Ianthasaurus was a small edaphosaurid from the Late Pennsylvanian. It is one of the smallest pelycosaurs known, with an 8 cm skull and a total body length of 75 cm. Ianthasaurus lacks many of the spectacular specializations seen in Edaphosaurus. For example, the marginal dentition of Ianthasaurus is similar to that of insectivorous reptiles, with slender conical teeth which are slightly recurved at the tips, and there is a slight development of a caniniform region. The palatal and mandibular dentition is unspecialized, and there are no batteries of teeth for crushing of plant materials. Also unlike Edaphosaurus, Ianthasaurus was lightly built and was probably quite agile. The skull was similar to that to Haptodus, a sphenacodontid, though they were distantly related.