Dimetrodon was a prehistoric predacious reptile that flourished during the Permian period, living between 300 and 265 million years ago. It is known as the ancestor of mammals, having early characteristics from them. Dimetrodon was not a dinosaur; rather, it is classified as a pelycosaur.

Dimetrodon was a dominant carnivore, the largest of its day. It grew to up to 2 meters in length. The word Dimetrodon means "two-measures teeth;" it is so named because it had a large skull with two different types of teeth (shearing teeth and sharp canine teeth). This trait made Dimetrodon a very unique reptile. It walked on four side-sprawling legs and had a large tail.

In Zoo Tycoon 2

Dimetrodon is a small carnivore featured in Zoo Tycoon 2: Extinct Animals that lives in the Wetlands and can tolerate Scrub. It has two varient skins, alternating the eye and sail color: one varient has red eyes and sail, the other has orange/yellow eyes and sail. Dimetrodons are one of the most aggressive predators in Zoo Tycoon 2, often killing multiple animals, even when not hungry.

Juvenile Dimetrodons will interact with lookout posts as an enrichment item, but they will not use it as adults.

Dimetrodon's most distinctive characteristic is the spectacular sail on its back. The sail was probably used to regulate body temperature; the surface area would allow it to warm up or cool off more efficiently. It may also have been used in mating rituals and to ward off predators. The sail was supported by bony spines, each one sprouting from an individual spinal vertebra.