''.
Stephanospondylus is known only from several vertebrae and fragments of the upper and lower jaws. It was named in 1882 on the basis of two slabs, the fossils in which were thought to represent two individuals. With the erection of a new genus in 1905, the fossils were considered to be part of a single individual. In 1925,
Alfred Romer determined that only parts of the jaws and some vertebrae belonged to
Stephanospondylus; the other material belonged to the
temnospondyl amphibian Onchiodon.
Stephanospondylus has spade-shaped teeth adapted to cutting plant material. The vertebrae are distinct from those of other diadectids in that they lack
hyposphene-hypantrum articular surfaces. The
holotype specimen may represent a juvenile form of another diadectid. Because so little is known of the genus, the relationship of
Stephanospondylus to other diadectids is poorly known. ==References==