Dimetrodon was a species of carnivorous mammal-like reptile that roamed during the Permian period.


Dimetrodon was a large, quadrupedal synapsid, notable for its very large spinal sail, which grew to be about the same size as alligators. Its blunt-snouted head was equipped with very powerful jaws equipped with large teeth, which gave it a bone-crushing bite force. Dimetrodons also had a deadly amount of microbes and bacteria in their mouths, enough that even if a bitten animal were to get away alive, they would suffer massive infection which would be crippling and, in a human's case, slow but fatal.

Being cold-blooded, Dimetrodons usually gathered in large numbers early during the day to bask and warm up under the sun, with their sails serving as heat regulators. In this state, they were slow, sluggish and disinterested. But when Dimetrodons took interest in prey and became active, they could give disturbing bursts of speed and agility. Dimetrodons were also observed to have apparently had loose social structure, easily fighting rivals in the pursuit of food and being quick to cannibalism.

Incursions and encounters

Extinction Event

A large colony of basking Dimetrodons were encountered in the Permian wasteland by Helen Cutter, Jenny Lewis, Jake Hemple, blocking their way to an Anomaly to the Spaghetti Junction. The team attempted to make their way through the colony to the Anomaly while the creatures were basking and sluggish, but the colony grew disturbed and attacked. Hemple and his men shot some of the Dimetrodons dead in self-defence, and many of the creatures even attacked each-other over their prey. The group got through the Anomaly with almost no casualties, except Tim Jenkins was badly bitten, and the Dimetrodons lost interest once the group vanished through the Anomaly.

Jenkins never recovered from his Dimetrodon bite or the massive infection that ensued, but it was by a pack of Troodon in the Cretaceous that he died.

Other references

Episode 1.1

Dimetrodon was among the many prehistoric animals listed in Connor's database.

Real life

Dimetrodon (name meaning "two measures of teeth") was a synapsid genus, which lived from about 295 to 272 million years ago. It is most famous for the large sail on its back, with palaeontologists arguing over whether the sail was used for heat regulation, spine stabilisation or sexual display. Dimetrodon is thought to have fed on fish, reptiles and amphibians, and to have been among the top predators in its ecosyestem. Dimetrodon fossils have been found mostly in the southwestern U.S., specifically at the Red Beds geological deposit, but fossils have also been recently found in Germany.


  • The coloration of the Dimetrodons in Extinction Event was likely a reference to 'Walking With Monsters, a Walking With... documentary made by Impossible Pictures.