In modern times we've discovered thousands of dinosaur bones, and tons of skulls that clearly came from huge monsters completely different from anything alive today. I've heard theories of griffons being based off the skulls of protoceratops and dragons coming from dinosaurs, but one would think that many pristine skulls would have been found in ancient civilizations, and such unique discoveries would be kept as prized mythical treasures and passed down through generations. Do we have any evidence of this occurring?
This "ancient findings dinosaur fossils" question regularly pops up on this sub, mostly in relation to whetever it influenced or became the basis of the dragon myths.
Regarding the fossils themselves, you find detailed answers here and here, which essentialise summarize that it's very unlikely ancient people found full, recognisable fossils given the typical geological settings they are in, but please read in full if you are interested.
And you can find additional related threads in the faq