Image: Leg of an ape

Quadrupedal animals like apes  use all four limbs for locomotion. They have femurs in which the ball joint, the part that joins the pelvis, sits directly over the inside of the knee. The angle subtended by the femur at the knee in quadrupedal walkers is less than that of bipedal walkers, animals that walk upright on two limbs.
 

Illustrator:

Helen Beare

Rights:

© Australian Museum

Last Updated: 19 October 2009