An easy way to kill the giant Tyrannosaur is to quickly run to the giant tree in the middle of the nest site. Make sure you have a shotgun, explosive tip arrows, and grenades. Once in the tree, shoot a flare so that the dinosaur's head is in your line of fire. While she is looking at the flare, shoot every explosive tip arrow you can at or around the eye area. When she jams her head in the trunk to eat you, shoot her with the shotgun until she retreats. Once she frees her head, throw grenades. Repeat this until she falls. Then, quickly run over to her and finish her off with a knife through the eye. If done correctly, you should not have died.
When facing Mama Scarface in the final battle, you should have the bow and perhaps another weapon. When the battle starts she will run towards you. In the direction you are facing are little lights in different areas of the battleground. To your far right (her left) is a light against a fence or wall that has the pulse rifle. This weapon is your goal. It is the strongest weapon you will receive in this battle. It is also far better than the rocket launcher. As the battle starts if you do not have it already, the shotgun is to your left near some boxes and a body. The flare helps and she will follow it, giving you some time to run from cover to cover. Travel the battlefield starting in the clockwise position, running from cover to cover using the flare as a distraction. When you finally reach about 4'oclock (the pulse rifle position), use it on her. Shoot for the head and make sure not to miss. Pay attention to your overheating. Make sure it does not happen. Circle the nearby box for cover and just unload the entire weapon. She should drop before it get empty. Run at her with your knife and press the action button sequence on her.
To defeat the T-Rex after defeating Kane, notice the containers in the level. Run to the containers and around them you will find dead enemy bodies. Pick up their weapons and run around the containers shooting at the T-Rex. The ESUS Blackfly sticky bomb gun works very well. When the T-Rex falls, run over to its head with the knife to finish the beast off.
At the start of the battle you should have 10 Tek arrows. Use them to shoot the T-Rex in the head while looking for the shotgun to your left. When you get the shotgun, circle around the box where the shotgun was found and keep shooting her in the head while shooting flares to keep her disoriented. When the T-Rex fallsm go to her head and knife her. If done correctly, you should not have died.