 In 1986 , J. Scott Turner and C. Richard Tracy proposed that the evolution of a sail in Dimetrodon was related to the evolution of warm @-@ bloodedness in mammal ancestors . They thought that the sail of Dimetrodon enabled it to be homeothermic , maintaining a constant , albeit low , body temperature . Mammals are also homeothermic , although they differ from Dimetrodon in being endothermic , controlling their body temperature internally through heightened metabolism . Turner and Tracy noted that early therapsids , a more advanced group of synapsids closely related to mammals , had long limbs which can release heat in a manner similar to that of the sail of Dimetrodon . The homeothermy that developed in animals like Dimetrodon may have carried over to therapsids through a modification of body shape , which would eventually develop into the warm @-@ bloodedness of mammals . 
