All birds today are actually coelurosauria dinosaurs, a group of theropods (T-rex and raptor-shape dinosaurs) who are thought to have all had feathers for warmth, show, and/or gliding and flight. I know we have evidence that some other theropods had feathers (or at least hairy stuff), but I don’t know whether the rest of them are lacking evidence of feathers or whether we have evidence against them having feathers.

I would also love such a book, preferably with lots of pictures.