Build metal walls on a METAL foundation otherwise the giga will get out of the trap when you lure it into the trap. Make sure the walls are tall, and put a large bear trap in the center then make a metal dinosaur gateway without a door, but make one and put it in your inventory then get on a flying creature then stay low to the ground and make the Giganotosaurus follow you into the trap then fly up. Quickly put the door up while the giga is trapped in the bear trap. Then tranq it.

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