Brontosaurus is a Mystic pet added in the Prehistoric Event and can be obtained from a Dinosaur Egg with a 1% chance or from the DNA Converter. Appearance Brontosaurus has a long brown neck, with a light brown body and brown legs. Ability Giant Incubator: Pets hatched from eggs have a 5.2% increase in base size and weight! This size bonus is capped at 30% per egg and does not apply to Brontosaurus.