Tappenosaurus

The first specimen (the holotype) is a fragmentary skeleton including parts of the back of the skull, pieces of teeth and ribs, an axis vertebra, a dorsal vertebra, three neural spines, the ends of both humeri and a partial hip. The second specimen includes cervical vertebrae, a rib, and a scapulocoracoid. The third specimen is only represented by ribs. These bones are larger than comparable parts of the largest skeletons of Dimetrodon, a closely related and much better known sail-backed synapsid. Olson and Beerbower designated the type species Tappenosaurus magnus in reference to its large size, and also placed it in its own family, Tappenosauridae.[1] Olson later estimated the total length of Tappenosaurus to be 18 feet (5.5 m), comparing it in size with the largest of the dinocephalians, a more advanced group of synapsids that lived later in the Permian.[2]