Castor fiber
There are two currently extant species of beaver - The North American Beaver, and the Eurasian beaver, of which this skull is an example.
Beavers are nocturnal, and are well known for building dams and lodges, creating large, deep pools of still water. Groups consist of a mating pair, and their young offspring. Beavers are the second largest rodent in the world.
What is the largest rodent in the world?
Observe the oversized incisors present on both the upper and lower jaws - What are these adapted for?
What adaptations does a beaver possess for a semi-aquatic lifestyle?