Yochelcionella

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Yochelcionella is an extinct genus of basal molluscs which lived during the Tommotian epoch, the first epoch of the Cambrian period. This genus is often reconstructed to resemble snails.

Yochelcionella is the type genus of the family Yochelcionellidae.[1]

Description

File:Water current Yochelcionella cyrano svg hariadhi.svg
'Alternative reconstructions of water currents (arrowed) in Yochelcionella. The interpretation favoured by Pojeta & Runnegar (1976) with the anteriorly located snorkel housing the inhalant stream. and the reconstruction favoured by Geyer (in press) with the posteriorly located snorkel containing the exhalant current.[2]

This genus of molluscs possessed shells which were shaped like curved caps, with an exhaust pipe shaped "snorkel" emanating underneath where the apex (point of the shell) curves over. It is believed that the "snorkel" was used in breathing, allowing waste water to flow away from the gills.

Taxonomy

When they were first discovered, they were originally thought to be monoplacophorans. Their snorkel may represent a move towards a tubular shell, such as is seen in the modern scaphopods.[3] It has also been interpreted as a precursor to the cephalopod funnel[4] or siphuncle.[5]

The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005[1] categorizes Yochelcionella in the family Yochelcionellidae within the superfamilia Yochelcionelloidea within the Paleozoic molluscs of uncertain position within Mollusca (Gastropoda or Monoplacophora).

For an alternate 2007-2007 taxonomy by P. Yu. Parkhae see Helcionelloida.

Species

Species in the genus Yochelcionella include:

References

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  1. a b 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. Template:ISBN. Template:Catalog lookup linkScript error: No such module "check isxn".Script error: No such module "check isxn".Script error: No such module "check isxn".Script error: No such module "check isxn".Script error: No such module "check isxn".Script error: No such module "check isxn".Script error: No such module "check isxn".Script error: No such module "check isxn".Script error: No such module "check isxn".. 397 pp. http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278
  2. Yochelcionella (Mollusca) from the late Middle Cambrian of Bornholm, Denmark from researchgate.net
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  6. a b c d e Atkins C. J. & Peel J. S. (2008). "Yochelcionella (Mollusca, Helcionelloida) from the lower Cambrian of North America". Bulletin of Geosciences 83(1): 23-38 (8 figures). Script error: No such module "CS1 identifiers"..
  7. a b Vendrasco M. J., Porter S. M., Kouchinsky A., Li G. & Fernandez C. Z. (2010). "New data on molluscs and their shell microstructures from the Middle Cambrian Gowers Formation, Australia". Palaeontology 53(1): 97-135. Script error: No such module "CS1 identifiers"..

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External links

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