Use atleast 4 metal dinosaur gateways (i would suggest 5-6 just in case) place 3 in a formation where the giga can walk in and you can place the last one behind it while it is stuck in a bear trap that u can place in the middle of it.
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
Make 4 metal dino gates and 1 large bear trap. Place three frames and door into an incomplete square and the large bear trap in the I between them. Lure the Giga into the trap and while its trapped place 4th down to make the square. Then just light it up with tranqs