Family (Animalia): Castoridae

The family Castoridae contains the two living species of beavers and their fossil relatives. This was once a highly diverse group of rodents, but is now restricted to a single extant genus, Castor.

Characteristics

Castorids are medium-sized mammals, although large compared with most other rodents. They are semiaquatic, with sleek bodies and webbed hind feet, and are more agile in the water than on land. Their tails are flattened and scaly, adaptations that help them manoeuvre in the water. Castorids live in small family groups that each occupy a specific territory, based around a lodge and dam constructed from sticks and mud. They are herbivores, feeding on leaves and grasses in the summer, and woody plants such as willow in the winter. They have powerful incisors.

Reference: Wikipedia