Editing Therapsida (section)

===Physiology===

The physiology of therapsids is poorly understood. Most Permian therapsids had a pineal foramen, indicating that they had a [[parietal eye]] like many modern reptiles and amphibians. The parietal eye serves an important role in thermoregulation and the [[circadian rhythm]] of ectotherms, but is absent in modern mammals, which are [[endothermic]].<ref name=Benoit2016B/> Near the end of the Permian, dicynodonts, [[therocephalia]]ns and cynodonts show [[parallel evolution|parallel]] trends towards loss of the pineal foramen, and the foramen is completely absent in [[probainognathian cynodont]]s. Evidence from oxygen isotopes, which are correlated with body temperature, suggests that most Permian therapsids were ectotherms and that endothermy evolved convergently in dicynodonts and cynodonts near the end of the Permian.<ref name=Rey2017/> In contrast, evidence from histology suggests that endothermy is shared across Therapsida,<ref name=FraureBrac2020/> whereas estimates of blood flow rate and lifespan in the mammaliaform ''[[Morganucodon]]'' suggest that even early mammaliaforms had reptile-like metabolic rates.<ref name=Newham2020/> Evidence for respiratory turbinates, which have been hypothesized to be indicative of endothermy, was reported in the therocephalian ''[[Glanosuchus]]'', but subsequent study showed that the apparent attachment sites for turbinates may simply be the result of distortion of the skull.<ref name=Hopson2012/>