That's a dinosaur skull from the late Cretaceous. It was given the name as a tribute to the Harry Potter series.
Did I live in the medieval times? No. Did you?
However, the people who DID made records of all kinds of stuff. And you'd think that a large, flying, invulnerable, fire-breathing monster would be 1) written about A LOT and 2) leave some sort of evidence behind, like cities burned to a pile of ash, or armies reduced to charred bone.
We don't have those. Nor do we have a SINGLE dragon skeleton, nor a preserved dragon hide. We have legends in stories. Those aren't historically reliable, anymore than Beowulf is an accurate account of Scandanavian history.
And absence of of evidence of dragons does not somehow confirm their existence. If someone found a verifiable dragon skeleton from 1100 AD, I'd revise my thinking on the subject.
No one has.
The Leviathan in Job is basically a nasty Sea Serpent, yes? Did you know that the motif of a mighty sea serpent (representing the forces of chaos) being vanquished by a cultural hero or god (representing the forceful imposition of order upon chaos) is very common among most Middle Eastern religions? Marduk slaying Tiamat, Hadad defeating Lotan, Ninurta overcoming the seven-headed hydra, and the Jewish midrash, where God killed the female leviathan so they would not increase their numbers and consume all the world. It would be kind of a shock to find that a middle-eastern culture such as the Hebrew people NOT having such a story in their legends.
It even has a name for it: Chaoskampf (the struggle against chaos). It's pretty ubiquitous. Notice that even in Norse, Greek, and Vedic mythology this motif is found.
But in all of that, not a single one of the monsters immortalized in verse and prose is a real beastie. There is no Jormungandr encircling the world. Illuyanka isn't prowling the heavens to steal hearts and eyes. There is no Vritra holding back the waters of all the rivers behind his 99 fortresses. The world is not formed from the corpse of Tiamat. And there were no dragons ravaging the land in the middle ages.