|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Trilobita - Xandarellida - Helcionellidae
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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||"Cap-shaped low conical shell with subcentral blunt apex and oval or elliptic aperture. Posterior apertural margin cut by wide and shallow sinus. Ornamentation absent or represented by indistinct concentric folds."|