The evolution of the ear may be traced through transitional fossils, comparative anatomy and embryology. The organ of hearing evolved from receptors of the vestibulary organ of fish. The tympanic ear developed in amphibians at the transition to terrestrial life, and the hyomandibula was isolated as the first middle ear bone, the columella stapes. Reptile jaw bones, quadratum and articulare, transformed to malleus and incus in mammals. With selective advantages during the evolution, an increasing structural complexity of the ear accompanied improved sound transmission and reception.