Dimetrodon Fact Sheet

Carnivore (meat-eater)

Length - 11.5 feet (3.5 m) long
Height - about 3 ft (1 m) tall at the hips
Weight - 550 pounds (250 kg)

Permian period, about 280-245 million years ago (long before the dinosaurs appeared).

Fossils have been found in Texas and Oklahoma in the USA, North America. Trackways (fossilized footprints) of Dimetrodon have been found in Nova Scotia, Canada.

Dimetrodon is known from many fossils and some footprints.

• Kingdom Animalia (animals)
• Phylum Chordata (having a hollow nerve chord ending in a brain)
• Class Synapsida (synapsids) - these include the mammals, sphecodonts, basal therapsids, caseasaurs, and pelycosaurs. They are distinguished by having a skull with a low opening behind their eyes, whose only non-extinct members are the mammals.
• Order Pelycosauria (pelycosaurs) - the earliest synapsids which evolved during the Carboniferous period, 300 million years ago. These included Archaeothyris, Ophiacodon, Varanosaurus, Casea, and Edaphosaurus.
• Family Sphenacodontidae (sail-finned pelycosaurs)
• Genus Dimetrodon
• Species Many species - the largest is D. angelensis (Olson, 1962)

Dimetrodon had a large sail-like flap of skin along its back, dense with blood vessels. The sail was supported by long, bony spines, each of which grew out of a separate spinal vertebra (a bone in the back). The sail may have been a thermoregulatory structure, used to absorb and release heat. The sail may have also been used for mating and dominance rituals, and/or for making it look much larger to predators. Dimetrodon had sharp teeth and clawed feet.
Dimetrodon was not a dinosaur, but a pelycosaur, a so-called mammal-like reptile. The pelycosaurs led to the mammals; they are more closely related to us than to the dinosaurs.

A detailed page on Dimetrodon.
Dimetrodon printout to color
Dimetrodon printout to color - Simple version