Prehistoric Park

• Late Cretaceous Montana, 65 million years ago

The episode starts with the crew erecting the prehistoric animal enclosures. Nigel immediately knows which animal he wants to bring back first: the huge and most famous dinosaur Tyrannosaurus rex. Nigel goes through the time portal, aiming to bring back a Tyrannosaurus. He finds a flock of Ornithomimus and tries to catch one by putting a sock over its head to quieten it, but must let it go when three Tyrannosaurus arrive. Nigel is pursued by the Tyrannosaurus, but they give up when he heads into the deeper forest where they cannot pursue as they are so top-heavy, tripping could kill them. He tracks the Tyrannosaurus to the middle of their territory. He finds some Tyrannosaurus eggs, hoping to bring some back for hatching, but they are broken and empty, either hatched or eaten. As he returns to camp, in the sky are meteors running ahead of the asteroid which will wipe out the dinosaurs. The next day he finds a herd of Triceratops. The Tyrannosaurus pack attack the Triceratops herd. A female Tyrannosaurus is gored in the thigh during the attack. The males back off, leaving the wounded female to catch her prey alone. She goes after a 3-ton young male Triceratops, Nigel opens the time portal and leads the Triceratops through it by waving his jacket at it matador-fashion. It follows him through but the female does not follow. The young Triceratops is then named Theo and becomes the park's first exhibit. Theo starts persistently charging the same tree, and his neck frill changes colour. Suzanne thinks that it is rutting. This gives Bob an idea. Nigel heads back through the time portal and finds Tyrannosaurus tracks in volcanic ash, and sees by the dragged toes that it is the female with the gored thigh. Nigel sees that the wounded female is walking alongside a river following a drifting Triceratops carcass. The carcass gets stuck in rocks in the riverbed. She cannot reach it and carries on downriver. Nigel and others build a crude stockade wall alongside the river out of local fallen timber, trying to funnel her through the time portal. A flock of Ornithomimus appear and run ahead, and the female chases them through the time portal into the park. She successfully catches a straggler, a young Ornithomimus near Nigel and turns back. Instead of eating it there, she carries it towards the volcano despite her injured thigh. Nigel follows. Back at the park, Bob puts the Ornithomimus flock into their new paddock and gets back to his plan for Theo. Meanwhile, Nigel continues to follow the wounded Tyrannosaurus rex until he finds that she has two babies. Nigel plans to bring the mother and her babies back to the park with him, but a male Tyrannosaurus rex attacks the female for her kill. In the ensuing battle, the male Tyrannosaurus smashes the female's head against a rock formation, an injury that results in the mother's death after her last roar to Nigel to save her children. At this point, a 6-mile-wide asteroid enters the Earth's atmosphere at 20,000 mph (32,000 km/h) and hits the Gulf of Mexico. The explosion is 7 billion times more powerful than 40 Hiroshima bombs, and its blast column can be seen in Montana. It leaves Nigel with three minutes while the blast front travels from Chicxulub to Montana at 200 times the speed of sound (c 245,000 km/h) and reaches him. Under a sky full of bright meteors, he uses the only meat that he has (what appears to be a ham sandwich) to entice the two young Tyrannosaurus through the time portal with a second to spare; a bit of the impact blast chases him through the Time Portal. In the park, they are put in an observation pen and named Terence and Matilda. The head keeper copes with Theo's rutting by making a "rival" for Theo by using old tires and oddments to build a crude mock Triceratops head and neck on the front of a tractor, providing something for Theo to take his aggression out on. Later, Terence and Matilda are moved to their new enclosure. The Park takes into account that keeping the pair under control is going to be a major challenge.

