- Lure it into a flat and peaceful area.

- Trap it. 4 metal billboards and a large bear trap will do the job nicely.

- Tranq it (staying on a quetz platform is a good option if there're many predators on the ground).

- Clear the area with your favorite pet as soon as the giga is sleeping.

- Check regularly it's torpor, you don't want it to wake up.

- When its hunger has dropped significantly, give him some kibbles (or your taming food).

- Once tamed, use it to murder all the microraptors and ichtyornises of the map.