Fossil shows ancient bear had a sweet tooth

The fossil belongs to an extinct species called Protarctos abstrusus, a close relative of modern bears. The bear was slightly smaller than a black bear. It featured a flat head on a combination of both primitive and modern dental characteristics, evidence of its transitional position on the evolutionary tree.

"This is evidence of the most northerly record for primitive bears, and provides an idea of what the ancestor of modern bears may have looked like," Xiaoming Wang, head of vertebrate paleontology at the Natural History Museum of Los Angeles County, said in a news release. "Just as interesting is the presence of dental caries, showing that oral infections have a long evolutionary history in the animals, which can tell us about their sugary diet, presumably from berries."

Researchers at NHMLA and the Canadian Museum of Nature were able to analyze bones from the bear's skull, jaws and teeth. The extraction of the bones from the fossil-rich peat of Ellesmere Island took some 20 years.

Scientists detailed their discovery in a new paper published this week in the journal Scientific Reports.

The Beaver Pond site where the bear was found has also yielded a number of other fossils, including the remains of fish, small carnivores and deerlets. Researchers have also excavated the bones of a beaver and a three-toed horse. Fossilized plants found among the strata suggest these ancient animals occupied a boreal-type wetland forest.

"It is a significant find, in part because all other ancient fossil ursine bears, and even some modern bear species like the sloth bear and sun bear, are associated with lower-latitude, milder habitats," said Natalia Rybczynski, research associate and paleontologist with the Canadian Museum of Nature. "So, the Ellesmere bear is important because it suggests that the capacity to exploit the harshest, most northern forests on the planet is not an innovation of modern grizzlies and black bears, but may have characterized the ursine lineage from its beginning."

The closest relatives of modern bears are found in Eurasia and date to roughly 5 million years ago. While the newly discovered bear was one of the earliest bear migrants from Eurasia to North America, researchers don't think it was a direct ancestor to the modern American black bear.

But the bear's rotted teeth prove the modern black bear's predilection for berries can be traced back several million years.

"We know that modern bears consume sugary fruits in the fall to promote fat accumulation that allows for winter survival via hibernation," Rybczynski said. "The dental cavities in Protarctos suggest that consumption of sugar-rich foods like berries, in preparation for winter hibernation, developed early in the evolution of bears as a survival strategy."