New Mexico Geological Society Annual Spring Meeting — Abstracts

An incomplete, articulated skeleton of a medium-sized edaphosaurid from the Early Permian (early Wolfcampian: Newwellian) Bursum Formation in Otero County, New Mexico, likely represents an undescribed taxon. It shares many features with the small and primitive edaphosaurid, Ianthasaurus hardestii, especially in the elongate, tubercle-bearing neural spines that form the sail. The specimen (NMMNH [New Mexico Museum of Natural History] P-70796) consists of at least 17 partial and articulated neural spines that bear small, widely and irregularly spaced tubercles along their lateral surfaces. There are between 3 and 5 tubercles per neural spine. The spines are proximally round in cross section and flatten out distally. While the morphology of the tubercles and neural spines is most consistent with those of Ianthasaurus, it is unlikely that P-70796 can be referred to that genus. This is based on the typical size of the sail of Ianthasaurus, which reconstructions estimate to be approximately 25 cm long with a maximum height of approximately 15 cm. NMMNH P-70796 has a sail with a length of at least 60 cm and a maximum height of at least 30 cm. Thus, NMMNH P-70796 may belong to an undescribed taxon, possibly representing an intermediate group between the small primitive insectivore Ianthasaurus, and the larger, more derived herbivore Edaphosaurus.