(a) Homologous organs. Those organs which have same basic structure among different types of living beings but perform different function are called Homologrous organs. For example, arms of human being and forelegs of horse, lion, etc. Are Homologous organs. Their same basic structure shows that these have been evolved from some common ancestors.
(b) Analogous Organs. Those organs which have different basic structure but perform same functions in different types of living being are known as Analogous organs. For example, wings of birds and wings of bat are analogous organs. similiarity in these organs is superficial and the design and structure of these organs is very different. organs is superficial and the design and structure of these organs is very different.
(c) Fossils. Fossils are the dead remain parts of the extinct from of living beings. They provide the mission link between the species, e.g., Fossils of dinosours with feathers/fosils of prehistoric horse, etc.
