When I find a giga, I lure it to a location I find easiest to get it stuck. Easiest way to lure it is by placing a dodo or a monkey on the platform on your quetz. It'll register as a land dino and remain aggressive to you. Then get it into a position where if it runs away it gets stuck. I do this with natural traps and solo. Good luck.
I dare you to raise one!! They are savage if you got two high lvl parents (about lvl 140ish) and you get imprinting on it. The thing will become an adult with about 230% melee and basically one chomp any bronto!!! But on the down side you loose your job and your girlfriend