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Morphology Ecology and taphonomy   Age range and collections

Helicoplacoidea

Helicoplacoidea -

Synonyms
Synonymy list
YearName and author
1963Helicoplacoidea Durham and Caster
1993Westgardellidae Durham p. 601
2002Helicoplacoidea Sepkoski, Jr.

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
RankNameAuthor
Ambulacraria
phylumEchinodermata
classHelicoplacoidea
classHelicoplacoidea

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.

Diagnosis
ReferenceDiagnosis
J. W. Durham and K. E. Caster 1963Free living, fusiform placoid echinoderms with spirally pleated, expansible test; apical and oral poles at opposite extremities; columns of plates arranged in a spiral; ambulacra and "inter ambulacra" present; new "interambulacral" plates originating at apical pole and becoming more oral in position as subsequent plates are added (origin of ambulacral plates obscure). Lower Cambrian, California