Ancient Observation of the Gryffin

Adrienne Mayor is an independent scholor who studies ancient folklore and attempts to plot it against known archaeology and geology. This method led her to a conclusion that the ancient mythological beasts, at least some of them, have their origins in the scientific observation of the day, not sheer flights of fancy. In other words, the ancients were astute fossil hunters and reconstructive archaeologists and anthropologists.

A part of me wonders that if Mayor's basic assumptions are correct, is it not possible that the ancients were also astute naturalists, as well? Is it at all within the realm of scientific possibility, that the bones where fossils now lie were once, more recently than we might normally make conjencture, covered in flesh?