Clash of Titans

250 million years ago: Late Permian Place: Siberia Global Temp: 60% hotter than today Hazards: extreme heat, volcanic activity

The third episode is set in the Late Permian, on the supercontinent Pangaea, which was covered by a vast and inhospitable desert. In this arid climate, early therapsids, which are described as more "mammal-like" than reptile, are shown fighting to survive alongside other animals. The programme starts with an old Scutosaurus, a relative of turtles, being killed by a female Inostrancevia, a type of gorgonopsid which later joins others of her kind at a small waterhole. Other inhabitants of the area include Diictodon, a small burrowing dicynodont. In the pool itself is a starving labyrinthodont that ambushes the female gorgonopsid in desperation and quickly retreats. A herd of Scutosaurus arrive and eventually drink the waterhole dry. The female gorgonopsid tries to dig out a pair of Diictodon but is unsuccessful. Upon returning to the waterhole, she unearths the labyrinthodont wrapped in a "cocoon" which it utilized to survive drought. In a torpid state, it is helpless and quickly killed. The gorgonopsid is eventually killed by a sandstorm, foreshadowing the oncoming Permian–Triassic extinction event. The Diictodon meanwhile are able to adapt by digging their burrows deeper, occasionally unearthing plant tubers for sustenance.

Animals: Inostrancevia (identified as Gorgonopsid) · Diictodon · Rhinesuchus (identified as Labyrinthodont) · Scutosaurus

248 million years ago: Early Triassic Place: Antarctica Global Temp: 40% hotter than today Hazards: Ambush Predators

Diictodon is seen evolving into the larger Lystrosaurus. The Lystrosaurus multiply into vast herds that must continually migrate in order to find fresh foliage. Also featured is the small insectivorous Euparkeria that is depicted as an ancestor of the dinosaurs. When the Lystrosaurus herd traverses a ravine, one is killed by a pack of venomous Therocephalians, though the herd doesn't show concern for the victim. Encountering a river, the herd enters the water and is attacked by numerous Proterosuchus. Many are killed, but the majority escape and continue their migration. The narrator explains that despite the dominance of Lystrosaurus, eventually the world will recover in full from the Permian-Triassic extinction event and other reptiles will overtake them. The episode ends as a Euparkeria is confronted by a Proterosuchus: as the smaller reptile rapidly begins to evolve into an Allosaurus and the scene cuts to the Late Jurassic where it passes two Stegosaurus, the narrator explains that mammals are destined to be confined to the shadows as a new group of animals becomes the dominant species on Earth. The Age of Monsters is over. This is the beginning of the Age of Dinosaurs.

Animals: Lystrosaurus · Euparkeria · Proterosuchus (identified as Chasmatosaur) · Euchambersia (identified as Therocephalian) · prehistoric Dragonfly Late Triassic (220 MYA)/Late Jurassic (150 Mya) · Allosaurus · Stegosaurus · Diplodocus (archive footage) · Anurognathus (archive footage) · Brachiosaurus (archive footage) · Epanterias