Fig. 2.

Schematics of a sauropsid (bird, lizard) and mammal ear. In sauropsids (a) sound is transmitted from the ear drum to the sensory cells of the cochlea via a single bone, the stapes (S) in the middle ear cavity (MEC). Mammals (b) have two extra bones, the malleus (M) and incus (I). Reproduced from [3]