An excerpt from Merian C. Cooper's King Kong

Kong beat the beast back, and it snapped to try and retaliate, but Kong pushed the beast over. The bulky Meat-Eater flailed about in an attempt to regain its footing while Kong roared in victory. The T-rex roared back in defiance, and was nearly back on its feet before Kong began beating it again. The T-rex, once again, pushed Kong away with a kick before he returned and tried to attack it again. The Meat-Eater however, turned around and struck him with its tail. Kong grabbed the tail, and began to pound the Meat Eater’s hips mercilessly, causing one of its legs to give way and break under the weight. As the Meat-Eater attempted to get up, Kong grabbed its skull from behind and beat the reptile’s head, shattering many of its teeth. The Meat-Eater attempted to thrash Kong off to the bitter end, when he snapped its jaws. If you looked closely you can Ann within the T-rex's jaws referenced by an concept art for the 2005 film