Give an example of how geographic distribution can support evolution?

The fossils of a animal will be near the geography of where it died. Such as a bird fossil; if we are able to study the difference between birds now and there fossils we will be able to study changes over time and evolution. So if we find a fossil of a finch in the Galapagos islands, we can see the differences of each bird but also in whatbera they lived upon. we can figure out the type of nature they lived in before the death occured which would help us figure out its past.