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

In the park, the dinosaurs are settling in. The Tyrannosaurus rex are being fed. Nigel goes to visit a herd of African elephants in the park: there are at least four including a young calf. He now wants to rescue a woolly mammoth from extinction. He goes through the Time Portal to 10,000 BC northwest Siberia just east of the Ural Mountains where the last mammoths lived. It is early spring but the land is still under snow. He drives a snowmobile over a frozen lake. He sees nothing but dense taiga forest and rocky mountains: as the land became warmer as the Ice Age ended, trees replaced tundra grass and mammoths lost their grazing lands. As they cannot eat pine needles, this reduced their numbers. Then prehistoric Cro-Magnon humans finished them off by hunting them for food. He explores a nearby cave and comes face to face with a muscular male Cave bear; he had disturbed its hibernation. He had thought that the cave bear would already be extinct by this point. It chases Nigel and the cameraman away. Without the equipment to transport it safely, Nigel cannot save it, so he decides to get back to saving a mammoth. Nigel goes up a rocky slope to scout the area. He sees what looks like a gap in the trees: it may be open land, and perhaps there are mammoths there. He decides to check. He finds two adolescent female mammoths. The older mammoth is dead in a pit. The younger mammoth makes rumblings in her stomach, trying to communicate with her dead companion. She looks ill. She staggers and collapses to the ground. She is so weak that she can barely lift her trunk. She is staying with the fallen mammoth; they may be sisters. Nigel sees a spear wound in her left shoulder. He brings in his team to help. In the park, the Ornithomimus are not eating the grass, nor the beetles living there. Bob realises that they have duck-like mouths: rough like sandpaper. He decides to put them into an enclosure with a pond. The Ornithomimus thrive in their new home. Nigel needs to get the mammoth strong enough to walk through the Time Portal. He gives her an antibiotic injection. Evening comes and the palaeolithic hunters are back. The Park men put up a line of big burning torches stuck in the ground. The men plan to guard in turns, but Nigel decides to sit up with the mammoth all night, to keep her company. Wolves prowl about at a distance all night. Morning comes and the mammoth is strong enough to stand. She shows no aggression, and stays with her dead sister, but the team must get her back to the park. They set up the Time Portal. Nigel leads the mammoth back to the present and calls on a walkie-talkie for urgent medical help. In the park, Susanne gives sedative and antibiotic to the mammoth, treats the wound, and after some pulling extracts a stone spearhead from it. She is on the road to recovery. They name her Martha. Martha is healthy, but is not eating, and needs to eat for strength to recover. They put Martha in an enclosure labeled "Mammoth Mount". Suzanne looks at an African elephant molar and a mammoth molar, and sees that they are designed to chew about the same sorts of food. Maybe Martha is not eating because she needs a specific diet. To solve the mystery, Nigel goes through the Time Portal to the same place in Siberia 150,000 years ago at the peak of the ice age. Mammoths range across from Europe to northeast Asia. He finds a large herd of adult female mammoths. The land is cold but dry and has many kinds of grass and no trees. Each herd follows a matriarch, who is 50 or 60 years old. He collects a large sample of grass and mosses to bring back and analyse. A male mammoth on musth comes, looking for females ready to mate. All the mammoths are thriving on the grassland diet. He sees a sub-adult male Elasmotherium by the snowmobile. It is downwind from him. but there is a risk of it seeing him, and if it sees anything unexpected it may charge. Nigel is between the Elasmotherium and the musth male mammoth. He drops the bag of vegetation and runs to the snowmobile and drives to a safe distance. Nigel decides to bring the Elasmotherium back, riskily using himself as bait, as Elasmotherium will soon be extinct due to climate change. Nigel runs to the sample bag. The Elasmotherium charges at him. Nigel picks the bag up and runs. The Elasmotherium chases him through the Time Portal into the entrance stockade in the park. Back at the Park, Nigel offers Martha the Ice Age grass, but Martha still refuses to eat. Whilst he admits it is anthropomorphic to say so, Nigel thinks that she looks lonely; in the wild female mammoths are always in groups. The Elasmotherium, which is accustomed to being alone, is settling in but Martha is accustomed to being with relatives. There is a council, to decide on putting Martha with the elephants. It is risky: elephant matriarchs have been known to kill new elephants that tried to push into an established herd, but they decide to try it. At Mammoth Mount, the elephants come up to Martha's enclosure. Martha and the elephants' matriarch approach each other, curious, and non-aggressively. Nigel calls to open the gate. Martha follows the elephant matriarch. Martha is now eating well.

