Series
Unmarked spoilers below!
- The future predators.
- The death of the father on the beach, who dig under the sand by his children and was abandoned when the Silurian scorpion attack. The father managed to survive the initial attack, but in a cruel twist of fate, he couldn't get out when the scorpion finally noticed him and all he could do was scream as it approached him. Not only is his death horrifying, you can't help but pity his children for unwittingly causing his death in the first place and how guilty they felt for the rest of their lives.
- The freakin' fungus monster. To quote Lester, "I'll never look at athlete's foot the same way again."
- The goblin from Season 3. That thing looks and acts exactly like you'd expect a psychopathic little gremlin to, and it can become invisible at will.
- The Season 3 episode "For the Birds". The Phorusrhacids are terrifying under any circumstances, but watching the team trapped inside an old shack in the woods, as the shrieking predators smash their way in...
- The dodo parasite, especially the scene where you can clearly see it ''slithering'' up the inside of a man's neck!
- On that note, the effect it has on hosts as well, who can go from calm to batshit crazy in the space of a second.
- The Angurognathus from season one; even a die-hard pterosaur lover would agree with Cutter that char-broiling those little winged nightmares was a good idea. To paint a picture: you've got something that has the head of a piranha, the wings of a bat and the body of a small bird of prey. They're carnivorous, attack in swarms with up to a million pterosaurs in it, and they arrive with almost zero warning. And they eat their prey alive, in seconds, in a way that, judging from how much their victims scream, is excruciatingly painful.
- The final episode of season 3 is disturbing. One moment you see a troop of early hominids playing and splashing around by a river and seemingly having a good time, the next minute Danny turns a corner and sees their dead and dying bodies littering the ground after Helen poisoned their water supply. Even once Danny stops them he can't reach the anomaly back to the Cretaceous in time, leaving him marooned in the Pliocene
- The end of the series finale was pretty chilling. Everyone's all happy because they thought they'd stopped the New Dawn for good. But as the team is preparing for another mission, Matt sees an exact clone of himself step from the shadows, scarred and bruised, and he whispers "You have to go back!". The next instant, he is gone. It would seem this was just in Matt's imagination, but we can't be sure.
- The beginning of the second to last episode of season 5. One minute you see two teenage girls shopping then suddenly a T. rex is rampaging through the streets leaving death and devastation in its wake. Bonus points for it revealing to the world that rips in time exist allowing monsters from the distant past and future to come to the present any time. This is nightmare fuel for both the viewer and the people in the show.
- The Titanoboa from the Canadian spin-off Primeval: New World. Its deep, rumbling hiss is bad enough. But then you notice its eerily slow movement, dark scales, and the permanent expression of hunger in its unblinking eyes. Yikes! The moment where it ever so slowly opens its mouth is also quite creepy (although it sort of subtly goes from ordinary Nightmare Fuel to Nightmare Retardant when you see that its jaws are toothless, but it quickly goes back to being scary). It doesn't help that this animal, like most snakes, hunts by detecting vibrations. One especially heavy footstep and you're screwed, buddy. Plus, there's the moment when the team realizes that the aquatic creature they've been tracking isn't an eel, but a snake, meaning it can go onto land!
- On the topic of the spin-off, there was also the Albertosaurus that killed the protagonist's wife. It was practically Satanic-looking!
- The angry Pteranodon is pretty scary too. The remains of its victim, for example, are...in poor condition to say the least.
