Fig. 10. Captorhinus. Diagram, showing areas of internal thickening. Approx. × 1.
Fig. 11. Captorhinus. Diagram, showing orientation of sculpture. Approx. × 1.
Secondly, the vectors of mechanical force associated with the temporal region are complex ([Fig. 9]). Presumably it was toward a more efficient mechanism to withstand these that selection on the cheek region was operating. The simpler and more readily analyzed of these forces are:
1. The force exerted by the weight of the skull anterior to the cheek and the distribution of that weight depending upon, for example, the length of the snout in relation to its width, and the density of the bone.
2. The weight of the jaw pulling down on the suspensorium when the jaw is at rest and the compression against the suspensorium when the jaw is adducted; the distribution of these stresses depending upon the length and breadth of the snout, the rigidity of the anterior symphysis, and the extent of the quadrate-articular joint.