This similarity is an example of homology.
Here is why:
- Homology refers to structures in different species that share a common ancestry. These structures may have different functions, but they share a similar underlying structure because they evolved from a common ancestor.
- The forelimbs of birds and mammals, despite their different uses (wings for flight vs. walking, running, etc.), share the same basic skeletal elements: humerus, radius, ulna, carpals, metacarpals, and phalanges. This similarity strongly suggests they evolved from a common ancestor that also possessed this basic forelimb structure.
Other examples of homology:
- The flipper of a whale and the arm of a human
- The wing of a bat and the arm of a human
- The leg of a lizard and the leg of a dog
These examples highlight how evolution often modifies existing structures for new purposes, while preserving the underlying shared ancestry.