Walking with Dinosaurs

220 million years ago, Late Triassic (Arizona)

Filming location: New Caledonia

By a river, a female Coelophysis stalks a herd of dicynodonts called Placerias, looking for weak members to prey upon. Downstream, a male cynodont resides in a burrow with his family. A female Postosuchus, a rauisuchian and one of the largest carnivores alive in the Triassic, attacks the Placerias herd, and wounds one individual; the herd scatters, leaving the wounded Placerias to the Postosuchus. Early pterosaurs called Peteinosaurus are depicted feeding on dragonflies and cooling themselves in the little water remaining during the drought. Still searching for food, the Coelophysis discover the cynodont burrow; the male wards them off. Later that evening, after he goes off hunting, an inquisitive pup follows the male to the entrance and is eaten by the female Coelophysis. At night, the cynodont pair eat their remaining young and then move away. On the next day, the Coelophysis work to expose the nest. The female Postosuchus is later shown to have been wounded by the Placerias, a prior attack on them leaving her with a tusk wound on her thigh. After being unable to successfully hunt another Placerias, she is expelled from her territory by a rival male. Wounded, sick, and without a territory, the female dies and is eaten by a pack of Coelophysis. As the dry season continues, food becomes scarce. The Placerias herd embarks on a journey in search of water, while the Coelophysis begin to cannibalise their young, and the male cynodont also resorts to hunting baby Coelophysis at night. Finally, the wet season arrives; the majority of the Coelophysis have survived (including the lead female), and the cynodont pair have a new clutch of eggs. The episode ends with the arrival of a migrating herd of Plateosaurus, foreshadowing the dominance of the sauropods after the Triassic–Jurassic extinction event.

In the credits it is explained that 20 million years later, the aforementioned extinction wiped out many reptile species, but the dinosaurs continued to evolve, with carnivores growing to massive sizes and their prey becoming even larger, setting the stage for the giants of the Jurassic.

152 million years ago, Late Jurassic (Colorado)

Filming location: California State Parks, Chile, Tasmania, New Zealand

This episode follows the life of a female Diplodocus, beginning at the moment when her mother lays a clutch of eggs at the edge of a conifer forest. Months later, some of the eggs hatch; the young sauropods are preyed upon by Ornitholestes. After hatching, the hatchlings retreat to the safety of the denser trees. They face many dangers as they grow, including predation by Ornitholestes and Allosaurus. While fending off a pair of Allosaurus, a Stegosaurus also accidentally kills one of the hatchlings while swinging its tail. Elsewhere, adult herds of Diplodocus are shown using their massive weight to topple trees in order to reach cycad leaves. Each Diplodocus hosts a small mobile habitat of damselflies, Anurognathus, and dung beetles. After some time, the creche of Diplodocus have grown into subadults. Nearly all are killed by a huge forest fire; only three survivors emerge onto the open plains, including the young female. They encounter several Brachiosaurus before two reach safety to a herd of adult Diplodocus. Several years later, the female mates, and is attacked by a bull Allosaurus. She is saved when another Diplodocus strikes the Allosaurus with its tail. Although she is wounded, she rejoins the herd. The closing narration notes that the sauropods will only get larger, becoming the largest animals ever to walk the Earth.

In the credits it is stated that the sauropods eventually went into decline with their prairies becoming flooded by rising sea levels, resulting in vast inland seas and the giant marine reptiles that patrolled them.

Eustreptospondylus puppet head that was used in Walking with Dinosaurs at the Oxford University Museum of Natural History

149 million years ago, Late Jurassic (Oxfordshire)

Filming location: The Bahamas, New Caledonia

The episode begins with a Eustreptospondylus being snatched from the shore by Liopleurodon. Meanwhile, hundreds of Ophthalmosaurus arrive from the open ocean to give birth. Hybodus and a Liopleurodon are on the hunt; when a mother Ophthalmosaurus has trouble giving birth, a pair of Hybodus pursue her. They are frightened off by a male Liopleurodon, which eats the front half of the ichthyosaur. Meanwhile, a Eustreptospondylus swims to an island and discovers a turtle carcass; it fights over the carcass with another Eustreptospondylus. Later, during the night, a group of horseshoe crabs gather at the shore to lay their eggs, which attracts a flock of Rhamphorhynchus in the morning to eat the eggs. However, a few of the pterosaurs are caught and eaten by a Eustreptospondylus. While the Ophthalmosaurus juveniles are growing up, they are hunted by Hybodus, which in turn, are prey for the Liopleurodon. While the male Liopleurodon is hunting, he encounters a female Liopleurodon; after the male bites one of her flippers, she retreats from his territory, and a group of Hybodus follows the trail of her blood. A cyclone strikes the islands, killing many animals, including several Rhamphorhynchus and the Liopleurodon, who is washed ashore and eventually suffocates under his own weight. A group of Eustreptospondylus feed on his carcass. At the end of the episode, the juvenile Ophthalmosaurus that survived the storm are now large enough to swim off and live in the open sea.

