Bellerophontoidea

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Bellerophontoidea
Temporal range: Late Cambrian–Triassic
Bucanopsis leda.jpg
Bucanopsis leda (family Bellerophontidae, subfamily Bucanopsinae)
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda (?)
Order:† Bellerophontida
Superfamily:† Bellerophontoidea
McCoy, 1852 [1]
Families

See text

Synonyms

Bellerophontaceae Ulrich & Schofield, 1897

Bellerophontoidea, common name "bellerophonts", [2] is a superfamily of extinct planospirally-coiled globose molluscs. This superfamily is generally included within the Gastropoda, but may instead be a group of monoplacophorans. The taxon first appeared late in the Cambrian and continued until late in the Triassic.

Contents

Biology

Unlike normal gastropods, the shells of Bellerophonts are characterised by a completely planispiral pattern of coiling, such as one finds in shelled cephalopods. 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. [3]

J.B. Knight, et al. [4] (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 [5] and included the families Bellerophontidae, Bucaniidae, Cyrtolitidae, and Protowarthiidae.

Knight, et al. 1960 (Treatise Part I reprinted 1989) [6] discuss the Superfamily Bellerophontacea at some length and include within it the Bellerophontidae, Cyrtolitidae, Sinuopeidae and Tropidodiscidae.

2005 Bellerophontid taxonomy

Bouchet et al. (2005) [2] leaves the higher taxonomic position of the Bellerophontoidea as uncertain (Gastropoda 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) [2] 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 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.

Related Research Articles

Monoplacophora

Monoplacophora, meaning "bearing one plate", is a polyphyletic superclass of molluscs with a cap-like shell now living at the bottom of the deep sea. Extant representatives were not recognized as such until 1952; previously they were known only from the fossil record, and were previously thought to have become extinct over 380 million years ago.

<i>Bellerophon</i> (genus) Extinct genus of gastropods

Bellerophon is a genus of extinct paleozoic marine molluscs of uncertain position in the family Bellerophontidae.

Strepsodiscus is an extinct genus of very primitive fossil snail-like molluscs from the early part of the Late Cambrian of North America. The coiled, slightly asymmetrical shells are about 3 cm in height. It is not known whether these are shells of gastropods or monoplacophorans, which are more primitive mollusks.

The Bellerophontida is a taxonomic order of extinct marine mollusks that are found in the fossil record from the Lower Cambrian to the Lower Triassic. They are considered by some experts to be primitive sea snails with primarily symmetrically coiled shells, marine gastropod mollusks.

Bellerophontidae Extinct family of gastropods

The Bellerophontidae are an extinct family of specialized globose bellerophontids, Paleozoic and early Triassic mollusks of the class Gastropoda.

Cypraeoidea Superfamily of gastropods

Cypraeoidea, the cowries and cowry allies, is a superfamily of sea snails, marine gastropods included in the clade Littorinimorpha. This superfamily had been called Cypraeacea and was named by Rafinesque in 1815.

Euomphalina

The Euomphalina comprise a major suborder of mainly Paleozoic archaeogastropods, shells of which are hyperstophic to depressed orthstrophic, commonly with an angulation at the outer upper whorl surface thought to be coincident with the exhalent channel; shell wall thick, outer layer calcitic, inner layers aragonitic but not nacreous; operculum calcareous and heavy. Their range is from the Upper Cambrian to the Triassic, and possibly as high as the Upper Cretaceous.

Stomatellinae is a subfamily of small sea snails with a brilliantly nacreous interior of the shell, marine gastropod mollusks in the family Trochidae, the top snails.

Velainellidae is a very small taxonomic family of fossil sea snails, marine gastropod mollusks in the superfamily Trochoidea, the top snails, turban snails and their allies.

Coreospiridae

Coreospiridae is an extinct family of Paleozoic molluscs of uncertain position taxonomically. They might be snails (Gastropoda), Helcionelloida, or they might be Monoplacophora.

Khairkhaniidae is an extinct family of Paleozoic fossil molluscs of uncertain position. They are thought to belong to either the Gastropoda or Monoplacophora. They possess planispiral coiled shells with a columnar microstructure.

Archinacellidae Extinct family of gastropods

†Archinacellidae is an extinct family of paleozoic molluscs of uncertain position.

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 small median sinus in the upper margin of the aperture, and collabral (transverse) or spiral (longitudinal) threads covering the shell. The shells are planispirally coiled rather than trochospirally with a spire as is the case with most shelled gastropods.

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 which the apertural margins tend to flare. Most genera have a slit and selenizone, others some modification of this feature.

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.

Pterothecidae is an extinct family of Paleozoic molluscs of uncertain position, either Gastropoda or Monoplacophora, with isostrophically coiled shells.

Sinuitidae is an extinct family of Paleozoic molluscs of uncertain position. They had isostrophically coiled shells.

Macluritidae

Macluritidae is an extinct family of relatively large, Lower Ordovician to Devonian, macluritacean gastropods(?), hypserstrophically coiled, that is dextral while appearing sinsitral, of which the genus Maclurites is arch-typical. The base of their shells is flat or gently protruding while the upper side is generally concave.

Euomphaloidea

Euomphaloidea, originally Euomphalacea, is an extinct superfamily of marine molluscs that lived from the Early Ordovician to the Late Cretaceous, included in the Gastropoda but speculated as instead perhaps Monoplacophora.

The Helcionellacea is one of two taxonomic superfamilies of extinct primitive marine molluscs within the order Bellerophontida. This superfamily is thought to be the more primitive of the two superfamilies, the other being the Bellerophontacea. These molluscs are thought to be sea snails, marine gastropod mollusks, rather than monoplacophorans.

References

  1. ↑ McCoy F. 1852. A synonpsis of the classification of the British Palaeozoic rocks, with a systematic description of the British Palaeozoic fossils in the Geological Museum of the University of Cambridge with figures of the new and imperfectly known species. Parker & Son, London, 661 pp., 25 plates. Bellerophontidae is at page 307.
  2. 1 2 3 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. ISBN   3-925919-72-4. ISSN 0076-2997. 397 pp. http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278
  3. ↑ Wagner, P. J. 2001 Gastropod phylogenetics: progress, problems and implications. Journal of Paleontology 75: 1128 - 1140
  4. ↑ J.B. Knight, et al. 1960. Treatise on Invertebrate Paleontology, Part I, Mollusca 1; R.C. Moore,(ed); Geological Society of America and Univ Kansas Press.
  5. ↑ 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 on page 844.
  6. ↑ 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.
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