(a) The function of feathers initially was to provide insulation but later on they became useful for flight in birds only. Similarly, some dinosaurs had feathers, although they could not fly using the feathers. Birds seem to have later adapted the feathers to flight. This, of course, means that birds are very closely related to reptiles, since dinosaurs were reptiles.
(b) The structure of the eye in each of these organisms is different. This indicates that, these organisms have separate evolutionary origins.