At university, I was taught (as definitive fact) that the scales on reptiles slowly evolved into feathers. While you can still find this idea in popular literature, serious evolutionists no longer suggest it, because there is simply too much evidence to the contrary. Most evolutionists today suggest that feathers, scales, and hair all evolved from a common ancestral structure. I am sure that if serious scientists are still discussing flagellate-to-philosopher evolution in 50 years, there will be yet another idea of how these structures evolved.
Because evolutionists no longer think that feathers evolved from scales, the currently-fashionable thing to teach as definitive fact is that at least some (if not all) dinosaurs had feathers. The problem is that solid evidence to back up this “fact” has been sorely lacking. There are some dinosaur fossils that give hints of feathers, but there are alternate interpretations of what those hints mean. There are other fossils that clearly show feathers, but it’s not clear the fossils are of dinosaurs.
Now all that has changed, at least according to some sources, because of a recently-reported fossil. The remarkable specimen (pictured above) is part of a tail that has been encased in amber. The amber has preserved both the bones in the tail and the feathers that covered it, giving paleontologists a superb sample to analyze. While the results of the analysis are not conclusive, I do think that they add to the case that at least some dinosaurs had feathers.