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Polyplacus

Helicoplacoidea - Helicoplacidae

Taxonomy
Polyplacus was named by Durham (1967) [Sepkoski's age data: Cm Atda Sepkoski's reference number: 654]. Its type is Polyplacus kilmeri.

It was assigned to Polyplacida by Durham (1967) and Durham (1993); to Helicoplacoidea by Sepkoski (2002); and to Helicoplacidae by Wilbur (2006).

Synonymy list
YearName and author
1967Polyplacus Durham p. 101
1993Polyplacus Durham p. 603
2002Polyplacus Sepkoski, Jr.
2006Polyplacus Wilbur p. 291

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
Ambulacraria
RankNameAuthor
phylumEchinodermata
classHelicoplacoidea
familyHelicoplacidaeDurham and Caster 1966
genusPolyplacus

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 1967Test with numerous pleats, possibly as many as 18 to 20; pleats apparently expansible, produced into numerous regularly spaced conical protuberances on margin, giving scalloped appearance; ambulacra unknown.
J. W. Durham 1993Test built of a mosaic of numerous small plates arranged in expansible pleats that spiral around central axis like those of other helicoplacoids. Ambulacra unknown.
B. C. Wilbur 2006Helicoplacoids with interambulacra composed of fused basal plates in the shape of a pentagon, and twice as many distal polygonal plates.