Q1: As we know the limbs, especially arms are homologous structures, which means that possess a common ancestor, so we can find structures that have the same origin, even when each has suffered changes accordingly to their adaptations, the origin is the same, and the same bones are present such as radius and ulna.
Q2: As we said the evolutive origin is the same, however, the function is the same, the ancestral structure suffered changes according to their own selective pressures, for example, bats possess long phalanges that allow flight, meanwhile human has opposable thumbs that allow tool management.
