Bellerophon (mollusc)

Bellerophon is a genus of extinct, mostly Paleozoic sea snail. These are fossil marine gastropod molluscs in the order Bellerophontida. The genus was named after Bellerophon, the ancient Greek hero.

Shell description

The genus is characterised by a shell which is globose, convolute, and planispiral (symmetrically coiled). The shell of Bellerophon superficially resembles that of a miniature cephalopod (e.g. Nautilus or an ammonite), except that septa are lacking.

The shell of Bellerophon is often a couple of centimeters in maximum dimension. The external surface is smooth, ornamented only by growth lines. There is a low crest or ridge running along the midline of the shell.

Many specimens of Bellerophon show something resembling a "waterline" about half-way up the shell, suggesting that a large amount of the mantle and foot were exposed and covered the outside of the shell, as in the extant Cypraeidae and Naticidae.

Possible life habits

These animals were probably quick moving, relying on speed to avoid predators and, when this was not possible, withdrawing deeply into the shell. (Linsley 1978 p.201)

Range of distribution

The genus occurs world-wide, and is known from the Silurian to the Early Triassic periods. (Knight et al 1960)

Discussion of the taxonomy

Although usually classified as a primitive gastropod, there is a minority view that the Bellerophontida actually represented a more primitive, untorted type of mollusk, (see Torsion) which evolved a spiral shell independently. Another view is that some Bellerophontids, including Bellerophon, were torted gastropods, but that others were untorted forms. (Wagner, 2001 p.1130)

Species within the genus Bellerophon

• Bellerophon bicarenus Lévillé from early Carboniferous
• Bellerophon graphicus Moore from the late Pennsylvanian (Virgilian) of Kansas
• Bellerophon regularis (Waagen) from the Permian of India
• Bellerophon vasulites Montfort - the type species, from the Middle Devonian of Germany
• ...

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, Geological Society of America and Kansas University Press, Colorado and Kansas.
• Linsley, R. M. 1978. Locomotion rates and shell form in the gastropoda. Malacologia 17, 193-206
• Moore, R.C., Lalicker, C.G., and Fischer, A. G., 1952, Invertebrate Fossils, McGraw Hill Book Company, New York; 766 pp.
• Wagner, P. J. 2001 Gastropod phylogenetics: progress, problems and implications. Journal of Paleontology 75: 1128 - 1140

External links

• Bellerophontida - Palaeos