• Early Cretaceous Manchuria, China, 125 million years ago

This is a rescue mission just before the site area's dinosaurs were wiped out by a volcano. It is aimed at getting specimens of Microraptor, which is threatened by volcanoes and with being out-competed by the coming birds. In the park, there are now more than 24 animals. The two juvenile Tyrannosaurus often threaten each other. There is a heat wave and Martha the mammoth with her small ears and long hair and blubber is affected by the heat, as she had been brought from an Ice Age winter. Nigel and four other people go on foot through the time portal to the site. A large threatening volcano stands over the area. There are hot springs, and a risk of natural carbon dioxide seepage. There is a small earthquake. They get away onto higher ground. They come to an apparently non-volcanic lake. Pterosaurs fly in and fly with their lower jaws skimming in the surface of the lake for fish. When they get back to camp they find that something had raided their camp and torn much of their equipment apart looking for the meat that was part of their rations. This loss of food supplies causes a crisis. As they walk through a forest, something follows them through the fern undergrowth, then goes away. In the park, Martha the mammoth is led to stand between two jeeps, and several members of the team stand on one of them to clip her hair short to avoid the overheating. During this, Martha sneezes over everybody and the camera. On site, four Mei long attack one of the party, who gets them off him by jettisoning his pack, which contains the meat which they were after. Due to the nature of the attack, it is implied that the Mei long were responsible for the destruction and raid of the camp. Nigel finds an Incisivosaurus. It displays at him and then charges, and bumps the camera with its nose, leaving spit and snot on its lens. It has short quill feathers on its arms, too short for flight, and also quill feathers on the sides of the ends of its tail. It was thought that dinosaur feathers first arose for insulation for warmth, then the quill feathers arose for displaying and later got big enough for gliding. In the park, Bob is looking at the Ornithomimus from a hide and sees that one of the Ornithomimus starts to go off by itself looking in undergrowth, and there are fears about its health. On site, Nigel using binoculars sees some Microraptors going in the same direction, and follows them. This brings him to a herd of titanosaurs pushing through the dense forest making a trampled track as if a convoy of trucks had gone that way. That is not a usual habitat for titanosaurs, and it turns out that they are looking for somewhere to lay eggs safely hidden from egg-eaters. Twelve Microraptors come: they were after insects disturbed by the titanosaurs pushing through vegetation and tearing up the ground and treading on insect-ridden rotten logs. Nigel tries to catch some Microraptors, but they are all too quick for him. Nigel makes an enclosure of net, with inside it a hollow baited with insects, as Microraptors can only glide and cannot take off from flat ground. The Microraptors see the insects but mistrust the net. Out of nowhere, two male Incisivosaurus, one chasing the other, run into the net and flatten it and get away. Then the Microraptors land and eat the insects. Nigel runs at them but catches nothing. The men go back through the time portal to the park. In the park the one Ornithomimus has started lying about in the shade. Nigel has seen this behavior in birds, and guesses that the Ornithomimus is broody. Nigel and at least four others go back through the time portal to the site. Nigel now has a net gun (which he has tested on Bob), and a carbon dioxide detector. Each man has a gasmask in his pack, as volcanic ash in the air damages the lungs. In a forest Nigel comes across a pair of Incisivosaurus who seem to be courting, by calling and displaying at each other close up. In the park, the Ornithomimus is taken into the vet's examination room. A bag is put over its head, to quieten it. Medical ultrasound shows that it has two fully developed functioning oviducts, each containing an egg. (Modern birds only have a left oviduct.) The two Tyrannosaurus are threatening each other. On site Nigel sees that the titanosaur trail goes downhill towards the volcano, but he must follow it. They find several Mei long which had gone to sleep in a flat-bottomed hollow. Nigel plans to avoid the hollow to avoid waking them, but something seems wrong. He claps a few times, but nothing happens. He pokes one with a stick, but it does not wake. He realizes that the Mei longs are dead from gassing by carbon dioxide of volcanic origin. He looks at his carbon dioxide detector, which gives a reading. He calls out "carbon dioxide!" and tells everybody to go to higher ground. In the park, the two Tyrannosaurus start to fight. They are separated by water blast from a watercannon mounted on a large water tanker truck and put in separate small pens while a partition is built dividing their enclosure. Both growl and roar in frustration. On site, Nigel and his party finds the titanosaurs laying eggs in ground warmed by underground volcanic heat, a good place for incubation. He picks up one of the eggs and puts it back in the nest. Unlike with a hen's egg, it must always be the same way up, to avoid damage to the embryo. He reflects that the hatchling would grow to 30,000 times the weight to become adult. The Microraptors arrive, and with his netgun Nigel catches 4 of them. The strongest quake yet happens, and the top of the volcano explodes violently with an ash cloud. This spooks the titanosaurs, which stampede. Some titanosaurs are coming straight at Nigel, who curls up on the ground wrapped around the Microraptors until they pass. He is uninjured but one of the Microraptor has a simple broken left forearm bone. The volcano erupts, blasting out a huge ash cloud. The dinosaurs stampede. Nigel and his team put their gas masks on and quickly set up the time portal in the falling volcanic ash. It comes active just in time, and nine titanosaurs come through it, surprising the men in the park, who have to find somewhere to put them; Bob says "I don't believe it." seeing them come through the time portal. In the park the broody Ornithomimus starts to lay eggs: it has laid six eggs (one pair per day) in a part circle when the episode ends. The injured Microraptor's arm is splinted under anaesthetic; one of the staff refers to it as "she". Bob erects a new fence which he believes will keep the Titanosaurs contained: however, the dinosaurs beg to differ...

