(i) Homologous Organs: The study of these organs suggests that these organisms with organs having same structure but performing different functions have evolved from a common ancestor, e.g. forelimbs of different vertebrates.
(ii) Analogous Organs: The study of these apparently similar organs suggests that the organisms with apparently similar organs do not share common ancestory. Similarity in these organs is superficial, design and the structure of these organs are very different, e.g. wings of bird and wings of butterfly.
(iii) Fossils: They provide the missing link between the species, e.g. fossils of dinosaurs with feathers, fossils of prehistoric horse.
