Bellerophontoidea
Encyclopedia
The Bellerophontoidea, (Bellerophontaceae Ulrich & Schofield, 1897, ex Bellerophontidae McCoy 1951), common name "bellerophonts", is a superfamily
of extinct planospirally coiled globose molluscs, generally included in the Gastropoda
that first appeared late in the Cambrian
and continued until late in the Triassic
.
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 with 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.
The Bellerophontacea were placed in the order Bellerophontida established by Ulrich
and Scofield in 1897 and included the families Bellerophontidae
, Bucaniidae, Cyrtolitidae, and Protowarthiidae.
Knight, et al. 1960 (Treatise
Part I reprinted 1989) discuss the Superfamily Bellerophontacea at some length and include within it the Bellerophontidae, Cyrtolitidae, Sinuopeidae and Tropidodiscidae.
or Monoplacophora
) and divides the group into 8 families as listed:
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 "symetrical univalved mollusks "bellerophonts" either to Gastropoda or to Monoplacophora or Tergomya is controversial."
, -ACEA, or -ACEAE, was pretty much the standard ending for superfamilies in invertebrate paleontology and zoology. -OIDEA used now as the ending on superfamily names was generally reserved for subclasses and superorders
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
of extinct planospirally coiled globose molluscs, generally included in the Gastropoda
Gastropoda
The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to quite large...
that first appeared late in the Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
and continued until late in the Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
.
Biology
Unlike normal gastropods, the shells of Bellerophonts are characterised by a completely planispiral pattern of coiling, such as one finds in shelled cephalopodCephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s. Experts disagree whether Bellerophontids should be classified as torted
Torsion (gastropod)
Torsion is an anatomical event which takes place during the very early part of the life of snails and slugs of all kinds. In other words, torsion is a gastropod synapomorphy which occurs in all gastropods during larval development. Torsion is the rotation of the visceral mass, mantle and shell 180˚...
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 with 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.
Historical Background
The taxomony 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 WahlmanThe Bellerophontacea were placed in the order Bellerophontida established by Ulrich
Edward Oscar Ulrich
Edward Oscar Ulrich was an invertebrate paleontologist specializing in the study of Paleozoic fossils.-Biography:...
and Scofield in 1897 and included the families Bellerophontidae
Bellerophontidae
The Bellerophontidae is an extinct family of specialized globose bellerophontids; Paleozoic and Early Triassic mollusks of uncertain position .-Geological range:...
, Bucaniidae, Cyrtolitidae, and Protowarthiidae.
Knight, et al. 1960 (Treatise
Treatise on Invertebrate Paleontology
The Treatise on Invertebrate Paleontology published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and...
Part I reprinted 1989) 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 (GastropodaGastropoda
The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to quite large...
or Monoplacophora
Monoplacophora
Monoplacophora, meaning "bearing one plate", is a polyphyletic class of mollusks with a cap-like shell, living on the bottom of deep sea. Extant representatives were unknown until 1952; previously they were known only from the fossil record.- Definition :...
) and divides the group into 8 families as listed:
- Bellerophontoidea
- † BellerophontidaeBellerophontidaeThe Bellerophontidae is an extinct family of specialized globose bellerophontids; Paleozoic and Early Triassic mollusks of uncertain position .-Geological range:...
- † BucanellidaeBucanellidaeBucanellidae is an extinct family of paleozoic molluscs of uncertain position with isostrophically coiled shells.- Taxonomy :...
- † BucaniidaeBucaniidaeBucaniidae is an extinct family of paleozoic molluscs of uncertain position with isostrophically coiled shells.- Taxonomy :...
- † EuphemitidaeEuphemitidaeEuphemitidae is an extinct family of Paleozoic fossil molluscs of uncertain position. They have isostrophically coiled shells and may be either Gastropoda sea s, or Monoplacophora.- Taxonomy :...
- † PterothecidaePterothecidaePterothecidae is an extinct family of paleozoic molluscs of uncertain position with isostrophically coiled shells.- Taxonomy :...
- † SinuitidaeSinuitidaeSinuitidae is an extinct family of paleozoic molluscs of uncertain position with isostrophically coiled shells.- Taxonomy :...
- † TremanotidaeTremanotidaeTremanotidae is an extinct family of paleozoic molluscs of uncertain position with isostrophically coiled shells.- Taxonomy :...
- † TropidodiscidaeTropidodiscidaeTropidodiscidae is an extinct family of paleozoic molluscs of uncertain position with isostrophically coiled shells.- Taxonomy :...
- † Bellerophontidae
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 "symetrical univalved mollusks "bellerophonts" either to Gastropoda or to Monoplacophora or Tergomya is controversial."
Note on Nomenclature
Until recently with the ruling of the ICZNInternational Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...
, -ACEA, or -ACEAE, was pretty much the standard ending for superfamilies in invertebrate paleontology and zoology. -OIDEA used now as the ending on superfamily names was generally reserved for subclasses and superorders
External links
- Palaeos
- http://pjw3.fmnh.org/GastroTaxonomy.htmlSystematic Paleontology of the Earliest Gastropods (Including Family and Genus Level Stratigraphic Ranges and Synonyms) - Peter J. WagnerPeter J. WagnerPeter J. Wagner is a paleontologist and curator at the Smithsonian Institution. He received his Ph.D. in Geophysical Sciences from The University of Chicago in 1995, conducted postdoctoral research at the Smithsonian Institution, and served as a curator at the Field Museum of Natural History from...
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