sail

…and had a large “sail” on its back that may have functioned in temperature regulation. The sail was presumably formed by elongated vertebral spines connected by a membrane containing many blood vessels. The skull of Dimetrodon was high and narrow, and the region in front of the eyes was…

…however, was the large “sail” on its back formed by elongated vertebral arches; the arches were probably connected by a membrane that had bony knobs or crossbars along its length. The sail may have functioned in thermoregulation and also may have served as a storehouse for phosphates, which could…