-Activate the "Debug mode" code, then get a T-Rex to follow you into deep water (shoot at him and hold CTRL). While holdingSPACE, take out your gun. The T-Rex cannot kill you in deep water.
-Use the following steps to kill a T-Rex with one hit with the pistol. Note: This procedure requires editing a game file; creating a backup copy of the file before proceeding is recommended. With a text editor, edit the "res_" file in the "huntdat" folder. Find the section that defines the pistol and change the power to 1024. Then, find the T-Rex section and change the health to 1. You should now be able to kill the T-Rex with one shot. You can also change the power of the Rifle, X-Bow, Double Barrel Shotgun, Shotgun, and Sniper Rifle. Changing the number to anything over 1024 will not register.
-While in the correct location where your sniper rifle is at the eye, enable the "debugup" code and toggle on the slow motion code to kill it. If you miss, you will run faster than the T-Rex to get to a new part. Then, hit him in the eye.
-Killing carnivores can be tough because if they touch you, you will die instantly. It is also difficult when they get within medium range, because they can strafe your shots and close the distance very quickly. Once easy way to kill any carnivore is to lure them into deep water. Once there, the carnivore is forced to slowly doggy paddle in a straight line towards you. This makes them easy to pick them off at your leisure. This method even works on the Tyrannosaurus Rex, although you do have to shoot him accurately in the eye. In fact, the bigger carnivores like T-Rex cannot hurt you while you are floating in deep water (as long as their feet are not on the ground) because you are floating above their hit detection zone, which is at their feet instead of near their head.