Giant Beavers the Size of Black Bears Once Roamed North America Vanished Suddenly 10,000 Years Ago, Scientists Know Why

Giant, human-sized beavers once roamed the wetlands and lakes of North America, coexisting with other Ice Age megafauna such as woolly mammoths and huge ground sloths. Weighing over 100 kilograms and standing nearly two meters tall, these prehistoric rodents flourished for thousands of years. However, roughly 10,000 years ago, they disappeared suddenly, leaving scientists perplexed for centuries. Recent research has finally unraveled the key reasons behind their extinction, shedding light on an incredible chapter of prehistoric life, stated The Conversation.

Unlike modern beavers, which are tiny and popular for their impressive ability to engineer their environments by building dams and lodges, the giant beaver (Castoroides) had a complete 360-degree way of life. One of the most critical differences was its diet. Isotopic analysis of fossilized bones, conducted by researcher, Tessa Plint, and her team, at Western University in Ontario, discovered that these monstrous rodents fed exclusively on aquatic plants. They lacked the sharp, chisel-like incisors of today’s beavers, instead possessing bulky, curved teeth that were not ideal for cutting down trees. This meant that, unlike their smaller relatives, these humungous beavers did not mold their wetland habitats or build structures to aid them survive environmental changes, stated Smithsonian magazine.

Plint noted "We actually found out that the giant beavers were eating a diet of aquatic plants. So we didn't find any evidence that they were actually cutting down and eating trees…They weren't ecosystem engineers the same way that modern beavers are…And that made them very, very susceptible to climate change, especially as the climate got warmer and drier towards the end of the last ice age," according to CBC. Their total dependency on aquatic diet proved to be the main reason for the giant beaver’s downfall. As the last Ice Age came to an end, the climate underwent major changes. Huge ice sheets that had once covered much of North America began to vanish, leading to a not-so-favorable climate for them. This unfortunately led to the drying up of wetlands, which were crucial for the giant beaver’s survival. Without access to their primary food source, these huge rodents ceased to exist.

Proofs indicate that the giant beaver first began to go extinct in the northern regions of its range around 25,000 years ago. As time passed, and conditions went downward, populations escaped further south, leaving only one last straw for survival—the Great Lakes region. However, it was all about survival of the fittest and the immense competition pushed them to complete extinction. Plint remarked, "We all know the modern beaver can dam up the river to build its own nice little pond to live in. And that's pretty handy when wetlands are starting to dry up and they're in short supply. So I think it probably did give it a bit of an advantage," via CBC.

As paleontologist Grant Zazula, noted, "I think anytime anyone sees [a] giant beaver skull, they’re like, 'Wow, it must have been a saber-tooth cat and eating people…You have this animal that’s seven feet tall that just eats little pond weeds…and you want it to be more dramatic than that, but it’s not," stated Smithsonian magazine.