Dimetrodon: A Permian Predator

Dimetrodon was a reptilian predator of the Permian period, belonging to a family of reptiles known as pelycosaurs. During its peak in the early Permian, it was the largest carnivore on land at around twelve feet long. It dominated terrestrial food chains and fed on a variety of animals, including other reptiles. It was one of the first backboned terrestrial predators able to hunt and kill animals its own size, especially other sail-backs like edaphosaurus.

Dimetrodon's possession of both reptilian and mammalian characteristics has often earned it the title of mammal-like reptile. It had a sprawling gait like modern reptiles and the evidence points to it being an ectothermic (cold-blooded animal). However, dimetrodon possessed two kinds of specialized teeth, incisors and canines. This kind of tooth differentiation is commonly found in mammals of today. Dimetrodon is often mistaken for a dinosaur, but is in fact unrelated to the ancestors of the dinosaurs. The most obvious difference is in its gait. Dinosaurs held their legs underneath them to support their large weights, and dimetrodon's legs sprawled out to the sides. Oddly enough, dimetrodon is more closely related to mammals and humans than to dinosaurs and birds.

Dimetrodon is best known for the presence of a large sail on its back, which was most likely an early means for regulating body temperature in a world that was becoming extremely seasonal and prone to heat extremes. In order to warm body temperature, the animal would turn the sail toward the sun, where the blood vessel-rich tissue would absorb and distribute the heat throughout the body as a whole. In hot conditions, the dimetrodon would face its sail away from the sun or else find a shady place to rest. The sail might have also been instrumental in mating rituals as well as making dimetrodon seem much bigger than it actually was. The sail itself was supported by spine-like bones projecting upward from the vertebrae.

Although dimetrodon was at the top of the food chain on land during the Permian, it seems unlikely that it was a very fast predator. Its sprawling gait in addition to the cumbersome sail on its back would have made it difficult to sustain high speeds for very long. However, there are many large reptiles alive today that are capable of high speeds such as the Komodo Dragon, an animal which has served as a model for many behavioral depictions of dimetrodon. It is likely it was opportunistic, feeding on whatever meat it could find, whether fresh or already dead.

Dimetrodon most likely laid eggs, and due to the seasonal extremes of the Permian, it is also likely that females would look after the eggs for a certain period of time. To shelter the eggs from the elements, some have suggested that dimetrodon females would bury the eggs under layers of earth in order to regulate their temperature. In the BBC documentary, "Walking With Monsters," the female is shown abandoning the young once they hatch: an instinctive maternal technique seen in many reptiles today.

Dimetrodon eventually went extinct due to climate changes taking place on Earth's single continent, Pangaea. As the global deserts increased in size, dimetrodon would suffer the fate of countless other land-dwelling animals in the great Permian-Triassic mass extinction.