The fossil record provides a comprehensive array of evidence for evolution. For example Darwin studied Brachiopods, and within rocks you can see the clear change in the Brachiopods through time. The fossil record also shows the potential ancestors for current extant species - for example Glyptodonts are the assumed ancestor for Armadillos. The discovery of Archeopteryx provides evidence for birds evolving from dinosaurs.
DNA as a universal molecule throughout all life forms suggest that life has evolved from one origin through many ancestors. Genes can be sequenced to look for percentage differences between species. Cytochrome C also provides strong evidence for evolution when it is sequenced in the same was as genes are. Differences between species show evidence for evolution from one another.