Evolution of the cochlea about 7 mm long. Like in lepidosaurs and archosaurs, it contains a lagena, a vestibular sensory epithelium, at its tip. Only in therian mammals (marsupials and placentals) is the cochlea truly coiled 1.5 to 3.5 times. Whereas in monotremes there are many rows of both inner and outer hair cells in the organ of Corti, in therian (marsupial and placental) mammals the number of inner hair-cell rows is one, and there are generally only three rows of outer hair cells. Amphibians have unique inner ear structures. There are two sensory papillae involved in hearing, the basilar (higher frequency) and amphibian
Evolution of the cochlea study, the basal turn of the cochlea was measured, and it was hypothesized that cochlear size correlates with body mass. The size of the basal turn of the cochlea was not different in Neanderthals and Holocene humans, however it became larger in early modern humans and Upper Paleolithic humans. Furthermore, the position and orientation of the cochlea is similar between Neanderthals and Holocene humans, relative to plane of the lateral canal, whereas early modern and upper Paleolithic humans have a more superiorly placed cochlea than Holocene humans. When comparing hominins of the Middle Pleistocene and Neanderthals and Holocene humans, the