The conodonts are divided into the Westergaardodinida and Conodontophorida orders. The latter (conodonts proper) are divided into 8 superfamilies. The Distacodontacea (Proconodontidae, Clavohamulidae, and Distacodontidae families) are on the whole a simple, ‘primitive’ group. The Chirognathacea include Oistodus (s.str.), Chirognathus, and Rhipidognathus. The Panderodontacea are mainly simple cones. The Prioniodinacea have compound, non-blade elements. The Prioniodontacea include the Periodontidae, Prioniodontidae, Balognathidae, and Icriodontidae families. Bryantodontace, Gondolellacea, and Polygnathacea are based on platform-stock genera. The Polygnathacea (spathognathodon-tids, polygnathids, and indiognathodontids) may comprise two major stocks independent since the Ordovician.