connected to connected to derived from ancestral fusion of derived from ancestral fusion of Homo sapiens tibia talus https://upload.wikimedia.org/wikipedia/commons/a/a9/Subtalar_Joint.PNG UBERON:0002395 major ankle bone MESH:D013628 EMAPA:19135 NCIT:C52799 os tarsi tibiale UMLS:C0039277 MA:0001351 FMA:9708 GAID:196 astragalus bone SCTID:182098005 A proximal tarsal bone resulting from fusion of intermedium and fibulare. astragalus os trigonum astragaloid bone Wikipedia:Talus_bone The talus is apparently derived from the fusion of three separate bones in the feet of primitive amphibians; the tibiale, articulating with tibia, the intermedium, between the bases of the tibia and fibula, and the fourth centrale, lying in the mid-part of the tarsus. These bones are still partially separate in modern amphibians, which therefore do not have a true talus. The talus forms a considerably more flexible joint in mammals than it does in reptiles. This reaches its greatest extent in artiodactyls, where the distal surface of the bone has a smooth keel to allow greater freedom of movement of the foot, and thus increase running speed BTO:0002354 galen:Talus hindlimb intermedium bone proximal tarsal bone fibulare