Final answer:
The coccyx, or tailbone, is a vestigial structure in humans, indicating it is a remnant from evolutionary ancestors and has lost its original function.
Step-by-step explanation:
The coccyx, commonly known as the tailbone, is considered to be a vestigial structure in humans. It is a remnant of a tail from our evolutionary ancestors, reflecting parts of our anatomy that have lost their original function through evolution. The human coccyx is formed by the fusion of four small coccygeal vertebrae and articulates with the inferior tip of the sacrum. While not weight bearing in the standing position, it does support some body weight when sitting. The concept of vestigial structures, such as the human tailbone and appendix, reinforces the theory of evolution by demonstrating how certain anatomical features shrink in size when they are no longer used, potentially reducing an organism's fitness if they were maintained at full size.