Bellerophontida or Bellerophontina are a group of extinct snail-like molluscs that appeared in the latest Cambrian and continued through to the Triassic. Representative genera include Sinuites, Euphemetites, Warthia, Tetranota, Bucanopsis, Tremanotus, Bellerophon, Knightites, and many others. Unlike normal gastropods, their shells are characterised by a planispiral pattern of coiling, such as one finds in shelled cephalopods shell. Experts disagree whether Bellerophontids should be classified as torted gastropods or as untorted Tergomya, or whether the group is an artificial one, consisting of a number of distinct groups of Palaeozoic molluscs that evolved the same type of spiral shell independently. Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... The Cambrian is a major division of the geologic timescale that begins about 542 million years before the present (BP) at the end of the Proterozoic eon and ended about 490 million years BP with the beginning of the Ordovician period. ... The Triassic is a geologic period that extends from about 245 to 202 million years ago (mya). ... For other uses, see Bellerophon (disambiguation). ... Subclass Subclass Eogastropoda     Patellogastropoda Subclass Orthogastropoda   Superorder Cocculiniformia   Superorder Hot Vent Taxa     Neomphaolida   Superorder Vetigastropoda   Superorder Neritaemorphi     Neritopsina   Superorder Caenogastropoda     Architaenioglossa     Sorbeoconcha   Superorder Heterobranchia     Heterostropha     Opisthobranchia     Pulmonata The gastropods, or univalves, are the largest and most successful class of mollusks, with 60,000-75,000 species, and second largest class... Orders Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida Nautilida The Cephalopods (head-foot) are the mollusc class Cephalopoda characterized by bilateral body symmetry, a prominent head, and a modification of the mollusc foot into the form of arms or tentacles. ...

References

• Knight, J. B., Cox, L. R., Keen, A. M., Batten, R. L., Yochelson, E. L., and Robertson, R. (1960). Systematic descriptions [Archaeogastropoda]. In Moore, R. C. (ed.) Treatise on Invertebrate Paleontology. Part I. Mollusca 1, pp. 169-310. Geological Society of America and Kansas University Press, Colorado and Kansas.
• Wagner, P. J. 2001 Gastropod phylogenetics: progress, problems and implications. Journal of Paleontology 75: 1128 - 1140

External Links

• Bellerophontida - Palaeos
• Systematic Paleontology of the Earliest Gastropods (Including Family and Genus Level Stratigraphic Ranges and Synonyms - Peter J. Wagner