3 genera are assigned to the class HELICOPLACOIDEA
| Order | Genus | FOP | FOS | LOP | LOS |
|---|
| uncertain | Helicoplacus | Cm | Atda-u | Cm | Boto-l |
| uncertain | Polyplacus | Cm | Atda | Cm | Atda |
| uncertain | Westgardella | Cm | Atda-u | Cm | Atda-u |
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FOP = Period of first occurrence
FOS = Stage of first occurrence
LOP = Period of last occurrence
LOS = Stage of last occurrence
Stage abbreviations follow Sepkoski (2002).