answer, no big words.

5. Vestigial Structures Some organisms have structures that are homologous to those in other organisms but no longer serve the same purpose. Some kinds of snakes, for instance, have tiny remnants of leg bones called "spurs." There tiny bones do not develop into legs. but are homologous to leg bones in other animals. Similarly, whales have leg bones, too. Whale leg bones are located deep within the whale's body, near the pelvic region, but they are greatly reduced in size and often fused together. They aren't used for swimming (or walking!)- Whale Skeleton 5. What does the presence of leg bones in whales suggest about their evolutionary ancestors? Claim Evidence Reasoning