|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||Age range and collections|
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.
|Yu. E. Demidenko 2016||Discoid (flattened, concave, or convex) millimetersized phosphatic sclerites. Outer surface of sclerite with distinct concentric growth lines. Apex field and apex itself displaced toward apical margin. Inner surface with muscular impressions (10–16) radially diverging from apex and bilaterally arranged relative to each other. Muscular impressions grouped into pairs; locally, paired patterns disturbed: muscular impressions near apical or distal margins sometimes unpaired. In some specimens, muscular impressions seen on outer side in juvenile part of sclerite.|