Kill the adult and imprint on the baby for an easy cerato (only do this if you are fine with a low level)

If you want the taming bonus to get a high level cerato, first tame a gigantoraptor must be 100% tame or a bread one(automatic 100% tame) kill the adult and claim the baby with the gigantoraptor for a 100% taming effectiveness(this is so you get the same level as if you proper tamed a cerato or possibly better(lets say you found a 150 baby it would usually claim with no extra levels but with a gigantoraptor it will get a bunch of extra levels))