Structures like the human tail bone and whale pelvis are called what?
adaptations
primordial structures
parasitic structures
vestigial structures
Structures like the human tail bone and whale pelvis are called vestigial structures . Evolution has reduced their size because the structures are no longer used. The human appendix is another example of a vestigial structure. It is a tiny remnant of a once-larger organ. In a distant ancestor, it was needed to digest food. It serves no purpose in humans today. Why do you think structures that are no longer used shrink in size? Why might a full-sized, unused structure reduce an organism’s fitness?.