Diictodon

Diictodon was an extremely common genus of therapsid, roughly 45 cm (18 inches) long. It belonged to the sub-group Dicynodontia. These mammal-like synapsids lived during the Late Permian period, approximately 255 million years ago. Fossils have been found in Africa and Asia (in fact, roughly half of all Permian vertebrates found in South Africa are that of Diictodon). This small herbivorous animal was one of the most successful synapsids in the Permian period.

In Primeval
A group of over fifteen individuals appear to be traversing air vents, chewing through the electricity that the team will need to remove them. Abby catches one which sends of a distress signal calling them all back through the anomaly but one drops from the roof (Sid) and lands inside a trolley Connor is pushing. A single Diictodon tried to escape through an anomaly, which closed. It later becomes apparent that Abby and Conner adopt two to keep Rex company. In Episode 5 of series 3 they are called Nancy and Sid.