In 1947 Willard Frank Libby creates the method of radiocarbon dating which allows you to determine, with a good approximation, the epoch of any object that contains carbon , therefore of any organism that lived even tens of thousands of years ago.
Knowing the half-life of Carbon 14 (or radiocarbon), you can evaluate the time elapsed since the death of the organism.
The impact of the radiocarbon dating technique on the life of modern man has made it one of the most significant discoveries of the twentieth century.
No other scientific method has revolutionized the understanding of man not only of its present, but also of events that occurred thousands of years ago.