Castoroides, also known as the giant beaver, was a massive rodent that lived during the Pleistocene epoch, around 2.5 million to 10,000 years ago in North America. It could grow up to 8 feet (2.5 meters) long and weigh over 200 pounds, making it the largest beaver species that ever lived. Unlike modern beavers, Castoroides had massive incisors shaped more for slicing than gnawing, and there’s no solid evidence that it built dams or lodges. It likely lived in wetlands, feeding on aquatic plants and shrubs.

Castoroides coexisted with other Ice Age megafauna such as mammoths, dire wolves, and saber-toothed cats. Its fossils are often found near ancient lakes and rivers, painting a picture of a giant, semi-aquatic herbivore that played a vital role in its ecosystem before going extinct at the end of the last Ice Age.