He is a big, purple dinosaur. He hatches out of what Buster thinks is his soccer ball. Buster names him, and tries to feed him, but he hates everything that Buster gives him. Buster then looks at a book titled Acme Prehistoric History, to find out what Rover will eat, and finds out that Rover is a Tyrannosaurus rex. He also finds out that Rover is a carnivore, and eats small mammals, like Buster. Rover chases Buster, and corners him in an empty pantry. Buster says that he can't let him go hungry, and is about to let Rover eat him. He then says, "Good night, son.", and makes Rover cry. Rover then says, "Mama!", and Buster starts taking care of him. Buster feeds him vegetables from his garden.
Rover grows to be quite huge, but gets discovered and hunted by Montana Max. Soon, he goes back to where Buster found him, an old cavern that was once full of eggs similar to Buster's soccer ball, so he can hide. (This is why Buster took Rover's egg home instead of his soccer ball.) There is a wall that opens up for him, which is where his family lives. Rover doesn't want to go, but Buster tells him that is important that he does, or else Monty will hunt him for the rest of his life. Rover reluctantly goes, and the wall starts to close up.
- In the episode, Rover is purple, but in the Golden Book adaptation, he was yellow.
- In 1992, there is a picture of Rover on Buster's locker in the movie How I Spent My Vacation; the only difference is the picture of Rover is green.