Bird feet and legs only a small extension of the cnemial crest. In grebes both a normal patella and an extension of the cnemial crest are found. The fibula is reduced and adheres extensively to the tibia, usually reaching two-thirds of its length. Only penguins have full-length fibulae. The bird knee joint between the femur and tibia (or rather tibiotarsus) points forwards, but is hidden within the feathers. The backward-pointing "heel" (ankle) that is easily visible is a joint between the tibiotarsus and tarsometatarsus. The joint inside the tarsus occurs also in some reptiles. It is worth noting here that the name "thick knee"
Vancleavea of archosaurs as well as the internal trochanter of basal archosauriforms. The midshaft of the femur is circular in cross-section. The lower portion of the femur includes both a medial condyle (which connects to the tibia) and a lateral condyle (which connects to the fibula), although neither of these knobs are particularly strongly developed. In general, the femur of Vancleavea is intermediate in structure between basal archosauriforms and archosaurs. The tibia and fibula (lower leg bones) are both slightly curved away from the center of the leg. They are also thinnest at their respective midshafts. The front edge of the