What is a vestigal disc?

A vestigial disc typically refers to a remnant structure in an organism that has lost its original function through evolution. An example is the vestigial pelvic bones in whales, which are remnants of their land-dwelling ancestors. These structures can provide insight into the evolutionary history of species, illustrating how adaptations occur over time. Vestigial discs may also refer to vestigial structures in other contexts, such as embryonic development.