312 – Dinosaur Islands

A panel from "Dinosaur Island!" in Batman #35, April 1946
A panel from “Dinosaur Island!” in Batman #35, April 1946

In Batman #35 (April 1946), Batman and Robin visit an island filled with animatronic dinosaurs called Dinosaur Island. Kind of a precursor to DC’s actual Dinosaur Island, and it appears this is where Batman and Robin pick up the mechanical T-Rex as a trophy for their Batcave.