User blog comment:Aandrew07/Discussion of the Week: Leviathans/@comment-5043481-20130216203856/@comment-4212769-20130217133527

Elder Dragon is actually no real Class at all, but a gathering of monsters that are worshipped as gods, feared as destroyers and omens for bad things, as well as summoning catastrophes. But it also includes monsters that doesn't fit in any other class, because they're pretty much unknown. They have that in common with all Elder Dragons actually, all of them are pretty much unknown.

So if you want to look at the Class Elder Dragons, you watch for the "True Elder Dragons".

And no, those are back legs, very degenerated like the back legs of the whales. They are apart from the tail fluke.