When you hear talk of evidence for evolution, the first thing that frequently comes to mind for most people is fossils. The fossil record has one important, unique characteristic: it is our only actual glimpse into the past where common descent is proposed to have taken place. As such it provides invaluable evidence for common descent. The fossil record is not "complete" ( fossilization is a rare event, so this is to be expected), but there is still a wealth of fossil information.