Super easy to tame. Build a dino gate trap about 30-50m from the nest and lure the mom in. PvP you can just pick the mom and drop her in the trap with a Rhynio.

Once the mom is secured, hide in the center of the nest and mimic the baby's dance moves (spin, bow, or flap).

If you kill the mother or drag her too far from the nest you can't tame the baby. She has to be close by, but not aggro'd.

If the nest is somewhere where you can't build a trap you'll have to lure mom away with fertilized eggs to start the tame. The bigger the egg the better. 1 bronto or giga egg should keep her busy for 2-3 rounds of dancing with the baby. When she finishes the egg she'll come back to check the nest. At that point hop out and drop another egg to kite her away and repeat the process.