Most typical fantasy dragons are huge, powerful things. Discworld is hilarious for essentially making them this but reptillian:
They also explode and die when they are upset/frightened. Which is uhhh... a lot of the time. Fucking pathetic beasts
Paul Kidby’s art of them is amazing
Pratchett is one of my two favorite authors of all time. I practically spent my teenage years with him and also with spec evo stuff, often about dragons. So I really love what he did there. Fire as a natural weapon would require some pretty drastic adaptions for an animal.
What always struck me as weird, though, is how he decided that dragons, of all classic mythical creatures probably the one with the most spec evo attached to it, are just to unrealistic to play them straight in his fantasy world that also has luggage that runs around on dozens of little feet and has a will of its own, wizards and witches as basically normal jobs and a turtle and four elephants the size of planets.
It's not just Pratchett. There's also this scene in Hellboy: The Nature of the Beast, where Hellboy, a demon from hell who has fought cyborg nazis, witches, gods, ghosts, fairies and eldritch abominations, when he is told he has to fight a dragon, initially doesn't believe that dragons existed. This is, as far as I know, the only time when Hellboy doubts the existence of something supernatural.
What is it about dragons that makes Fantasy authors go: "This is far more unrealistic than all those other fantasy tropes"? And why is it the same kind of mythical creature that gets (often pseudoscientific) natural explanations from not only spec evo fans but also cryptozoologists and creationists far more often than any other kind of mythical creature (except for modern ones like cryptids or aliens)?
Time has notably worn away the Dragon's prestige. We believe in the lion as reality and symbol; we believe in the Minotaur as symbol but no longer as reality. The Dragon is perhaps the best known but also the least fortunate of fantastic animals. It seems childish to us and usually spoils the stories in which it appears. It is worth remembering, however, that we are dealing with a modern prejudice, due perhaps to a surfeit of Dragons in fairy tales.
J. L. Borges, di Giovanni translation