Evolution of the cochlea of the ear, consisting of the scala media, the scala tympani, and the scala vestibuli. Regarding mammals, placental and marsupial cochleae have similar cochlear responses to auditory stimulation as well as DC resting potentials. This leads to the investigation of the relationship between these therian mammals and researching their ancestral species to trace the origin of the cochlea. This spiral-shaped cochlea that is in both marsupial and placental mammals is traced back to approximately 120 million years ago. The development of the most basic basilar papilla (the auditory organ that later evolved into the Organ of Corti in mammals) happened
Evolution of the cochlea (lower frequency) papillae, but it is uncertain whether either is homologous to the hearing organs of lepidosaurs, archosaurs and mammals and we have no idea when they arose. Fish have no dedicated auditory epithelium, but use various vestibular sensory organs that respond to sound. In most teleost fishes it is the saccular macula that responds to sound. In some, such as goldfishes, there is also a special bony connection to the gas bladder that increases sensitivity allowing hearing up to about 4 kHz. The size of cochlea has been measured throughout its evolution based on the fossil record. In one