Last Killers

"Last Killers" is the third episode of Planet Dinosaur. This episode first broadcast on 28 September 2011.

Plot
The episode begins with John Hurt telling the story about the tyrannosaurids. A Daspletosaurus stalks a Chasmosaurus in a forest but loses the element of surprise. The Chasmosaurus charges at the Daspletosaurus but even though it dodged the herbivore's horns, the Daspletosaurus retreats. A pack of younger Daspletosaurus stalk and chase the Chasmosaurus. While tyrannosaurs were to top predators of their ecosystems, Hurt reveals that this wasn't always the case in some environments, such as the Arctic. Here, a large variety of Troodon was the apex predator. At night, a pack of Alaskan Troodon attacks a herd of Edmontosaurus. A juvenile Edmontosaurus is attacked by the Troodons but an adult Edmontosaurus comes to its rescue, knocking down and killing a Troodon in the process. Unfortunately, the juvenile succumbs to its wounds and its carcass is scavenged by the remaining Troodons.

John Hurt then talks more about the ceratopsian-tyrannosaurid arms race in a database section, showing several tyrannosaurids and their contemporaneous ceratopsian counterparts, such as Triceratops and Tyrannosaurus. The episode returns to the Daspletosaurus pack, which is still chasing the Chasmosaurus. The Daspletosaurus pack eventually bring down the bigger herbivore by biting its neck. However, once the kills has been made, the Daspletosaurus start to fight over the kill. The larger adults bully the youngsters away the carcass, forcing them to wait until they have finished.

The episode then cuts to Madagascar, where a female Majungasaurus and her babies have found a carcass during the dry season. After scaring off the flock of Rahonavis scavenging the carcass, the Majungasaurus family begins to feast on the carcass. However, their meal is interrupted by the arrival of a large male Majungasaurus, who scares off the mother Majungasaurus and her young. As the family leaves, the male Majungasaurus begins gorging itself on the carcass, but he immediately sets his sights on one of the babies, after it tried to run away with a scrap of meat dropped by a Rahonavis. This prompts the female Majungasaurus to jump in and protect her offspring, resulting in a fight between the two abelisaurs. After a scuffle, the male Majungasaurus is killed by a bite to the neck, and the Majungasaurus family opts to cannibalize on the dead male's corpse rather than eating carrion.

The episode then returns to North America, where the Daspletosaurus pack attacks a migrating herd of Centrosaurus during a storm. The Daspletosaurus take down several unlucky Centrosaurus while several others aren't as lucky and are fended off by some of the Centrosaurus. Eventually, the Centrosaurus herd arrives at a flooded river, where they must make the tough decision of crossing the river and drowning or fall prey to the Daspletosaurus behind them. Opting for the former, the herd begins its perilous crossing to the other side of the river. As they try to cross the river, the herd begins to drop like flies, with some either being killed by the Deinosuchus living in the river or by large debris in the water. This results in the entire Centrosaurus herd drowning, and their bodies are then swept further downstream. Once the river dries, Daspletosaurus and other carnivorous dinosaurs take advantage of the large number of Centrosaurus carcasses and feast on them. A montage of Daspletosaurus and Majungasaurus is then shown before the episode ends with the narrator saying that "together, the tyrannosaurids and abelisaurids were the last of the killer dinosaurs."