AP BIOLOGY

Detailed explanation-1: -Structures that have no apparent function and appear to be residual parts from a past ancestor are called vestigial structures. Examples of vestigial structures include the human appendix, the pelvic bone of a snake, and the wings of flightless birds.

Detailed explanation-2: -A vestigial structure is a feature that a species inherited from an ancestor but that is now less elaborate and functional than in the ancestor.

Detailed explanation-3: -adjective. ves·ti·gial ve-ˈsti-jē-əl.-jəl. Synonyms of vestigial. of a body part or organ : remaining in a form that is small or imperfectly developed and not able to function : being or having the form of a vestige (see vestige sense 2)

Detailed explanation-4: -Charles Darwin listed a number of putative human vestigial features, which he termed rudimentary, in The Descent of Man (1871). These included the muscles of the ear; wisdom teeth; the appendix; the tail bone; body hair; and the semilunar fold in the corner of the eye.