The History of Auditory Research in Lizards

Although many early anatomical papers touched on lizard ears, the absence of accurate tools severely limited progress. After 1950, new techniques permitted detailed anatomical descriptions and revealed the remarkable variations between the auditory papillae of different lizard families and a recognition of their usefulness of the variations for systematics. From the late 1960s, much new anatomical and physiological work ensued from a number of labs, including recordings from the auditory nerve. Cochlear microphonic recordings were initially dominant, but lost significance due to their poor interpretability. The various studies led to a new understanding of the relationships between structure and function and of the evolutionary and functional significances of the large differences between lizard families. The structural characteristics of lizard papillae enabled modeling of how hair cells couple to produce both sensitive- and frequency-selective responses in the auditory nerve. They also permitted a localization of the active process of lizard ears to the hair cell bundle.