|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Helcionelloida - Helcionellida - Rugaeconidae
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|P. Y. Parkhaev and Y. Demidenko 2010||"Shell cap-shaped, low conical, longitudinally elongated, wide. Apex strongly displaced posteriorly and hooked downwards. Anterior field evenly convex, posterior field concave and sharply folded, so that wide flattened fold projects inside shell interior and divides it on main shell cavity and train space. Train very short, but wide and high. Exterior of shell smooth. Aperture varies from elongated (elliptical or pyriform) to circular. Posterior apertural margin cut by low and wide sinus."|