User blog comment:TheCarrotSaysYumYum/FT0 5 - A Moonlit Lake, Review./@comment-24744891-20141117132747/@comment-7418318-20141117215358

Looking at it again, I don't think it's either a Dragon (at least none of the sort we've seen so far) or a Wyvern, since that thing doesn't have any bones that would constitute wings.

Maybe they dug up some dinosaur bones and used magic to animate or remote controll it. Or they only put the skelleton there after ransacking the city to intimidate newcomers and that thing never moved in the first place.