Arguably biosonar is one of the ‘eye-opening’ discoveries about animal behavior and the auditory systems of echolocators are front and center in this story.  Echolocation by bats has proven to be a virtual gold mine for colleagues studying neurobiology, while providing many rich examples of its impact on other areas of bats’ lives.  In this volume we briefly review the history of the topic (reminding readers of the 1995 Hearing by Bats).  We use a chapter on new findings in the phylogeny of bats to put the information that follows in an evolutionary context. This includes an examination of the possible roles of Prestin and FoxP2 genes and various anatomical features affecting bat vocalizations.  We introduce recent work on the role of noseleafs, ears, and other facial components on the focusing of sound and collection of echoes.
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