PBDB Taxon

Basic info	Taxonomic history	Classification	Included Taxa
Morphology	Ecology and taphonomy	External Literature Search	Age range and collections

Helicoplacoidea

Taxonomy

Helicoplacoidea was named by Durham and Caster (1963).

It was assigned to Echinodermata by Durham and Caster (1963) and Sepkoski (2002).

Subtaxa

Helicoplacida, Helicoplacidae, Polyplacida, Westgardellidae

Synonyms

Westgardellidae was named by Durham (1993). Its type is Westgardella.

It was considered an invalid subgroup of Helicoplacoidea by Wilbur (2006).

It was assigned to Helicoplacida by Durham (1993).

Synonymy list

Year	Name and author
1963	Helicoplacoidea Durham and Caster
1993	Westgardellidae Durham p. 601
2002	Helicoplacoidea Sepkoski

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia

Rank	Name	Author
—	Ambulacraria
phylum	Echinodermata
class	Helicoplacoidea
class	Helicoplacoidea

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.

Cl. †Helicoplacoidea Durham and Caster 1963

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Fm. †Helicoplacidae Durham and Caster 1966

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G. †Helicoplacus Durham and Caster 1963

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†Helicoplacus gilberti Durham and Caster 1963

Invalid names: Helicoplacus casteri Durham 1993 [synonym], Helicoplacus curtisi Durham and Caster 1963 [synonym], Helicoplacus everndeni Durham 1967 [synonym], Helicoplacus guthi Durham 1993 [synonym], Westgardella blancoensis Durham 1993 [synonym], Westgardella firbyi Durham 1967 [synonym]

Invalid names: Westgardella Durham 1993 [synonym]

G. †Polyplacus Durham 1967

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†Polyplacus kilmeri Durham 1967

G. †Waucobella Durham 1967

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†Waucobella nelsoni Durham 1967

Invalid names: Helicoplacida Durham 1967 [empty], Polyplacida Durham 1967 [empty], Westgardellidae Durham 1993 [invalid subgroup]

Diagnosis

Reference	Diagnosis
J. W. Durham and K. E. Caster 1963	Free 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

Measurements

No measurements are available

Composition:

high Mg calcitep

Ontogeny:

accretion, addition of partsp

Environment:

marinep

Locomotion:

stationaryc

Attached:

yesc

Life habit:

low-level epifaunalc

Diet:

suspension feederc

Vision:

blindc

Dispersal:

waterp

Dispersal 2:

planktonicp

Comments:

LIFE HISTORY: Some genera known to be attached to trilobite fragments; other members probably attached as entire class share similar morphology; placed in low-level epifaunal tier following Bottjer & Ausich (1986)c

Created:

2004-02-29 10:47:30

Modified:

2010-02-11 03:32:08

Source: c = class, p = phylum

References: Aberhan 1992, Aberhan et al. 2004

Age range: Dyeran or 515.30000 to 511.20000 Ma

Collections (2 total)

Time interval	Ma	Country or state	Original ID and collection number
Dyeran	515.3 - 511.2	USA (California)	Helicoplacus gilberti, Waucobella nelsoni, Polyplacus kilmeri (90625) Helicoplacus sp. (204510)