Bellerophontoidea, common name "bellerophonts",Bouchet P. & Rocroi J.-P. (Ed.); Frýda J., Hausdorf B., Ponder W., Valdes A. & Warén A. 2005. ''Classification and nomenclator of gastropod families''. Malacologia: International Journal of Malacology, 47(1-2). ConchBooks: Hackenheim, Germany. . ISSN 0076-2997. 397 pp. http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278 is a

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

of extinct planospirally-coiled globose

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

s. This superfamily is generally included within the

Gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

a, but may instead be a group of monoplacophorans. The taxon first appeared late in the

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

and continued until late in the Triassic.

Biology

Unlike normal

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

s, the shells of Bellerophonts are characterised by a completely planispiral pattern of coiling, such as one finds in shelled

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s. Experts disagree whether Bellerophontids should be classified as torted gastropods, or as untorted Tergomya, or whether the group Bellerophontida is perhaps an artificial construct, consisting of a number of distinct groups of Palaeozoic molluscs which evolved the same type of spiral shell independently. J.B. Knight, ''et al.'' (1960) regarded the bellerophontids as torted gastropods even though they have essentially symmetrical, planispiral shells. The narrower apex was probably held to the rear while the wider aperture was oriented to the front where the animal could easily emerge or retreat.

Taxonomy

Historical background

The taxonomy of the Bellerophontoidea (renamed from the original Bellerophontacea) has gone through a number of revisions since M'Coy established the Bellerophontaceae in 1851 for planospiral archeogastropods. The naming followed the convention for superfamilies that prevailed until at least 1992 with Wahlman The Bellerophontacea were placed in the order Bellerophontida established by Ulrich and Scofield in 1897 Ulrich E. O. & Scofield W. H. 1897. ''The Lower Silurian Gastropoda of Minnesota''. In: Ulrich E. O., Scofield W. H., Clarke J. M. & Winchell N. H. The Geological and Natural History Survey of Minnesota
volume 3(2)
Harrison and Smith, Minneapolis, 48 plates. Pages 813-1081, plates 61-82. Bellerophontacea is o
page 844
and included the families

Bellerophontidae The Bellerophontidae are an extinct family of specialized globose bellerophontids, Paleozoic and early Triassic mollusks of the class Gastropoda. Geological range These mollusks appeared in the Late Cambrian and continued until the Early Triassi ...

, Bucaniidae, Cyrtolitidae, and Protowarthiidae. Knight, et al. 1960 ( Treatise Part I reprinted 1989)Knight, J. B., Cox, L. R., Keen, A. M., Batten, R. L., Yochelson, E. L., and Robertson, R. (1960). Systematic descriptions rchaeogastropoda 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. discuss the Superfamily Bellerophontacea at some length and include within it the Bellerophontidae, Cyrtolitidae, Sinuopeidae and Tropidodiscidae.

2005 Bellerophontid taxonomy

Bouchet et al. (2005) leaves the higher taxonomic position of the Bellerophontoidea as uncertain (

Gastropoda The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. ...

Monoplacophora Monoplacophora , meaning "bearing one plate", is a polyphyletic superclass of molluscs with a cap-like shell inhabiting deep sea environments . Extant representatives were not recognized as such until 1952; previously they were known only from ...

) and divides the group into 8 families as listed: * Bellerophontoidea ** †

** †

Bucanellidae Bucanellidae is an extinct family of Paleozoic molluscs of uncertain position, belonging either to Gastropoda (snails) or Monoplacophora. The family lived from the upper Cambrian to middle Permian and the shells are characterized by a relatively ...

** †

Bucaniidae Bucaniidae is an extinct family of Paleozoic molluscs of uncertain position possibly being either gastropods or monoplacophorans in the superfamily Bellerophontoidea. The family lived from the Lower Ordovician to the Devonian and have shells in ...

** †

Euphemitidae Euphemitidae is an extinct family of Paleozoic fossil molluscs of uncertain position. They have isostrophically coiled shells and may be either Gastropoda sea (snail)s, or Monoplacophora. Taxonomy The taxonomy of the Gastropoda by Bouchet & R ...

** †

Pterothecidae Pterothecidae is an extinct family of Paleozoic molluscs of uncertain position, either Gastropoda or Monoplacophora, with isostrophically coiled shells. Taxonomy The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005Bouchet P. & Rocroi J.-P ...

** †

Sinuitidae Sinuitidae is an extinct family of Paleozoic molluscs of uncertain position (they were either Gastropoda or Monoplacophora). They had isostrophically coiled shells. Taxonomy The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005Bouchet P. & ...

** †

Tremanotidae Tremanotidae is an extinct family of Paleozoic fossil molluscs with isostrophically coiled shells. They occupy an uncertain position taxonomically: it is not known whether they were (gastropods (snails) or monoplacophorans. Taxonomy The taxon ...

** †

Tropidodiscidae Tropidodiscidae is an extinct family of Paleozoic fossil molluscs with isostrophically coiled shells. They are of uncertain position taxonomically, in other words it is not known whether they were (Gastropoda (snails) or Monoplacophora)s. Taxon ...

The Bellerophontidae, Bucanitidae, Pterothacidae, and Tropododiscidae compare with the subfamilies Bellerophontinae, Bucanitinae, Pterothacinae, and Tropododiscinae included in the Bellerophontidae and the Bucanellidae, Euphemitidae, and Sinuitidae compare with the subfamilies Bucanellinae, Euphemitinae, and Sinuitinae included in the Sinuitidae, as found in the Treatise. The Tremanitiae is based on the genus ''Tremanotus'' which was included in the Bucanitinae in the Treatise. Bouchet & Rocroi (2005) points out (page 271) that assignment of "''symmetrical univalved mollusks "bellerophonts" either to Gastropoda or to Monoplacophora or Tergomya is controversial."''

Note on nomenclature

Until recently with the ruling of the

ICZN The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the I ...

, -the ending -ACEA, or -ACEAE, was more or less standard for superfamilies in invertebrate paleontology and zoology. The ending -OIDEA which is now used for superfamily names was previously often used for subclasses and superorders.

References

External links

Palaeos

{{Taxonbar, from=Q15235560 Prehistoric gastropods Gastropod superfamilies Prehistoric animal superfamilies Early Triassic extinctions