Evolution of the cochlea and the elongated cochlea allows for better sensitivity for higher frequencies. As in all lepidosaurs and archosaurs, the single-ossicle (columellar) middle ear transmits sound to the footplate of the columella, which sends a pressure wave through the inner ear. In snakes, the basilar papilla is roughly 1mm long and only responds to frequencies below about 1 kHz. In contrast, lizards tend to have two areas of hair cells, one responding below and the other above 1 kHz. The upper frequency limit in most lizards is roughly 5–8 kHz. The longest lizard papillae are about 2mm long and contain 2000 hair
Evolution of the cochlea also traces back to the Cretaceous period. The evolution of the human cochlea is a major area of scientific interest because of its favourable representation in the fossil record. During the last century, many scientists such as evolutionary biologists and paleontologists strove to develop new methods and techniques to overcome the many obstacles associated with working with ancient, delicate artifacts. In the past, scientists were limited in their ability to fully examine specimens without causing damage to them. In more recent times, technologies such as micro-CT scanning became available. These technologies allow for the visual differentiation between fossilized animal materials