“ideas about “dragons” came from?” Yes...
Dragons, Basilisks, Griffons, and other mythical monsters of all kinds found in literature from the Middle Ages and before-maybe even the Thunderbird (no-not the car)-plenty of people found fossilized bones of these “monsters” on construction sites, etc just like we do-they just didn’t know where they came from or a way to date them-so they made a supposition based on what they saw and wrote about it-there are written accounts/stories from as long ago as ancient Greece-and no doubt others we just haven’t found yet.
People didn’t have facts, so they made assumptions-primitive people still do it-check out “cargo cults” and a few other myths espoused by tribal societies who do not really interact with the outside world...
“Found these bones...” Bones?
Not by Webster’s definition are they bones.