In lots of barren, deserted or otherwise destroyed landscapes, there are bones of long dead animals to be found. Sometimes, it's a skull, sometimes, these are rib-cages, or ribs alone.
And sometimes, these bones are huge.
Is there any sort of common ratio that can be used to calculate the size of the whole body of the animal dead from the size of the bone alone.
(Or more specifically, suppose I have a rib sticking 500 m into the sky, coming from the stereotypical flying flame-breathing dragon, probably western style (though eastern is fine too). Ignore the obvious "dragon of such size could not possibly fly"; I'm making up a game lore, not a documentary. Also, magic.)