Other than creationists, there are a lot of authors who argue that dragons are based on vague reconstructions of extinct animal fossils. I haven't even seen proof of that connection, though. I think that connection is speculative. I would think that wyverns look so much like pterosaurs that some ancient person must have found some really sweet pterosaur fossils, but I haven't heard of anybody proving that connection. I've heard the argument that gryphons (yeah, not quite dragons, never mind) could have been fanciful reconstructions of protoceratops fossils (a four-legged animal with a beak). While it's possible and even likely that the ancients must have found dinosaur bones, we don't know that the ancients had a nice protoceratops fossil and decided it was a gryphon. The similarity between a protoceratops and a gryphon could still be coincidental.

The only example I know of where we know for sure that a specific dragon myth was based on a fossil-- and it's not even a dinosaur fossil-- is the linnorm of Austria, because the people in question displayed a weird skull and said it was a dragon's, and kept the skull, so moderns were able to identify it as a rhino skull.

Maybe we never based dragons on dinosaurs. Maybe we reconstruct dinosaurs to look dragon-like. Out of wishful thinking. What else could an unknown large reptile be, but the thing from our myths and preconceptions?

[Edited a minute later to add:] Wait no I am so stupid I forgot! We do know for sure that the "dragon bones" used in traditional Chinese medicine are fossils, and a lot of them are dinosaur fossils. But they get all ground up into powder, not reconstructed. So I don't know how people would figure that those bones would look like reptiles. ...This is what I get for posting about my favorite subject just off the top of my head, without consulting any of my notes.