New Giants starts with the birth of an Argentinosaurus hatchling. It caws for a bit before being attacked by a pterosaur. Just before the pterosaur kills the hatchling, a Skorpiovenator arrives. The pterosaur flies away while the Skorpiovenator eats the hatchling. It then proceeds to eat two more hatchlings before the Argentinosaurus herd returns. The Skorpiovenator runs away as the Argentinosaurs feed on the forest around them. The episode then cuts to the River of Giants, Africa. A juvenile Paralititan is mired in mud and a Sarcosuchus emerges from the river. Just before it strikes out at the Paralititan the screen goes black. The feature returns to Argentina, where the Argentinosaurus herd is travelling across some volcanic sand fields. The narrator(John Hurt) explains that adult Argentinosaurs are so heavy that they churn up the ground beneath them. This creates death traps of quicksand which hold threats for small creatures. After a database scene talking about how eighteen animals can be buried in a single step, the Argentinosaurus start feeding again. Suddenly, a gang of Mapusaurs strike out and snack on one of the herd. The victim escapes to rejoin it's comrades as they walk away. Then a flashback occurs, in which the Sarcosuchus studies the Paralititan. The flashback ends and comes back to present tense. The Sarcosuchus suddenly strikes out at the Paralititan and bites it's leg. It struggles to drag the Paralititan out of the mud while a Carcharodontosaurus eyes the incident. The apex predator decides to snatch the Paralititan from the Sarcosuchus. It bites the wounded juvenile on the neck as the Sarcosuchus pulls the Paralititan out of the mire. Both carnivores play a deadly game: tug-of-war. The Carcharodontosaurus eventually wins and it roars at the Sarcosuchus to scare it away. The huge crocodylimorph reluctantly retreats to the safety of the River of Giants. The Carcharodontosaurus is about to deliver the death blow to the poor Paralititan when the Paralititan's herd frightens the big predator away. The juvenile escapes from his mud trap and limps to the asylum of his herd. The episode then switches back to Argentina, where the Argentinosaurus who had been attacked by the Mapusaurus gang succumbs to it's injuries. A huge horde of scavengers gather round the carcass and feast on it for days. The episode ends with John Hurt explaining the fact that when the giant sauropods died out, their giant carnivorous neighbours died out as well.
1. Spinosaurus is the only African dinosaur that appears in Lost World but doesn't appear in New Giants.