Fig. 1. (A) Photograph of the head of a Pteropus giganteus after removal of the skin. The two most important jaw closer groups are the m. temporalis and the m. masseter. The m. digastricus is the jaw opener. For a detailed account of the morphology of the jaw muscles see Storch (Storch, 1968). (B) Skull of the same Pteropus giganteus after removal of the jaw muscles. Indicated are the center of rotation (COR), the bite points (BP1 and BP2), and the angle of the food reaction forces (AFRF), which are all defined in the model. The food reaction forces (FRF), the joint forces, and the angle of the joint forces are the variables that are calculated by the model.