago.