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Echinoidea - Hemicidaroida
It was reranked as the order Hemicidaroida by Durham and Melville (1957), Fell and Pawson (1966), Smith (1991) and Sepkoski (2002); it was reranked as the order Hemicidaroidea by Berndt (2003).
It was assigned to Echinacea by Durham and Melville (1957) and Fell and Pawson (1966); to Stirodonta by Smith (1991); and to Echinoidea by Sepkoski (2002) and Berndt (2003).
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.