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

Nigel is shown walking with a tame cheetah. He comments that specialization has threatened the cheetah, and later that specialization may have wiped out the Smilodon. In the park the titanosaurs break their fence and have to be let wander around the park. They go towards the park's main gates. Bob follows one in a tractor. During this he shouts at a titanosaur "Get back, you great lummox." To his disgust it discharges runny smelly faeces in front of him: its gut clearly does not like some of the modern vegetation. At the same time, Nigel radios to Bob that he will need a birdcage for a bird standing 10 feet high, but due to tractor engine noise and titanosaur noise, Bob only hears part of the message, and provides an ordinary parakeet-sized birdcage. Nigel explains to Bob what is needed. Nigel goes through the time portal to South America 1 million years ago when the sabre-tooth species known as Smilodon were in their prime (having recently entered South America after the Panama land bridge formed), but the terror birds were dying out; before that South America had been cut off from the other continents for 30 million years. He drives through a moving herd of Toxodon; he follows them to find where they were going, and he sees that they were going to water to swim or wallow in: he sees that they lived like modern hippopotamus, and thus may be dangerous like hippos. A huge male Toxodon chases Nigel's jeep, and he has to drive fast and far before it gives up the chase. In the park the female Ornithomimus had laid more eggs. Two of them have rolled out of the nest and she leaves them there, so Susanne must rescue them for artificial incubation, as all those eggs are precious. Susanne stalks up to them and picks them up; the Ornithomimus does not chase, but demonstrates, causing a flurry among some white egrets. Bob puts the 2 eggs in an incubator at 33 °C, as this is best temperature for crocodile and ostrich eggs. On site Nigel sees a female Smilodon stalk a Toxodon and then after a short chase, jump on its head and bite its throat to kill it. More Smilodon come, including some 6 to 8 week old cubs. While waiting Nigel has a coffee and the Smilodon eat their fill and go away. A Phorusrhacos starts to eat from the carcass. Another Smilodon appears and chases it away, forcing it to drop a lump of meat which it had pulled off. That sort of pressure is why the terror birds were dying out. Nigel stalks up to that dropped piece of meat and picks it up. The Smilodon on the kill demonstrates at him but does not charge at him. Nigel tows the piece of meat behind his jeep and entices the terror bird to chase it through the time portal into the park. In the park the eggs incubated by the Ornithomimus hatch and the resulting young run about (the first baby dinosaurs for 65 million years), but the two eggs in the incubator do not hatch. The young Ornithomimus are covered in downy feathers. Accompanied by big cat expert Saba Douglas-Hamilton, Nigel goes through the time portal to South America in 10,000BC when the sabertooth species were dying out. They find a drier climate and no big game. Nigel and Saba separate, on foot. Saba hears animals' alarm cries, but Nigel finds nothing. Saba finds a deposit of fresh Smilodon faeces. She pulls it apart with a knife and fork and finds that it is full of hair and bone and bits of animal hide, as if hunger had forced the Smilodon to scavenge old remains of carcasses. Nigel hears vegetation noise from an animal near him. He finds, catches and releases an ordinary modern-type armadillo and remarks that a million years earlier there were giant armadillos about. Saba later finds something in the grass; sadly, it is a dead Smilodon cub. Nigel cannot find any signs of ill health and realises that the cub must have died from starvation. This has at least given them a hint. A female Smilodon cannot be far away. However, she must be in very poor condition. Nigel has a videocamera with a movement detector: he leaves it overnight watching over a trail. In the morning he plays it back and finds that a male Smilodon had investigated it and knocked it over, urinated on it and left a musky mammal smell. Saba watches the female Smilodon hunting. It sees her and confronts her. She backs off. Nigel meets Saba. Due to lack of prey the female Smilodon is hunting unsuitably light fast prey, a deer: when she charges, the deer runs away easily. Later they see her suckling a live cub, but she is making little or no milk for it. A male Smilodon turns up: there is risk that it will kill the cub to bring its mother into oestrus sooner. In the jeep they anaesthetic-dart the male Smilodon and start to wait 10 minutes while the dart drug works. The Smilodon charges out of bushes and jumps on the front of the jeep; they back off. In the park the men have finished building a partition across the Tyrannosaurus enclosure, and put a Tyrannosaurus on each side. Matilda keeps threatening Terence but now cannot reach him. On site, they find the male Smilodon and load it up on the back of the jeep. Then they go for the female, planning to anaesthetic-dart her and load her and her cub. When they reach her, the cub has starved to death. The female Smilodon is badly underweight from trying to lactate on too little food, and is dying as well, so Saba anaesthetic darts her. A little while later, Nigel and Saba load the female into the jeep, but both are upset that the cub could not be saved. The two Ornithomimus eggs in the incubator hatch, late but successfully: Bob guesses that the incubator's temperature had been set a little too low. The two resulting hatchlings see Bob and imprint on him, thinking that he is their mother and follow him about. They eat food pellets out of his hand. With good food and no need to lactate, the two Smilodon and the terror bird recover from their hunger over the next fortnight. However, tensions remain high, as Matilda's increasingly aggressive behaviour could spell danger for the Park.

