Fig. 5. Mean kinematic profiles of humerus elevation and depression (i.e. angle from the horizontal plane) during turtle swimming. (A) Trachemys scripta, (B) Apalone spinifera. The format and method of profile calculation are the same as in Fig. 4. Angles of 0° indicate a horizontal humerus, while positive angles indicate that the distal end of the humerus is elevated above the proximal end, and negative angles indicate that the distal end of the humerus is depressed below the proximal end. The bold vertical line in each plot demarcates recovery phase (R) from thrust phase (T).