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 wrought iron. As steel became more readily available, anvils were faced with it. This was done to give the anvil a hard face and to stop the anvil from deforming from impact. Many regional styles of anvils evolved through time from the simple block that was first used by smiths. The majority of anvils found today in the US are based on the London pattern anvil of the mid-19th century. The wrought iron steel faced anvil was produced up until the early 20th century. Through the 19th and very early 20th centuries, this method of construction evolved to produce extremely