• Late Carboniferous Isle of Arran, Scotland, 300 million years ago

In the park, Bob puts the two imprinted baby Ornithomimus in an enclosure with the other baby Ornithomimus and tells them to stay there, one nips his leg. The Smilodon are in adjacent enclosures. The male wants the female, but the more mature female is not interested, either ignoring him or acting aggressively towards him. Nigel goes to modern Arran (in a large RIB with an A-frame and a steering wheel), and sees a fossil Arthropleura track in rock. He talks about what Arran was 300,000,000 years ago. He goes back to the park to serious trouble among the Tyrannosaurus: Matilda has broken into Terence's enclosure. Terence has refused to allow his sister to intrude on his territory and a fight has broken out, in which Matilda is gaining the upper hand, soon knocking him down. Terence has been badly wounded on the face and is losing blood. Bob has drug-darted Matilda, but these drugs take time to act on reptiles. When Terence is badly injured by his sister, Nigel arrives in a roofed jeep and encourages her to chase his jeep, distracting her from finishing off the wounded Terence. When he comes to dense woodland, he can drive no further and climbs a tree. Matilda pulls the cloth cover off the top of the jeep, and then collapses due to the tranquilliser. The injured Terence is in good hands, so Nigel, with assistants, drives in the jeep through the time portal to Upper Carboniferous Arran, where the land is covered with coal forest. He had aimed at an island of dry land, but drives out of the Time Portal's field into a swamp over his jeep's axles. The jeep's engine gets wet and stops and will not start. The forest is very quiet, as there is no bird song or tree-frog noise, only wind and insects. A Meganeura flies over. In the park, Terence is in the animal clinic, anaesthetized, and Susanne is operating on the wounds. She prefers absorbable sutures to surgical clips, since Terence would need to be anaesthetised again for the clips to be removed. She sews the wounds with the skin edges sticking out a bit, as is sometimes done when operating on reptiles. On site, Upper Carboniferous air is 35% oxygen, not 20% as now, and that is why the insects are so big. Nigel climbs a 150-foot-tall tree (Sigillaria or Lepidodendron or similar): it has no branches until near its top, and he must use a loop of strap around himself and the tree, to climb. He reaches its top and sees a wide view, and patches of open water: the place to look for Meganeura. A Meganeura flies over. In the park, an enclosed building to contain a 35% nitrox atmosphere for the coal forest wildlife is being built, with airlock doors. A titanosaur goes past, knocks a partly built wall down with its head, looks at the rubble, then goes away. Bob says that the titanosaurs cannot seem to settle in one area. Bob offers the titanosaur a cycad leaf, but it does not eat. On site, Nigel wades through a swamp. Something big moves about underwater and makes bubbles. Nigel hears something big moving about in undergrowth on land, and chases it, and finds an Arthropleura. It rears and confronts him. It is 10 feet long and has big dangerous-looking mandibles. Some modern millipedes (see Harpaphe haydeniana) can squirt cyanide, which smells of almonds, and Nigel fears that Arthropleura may also. In the park, Susanne has put climbing poles in the Smilodon enclosures: this is environmental enrichment, which will hopefully make them happier so she will be more accepting of the male. Bob suspects that the titanosaurs are looking for stomach stones, and collects stones for them. On site, the Arthropleura has gone, leaving a track. Nigel says that that may be the same track that he saw fossilized on modern Arran. He sees two male Meganeura have a dogfight. Afterwards, one flies away and the other looks for food. Nigel has a butterfly net, but a butterfly net big enough to catch a Meganeura is cumbersome. As Nigel makes a move to catch a Meganeura, something in the water bites his right ankle. He says "Animal bites for us wildlife folks are just a badge of courage." They look for a dry area to camp. Evening is coming. The crew camp for the night. They have head lights strapped to their heads. Nigel warns them never to walk without boots on in case of stinging animals. Someone by force of habit puts mosquito net up, and Nigel tells him to take it down, as mosquitoes have not evolved yet. Nigel sleeps under a waterproof sheet in a hammock slung between two giant lycopsid trees in the coal forest. There is a thunderstorm in the night. In the park, Bob brings a wheelbarrow full of the stones to some titanosaurs; one of them investigates it. In an observation enclosure, Terence is lethargic, and blood tests show Susanne that Terence has septicaemia, and she reluctantly gives him antibiotic (not knowing how the drugs will react with a