Spinosaurus was a light-built but very large bipedal theropod, approximately twice the height and length of a pickup truck. It possessed a long, narrow crocodile like snout filled with conical, non-serrated teeth, and it was recognisable by six-foot-tall neural spines along its back which were connected by membrane to form a sail-like structure. It also had very long, five-foot forearms, and while it spent much of its time on its two legs, it was shown to occasionally crouch down onto all fours.
In its natural habitat, Spinosaurus was a territorial creature which would chase after any potential prey it caught in its territory, and it would return once it knew that there was good prey in the area. In both hunts and combat, Spinosaurus would rely on its jaws as a weapon for crushing to death and eating its prey and opponents. It was also a highly resilient creature, as when one Spinosaurus was brought down by EMD shots, it recovered within a matter of seconds.
Though Spinosaurus was very powerful and fast, it would prefer to flee when it was disturbed and confused by alien surrounding; however, it could still be very volatile and aggressive, and would lash out dangerously if and when it was forced into a corner. Spinosaurus could be distracted and disoriented by loud modern sounds and lights akin to those of a music arena.
Incursions and encountersforest in the Cretaceous, a Spinosaurus found Connor fishing in its territory and reacted aggressively, chasing after him. Connor unintentionally led the Spinosaurus back to his and Abby Maitland's camp, where the Spinosaurus briefly attacked them in their den. Eventually it lost interest and left.
Later, when Connor and Abby moved two miles away to another location, the Spinosaurus followed them and blocked the two's path to an Anomaly. When the Spinosaurus was mesmerised by the sight of the Anomaly, Abby lured a male Raptor to the Spinosaurus. The two predators fought aggressively, and the Spinosaurus was ultimately able to overpower and kill the Raptor by crushing it in its jaws. While the Spinosaurus was distracted, Connor and Abby escaped through the Anomaly, which was then locked.
When Connor accidentally unlocked the Anomaly, the Spinosaurus came through to a square in the present. Confused and intimidated by the modern, urban environment, the creature went on a rampage through the streets of Liverpool; followed by Hilary Becker, Matt Anderson, Connor and Abby. Matt and Becker eventually blocked the Spinosaurus' path with a dumpster truck and Becker's car, until the creature became agitated and smashed into the dumpster truck. When Connor and Abby then arrived in a stolen car, and the Spinosaurus chased the car into a nearby arena.
After the team trapped the Spinosaurus in the arena, Connor went up to it to try and open a new Anomaly back to its era with the Anomaly Opening Device to send it through. The Spinosaurus almost devoured Connor until Abby activated the arena's light effects and music, which distracted and disoriented the Spinosaurus while Matt rescued Connor by pulling him up to the ceiling. Becker and his men brought the Spinosaurus down with the new EMDs, but the creature quickly recovered and tried to attack Matt and Connor (who were slightly too high up for it to reach).
When Connor accidentally dropped the Anomaly Opening Device down the Spinosaurus' throat, an Anomaly opened up from within the Spinosaurus and engulfed it, sending it through to an unknown time period.
Spinosaurus (name meaning "spine lizard") was a theropod dinosaur genus, which lived from 112 to 97 million years ago approx. in what is now North Africa. It has been estimated that Spinosaurus was 41-59 feet (12.4-17.9 metres) in length, and weighed 7-20.9 tonnes (7.7-23.0 tons). It is believed that Spinosaurus probably lived along mudflats and mangrove forests in shoreline conditions, alongside a variety of other animals. It has been hypothesised that Spinosaurus specialised as fish-eaters, but would occasionally scavenge for other prey such as pterosaurs and small Iguanodon. Over six confirmed incomplete Spinosaurus fossils have been discovered since 1912.
- The Spinosaurus in Primeval was presented almost being completely accurately based on what is already known about the animal, from its size to its diet; it is implied to have been a fish-eater.
- The brief fight sequence between the Spinosaurus and the Raptor was an obvious homage to a mirrored scenario depicted in Jurassic Park, between the Tyrannosaurus rex and a Velociraptor. If one listens carefully to when the Raptor is caught in the Spinosaurus’ jaws, the sound bytes of the Velociraptor squeals from the Jurassic Park series can be heard as the Raptor screams.
- Officially, the Spinosaurus is the first onscreen creature to have been shot by the EMD, which is shown to be an extremely effective weapon as it knocks the large Spinosaurus down momentarily.
- The Primeval Spinosaurus bears a similar shape and colour scheme to that of the Spinosaurus featured in Episode 1 of the BBC documentary Planet Dinosaur, which aired later that same year.
- Another, much smaller, version of the Spinosaurus' spine is visible on the creature's tail, which a real life Spinosaurus would have lacked.
- The Spinosaurus in Episode 4.1 appears to be smaller than the Giganotosaurus in Episode 3.4, when in real life, Spinosaurus would have been at least 2-3 meters longer.
- The Spinosaurus is a lighter built dinosaur than the Giganotosaurus, it could have been longer but appeared smaller than the larger built theropod.
- It is possible that the Spinosaurus wasn't fully grown when it came through the Anomaly.