One of my most surprising, "whow" books of 2004, was The Fossil Hunters, by Adrienne Mayor.
Posted on my blog is a reconstruction of the skeleton of a Protoceratops, a dinosaur that lived in what is now the Gobi desert. Below is a Scythian "griffin", placed into the same stance.
This very clear example is used to introduce the idea that the account of griffins was transmitted, initially orally, by the Scythian nomads who found these skeletons, quite often whole, and sometimes with nests of eggs, in the desert, then written down by the Greeks.
The Greeks and Romans also encountered fossils for themselves and their texts "contain some of the world's oldest written descriptions of fossil finds, many of them first hand. Writers like Herodotus, Pausanias and Aelian tell us what they and their contemporaries thought, said, and did when they came upon bones of startling magnitude." (p. 52)
Mayor suggests that these discoveries - still being made in many parts of the Classical lands - provided the grounds for "myths" about enormous ancient heroes and great monsters.
So, in about 560BC, the oracle at Delphi told the Spartans they needed to find the bones of the hero Orestes before they could defeat their regional rival, Arcadian Tegea. Herodotus says that by chance a Spartan cavalryman stumbled across, then stole, the bones found in a "huge coffin", more than 10 foot long, containing bones of a matching size. The suggestion is that these were the remains of a mammoth, found in the 7th-century BC, when the cult of heroes had begun, and given the coffin burial. A century or so later they were rediscovered, and gave the Spartans the confidence to dominate the Peloponnese.
This led to a long-lasting "Panhellenic bone rush". (p. 111)
Mammoth skulls may have produced the legend of the Cyclops. Quoting from p 35: "In 1914, Othenio Abel, an Austrian paleontologist, suggested that the Cyclops of Homeric legend was based on fossil elephant finds in antiquity. Abel, who excavated many Mediterranean fossil beds, related the image of one-eyed giant cavement to the remains of Pleistocene dwarf elephants, common in coastal caves in Italy and Greece. Shipwrecked sailors unfamiliar with elephants might easily mistake the skull's large nasal cavity for a central eye socket."