|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Orthothecida - Circothecidae
It was assigned to Calyptoptomatida by Qian and Zhang (1983) and Duan (1984); to Trilobozoa by Sepkoski (2002); and to Circothecidae by Parkhaev and Demidenko (2010).
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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 narrow conical and long, straight or slightly curved. Cross-section widely oval, expansion angle 6°–12°. Apical part of shell spherical. Aperture straight or almost straight. Shell ornamented by transverse ribs."|