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 related and much better-known sail-backed synapsid. Olson and Beerbower designated the type speciesTappenosaurus 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 (5.5m), comparing it in size with the largest of the dinocephalians, a more advanced group of synapsids that lived later in the Permian.[2]
References
12Olson, Everett C. and Beerbower, James R. (1953). "The San Angelo Formation, Permian of Texas, and its vertebrates". The Journal of Geology. 61 (5): 389–423. doi:10.1086/626109.
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