prehistoric reptile). While it is risky giving antibiotics to an unknown species, Suzanne knows if she does not, the infection of his injuries will probably kill Terence. On site, the thunderstorm stops, and it is still night, and animals tend to become active after rain. Nigel goes about with a large ultraviolet light. He finds a Pulmonoscorpius nearly a meter long, by its shell fluorescing. He films it, but his camera work is shaky and he would need the team's cameraman to take good footage. The Pulmonoscorpius then begins crawling onto Jim's bed, and looks as if it may sting him when he twitches in his sleep. Nigel grabs it by the tail end, and it nips him with its pincers. He lets it go away from the camp. This wakes Jim, and Nigel explains to Jim what happened. In the park Sabrina, the female Smilodon, seems happier, and as if she will accept the male. Susanne wonders whether to raise the door between their enclosures. On site, Nigel tries to catch a Meganeura by a technique known for catching modern dragonflies, by filling a long two-handed hand-pumped water-gun with detergent solution to squirt on a Meganeura so that it will fall in the water and become wet, so it can be caught easily. The Meganeura are very fast and agile, but after many failed attempts, he hits one perched on a floating log. Nigel gets his net and catches the Meganeura. In the water he sees a big amphibian. He passes the net with the Meganeura in to a companion and swims underwater (without a diving mask) and catches the amphibian after a struggle, as it is very strong and slippery. He shows that it is an underwater ambush predator. It has two rows of teeth in its upper jaw and one in its lower jaw. He sees that it is a Crassigyrinus, whose fossils have only been found in Scotland; he nicknames it a "swamp monster" as it has no common name. That is what bit his ankle earlier. He has to let it go, as he has no way to transport it safely. He holds the Meganeura vertically by its thorax so its wings fan his face, as the forest is very hot and damp, then puts the Meganeura in a net cage. In the park Susanne lifts the door between the Smilodon enclosures. They have a water jet ready to separate the two if they fight. The male goes into the female's enclosure. They growl somewhat at each other, but do not fight. On site, Nigel looks for the Pulmonoscorpius. He finds one nearly a meter long under a half casing of a rotted-out fallen lycopsid log. It has thin claws, so Nigel is worried, because with scorpions small claws mean big sting. He holds its attention with a thin stick and works his a hand behind it and grabs its telson just in front of its sting. As he puts it in a dog carrier, it stings the back of his right hand as he lets it go. But a worse danger is coming. In the park, Bob has filled the insect house with 35% nitrox atmosphere and has realized the resulting increased fire risk. He lights a thin piece of wood to show the fire risk. The lightning storm has started a forest fire, which is spreading fast towards them, and in the 35%-oxygen air vegetation is much more inflammable than in modern air. They run towards the jeep. Nigel trips over a big Arthropleura hidden in ground litter. It rears to confront him. Nigel, who was wanting to get away quickly, was not thankful for this delay, but says he must rescue it, otherwise it will be burned alive. After a struggle, he and another man wrap it in a plastic sheet and tie red cord around it. They load everything on the jeep and set up the Time Portal just in front of the jeep, whose engine still will not start. Nigel runs through the Time Portal, comes back with the end of a tow rope, and ties it to the jeep, which is towed out of the coal forest swamp back into the modern age. They see that the tow rope was being towed not by a towtruck or other vehicle, but by a titanosaur, which Bob was enticing with the wheelbarrowfull of gastrolith stones. (This seems to imply that someone went back through the Time Portal earlier to tell the park staff to arrange a tow.) The Arthropleura, the Meganeura, and the Pulmonoscorpius are put in the high-oxygen building. Terence is recovering well from his injury and infection but wrecks Suzanne's surgery once he wakes up from anaesthetic: Susanne had not restrained him, not realising he would come around so fast. Terence is taken back into his enclosure, since he seems likely to make a full recovery. Nigel's sting site has swollen but still shows no serious symptoms, so either the Pulmonoscorpius's venom does not affect mammals (it came from a time before mammals), or it did not inject any venom, or he pulled his hand away before it could inject. Bob seems to take a liking to the Arthropleura and hand-feeds it ferns. He says that he likes it because "it isn't some kind of creepy-crawly bug, it's more like a proper animal." At the end of the episode, Terence roars in the sunset.

