I have one thing that I'd like to add to the statement
If feather arose in birds there'd be some featherless birds at the base of their evolutionary tree but there aren't, so feathers arouse in the ancestors of birds; Theropod reptiles. This is a group of bipedal carnivorous dinosaurs that includes the Tyrannosaurs and Deinonychus. If anyones is interested in a reading more about the origin of feathers there are some good article in New Scientist - The untold story of feathers, Coloured feathers readied first birds for take off, Dinosaur reveals fully formed feathers, Living dinosaurs: How did feathers and flight evolve?rpetersen wrote:Feathers are one of the most prominent features of a bird's anatomy, and they are unique to birds. Every bird has feathers and everything that has feathers is a bird.