Reddit mentions of Feathers: The Evolution of a Natural Miracle

Ah, yes, I forgot that birds moult. But in my defense, it's not the same kind of thing as reptilian skin shedding.

And yes, the evolution of feathers is quite interesting. Thor Hanson's book does a fine job of outlining the journey from filaments to full specialized feathers.

It's not that anything came before them, they were just repurposed. Though always debated, scientists believe that feathers first functions were not for flight, but thermal regulation and/or displays. Eventually, this was "repurposed" into gliding and later, flight.

There is an amazing book called Feathers: The Evolution of a Natural Miracle that discusses exaptation of feathers in an engaging way, I hope you look into it!

edit: spelling