Yochelcionella
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.
Description
This genus of molluscs possessed shells which were shaped like curved caps, with an exhaust pipe shaped "snorkel" emanating underneath where the apex 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. It has also been interpreted as a precursor to the cephalopod funnel or siphuncle.The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005 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.