• Late Cretaceous Texas, 75 million years ago

In the park, near the Time Portal site there is a crocodile enclosure. There is a suspension bridge across it (the simple sort where the footway follows the catenary); Bob walks across it to feed the Nile crocodiles in the lake. Nigel plans to add a Deinosuchus, an ancient species of giant crocodilian (more closely related to alligators than crocodiles) which measures 50 feet long and weighs up to 9 tons, to the park. Bob mutters that Nigel may have bitten off more than he can chew this time. In a jeep, Nigel goes through the Time Portal to the Cretaceous in Texas, where Dallas is now. At this time North America is divided into three land areas by a Y-shaped internal epicontinental sea. The land around the Time Portal exit point is dry: gravelly sand with patches of trees and bushes. Two half-size juvenile Parasaurolophus go by and stop about 10 m away. Nigel chases them towards the jeep. Then two Albertosaurus appear. The Parasaurolophus honk and run away. Nigel revs his jeep's diesel engine: that makes the Albertosaurus back off, but not for long and they get accustomed to the noise (and presumably to diesel exhaust smell). He drives away. They chase him, at speed up to 30–38 mph, but they tire and turn away. In the park, Bob is planting young trees to help feed the titanosaurs: he says that he will have to plant 2000 trees each year for this. The titanosaurs, of course, are no help whatsoever at this, and keep trampling trees down. The Smilodon have bred and now have two cubs. Susanne sees that their mother is not making enough milk for the cubs, so she has to take the cubs and bottle-feed them, thus breaking the natural mother-cub link. If she were to put them back into their mother's enclosure, they would be killed. On site, Nigel drives onto a sea beach, and looks out to sea for signs of Deinosuchus which could survive for a limited time in salt water like modern saltwater crocodiles. He stops. A herd of Parasaurolophus run past. They are each 10 meters long. He shouts at them to clear off in case they damage his jeep's paintwork. He finds a conch-sized gastropod shell and makes a hole in it and blows it to try to have an exchange of vocalizations: they make noises using their hollow crests. Nigel, with binoculars, sees 5 Nyctosaurus fly in from the sea. They fish by skimming the lower jaw through the water surface. Nigel has brought a microlight with him: he uses it to fly with the Nyctosaurus. A Deinosuchus reaches its head out of the sea and grabs one of the Nyctosaurus. Nigel sees another Deinosuchus swimming from the sea up a river, and decides to head in that direction. In the park, Susanne visits Martha the mammoth, who tries to be an "auntie" to the elephant herd's matriarch's calf, but the frightened matriarch drives Martha away. Martha is becoming isolated again, and there is fear that she will again stop eating. On site, Nigel paddles in a red inflatable boat on the river. A Deinosuchus bites the boat's stern, does not like the taste of rubber, and lets go. It snaps out of the water again by the boat, then disappears. Nigel paddles two miles upstream to a freshwater lake, where he sees some Deinosuchus on a sandbank, and a herd of Parasaurolophus forced by thirst to come to the lake to drink. Nigel paddles. He mentions that Deinosuchus will (geologically) soon be wiped out when sea floods the area, as they have a specialised lifestyle, so he must rescue one. An unwary young Parasaurolophus goes to the lake to drink. A Deinosuchus rockets out of the lake and grabs it by the chest. The two roll over and over in the lake. More Deinosuchus swim in. They take turns to hold the kill while another tears at it. In the park, the Phorusrhacos has developed a habit of dust bathing near its enclosure's fence, undermining it. Each time, Bob fills the resulting hole with big stones. He realises that this tactic is only "firefighting" and that he will have to make a new fence with the bottom ends of all its posts buried four feet deep. On site, Nigel has made a long double row of wooden posts ending in a blind end. He plans to entice a Deinosuchus with meat up the fenced route to the blind end. To get back to the jeep, he walks through a dense forest, but he is worried about dangerous predators. Something is following him. He feels relieved when a Troodon sticks its head up out of bushes and shows that it is much smaller than an Albertosaurus. When he reaches the jeep, he sees that three Troodon are eating the meat that he had brought as bait. He chases them away using a portable aerosol-like horn. In the park Bob is shoveling up Elasmotherium dung when he sees the Phorusrhacos looking at him through a fence. He calls on his walkietalkie