Middle ear to sounds of higher frequency, because these are better taken up by the inner ear (which also responds to higher frequencies than those of non-mammals). The malleus, or "hammer", evolved from the articular bone of the lower jaw, and the incus, or "anvil", from the quadrate. In other vertebrates, these bones form the primary jaw joint, but the expansion of the dentary bone in mammals led to the evolution of an entirely new jaw joint, freeing up the old joint to become part of the ear. For a period of time, both jaw joints existed together, one medially and one
Ear (botany) Ear (botany) An ear is the grain-bearing tip part of the stem of a cereal plant, such as wheat or maize. It can also refer to "a prominent lobe in some leaves". The ear is a spike, consisting of a central stem on which tightly packed rows of flowers grow. These develop into fruits containing the edible seeds. In corn, it is protected by leaves called husks. In some species (including wheat), unripe ears contribute significantly to photosynthesis, in addition to the leaves lower down the plant. A parasite known as "Anguina tritici" (Ear Cockle) specifically affects the ears on