The mammalian tail and the human coccyx (tail bone) differ in their functions, but the close resemblance of these structures indicates a common evolutionary origin. \( \begin{array}{r}\text { The flippers of both penguins and } \\ \text { dolphins help them swim, but } \\ \text { the internal structures of the } \\ \text { flippers vary. }\end{array} \)

Did you know that the human coccyx is a remnant of what was once a fully functional tail in our primate ancestors? This small bone serves as an anchor for muscles and ligaments, reminding us of our evolutionary past. While it's no longer a tail, the coccyx still plays a role in maintaining balance and stability when we sit, a quirky example of evolution's design! When it comes to the flippers of penguins and dolphins, their similar shapes serve a common purpose: steering through water efficiently. However, the internal structures reveal fascinating evolutionary adaptations. Penguins are birds and have bones structured for flight (albeit, now adapted for swimming), while dolphins are mammals with a completely different evolutionary path, showcasing how similar environments can lead to analogous, yet structurally diverse, adaptations.