According to the study of evolution, the evolution of the bird’s feathers came from the reptile scales. They explain the theory of evolution of the bird’s feathers from the scales of the dinosaurs that lived a very long time ago. They showed the evolution like this:
The Crocodilians à The Archosauria à The Dinosauria à The Saurischia à The Therapoda à The Coelurosauria à The Maniraptora à Aves à Birds . This is how they believed birds feathers were evolved in the present.