Rex the Talking Dinosaur can be found in the Dinosaur exhibit at the Leyendecker museum. An animatronic created in what in 1925 was assumed to be the image of a Tyrannosaurus Rex, Rex will speak if one presses the button nearby. Rex will give an assortment of facts about the Tyrannosaurus Rex, before concluding with talking about its next meal.
At the end of Act V, it is revealed that a secret passage from the Furnace Room somehow exits through Rex's mouth. This proves to be very important when Laura Bow needs to trap a dangerous person pursuing her through the museum.