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 humerous, forearm is composed of radio-ulna, the wrist consists of carpels, and the palm contains metacarpels 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 functions.
Write about the ancestry and evolution of bat, horse and human on the basis of a comparative study of their forelimbs.What are these limbs categorized as?