were wolves

[Aganzir]

Originally Posted by Tuor in Gondolin

Still, it is interesting that the theme of a sort of
"shape shifting" exists in all three ages, Sauron
in the Second Age and Beorn in The Third,
plus, of course, Luthien, Beren,
and Sauron in The First.

Sauron is a bit special case when it comes to this, being a powerful Maia and all and having therefore the Ainur's ability to choose his appearance, at least in the beginning. Lúthien has Maian blood in her veins which kind of explains the "magical" things she did, but as for Lúthien and Beren's entering Thangorodrim, they hadn't actually turned into a wolf and a bat, only dressed up in their hides. Lúthien deserves some credit for making them fit, though.

And exactly what is to be made of the wargs
attacking The Fellowship between Caradhras
and Moria and their bodies vanishing?

I have always thought the living wolves or some other creatures just cleared up the mess, and Gandalf's remark about they being no ordinary wolves pointed merely at their calculation and cunning - or, even simpler, to the fact a pack of wolves attacked a considerable number of people in the first place.
Or maybe the crebain came and ate them.