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
Anvil Peak Anvil Peak Anvil Peak is a cone volcano located in Aleutian Islands, Alaska, United States. The volcano was originally named in 1951, on a map by the United States Geological Survey. Its name was taken after a plateau located on the northern side of the volcano's main summit, taking the appearance of an anvil. Anvil Peak is located on Semisopochnoi Island, in the Rat Islands of the western Aleutian Islands. It is one of the seven hills with a summit crater on the island. It is the highest point on the island as well as the highest point on all