But foxes of all species are undeniably canid, that is, members of Canidae, the dog family. Turning the skull over, the base of the ear sockets is fused into a bony casing called a tympanic bulla, protecting the fragile inner-ear bones. In canids it is uniquely divided by a septum: a thin, bony wall. It is believed that this extra echo-chamber enhances their ability to hear low frequencies.
