Dragons could maybe possibly exist
I don't know if this would be scientifically accurate, but the reptilian family tree kind of just ends with the Pterosauria part. The only reason it ends is because there isn't any proof of it continuing. But what if dragons do exist and no ones ever found them because of the hidden world, and so there's no proof to add to the evolutionary tree?
There's also a question mark above Euryapsida on the tree, because no one knows what's supposed to be there. It's a small chance, but dragons could be one of four things: non-existent, belonging where that question mark is, belonging somewhere on the family tree before the Pterosauria, or existing today, descending from the Pterosauria line.
I don't necessarily think dragons do exist, but there is a possibility.
