Grab a fertilized rex egg and place it about a Wyverns lenght from the nest, wait for the adult to get distracted pecking the egg (careful sometimes the adult will look at the egg and go straight back to the nest), get inside the nest pressing E, do the game with the Baby (ASD buttons on PC) then the baby will get distracted and come back after a couple of seconds for a second minigame, finish the second minigame and hop off the nest (E on PC) run straight back to your egg and grab it, lose aggro from the parent by flying on a mount (usually you dont get aggro), repeat the first step by placing the egg back down (the adult won't break it if you time this correctly) until you have tamed the baby. Also the baby only eats berries.

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