What are vestigial organs ? Name any two vestigial organs in human beings and name the organ which is vestigial for us but not in birds ?

Organs present in a reduced form, which do not play any role in normal body functions are known as vestigial organs. Two vestigial organs in humans are vermiform appendix and third pair of molars(wisdom teeth). The organ vestigial for us but not in birds is the nictitating membrane of the eye.