How did dinosaurs evolve beaks and become birds? Scientists think they have the answer
(PHYSorg.com Archaeology & Fossils)

Once you know that many dinosaurs had feathers, it seems much more obvious that they probably evolved into birds. But there`s still a big question. How did a set of dinosaurian jaws with abundant teeth (think T. rex) turn into the toothless jaws of modern birds, covered by a beak? Two things had to happen in this transition, suppression of the teeth and growth of the beak. Now new fossil evidence has shown how it happened.