Kiddo was the name given to a baby Brontosaurus by Eddie Spenser Jr.. It's egg had recently been discovered in San Francisco in the year 1986. Professor Von Ziflin kept the egg in a specially prepared incubation chamber in his laboratory until it hatched. But he realized he did not know what to feed or how to raise a dinosaur, and so the Ghostbusters decided to take the egg back to prehistory to reunite it with it's mommy.
However, Kiddo hatched out of his egg while still inside Ghost Buggy. The first person he saw was Tracy the Gorilla and therefore Kiddo assumed Tracy was his mother. To add to the confusion, circumstances conspired to make Kiddo's mother think that Tracy was her child.
Not to be outdone, Prime Evil sent Mysteria back in time as well to bring him back an army of dinosaurs. Amongst the dinosaurs she transported to 1986 were Kiddo and his mother, and the two were finally reunited at the Golden Gate bridge. After defeating Mysteria and Haunter, Jake Kong Jr. set the Time Turbo on wide angle, and send all the dinosaurs back to their own time period.
Kiddo first appeared in the episode Dynamite Dinosaurs.