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 of extinct planospirally-coiled globose
molluscs. This superfamily is generally included within the
Gastropoda, but may instead be a group of
monoplacophoran
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 th ...
s. The taxon first appeared late in the
Cambrian and continued until late in the
Triassic
The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...
.
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.
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 Ulrich (), is a German given name, derived from Old High German ''Uodalrich'', ''Odalric''. It is composed of the elements '' uodal-'' meaning "(noble) heritage" and ''-rich'' meaning "rich, powerful". Attested from the 8th century as the name of Al ...
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, Bucaniidae, Cyrtolitidae, and Protowarthiidae.
Knight, et al. 1960 (
Treatise
A treatise is a formal and systematic written discourse on some subject, generally longer and treating it in greater depth than an essay, and more concerned with investigating or exposing the principles of the subject and its conclusions." Tre ...
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
The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') 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 co ...
. 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 or
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
** †
Bellerophontidae
** †
Bucanellidae
** †
Bucaniidae
** †
Euphemitidae
** †
Pterothecidae
** †
Sinuitidae
** †
Tremanotidae
** †
Tropidodiscidae
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 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