|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Orthothecida - Allathecidae
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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 conical, long, and curved. Expansion angle changes from 8° in apical part to 22° in middle part, then towards aperture decreases to 9° (Sysoev, 1972). Cross-section rounded-triangular, sometimes rounded-trapeziform. Apical part of shell pointed. Aperture straight or almost straight. Shell smooth or with slightly developed longitudinal and transverse ribs."|