While it could never be proven that Dino Boy in the Lost Valley, the backup feature on Space Ghost, was actually set in the Stone Age, Hanna-Barbera decided to return to that era with the original caveman superhero, Mighty Mightor, in 1967.
As the origin story goes at the beginning of the show, a young caveman, Tor, rescued a hermit, who then rewarded him with a mystic club, which, when raised, transforms Tor into Mightor.
As The Flintstones transposed the Stone Age into a semi-modern setting from 1960-66, Mightor would seem to be in a more traditional setting depicting the era. Here, Mightor battles "The Monster Keeper" in this excerpt:
Only one season's worth of episodes was produced. Mightor somehow found his way into the 21st century, thanks to the wackjobs at [adult swim], who decided that Mightor would now be a judge named Hiram Mightor, a supporting character on Harvey Birdman, Attorney-At-Law. Those blasphemous dullards wouldn't know the value of quality entertainment if it came up and bit them on their tuchis. I digress.