The fourth series of the British science fiction programme Primeval began on 1 January 2011 and concluded on 5 February 2011 after airing seven episodes.

Primeval follows a team of scientists tasked with investigating the appearance of temporal anomalies across the United Kingdom through which prehistoric and futuristic creatures enter the present.

The disappearances of Danny Quinn (Jason Flemyng), Connor Temple (Andrew-Lee Potts) and Abby Maitland (Hannah Spearritt) has forced the ARC to recruit new personnel, including the new field leader Matt Anderson (Ciarán McMenamin) and the field coordinator Jess Parker (Ruth Kearney).

[2] After a year trapped in the Cretaceous period, Abby and Connor finally return to the present, followed by a giant Spinosaurus, the longest known carnivorous dinosaur.

[11] Upon receiving the news of the cancellation, the production team of the series stated that they had "every intention of keeping Primeval alive in other ways".

[20] Jason Flemyng, who played the new lead character Danny Quinn, was also unable to return in a large capacity on account of a movie role[21] and ultimately only made an appearance in the final episode of the fourth series.

[1] Much of the fourth series as envisioned prior to the cancellation would have revolved around Danny Quinn's relationships with the other characters which meant that a lot had to be reworked.

[22] In addition to Danny Quinn, the third series also left Connor Temple (Andrew-Lee Potts) and Abby Maitland (Hannah Spearritt) stranded in the past.

[26] The new cast members Ciarán McMenamin, Ruth Kearney and Alexander Siddig were announced on the ITV website on 8 April 2010.

[28] Matt Anderson was written to be a quite mysterious character, having a hidden agenda of his own and combining elements of both Nick and Helen Cutter.

[23] Siddig was approached about Primeval by Adrian Hodges, whom he knew through yearly Sunday lunches at a mutual friend's house.

[29] Philip Burton was as an antagonist initially envisioned as a "problem child"-type character who was relatively nice but caused trouble out of greed and ambition rather than maliciousness;[29] his growing interest in the anomalies was to be based on ideas of scientific exploitation rather than a desire to protect the public.

[29] A new set was created for the ARC to reflect the organisation having received a large upgrade and major increase in funding by Burton.

[33] Becker was also written to be remorseful and more careful due to feeling that he was partly to blame for the great losses suffered by the team.

[34] Time was also spent on developing the other returning characters further; Connor Temple (Andrew-Lee Potts) and Abby Maitland (Hannah Spearritt) were at last made a couple after a long "will-they-won't-they" relationship and the two were, due to having been stranded in the past for a year, written to be a stronger unit together and as having picked up new skills.

[46] duration of episodes Dan Owen of WhatCulture gave the opening episode of the fourth series a mixed review, considering the series from the start as having placed greater emphasis on "CGI beasties over characterization and acting" and, though showing understanding on account of the behind-the-scenes troubles, finding the frequent cast changes disappointing.

He did however conclude that the series remained a "ridiculous show with a fun premise", working well when it did not take itself too seriously, and praised the special effects as "undeniably impressive" and "a definite improvement on what's gone before".

[53] McLaughlin praised the action of the series as "fun" and the visual effects as "top-notch, especially for a Saturday night television show".

Simpson also felt that the narrative progression was somewhat slow in the fourth series, only "finally" starting to bring things together in the fifth episode.

[60] Overall, she thought the fourth series was experiencing something of an identity crisis, with the set-up being military-based but the storyline being more geared towards a small group of people surviving dinosaurs and having love lives.