Source: Bestiary 3, pg(s). 78
The dimetrodon is a squat quadrupedal reptile that often lives in regions inhabited by dinosaurs. It resembles a crocodile with a blunter snout filled with jagged, sharp teeth. Its most distinguishing feature is the massive sail on its back that allows it to control its body temperature. A fully grown adult dimetrodon can reach a length of up to 15 feet and weigh upward of 2,000 pounds.
- Wikipedia:Dimetrodon (extinct real-world animal)