any point in keeping on to these? they weight me down alot and are valuable. do I sell them or they needed for something else?

There used to make legendary dragon bone armour. (When you have 100 smithing I think)

Aww crap. I sold a bunch of them already. Guess I'll store them all in my house from now on.

Can't you buy them back?

Probably, but they'd be too expensive to be worth it (I think).

Besides, surely you don't need the dragon scales and bones from every single dragon in the game to get the dragon armour?

Yeah your probaly right