Prehistoric Reptile of the Day - Dimetrodon

It's often mistaken for a genuine dinosaur, but Dimetrodon lived long before the first dinosaurs evolved--280 million years ago, during the Permian period. An example of a pelycosaur--among the first reptiles to live entirely on land--it went kaput about 250 million years ago, along with countless other species, in the Permian/Triassic Extinction event.

Dimetrodon's most spectacular feature was its large sail, which ran along the entire length of its back. Paleontologists speculate that the main purpose of this sail was to regulate this reptile's temperature: it soaked up sunshine during the day (much like a solar panel) and also helped dissipate energy if the creature became overheated. Secondarily, this sail may have served as a mating display, and helped Dimetrodon look a lot bigger in the eyes of any hungry carnivores lurking nearby.

Read more about prehistoric reptiles like Dimetrodon: Before the Dinosaurs - Archosaurs, Pelycosaurs and "Mammal-Like Reptiles"

Illustration: Wikimedia Commons