CT slices through ear region of<i>Sorex monticolus</i>.

<p>Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p

Bony labyrinth of<i>Macroscelides proboscideus</i>.

<p><b>A</b>, stereopair and labeled line drawing of digital endocast in anterior view; <b>B</b>, stereopair and labeled line drawing of digital endocast in dorsal view; <b>C</b>, stereopair and labeled line drawing of digital endocast in lateral view; <b>D</b>, line drawing of cochlea viewed down axis of rotation to display degree of coiling; <b>E</b>, line drawing of cochlea in profile. Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p

CT slices through ear region of<i>Equus caballus.</i>

<p>Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p

CT slices through ear region of<i>Chrysochloris</i> sp.

<p>Numbers refer to specific CT slices. Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p

Bony labyrinth of the fossil elephantimorph proboscidean.

<p>The endocast is figured in different orientations elsewhere <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#pone.0066624-Ekdale4" target="_blank">[84]</a>. <b>A</b>, stereopair and labeled line drawing of digital endocast in anterior view; <b>B</b>, stereopair and labeled line drawing of digital endocast in dorsal view; <b>C</b>, stereopair and labeled line drawing of digital endocast in lateral view; <b>D</b>, line drawing of cochlea viewed down axis of rotation to display degree of coiling; <b>E</b>, line drawing of cochlea in profile. Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p

CT slices through ear region of<i>Rhinolophus ferrumequinum.</i>

<p>Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p

Dimensions and orientations of the cochlea of placentals^a.

a<p>Measurements: Volume, total volume of cochlear canal (mm³); Coil, the total degrees completed by the cochlea; 2° Lamina, extension of secondary lamina through cochlea (°); Length, length of canal (mm); Aqueduct, length of cochlear aqueduct (mm); Ratio, aspect ratio calculated as height of spiral over width; Angle, formed between basal turn of cochlea and lateral semicircular canal (°). Values for extinct eutherians are averages <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#pone.0066624-Ekdale3" target="_blank">[83]</a>.</p

Bony labyrinth of<i>Orycteropus afer</i>.

<p><b>A</b>, stereopair and labeled line drawing of digital endocast in anterior view; <b>B</b>, stereopair and labeled line drawing of digital endocast in dorsal view; <b>C</b>, stereopair and labeled line drawing of digital endocast in lateral view; <b>D</b>, line drawing of cochlea viewed down axis of rotation to display degree of coiling; <b>E</b>, line drawing of cochlea in profile. Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p

CT slices through ear region of<i>Homo sapiens</i>.

<p>Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p

CT slices through ear region of<i>Mus musculus</i>.

<p>Abbreviations listed at the end of the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066624#s2" target="_blank">Materials and Methods</a> section.</p