Fig. 4. Example 3D renderings of the bifulcral mandibular leverage parameters used in this analysis. A. Example of bifulcral lever arms corresponding to the working-side superficial masseter (SM-W) shown in a semi-transparent hemimandible of Canis familiaris Linnaeus, 1758; the muscular resultant vector is shown as a red arrow, with corresponding bite force vectors (yellow arrows) and working-side joint force vectors (purple arrows) shown for three positions on the lower postcanine tooth row. As can be seen, the in-lever lengths around the bite point fulcra (used in the calculation of joint force) increase significantly mesially. In labial (A1) and oblique (A2) views. B. Example of the varying condylar planes (CP) and bite planes (BP) used in the 3D bifulcral analysis, shown in Diceros bicornis (Linnaeus, 1758) for a bite point on the lower first molar. The mandible is shown in semi-transparent gray, while the working- and balancing-side origin surfaces for the deep masseter muscles on the skull are shown bilaterally in solid pink; similarly, the isolated origin surfaces of the medial pterygoids are shown in solid green. The muscular lines of action (LOA) for these four muscles are also shown as solid tubes, while transparent triangles demonstrate the orientations of the CP and BP for the corresponding muscle. In superior (B1) and oblique (B2) views. Not to scale. Abbreviations: BS, balancing-side; BV, bite vertex; ILBP-W, in-lever of the bite plane on the working-side; SM-W, superficial masseter working-side; WS, working-side.