Archaeopteryx made a massive stir when found and its feathers hinted at the link between dinosaurs and birds
There are now at least 8 well preserved and documented specimens of Archaeopteryx or very close relatives.
By H. Raab (User: Vesta) , CC BY-SA 3.0, Link
Reptiles developed a dry skin and scales to enable them to be less dependent on moist conditions than their amphibian predecessors.
Scales were modified to form feathers in birds and hair in mammals.
Archaeopteryx was pretty special for a while but more fossil finds indicate that the feathered Archaeopteryx is not so unique.
In fact, new finds in china are producing a number of feathered dinosaurs.
Yutyrannus Huali is the largest known dinosaur to definitely have had feathers (more downy) and the fact that its related to the famous T-rex makes it all the more mentionable.
Although not as big as T-rex, still a decent size.
By Conty , CC BY-SA 3.0, Link