“…The mammalian inner ear labyrinth has garnered scientific interest since the late 19 th century, and more recently computed tomographic (CT) scans have allowed the unprecedented exploration of this region (e.g., Geisler & Luo, 1996;Spoor et al, 2002;Yamato et al, 2008;Macrini et al, 2010Macrini et al, , 2013Ni, Flynn & Wyss, 2010;Ekdale, 2013;Gutstein et al, 2014;Ekdale & Racicot, 2015;Groh e et al, 2015). Odontocete (Cetacea: Odontoceti) hearing in general has received a great deal of attention because of interest in studying anatomical modifications associated with echolocation in mammals (e.g., Ketten & Wartzok, 1990;Luo & Eastman, 1995;Cranford, Krysl & Amundin, 2010;Houser et al, 2010;Park, Fitzgerald & Evans, 2016), but few studies exist that have specifically explored the inner ear labyrinths at fine taxonomic resolution within major clades.…”