The Acrocanthosaurus is immune to ranged tranquilizers and must be rendered unconscious by hand-feeding it Narcoberries, Narcotic, or Bio Toxin during its frustrated roar. Place the narcotic in the last hotbar slot, approach the open mouth, aim for the upper jaw, and press the interact key to feed it. Using a Fabricated Sniper Rifle to trigger the shield stance and track adrenaline phases is recommended. A Pump-Action Shotgun also works well, as excess damage is ignored and does not affect taming effectiveness until the unconscious animation plays (especially viable for higher-level Acrocanthosaurus). As a last resort, trapping one and using a melee-leveled Ice Wyvern is possible, though risky. Avoid Fire, Crystal, Poison, and Lightning Wyverns due to lingering damage effects that reduce taming effectiveness.