Robbie gets fed up with Earl always telling him what to do, so he challenges Earl for male domination and wins; but he quickly becomes aware of how much responsibility is involved in being the male of the house.
Charlene signs up for a foreign student exchange program to get away from her family who doesn't understand her; and the Sinclairs get a bitter taste of a different culture when a French bird moves in with them in Charlene's place, who has an unfortunate encounter with the Baby.
The Chief Elder passes a law that forbids four legged dinosaurs from living in Pangea and demands in 24 hours they either marry a two legged dinosaur or retreat back to the other side of the swamp. Monica is fired and threatened with deportation until Roy proposes to her so she can stay.
Baby becomes a hit sensation when he and Earl star in a series of commercials for the Myman P-2000, a new and improved frying pan that is strong enough to endure hitting Earl's head. Earl is fired from the commercials and he and Monica start to worry that fame is going to the Baby's and Fran's heads.
Robbie tries to bulk up to impress a girl, but her attention seems to be drawn to a bigger guy named Dolf. When exercise doesn't cut it for Robbie, he resorts to Thornoids and finds out his new, bulky body comes at a high price.
Fran finds being a housewife and mother unfulfilling and does volunteer work at a halfway house for amphibians; Earl gets stuck taking on the household chores and the kids and finds out what it's like being the mother.
Robbie starts doing the mating dance in his sleep and at school. Fran finds out and decides since Earl won't talk to his son about it, that the school needs to offer a course to the teenagers so they'll understand all about the mating dance, and Robbie is mortified when Fran is volunteered to teach it.
Robbie tries to get Earl interested in preserving Pangea just as his boss is ordering him to bury drums of toxic waste in his back yard. On one such night, Earl and Roy get a visit from an extraterrestrial from the planet Kyron who warns them to change their ways or face annihilation.
Charlene feels her family is neglecting her, so she gets their attention by winning the school talent show; but her rising fame is riding on the backs of three young cavelings she found in the forest whose mother is looking for them.