Proper noun
the Old Stone Age
The Paleolithic period.
The Mesolithic was to him "a mere continuance of the Old Stone Age mode of life" between the end of the Pleistocene and the start of the Neolithic. Source: Internet
This period is not to be identified with "Old Stone Age", a translation of Paleolithic, or with Paleolithic, or with the "Earlier Stone Age" that originally meant what became the Paleolithic and Mesolithic. Source: Internet