A structure or organ is vestigial if it has diminished in size or usefulness in the course of evolution. Vestigial structures are markers of evolutionary descent. For example, boa constrictors, which are descended from four-legged reptiles, grow tiny...

Vestigiality describes homologous characters of organisms which have lost all or most of their original function in a species through evolution. These may take various forms such as anatomical structures, behaviors and biochemical pathways. Some of...