The similar bone and joint structure in the human hand, whale flipper and bat patagium is taken as which evidence of evolution?

1. The human hand, ox foreleg, whale flipper and bat patagium look very different on the surface. 2. Each is also used for a different purpose in its animal. 3. Yet their internal bones and joints follow a similar arrangement. 4. Internal structural similarity points to a common ancestor. 5. Such internal evidence is classed as anatomical evidence. 6. Trap (morphological): that concerns external form similarity, but here the surface forms differ. 7. Trap (embryological): that uses embryo stages, not adult bone structure. 8. Trap (palaeontological): that uses fossils, which are not involved in this comparison. 9. So the correct category is anatomical evidence. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology Part 2, Ch 1 "Heredity and Evolution", p.13_