Prehistoric Park

• Late Cretaceous Montana, 65 million years ago

Following the construction of Prehistoric Park, zoologist Nigel Marven travels back to the Hell Creek Formation to seek out his first target for the park: one of the most famous dinosaurs, Tyrannosaurus rex. In the process, Nigel successfully brings back a Triceratops named Theo and a flock of Ornithomimus. He attempts to bring back a mother Tyrannosaurus and her two offspring, but the mother is fatally wounded in a fight with an adult male. Moments later, an asteroid strikes the Earth, but Nigel manages to lure the juveniles through a time portal before the blast front arrives. The two adolescent Tyrannosaurus are named Terrence and Matilda, and the park's employees accommodate the needs of all the dinosaurs in their new enclosures.

• Early Holocene and Late Pleistocene Siberia, 10,000 years ago and 150,000 years ago

On his next mission, Nigel travels back 10,000 years to Siberia, hoping to rescue a woolly mammoth for the park. After an encounter with a cave bear, he finds an injured female mammoth whose sister has been killed by Ice Age human hunters, and manages to bring her back to the park after protecting her from cave hyenas and wolves. When the mammoth, who he names Martha, has difficulty recovering, Nigel travels back 150,000 years to study the behavior and diet of mammoths, and obtains an Elasmotherium for the park in the process. Head keeper Bob moves the Ornithomimus flock into a new enclosure with a pond so that they can filter-feed. Deducing that Martha may be lonely due to the absence of other mammoths, Nigel introduces her to the park's herd of African elephants.

• Early Cretaceous China, 125 million years ago

Nigel travels back to the Yixian Formation in China, during the Early Cretaceous. His goal is to obtain the bizarre Microraptor, a four-winged dinosaur capable of gliding. After encountering other dinosaurs such as Incisivosaurus, Mei long, and a herd of giant titanosaurs, Nigel finally manages to capture four Microraptors. As a nearby volcano erupts, Nigel returns to the present with the Microraptors, and manages to bring the titanosaur herd back with him as well. Meanwhile, Bob discovers that one of the Ornithomimus is pregnant, and it eventually lays eggs. Head vet Suzanne trims Martha's hair to help her cool down when the Park suffers a heat wave. The two Tyrannosaurus start to fight over territory, forcing Bob to put them in holding pens while a partition is built dividing their enclosure.

• Early Pleistocene and Early Holocene South America, 1 million years ago and 10,000 years ago

For his next mission, Nigel wants to bring back an extinct species of cat, and ultimately chooses the Smilodon, or saber-toothed cat, of South America. In addition, he also decides to target Phorusrhacos, a species of giant terror bird. On his first trip to 1 million years ago, Nigel encounters a herd of Toxodon and a pride of Smilodon, and manages to bring back a Phorusrhacos. On his second trip to 10,000 years ago, he is accompanied by big cat expert Saba Douglas-Hamilton and successfully brings back a male and female Smilodon, although sadly the female's two cubs have died of starvation. At the park, the titanosaurs break out of the enclosure that Bob had built for them, so he reluctantly allows them to wander around the park. The female Ornithomimus has laid a full clutch of eggs. Two of the eggs have rolled out of the nest and she leaves them there, so Suzanne rescues them for artificial incubation, which eventually succeeds. The keepers have finished building a partition across the Tyrannosaurus enclosure to keep them apart, but tensions remain high, as Matilda's increasingly-aggressive behavior could spell danger for the park.

• Late Carboniferous Scotland, 300 million years ago

Suzanne tries to start a breeding program for the pair of Smilodon, while Nigel chooses to target the giant bugs of the Carboniferous for his next mission. A serious emergency occurs when Matilda breaks into Terrence's enclosure and a fight breaks out. Bob and Nigel manage to stop Matilda by tranquilizing her, but Terrence is badly wounded and Suzanne tends to him. Nigel and his team travel back to the Carboniferous, where he captures a Meganeura and encounters a Crassigyrinus. At the park, an enclosed building to contain a 35% nitrox atmosphere for the Carboniferous animals is built, while Suzanne installs climbing poles in the Smilodon enclosures as environmental enrichment. Nigel catches a Pulmonoscorpius, and the team realize that a forest fire is spreading towards them. As they flee from it, Nigel manages to capture an Arthropleura, and then uses one of the titanosaurs to tow his disabled Jeep through the time portal and back to the park. The captured arthropods are put in the high-oxygen bug house, while Terrence recovers from his injury.

• Late Cretaceous Texas, 75 million years ago

Nigel targets Deinosuchus, an ancient species of giant crocodilian, and travels back to the Aguja Formation in Cretaceous-era Texas, where he encounters Parasaurolophus, Albertosaurus, and Nyctosaurus. At the park, Bob is planting young trees to help feed the titanosaurs, while the Smilodon now have two cubs, and Martha has some trouble bonding with the elephants. Nigel eventually finds several Deinosuchus in a freshwater lake and sets up a trap for them, but his bait is stolen by a group of Troodon. Using himself as bait, he successfully lures a Deinosuchus through the portal and back to the park. Bob drives Nigel's Jeep to his next job, but is attacked by a Troodon that stowed away in the vehicle. The swerving Jeep spooks the titanosaurs, causing them to stampede through several enclosures and allowing the Ornithomimus flock, the Phorusrhacos, the Elasmotherium, and Matilda the Tyrannosaurus to escape. Matilda attacks the elephants, but Martha blocks her path. Nigel lures Matilda into chasing him, and manages to contain her. A few weeks later, more keepers have been hired and the escaped animals are all back in their enclosures. The Smilodon cubs have been weaned, Martha fully joins the elephant herd, Bob captures the Troodon, and Nigel plans his next mission, suggesting future expeditions into prehistory.