An idea that could have saved the series...

What killed the series was the redundancy of the episodes all taking place in the prehistoric world.

What might have been an idea would be to have the Astronauts jump back and forwards through time to different periods (The Middle Ages, The Wild West, The Roman Empire, The American Revolution, etc.).

Then have two to four episodes run in a story arc like 'The Beverly Hillbillies' did with the heroes spending time in each period.

And the running gag of the series could have been that Imogene Coca and the rest of the supporting cast would re-appear in each story arc as the ancestors and descendants of the previous families that took the Astronauts in.