Figure 1.
Bony inner ear endocast of Petauroides volans (AMNH 150055) showing embedded head-centered reference planes and SCC canal pair types.
A, dorsal view showing X, Y, and Z axes. Center point occurs at intersection of all three planes. Axial plane = YZ reference plane passing through the interaural line; frontal plane = XY reference plane defined by Reid's Plane (perpendicular to viewer); sagittal plane = XZ reference plane passing through central features. B, Left lateral view with sagittal plane perpendicular to viewer. Abbreviations: A, ampulla; C, cochlea; CC, common crus; LASC, left anterior semicircular canal; LLSC, left lateral semicircular canal; LPSC, left posterior semicircular canal; R, arc radius of curvature of the left anterior semicircular canal; S, saccule; U, utricle.
Table 1.
Taxa, museum specimen number, High Resolution X-ray Computed Tomography image slices used for skull images, spacing between image slices in image stack, Field of Reconstruction, and image slice pixel size.
Table 2.
Summary of semicircular canal angle relationships.
Table 3.
Summary data for the 39 mammalian species in the comparative sample.
Table 4.
Deviations from orthogonality (90var), side-to-side angle symmetry (Angle Symmetrydev), and synergistic canal coplanarity (Coplanaritydev).
Figure 2.
Effect of constraining semicircular canals to strict orthogonality.
This plot shows the relationship between 90var (x-axis) and two ratios (y-axis): (1) Maximum observed sensitivity (Smax) : Maximum sensitivity with orthogonality constrained (OSmax) (blue diamonds), and (2) Average observed sensitivity (Save) : Average sensitivity with orthogonality constrained (OSave) (green squares). Data from Table 4.
Table 5.
Results of Statistical Tests.
Figure 3.
Comparison of ipsilateral canal pair angles from left and right inner ears.
Data from Table 2.
Figure 4.
Regressions of mean estimated semicircular canal sensitivity (Sensitivityave) on Log10 90var.
Table 6.
Previous semicircular canal pair angle research results.