Imagine a beaver. Now make it bigger than a modern-day black bear. At two metres in length and weighing up to two hundred kilograms, the giant beaver was the largest rodent of the interglacial periods. The teeth of the giant beaver could grow up to twelve centimetres long. Contrary to popular belief, modern beavers aren’t directly descended from the giant beaver. Indeed, competition from modern beavers may have helped to cause the giant beaver’s extinction.