Quote Originally Posted by PhilosopherStoned View Post
It still seems like the simpler solution is that the fixed femur evolved in late stage gliders and that feathers evolved once. They're pretty complicated and the likely hood of the sequence of mutations occuring twice is, imo, much less than that of there being gaps in the fossil record to make it appear as if birds were around before feathered therapods.

I think that it's gonna take a little more than this to knock the 'birdosour' (love that word) theory down.
Mutations don't really occur twice. Don't you forget evolution is not about species generating others, but about a species differentiating into two new one - a species doesn't end as a new one begins. Who knows for how long birds and feathered therapods (or any other species for that matter) lived together.