Winged Nazgul- Dragons, winged horses, something else? WHAT WERE THEY.

[Daisy Sandybanks]

... if bird, then greater than all other birds, and it was naked, and neither quill nor feather did it bear, and its vast pinions were as webs of hide between horned fingers; and it stank.

Hmmm, well Im thinking Dragon type of creature here. Though, then again, 'greater than all other birds', isn't that big for a Dragon. Although I could be wrong, Dragon's can get pretty small.
'and its vast pinions were as webs of hide between horned fingers' To me, this definitly sounds like Dragon wings, though, I could be wrong on this on too, Im not an expert on Dragons.
But, in any case, in my mind, it dosn't sound like any sort of bird.