|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Asteroidea - Hemizonida - Helianthasteridae
It was synonymized subjectively with Lepidasteridae by Schuchert (1915).
It was assigned to Gnathasterina by Owen (1965); to Eugnathina by Spencer and Wright (1966) and Welsh (1984); to Forcipulatida by Gale (1987); to Hemizonida by Blake (1989); and to Asteroidea by Blake (2009).
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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.
|D. B. Blake 2009||Large, multiarmed asteroids of low body profile; disk small to large, arms straight-sided, tapering to pointed tips. Interbrachial angles tightly rounded but not angular. Dorsal skeleton reduced, primary ossicles delicate, platelike. Madreporite large, dorsal. Marginals in a single robust series in interbrachia but probably absent from arms; actinals robust, axillary not recognized. Ambulacrals platelike, articular facets (e.g. cross furrow; between longitudinally successive ambulacrals; between ambulacrals, adambulacrals) robust. Adambulacrals robust, platelike; exposed ventral expression of adambulacrals T-shaped, dorsal portion of ossicle internal in life, roofing ampullae. Circumorals similar to subsequent ambulacrals. MAO large, narrow, bladelike. Accessory granules, pedicellariae, spines abundant.|