Sphenodiscidae Hyatt, 1900
Key morphological features: Shell involute with weak ornamentation, often smooth. Suture lines narrow, but frilly with many lobes and complex elements.
MOBILITY: Mobile (swim)
FEEDING MODE: Predator
Wright, C. W., 1996. Ammonoidea, in Kaesler, R. L., ed., Treatise on Invertebrate Paleontology, Part L, Mollusca 4 Revised, Volume 4. The University of Kansas and Geological Society of America. 362 pp.