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Hemizonida
Taxonomy
Hemizonida was named by Spencer (1951). It is not extant.
It was reranked as the suborder Hemizonina by Spencer and Wright (1966); it was considered an invalid subgroup of Asteroidea by Blake (2018).
It was assigned to Asteroidea by Lehmann (1957) and Owen (1965); to Paxillosida by Spencer and Wright (1966); and to Asteroidea by Spencer (1951), Blake (1989) and Sepkoski (2002).
It was reranked as the suborder Hemizonina by Spencer and Wright (1966); it was considered an invalid subgroup of Asteroidea by Blake (2018).
It was assigned to Asteroidea by Lehmann (1957) and Owen (1965); to Paxillosida by Spencer and Wright (1966); and to Asteroidea by Spencer (1951), Blake (1989) and Sepkoski (2002).
Subtaxa
Synonyms
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Synonymy list
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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.
Or. †Hemizonida Spencer 1951
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Fm. †Taeniactinidae Spencer 1927
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Subfm. †Protactininae Spencer 1927
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Invalid names: Calyptactininae Spencer 1930 [empty], Taeniactininae Spencer 1927 [empty]
Invalid names: Gnathasterina Spencer 1951 [synonym], Lepyriactinidae Spencer and Wright 1966 [empty]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| W. K. Spencer 1951 | The adambulacralia form a defined wall. The buttressing skeleton is confined mainly to the arm axils and the ambulacral skeleton is the main arm skeleton. | |
| W. K. Spencer 1951 (Gnathasterina) | With conspicuous mout-anlgle plates. |