In a clearing, they encounter a prehistoric creature - a Stegosaurus. The armor-hide of the reptile reflects their rifle bullets as it charges toward the men. The beast has to be brought down with a knock-out gas bomb. As they approach the gigantic dinosaur on the ground, it rises up again and lashes around with its spiked tail. After more gun shots, it falls again, and Denham puts a fatal bullet into its brain. Then, the crew reaches the edge of a fog-covered swamp, and they hear Kong splashing across ahead of them.
To keep in close pursuit, they perilously cross on a hastily-constructed makeshift raft. Suddenly, a rampaging long-necked Brontosaurus emerges from the water. Its ugly face glares down at the men, and then submerges to escape a volley of rifle fire. The dinosaur rises again directly under the raft, throwing the men into the water. It snatches, chews up, and hurls away a number of sailors - one hapless man in the water is seized head-first.
The survivors who have struggled to the shore race ahead of the creature. A sailor who has fallen behind in the chase through the swamp climbs a tree to escape, but is viciously grabbed from the tree branches by the menacing jaws. Kong, carrying Ann, crosses a log bridge over a deep chasm.
In a clearing, he hears the approaching pursuit so he places Ann high in the fork of an upright dead tree. He returns to the location of the pursuing search party to do battle, finding Driscoll and seven of the surviving sailors crossing the deep ravine. (Denham has dropped back and hasn't reached the bridge yet.)
In the frighteningly horrific log sequence, Kong picks up, shakes, and overturns the chasm-bridging log as the men cling for their lives.
All the sailors on the log roll off and are sent screaming to their deaths deep into the gorge. Driscoll has managed to cross the bridge and has climbed down a large plant vine to hide in the small hollow of a cave under the side of the cliff wall.
Kong reaches over to grope and grab for Driscoll, but the sailor, in a deadly game of cat and mouse, defends himself with his knife, and Kong withdraws his paw, angry and puzzled. Below the cave, Driscoll is nearly seized by a lizard-like reptile that has crawled up from the ravine on a vine. But he cuts the vine on which the creature is crawling.
The giant ape tries to reach for the annoying Driscoll one more time but he is interrupted by Ann's screams of terror. She has just seen a vicious, flesh-eating dinosaur approaching in the glade in the background. As she delivers a piercing scream, the Rex scratches its ear.
Kong leaves his prey, hastily leaps over a fallen log, and returns to his golden-haired Ann just as the huge, monstrous creature is ready to put his large jaws on her. In the next spectacular sequence - one of the most exciting bits of stop-motion animation in the film - the primordial Kong and Tyrannosaurus Rex battle to the death, as Ann in horrible fascination watches the combatants from her treetop perch.
To start the furious, titanic battle, the two first face off and measure each other. Then, Kong leaps onto the dinosaur's back and the creature viciously struggles and frees itself by shaking the ape off. The Rex affixes its huge, sharp-toothed jaws around Kong's protecting forearm. When they separate, Kong boxes and swings punches at the Rex's head.
Like two collegiate wrestlers, the ape grabs the monster's tree-sized leg and crashes it to the jungle floor. As Kong pummels the creature's head, it furiously kicks its tail and legs, flinging Kong off. In the wrestling melee, Kong reels backward against the tree where Ann is sitting. The camera follows the tree as it crashes down to the ground, pinning Ann there - miraculously, she is uninjured.
From the ground-level perspective, the two creatures are even more frightening and awesome. At the end of their struggle, Kong leaps onto the back of the Tyrannosaurus and tears apart the gigantic, razor-sharp jaws of the dinosaur. Blood oozes from its cracked-open mouth - Kong inspects to make sure his opponent is truly dead by moving the lifeless mandibles. With the Rex silent, Kong beats his massive breast in triumph. Tenderly, the Beast frees Ann from the tree and carries her deeper into the jungle.