I tamed one alone on the center. I only use the best crossbow and 100 arrows and 20 parachutes. It's easy to fly over it with your pterodactyl or someone else and then drop it, open the parachute and shoot it. If you think you are out of range then drop and open the next parachute so that you get no fall damage. And repeat it
If you drop a quetzal due to knockout, and it lands next to a giga...just know, the quetzal belong to the giga. Now you get to watch your would be quetzal get eaten by a giga. Now you can go home and cry.