Dimetrodon was a prehistoric reptile that lived during the early Permian period, around 295 to 272 million years ago. It is often mistaken for a dinosaur, but it actually belongs to a group called synapsids, which are more closely related to mammals. Dimetrodon is easily recognized by its large, sail-like structure on its back, formed by elongated neural spines. This creature could grow up to 13 feet long and was a carnivore, primarily feeding on smaller animals. Its sharp teeth and powerful jaws made it an effective predator in its environment. Dimetrodon is an important part of the evolutionary history leading to modern mammals.