 Dimetrodon was probably one of the top predators in Early Permian ecosystems , feeding on fish and tetrapods , including reptiles as well as amphibians . Smaller Dimetrodon species may have had different ecological roles . The sail of Dimetrodon may have been used to stabilize its spine or to heat and cool its body as a form of thermoregulation . Some recent studies argue that the sail would have been ineffective at removing heat from the body , and was most likely used in sexual display . 
