Even 'Primitive' Dinos had Feathers

Galvasean

The earliest dinosaur known to have feathers has been found. Dating some 130million years old, Tianyulong confuciusi was just over two feet long.
This discovery is deemed very important as it is a somewhat older feathered dinosaur than those previously found.
Also, it is the first ever member of the Ornithischia dinosaur supergroup (which includes Stegosaurus and Triceratops to be found with feathers. Before this discovery the only feathered dinosaurs to be found were of the Sauroschia order, more specific the theropod (the two legged family which includes all of the meat eating dinosaurs).
So it appears that feathers were far more common among a broad range of dinosaurs than once taught.
Scientists are now looking into the posibility that feathers may have originated in a type of creature which predated and gave rise to these dinosaurs.
http://news.nationalgeographic.com/news/2009/03/090318-new-dinosaur-feathers.html