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Scientists Figure Out Why Giant Human-Sized Beavers Became Extinct

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About 10,000 years ago, giant beavers that roamed across North America went extinct .A team of researchers used stable isotope ratios to determine the diet and behavior of the mega-rodents.   ( Tessa Plint | Heriot-Watt University )

Giant beavers that grew to about 2 meters long and weighed to up to 100 kilograms once roamed across North America.

However, toward the end of the last Ice Age, the mega-rodents disappeared. Their extinction coincided with the disappearance of other large animals, including the wooly mammoth.

However, until today, scientists do not know how exactly giant beavers died out around 10,000 years ago.

Giant Beavers In North America

Giant beavers were considered to be a very successful species. Scientists found fossil remains of the mega-rodents across North America — from Florida all the way to Alaska and the Yukon.

In terms of appearance, the giants of the Ice Age look pretty much like modern beavers but with two crucial differences. Instead of paddle-shaped tails, giant beavers had long skinny tails like that of a muskrat. The now-extinct animals also had bulkier and curved front teeth, not the sharp and chisel-like incisions of their modern counterparts.

Why Giant Beavers Went Extinct 10,000 Years Ago

To further understand giant beavers, specifically what caused their extinction, researchers investigated fossil remains of the mega-rodents. Using stable isotope ratios from ancient bones and teeth, the team figured out the diet and behavior of the creatures.

"Basically, the isotopic signature of the food you eat becomes incorporated into your tissues," explained Tessa Plint, a post-graduate student and one of the authors of a study published in Scientific Reports. "Because the isotopic ratios remain stable even after the death of the organism, we can look at the isotopic signature of fossil material and extract information about what that animal was eating, even if that animal lived and died tens of thousands of years ago."

The study revealed that unlike modern beavers, giant beavers did not cut down and eat trees. They preferred to munch on aquatic plants.

"Giant beavers were not 'ecosystem-engineers' the way that the North American beaver is," added Plint.

Previous studies suggested that giant beavers preferred warmer and wetter environments. Their fossil remains were more commonly found in sediments that come from ancient wetlands.

Their reliance on wetlands for habitat and food caused their downfall. According to Plint, when the ice sheets retreated after the Last Glacial Maximum around 10,000 years ago, the climate became drier and the giant beavers disappeared.

The smaller modern beavers, however, survived the climate change thanks to their ability to build dams and lodges. Unlike the larger species, the modern beaver can alter any environment and make it a more suitable habitat.

The findings support the claim that climate change and human impact caused the global megafauna extinction at the end of the last Ice Age.

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