Read Stephen Jay Gould's book "The Lying Stones of Marrakesh". Then develop just a rudimentary bullshit filter.

Hints: there weren't any dinosaurs 13 million years ago. Nor people. When you get juxtapositions like that, it's a fair bet that some conman has spotted their mark.

Now what WOULD convince me? A mummified pterodactyl with a human in its stomach!