[A comparative morphological analysis of the development of the ear in mammals]

This paper is the first comparative study into prenatal ontogenesis of the peripheral auditory system in mammals. A wide range of ecologically different species was studied, including terrestrial, semi-aquatic and aquatic forms with auditory systems functioning at low, medium, and high frequencies. Structural peculiarities of the development of auditory organ were determined for each studied species in relation to its operation frequency and acoustic properties of the outer medium. The origin and individual stages of morphological adaptations found in semi-aquatic, aquatic, and echolocating species are described. The data obtained allowed to reveal general principles of development of the peripheral auditory system in mammals with different ecological specialization.