Therapsids were synapsids that began to apppear in the Early Permian. They had larger temporal fenstrae (openings of the sides of the skull) than the pelycosaurs. Early therapsids were scaly, and cold-blooded. The most advanced therapsids are the cynodonts, which were ancestral to mammals. For more information, see Therapsid. This Category is for mammal-like reptiles (therapsida) Synapsids