Technically, each culture had a stone age, or an age prior to technology. Primitive cultures in South America that do not use tools forged from metals are living in a stone age.
Biblically speaking human culture started in the fertile crescent or modern day Iraq. I do not know of any fossil beds in the Middle East, which is rich in human artifacts of developing cultures. Also Biblically speaking it was only after the Tower of Babel that God scattered mankind across the globe. Now, all I can do is speculate concerning what happened in those scattered communities, however it would have taken generations for them to populate their geographical area and migrate to other parts of their perspective continent. Therefore, I personally would not expect to find human fossils in the major fossil beds in the Dakotas, Utah, Colorado, and South America.
As to cavemen, speciation in finches occurs over several generations and can explain why humanoid fossils differ. Physiologists discovered that diet can effect cranial features, for instance a diet high in blubber results in a people who have larger brow ridges.
Since most fossil beds are the result of some catastrophic event, if there was not a local humanoid population there would not be human fossils found with the dinosaur fossils.