The forelimbs of frog, lizard, pigeon, bat, whale and horse have the same basic structural plan as human hand. In each case, the forelimb consists of an upper arm, forearm, wrist, palm and fingers. The upper arm is made up of humerus, forearm is composed of radio-ulna, the wrist consists of carpals, and the palm contains metacarpals and digits. The forelimbs of all these vertebrates are categorized as homologous organs because these are similar in structure and arrangements but are different in shape and function because as they developed along different direction due to adaption to different needs.
