It's prehistoric mayhem as Cave Kitten Tom chases Cave Mouse Jerry out a cave and encounters a baby dinosaur and his mother.
In the prehistoric times, a caveman uses a club to smash coconuts while Tom and Jerry are sleeping. Jerry wakes up and chews on a piece of coconut. The angry caveman aims at his coconut at Jerry, ending up smashing his foot. The caveman wakes up Tom and tells him that if Jerry is not out of the cave, it's curtains for Tom. Tom drops pieces of cheeses and hides behind a rock, waiting to smash Jerry with two pieces of rock. Jerry follows the pieces and sees Tom. Then Tom accidentally smashes his tail while Jerry runs away. Jerry is chased to a dead end and cornered by Tom. Suddenly, a volcano explodes and Jerry takes cover on a tree while Tom is send down the river. The egg hatches a baby dinosaur, who is crying for his mother. Jerry tells the dinosaur to grab on the tree and the dinosaur is pulled to safety. The dinosaur thanks Jerry for saving his life and in return, the Dinosaur protects Jerry from being tormented by Tom. Tom then lays out a trap for the dinosaur. However, the trap didn't work and Tom tested the trap out himself, but falls in. Later, Jerry and the dinosaur are bathing in a lake and Tom swings on a vine but misses Jerry. Tom then uses two leaves to catch Jerry, but he is chased by a Pterodactyl. Tom then lands on a tree. Tom then sees Jerry and the dinosaur and grabs them, only to be stomped on by the dinosaur's mother. Jerry then rides off with the two dinosaurs as the now flatten Tom walks back to his master's cave.
- This episode's time frame precedes all other episodes, and features the oldest ancestry of Tom and Jerry. The other episode that also takes place in the prehistoric era is Cave Mouse.
- Prehistoric Pals is the only Cartoon written by Jack Hanrahan.