Ancient beavers as big as bears died out because of their woodless diet
As the landscape dried this dam-less beaver couldn't create it's own home
10,000 years ago giant beavers weighing 100kg, and standing two meters tall disappeared into extinction. Now scientists think they know why.
Researcher Tessa Plint studied giant beaver fossils when she was in the Department of Earth Sciences at Western University in London, Ontario. Her work revealed that these less-than industrious giant rodents didn't eat wood or make dams and as a result had nowhere to live when the climate changed at the end of the last ice-age
A tale of two beavers
Even though the beavers we see today and giant beavers co-existed for tens of thousand of years, the mega version - about the size of a small black bear - was quite different. Their size was one difference. They also lacked the distinctive paddle-shaped tail of today's beaver.
But Plint's work has revealed that the most important factor in their extinction might have been that they lacked a taste for wood.
Isotope analysis of fossil bones and teeth revealed that they survived on a diet of submerged aquatic plants in their wetland habitat. They did have large incisors, but those teeth did not have the thin, chisel-like edge of beaver teeth today.
Instead they were rounded, similar to bananas in shape and size. This made them better suited to eating softer plants.
Why we don't see the giant beaver today
At the end of the Pleistocene just over 11,000 years ago, nearly all of Canada and the northern United States was covered in ice. As the ice sheets retreated, the climate became warmer and drier. This was not good news for the giant beavers because their wetland habitats began to dry up all across North America.
Unlike their smaller relatives, the giant beavers were not able to build dams and change the landscape to create their own wetlands.
The fossil record suggests an isolated population existed in the lowlands south of the Great Lakes until competition for space and the ongoing change in climate ultimately contributed to their extinction about 10,000 years ago. It was one of the last surviving members of the Pleistocene megafauna community in North America, along with mastodons and wooly mammoths.