Other discoveries of huge mammal bones were viewed as confirmation of the ancient Greek belief in ancestral heroes as 15-foot giants. Mastodon fossils on Samos were hailed as the remains of the war elephants Dionysus is supposed to have deployed in his mythic battle with the Amazons.

And where did the idea of the griffin come from? Aristeas, a seventh-century B.C. traveler, wrote of the gold-seeking Scythians who fought creatures in the Gobi Desert that resembled ''lions but with the beak and wings of an eagle.'' These fierce creatures presumably nested on the ground and guarded deposits of gold. In reality, Ms. Mayor concluded, the griffin ''was based on illiterate nomads' observations of dinosaur skeletons in the deserts of Central Asia.''

Ms. Mayor's success in piecing together the griffin legend encouraged her to examine other Greek and Roman texts for ''the world's oldest written descriptions of fossil finds,'' which had been overlooked by most classics scholars and historians of science. On a visit to Samos, she studied a rich collection of prehistoric bones and skulls with which the ancients must have been familiar. She began to put texts and fossils together and saw the ancients in a new light.

''Just as a fossil is 'petrified time,' so is an ancient artifact or text,'' she wrote. ''The tasks of paleontologists and classical historians and archaeologists are remarkably similar -- to excavate, decipher and bring to life the tantalizing remnants of a time we will never see.''

Although Ms. Mayor's interpretations may draw fire from some scholars, the response to her book has so far been favorable. John R. Horner, a dinosaur paleontologist at the Museum of the Rockies in Bozeman, Mont., has called it ''the best account ever concerning the real meaning of mythical creatures.''

In a review in the journal Science, Dr. Mott T. Greene, a historian of geology at the University of Puget Sound in Tacoma, Wash., praised Ms. Mayor's ''well-documented contention that the ancients constructed their deep time as we have constructed ours, through the discovery and analysis of the fossil bones of extinct creatures.''

''If they told stories about these fossils that differ from our own,'' Dr. Greene continued, ''they examined the fossils with the same techniques we employ today: comparative anatomy, skeletal reconstruction, paleogeography and museum display.''