Dimetrodon lived during the early Permian Period, long before the dinosaurs it would come to be so closely associated with. It was more closely related to mammals than to dinosaurs, or to any modern day reptile. Unlike dinosaurs it walked with its legs splayed out to the side instead of held straight below the body.
Dimetrodon’s sail has sparked debate ever since its discovery in the 1870s by Edward Drinker Cope. Earlier interpretations of the sail suggested it was used to regulate Dimetrodon’s body temperature by absorbing heat. However, more recent studies suggest it may have been poorly suited for such a task. Scientists now believe it may have been used for display purposes, to attract mates, and it may have had intricate, brightly colored patterns to achieve this purpose.