Dimetrodon: The Non-Dinosaur with a Sail

Dimetrodon is one of the reptiles that lived on earth long ago, long before the dinosaurs, but it is not classified as a dinosaur by paleontologists (dinosaur-scientists). Dimetrodon shares a startling characteristic with Spinosaurus, perhaps the largest of all the carnivorous (meat-eating) dinosaurs, a large sail on its back, supported by spines. You can learn more about Spinosaurus in my article here.

The name Dimetrodon means "two sizes of teeth." Dimetrodon had typical reptilian teeth as well as specialized canine teeth. When Dimetrodon is portrayed with its jaws closed, it appears to be smiling.

Scientists believe that Dimetrodon may have been warm-blooded, but what most obviously distinguishes Dimetrodon from dinosaurs to the casual observer is the legs. While dinosaurs' legs extended straight from the body, Dimetrodon walked as if it were doing push-ups. Look closely at the leg in the picture, and you will see that it is the same as that of a modern alligator.

The most noticeable characteristic of Dimetrodon is its large sail or fin. There is disagreement about the function of Dimetrodon's sail, as there is about the function of a similar sail on Spinosaurus. It could have given the animal more surface to absorb the heat of the sun. Then again, it could have provided more surface to cool the blood on hot days. Being able to control body temperature would have been quite an advantage for a carnivorous animal like Dimetrodon in a world inhabited mainly by cold-blooded creatures.

It might have changed color to show the animal's emotions, either to scare off an enemy or to attract a mate. Such mysteries are part of the ongoing charm of the dinosaurs and, in the case of Dimetrodon, other prehistoric animals.

Like the meat-eating dinosaurs, Dimetrodon had a very large skull in comparison to the rest of its body. Dimetrodon's weight was supported by outstretched legs. As Dimetrodon crawled forward, perhaps with a swaying motion like that of modern lizards, its claws gave it greater stability, and it could have used them as weapons.

Dimetrodon specimens average about three meters , about ten feet, in length. It lived about 280 million years, a period called the early Permian, long before the dinosaurs. Dimetrodon fossils are found in the United States.

You can find an index to my other articles about dinosaurs here.