. because forelimbs have different functions in different animals, their bones may be somewhat modified. for example, the weight-bearing bones of a horse's leg are heavier than the slender bones of an eagle's wings. the bones in an eagle's wing are heavier than the delicate bones of a bat. despite such modifications, these animals have the same basic bones in their forelimbs. the most logical explanation for these similarities is that all these animals share a common ancestor