It is stated that, one day, Nigel Marven hopes to breed extinct animals in captivity. However, Prehistoric Park as it is seen in the series, is mostly a home for a few individuals that Nigel has brought back.
Arthropleura
The Arthropleura in the wild.
An Arthropleuralives in the Bughouse. It made an appearance in the episode The Bug House. Nigel sees a forest fire, so he carries a Pulmonoscorpius in the cage. He observes some creatures escaping from the fire. Nigel tripped on something, but it was no ordinary fallen log. It was an Arthropleura. Nigel realized that the giant arthropod buried itself in the leaves due to the heat, but that it would be burned alive unless Nigel could save it. Nigel pounces on the Arthropleura with a tarp, and Jim, one of Nigel's crew members, ties it so it won't escape. It was then, along with the other rescued Carboniferous creatures, transported back to Prehistoric Park with the help of a titanosaur, and put in the bughouse. While checking on the bughouse's inhabitants, Bob said, in reference to the Arthropleura, "I'm really rather fond of him. I think it's because he's big. He's not like any wiggly, little spider or something that creeps up behind you, like a proper animal."
Elephant Matriarch
The herd of elephants
The elephant matriarch leads the elephant herd. She is involved with Martha, a woolly mammoth that was brought back in the episode A Mammoth Undertaking. Mammoths, like modern elephants, were social creatures, and Martha suffered from "depression" due to her lack of company in the 21st century. However, Bob, Nigel, and Suzanne agreed to introduce her to the elephant herd, which would hopefully help. The Matriarch accepted Martha, and the problem seemed fixed. However, she eventually rejected Martha from the herd in the episode Supercroc when she thought her calf was under threat from her, but withdrew her rejection after Martha protected the calf from Matilda.
Henry
Henry is a male Nile Crocodile that lives in Prehistoric Park with six other Nile crocs. He is briefly seen being fed by Bob before Nigel shows up with a replica skull of a Deinosuchus, a crocodile even larger than the Nile Crocodile. Later, during the Mass Break-Out, some crocs, likely including Henry, run off when they see Nigel being chased by Matilda the T. rex.
Martha is a female woolly mammoth that was rescued in the episode A Mammoth Undertaking. When she arrived at Prehistoric Park, she quickly became "lonely" due to the lack of other mammoths. However, later in the episode, she was introduced to the elephant herd. While this initially was very productive, assimilating new individuals to elephant herds can be a long process, and she is rejected in the episode Supercroc. However, she saves the elephant matriarch's calf from a Tyrannosaurus during the mass break-out and is once again accepted back into the herd.
Matilda is a female Tyrannosaurus rex rescued in the episode T-Rex Returns. As the series progressed, she started to fight with her brother. She also began to cause trouble in the park, sometimes serving in an antagonistic role.
Ornithomimus chicks
A pair of Ornithomimus eggs are rejected by a mother in Episode 4. They are used as "bait" to be sacrificed to predators in order to preserve the main clutch. However, Suzanne manages to sneak the outcast eggs away. Bob tries to incubate them, hoping they will still be able to hatch. It takes them longer to hatch than the other eggs, presumably due to the incubator temperature being a little too low, but they do eventually. However, the chicks imprint onto Bob and follow him around throughout episodes 4 and 5.
Smilodon
In Saving the Sabretooth, Nigel invited Saba Douglas-Hamilton, a big cat expert, to join him in rescuing sabre-tooth cats. Together, they travelled back to South America 10,000 years ago, when the last of the sabre-tooth cats were struggling to survive. During the expedition, Saba finds a dead cub and informs Nigel. Both take the death of the cub as a clue that the mother is in bad shape. The next day, Saba finds the mother on an elevated rock, looking at her as a potential meal. However, Nigel calls Saba, scaring off the Smilodon. Later on, Saba and Nigel track the cat down to a ledge and witness her hunt a deer. Unfortunately, the deer catches her scent and bolts. Nigel and Saba then follow her to her den and discover that she has one living cub. She tries to nurse it, but it is unable to get any milk from her. As Nigel and Saba move in to tranquillize her, they notice a young male heading toward the female. Saba fears that the male will try to kill the cub. They tranquilize the male first. However, the cub passes away in the time it takes the male to become sedated. Both living Smilodons are then taken back to the park.
In The Bug House, Suzanne hopes to get the two cats to breed with each other. However, the female is aggressive toward the male, making Suzanne hesitant to put them together. Suzanne uses a technique known as "environmental enrichment," where she has some structures built in their enclosures. These make the enclosures more interesting for the Smilodon, and also put them in "a better mood." Eventually, Suzanne is comfortable with letting the male Smilodon into the female's enclosure. They have a brief stand-off but eventually, they become comfortable with each other and eventually mate.
In the episode Supercroc, it was revealed that the female gave birth to two healthy cubs. However, she was no longer producing milk, meaning that Suzanne has to raise them on a bottle. This also means that they are no longer bonded to their mother and that she might kill them if they are put back into the enclosure.
Troodon
While Nigel was capturing a Deinosuchus in the episode Supercroc, a Troodon got into his jeep to steal what remained of the bait meat. Then, when Bob was driving Nigel's jeep, the stowaway Troodon popped out and attacked him, causing him to almost hit one of the park's titanosaurs, scaring it and causing it to rampage, leading to the mass break-out. The Troodon then escaped out the door of the jeep and was later seen chasing a park worker over the security cameras. Weeks later, it was caught by Bob, who proceeded to name it Rascal.
Terrence is a male Tyrannosaurus rex and Matilda's brother. Like her, he was rescued from the KT extinction in the episode T-Rex Returns. However, as the story progresses, Terrence and Matilda's play fights begin to turn violent to the point where they had to be separated. During the episode The Bug House, Terrence is nearly killed by Matilda. Suzanne, with the help of antibiotics, is able to keep him alive and he makes a full recovery.
Theo is a young male Triceratops rescued during the episode T-Rex Returns. He was in the process of maturing when Nigel rescued him from the Cretaceous. As such, he became highly aggressive. Bob modified a tractor that he could use to "joust" with Theo, which helped the Triceratops "take out its aggression" at the end of the episode.