In the credits, it is stated that even though only turtles remain, marine reptiles were a glory of their age and that another group shared the dinosaur's world, the flying pterosaurs, which are claimed to be just as spectacular.

Ornithocheirus puppet head that was used in Walking with Dinosaurs at the Oxford University Museum of Natural History

127 million years ago, Early Cretaceous (Brazil, North America, Europe and Cantabria)

Filming location: New Zealand, Tasmania

The episode begins with a male Ornithocheirus dead on a beach. Six months earlier, the Ornithocheirus, resting among a colony of breeding Tapejaras in Brazil, flies off for Cantabria where it too must mate. He flies past a migrating group of the iguanodont Dakotadon and the nodosaur Polacanthus. He reaches the southern tip of North America, where he is forced to shelter from a storm. He grooms himself, expelling his body of Saurophthirus fleas; the crest on his jaw begins to change colour in preparation for the mating season. He then sets off across the Atlantic, which was then only 300 kilometres wide, and after a whole day on the wing, reaches the westernmost of the European islands. He does not rest there however, as a pack of Utahraptor are hunting Iguanodon; a young Utahraptor is bullied off an Iguanodon carcass by the adults. The Ornithocheirus flies to the outskirts of a forest to rest after stealing a fish from another pterosaur, but is driven away by Iberomesornis. Flying on, he reaches Cantabria, but due to the delays, exhaustion, and old age he cannot reach the centre of the many grounded male Ornithocheirus and consequently he does not mate. After several days under the sun trying to attract a mate, the protagonist Ornithocheirus alongside others who lost out, dies from heat exhaustion and starvation. The next generation of Ornithocheirus feeds on their corpses.

In the credits, it is stated that the pterosaurs continued to rule the skies for millions of years while the dinosaurs continued to spread across the globe, even to the most unexpected of environments, such as the South Pole.

106 million years ago, Early Cretaceous (Antarctica)

Filming location: New Zealand

A few hundred kilometres from the South Pole, a clan of Leaellynasaura emerge during spring after several months of total darkness. They feed on the fresh plant growth, and build nests to lay their eggs; a male Koolasuchus also wakes and heads to a river, where he will stay during the summer. Out on the banks of the river, migrating herds of Muttaburrasaurus have also arrived to feed and lay their eggs. When summer arrives, many of the Leaellynasaura clan's eggs have been eaten; however, those of the matriarch hatch successfully. Meanwhile, a male Australovenator (6m) hunts both the Leaellynasaura and the Muttaburrasaurus, the latter species also having to deal with blood-sucking insects. When autumn arrives, the Muttaburrasaurus herd begins to migrate, and the Koolasuchus leaves the river to find a pool for hibernation. During the migration, some Muttaburrasaurus become lost in the forest; they vocalize loudly while trying to return to their herd, preventing the Leaellynasaura clan's sentries from hearing the Australovenator approaching. It manages to kill the matriarch of the clan. Winter descends and the forest is shrouded in darkness, but the now matriarch-less Leaellynasaura clan is able to stay active, using their large eyes to help them forage for food. The clan and other creatures are also shown to use various methods of coping with the cold such as being frozen alive or suspended animation. Finally, spring returns, and two Leaellynasaura males challenge each other for the right to mate, and the clan establishes a new dominant pair. The closing narration states that continental drift will soon pull this landmass closer to the South Pole, and this unique ecosystem will soon disappear.

In the credits, it is explained that away from the poles, the dinosaurs continued to rule the Earth for another 40 million years before extinction and hints that just before the end of their reign, they had evolved their most infamous predator ever.

Tyrannosaurus puppet head that was used in Walking with Dinosaurs at the Oxford University Museum of Natural History

65.5 million years ago, Late Cretaceous (Montana)

Filming location: Chile, New Zealand

Several months before the Cretaceous–Paleogene extinction event, the last dinosaurs are living under intense environmental stress due to excessive volcanism. A female Tyrannosaurus abandons her nest, the eggs rendered infertile due to poisonous volcanic gases. Her calls for a mate are answered by a smaller male, who kills a young Triceratops to appease her. Three days later, after repeated copulation, she drives him off. The mother fasts as she tends to her nest, contending with raids by Dromaeosaurus and Didelphodon. Meanwhile, herds of Anatotitan wander between islands of vegetation among the volcanic ash, and Torosaurus rut for the right to mate, while losing their young to attacking dromaeosaurs. Only three of the Tyrannosaurus eggs hatch; the mother hunts an Anatotitan to feed herself and her brood. Several days later, while defending her two surviving offspring, the mother is fatally injured by the tail of an Ankylosaurus. The juveniles remain expectantly next to the carcass of their mother the next morning; several hours later, they are killed along with the other dinosaurs in the region by the impact of an asteroid. The impact, said to be as powerful as ten billion Hiroshima bombs, resulted in 65% of life -the dinosaurs included- dying out in the resulting cataclysmic climate changes. In an epilogue, the present-day African plains are shown; while they are now dominated by mammals after the extinction, they are still populated by numerous surviving dinosaurs: the birds.