Fig. 4. Typical two-dimensional hindlimb force vectors and femoral strains for alligators using a walking trot. Orientations of the (A) sagittal and (B) transverse hindlimb force vectors are shown in relation to the dynamic hindlimb stance phases shown in Fig. 3 (vertical bars). Note that these vectors are equal in magnitude but opposite in direction to the components of the ground reaction force; thus, when the hindlimb force vector is directed posteriorly (>90°), the ground reaction force is directed anteriorly. (C-E) In vivo principal, shear, and axial strains recorded from the alligator femur during the stance phase (at 0.37 m s^-1; from Blob and Biewener, 1999). (C,D) Strain traces from the dorsal femur. (E) Strain trace from the anterior femur.