Mechanical advantage of main mandibular muscles expressed as ratios of moment arms to incisor resistance arm for mean shapes of dietary groups.

We also include the same calculations for reconstructed shape changes along the main PCA axes Analysis (Fig. 3); along the main CVA axes (Fig. 4); and for the regression of shape on centroid size (Fig. 2). Lever arm for most ventral fibers of the temporalis (MT) of reconstructed shapes had to be calculated as the distance between the tip of articular process and landmark 4 (see Fig. 1).MT2′ = moment arm of the most dorsal fiber of the temporalis; MT = moment arm of the most ventral fibers of the temporalis; MSM9′ = moment arm of the most dorsally inserting fibers of the superficial masseter; MSM8′ = moment arm of the most ventral fibers of the superficial masseter; MADM = moment arm of the most anterior fibers o the anterior deep masseter.