Final answer:
The similarities in bones within a dolphin's flipper and a human hand are an example of homologous structures that evolved from a common ancestor. Comparative embryology shows shared features among embryos of different vertebrates, supporting evolutionary connections. These observations are crucial for understanding phylogeny of species.
Step-by-step explanation:
If you observed the bones in a dolphin's flippers and the bones in a human hand, you would notice that despite differences in shape, they share a common pattern and origin. This commonality is an example of homologous structures, which derive from the same embryonic tissue as a result of inheriting from a common ancestor. Over time, evolution has altered these structures in the various species, but the overall layout has been conserved. The bones in the appendages of humans and dolphins are evidence of descent from a common ancestor, providing a strong example of how comparative anatomy and embryology support the theory of evolution.
Comparative embryology also reveals that despite the vast differences among adult forms of organisms, there are often remarkable similarities during their embryonic stages. These similarities, such as gill slits and tails found in the embryos of all vertebrates, are indicative of a shared evolutionary history, even though these features might not be present in the adult form. Structures appearing in the embryonic stage but disappearing by adulthood are adaptations shaped by evolutionary pressures over time and are essential considerations for scientists to decipher the phylogeny of species.