Figure 1.

Skull of Phrynosoma hernandesi displaying the measurements made using the static bite force model. The model was set to measure food reaction forces (bite forces are equal magnitude but opposite in direction) at orientations ranging between −30 and −150, which were calculated relative to the long axis of the mandible. The model also calculates the joint force and angle of joint forces about the quadrate joint. The origins and insertions of all muscles input into the model were measured relative to the center of rotation (X = 0, Y = 0) and to the midline of the head (Z = 0).