In the recent movie "Evolution", microscopic alien life forms fall to Earth and start evolving at an incredibly fast rate. At one point, they develop into beasts that look like velociraptors, except they have big leathery wings on their backs. When one of them flaps its wings and takes off into the air, it looks more than anything else like a dragon! Straight off the cover of a fantasy novel! But when the main characters, played by David Duchovny and Orlando Jones, see this, what do they refer to the creature as? A "bird".
In the "Tremors" trilogy, the monsters start out as giant underground worms called "graboids", then develop into walking two-legged beasts called "shriekers", and finally into rocket-propelled flying predators called... well, if I'd been a character in the story, I would've dubbed them "rocket dragons". But instead the folks in the movie name them "ass-blasters". Tuh!
I'm not really bothered by all that; it just seems a tad unimaginative. :}