Several Muppet sketches took place in prehistoric times starring Ernie, paired with either Bert (as either his dad or his son) or Sherlock Hemlock (as "The Royal Smart Person"). Each one with Ernie and Bert contained a narrator, who would help translate their utterings of "ooga-mooga-mooga" and such. The sketches were titled Caveman Days and Caveperson Days.
- Everyone wants to go outside the cave, but they're not sure which way to go out until the Royal Smart Person invents an EXIT sign.
- King Ernie has a problem -- the cavemen write everything on rocks, which are too heavy to carry around. He calls upon the Royal Smart Person to invent something lighter to write on. (This sketch was adapted into a book, The Invention of Paper.)
- King Ernie wants something to drink, so he calls on the Royal Smart Person for help. The royal cow has quit, so there's no milk available. Ernie also shows that there is no liquid inside a rock or a stick. Then the Royal Smart Person suggests that Ernie should try squeezing a round orange thing (an orange), which turns out to have juice inside.
- Ernie (the father) and Bert (the kid) go over the procedure of crossing the street.
- Bert invents a window so that people can see what the weather is like without going outside.
- Ernie (the kid) realizes that a drum (his favorite instrument) can also be used as a wastebasket, which he can use to take several pieces of garbage to the dump at once, instead of one at a time.
- King Ernie needs to clean his yucky teeth. The Royal Smart Person brings a big brush (used for sweeping), then a middle-sized brush (used for brushing hair), then a smaller brush (used for painting), and finally a really small brush (a toothbrush). Just as Ernie proclaims that he'll "brush every tooth in the entire kingdom," a saber-toothed tiger comes in, seizes the toothbrush, and begins to use it himself! (The sabertooth in this sketch was the first puppet created by Ed Christie for a Henson-related production.)