A recurring weird thing I've encountered all over the world is the concept of dragons. Interestingly the hypothesis of dragons did predict the formal discovery of dinosaurs, most specifically the coelurosaurian theropod Tyrannosaurus, otherwise known as a T-rex, making it surprisingly fruitful.

The dragon hypothesis does ask us to assume that dinosaurs could breath fire and while there were dinosaurs that could spit poison there is no indication that they could spit fire. It also asks us to assume that they had wings and could fly. While there were pterodactyls which were dinosaur like and had wings they could not breath fire. The dragon hypothesis also generally asks us to assume that dragons interacted both positively and negatively with humans, however there is a significant body of evidence that dinosaurs did not exist a the same time as humans. Because of multiple assumptions and contradiction to existing knowledge I would say that it scores low on both conservatism and simplicity.

It has been argued that there are no "dragon" bones in the same areas/times as human bones (showing the possibility of interaction) because they were all burned or destroyed by frightened and superstitious people but this seem like a very ad hoc hypothesis.

Testability brings mixed results, while the base concept of the creature did exist, some of its qualities have have no evidence to support them. While it did predict many dragon-like creatures it was inaccurate in their physical capabilities.

The diversity of dinosaurs and many corresponding types of dragons as well as matching worldwide locations give the hypothesis significant scope.

In thinking through this process, while I have never personally read it, I have come to a new hypothesis based on what I considered to be a myth: Humanity all over the world has come across dinosaur remains and thought they were fantastic magical creatures. Probably usually found by people digging in the dirt, namely farmers and laborers, they did not adequately understand or document their findings so naturally every time their story was relayed it was also embellished.

To sum up some aspects of the dragon hypothesis have high believability (that dinosaurs existed) and others (fire breathing, human interaction) score poorly.

Thats the most fun I've had thinking in a while.
-Peter Ochabski