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"
Tibia fusus Tibia fusus Tibia fusus, common name Spindle tibia or Shinbone Tibia Gastropod, is a species of large sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs. This species is widespread in Western Indian Ocean and Western Pacific, from Indochina, China Sea, southern Japan and the Philippines to the Banda Sea, Indonesia, Australia and Oceania. Most "Tibia fusus" live in tropical offshore waters where there is plenty of sand, at depths of 5 to 50 m. The shells of "Tibia fusus" can reach a length of (including the long siphonal canal), with a typical length of 23