that the terror bird has escaped again. A keeper comes in a jeep, and by towing some meat behind the jeep leads the terror bird back to its enclosure. On site, Nigel plans to use the rest of his meat to bait a Deinosuchus up the stockade. He sets the bait at the stockade's end. They rig hammocks. It gets dark. With their helmet headlights they see that some a Troodon was pulling away his bait. When Nigel chased after it, another came and ran off with the rest. The meat that was left was not enough to lure a Deinosuchus. They go to bed. They are woken in the morning by the noise when three Albertosaurus kill a Parasaurolophus. Three Deinosuchus come out of the lake to steal the kill. There is noisy confrontation and some biting, and tugs-of-war over the flesh. The Albertosaurus admit defeat and back off. In the park Martha the mammoth is still isolated from the elephant herd. On site, Nigel must use himself as bait. He wades into the water and splashes it hard with a paddle until a Deinosuchus investigates. He backs off too soon; the Deinosuchus backs off. He splashes again. The Deinosuchus charges out of the sea and chases Nigel, who runs up the stockade path and at its blind end squeezes between two of its posts. He and 4 men with him struggle to hold the stockade posts upright, until the Deinosuchus tires, as cold-blooded reptiles tire quickly. They set up the time portal close outside the blind end of the stockade. Nigel in the jeep tows three of the end stockade posts out and through the Time Portal; the Deinosuchus is confined too closely to turn round, so it must follow him through the portal. It is enticed with a piece of meat to its pond (made close by the time portal), which it goes into. In the park Bob as usual has to "pick up the pieces". He drives the jeep to his next job, and mutters that Prehistoric Park needs more keepers, as they have so many problems: the terror bird escaped its enclosure again; the Smilodon cubs have had Suzanne up half the night, the titanosaurs eat too much, and to make matters worse, their digestive systems cannot handle the modern vegetation resulting in bad diarrhea, and Nigel constantly bringing back more creatures is not helping. Suddenly, a Troodon emerges from the kit on the back of the jeep: enticed by the meat in the jeep intended to lure the Deinosuchus, it has stowed away. It attacks Bob, and the swerving jeep runs straight at the titanosaurs, causing them to stampede through several enclosures, causing the Ornithomimus flock, Phorusrhacos, Elasmotherium, and, worst of all, Matilda the Tyrannosaurus, to flee through the broken fences and run around freely through the park. Paying no attention to the titanosaurs lumbering through her enclosure, Matilda walks right out into freedom, getting the scent of an easy meal. Bob manages to stop the jeep, and the Troodon leaps out and escapes into the undergrowth nearby. Bob runs off to try to capture the escapees. When trying to round up a group of escaped Ornithomimus and the Elasmotherium, Bob is warned that Matilda is on the loose and closing in on him, so he must flee. Matilda then heads for the elephants – she separates the calf from the rest of the herd and quickly runs it to the ground, but Martha blocks her path, and defends the calf by trumpeting, growling, roaring and waving her trunk and tusks. Nigel then arrives and runs away on foot, trying to lure Matilda away to follow him. Matilda, seeing the prospect of an easy meal, turns away from Martha and starts chasing Nigel. In the chase, Nigel runs past Theo the Triceratops, the Nile crocodile pond, across an open area, and along a jeep track past the Deinosuchus lake, with Matilda closing the gap behind him. The Deinosuchus, accustomed to fighting giant theropods, surges out of the lake at Matilda, who swings around just in time to dodge the attack. This delay buys time for Nigel, who runs into the Time Portal's entry stockaded enclosure and climbs out of it by a ladder. Matilda's jaws are only about a foot distance from one of his feet as he climbs to safety. Nigel shuts the enclosure and Matilda is contained. A few weeks later, extra keepers have been hired. The escaped animals are back in their enclosures. Bob catches the Troodon in a long tunnel trap with droppable doors at both ends, and presumably finds somewhere to keep it. The elephants, thankful for the help and rescue, let Martha join them as a full herd member and be an "auntie" to the elephant calf. The Smilodon cubs have been weaned and are eating meat, but they have not grown visible saber teeth yet.

At the end of the episode we see Nigel at his headquarters planning his next mission before travelling through the time portal, suggesting future expeditions into prehistory.