416-359 million years ago
Ancestral rhipidistian fish evolved pectoral fins with bones homologous to the humerus, radius, ulna, and carpals of tetrapods and pelvic fins with bones homologous to the femur, tibia, fibula, and tarsals of tetrapods.
The first vertebrates to evolve a humerus were the rhipidistian sarcopterygians
which preceded the amphibians. They possessed a joint in the region of
the elbow, although the rest of the fin was fairly stiff (Carroll, p.
161). Before the evolution of amphibians, rhipidistian fish evolved two
bones to articulate with the humerus, the radius and ulna.The fish ancestors
of amphibians possessed small bones in the region of the wrist and cartilaginous
fin rays in the region of tetrapod fingers. Rhipidistians possessed an
ulnare and intermedium of the wrist (Carroll, p. 163). Rhipidistian fish
possessed a femur which included a joint in the area of the knee, although
the rest of the fin was fairly stiff (Carroll, p. 161). In rhipidistian
fish, the tibia and fibula possessed a hingelike connection with the femur
(Carroll, p. 163).