possible indicator of early social stratification. References Further reading For a comprehensive overview, see Scarabino V. 1995. — Scaphopoda of the tropical Pacific and Indian Oceans, with description of 3 new genera and 42 new species, in BOUCHET P. (ed.), Résultats des Campagnes MUSORSTOM, Volume 14. Mémoires du Muséum National d’Histoire naturelle 167: 189-379 Steiner G. & Kabat A. 2004. Catalog of species-group names of Recent and fossil Scaphopoda (Mollusca). Zoosystema 26 (4): 549-726 Steiner, G.; Kabat, A. R. (2001). Catalogue of supraspecific taxa of Scaphopoda (Mollusca). Zoosystema. 23(3): 433-460 Mollusc shells Mississippian first appearances Extant Carboniferous first appearances Taxa named by Heinrich Georg Bronn