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Orthoceratoidea

Orthoceratoidea is a subclass, formerly considered an infraclass or a superorder, that comprises Cephalopoda orders that have orthoconic to slightly cyrtoconic shells and central to subcentral siphuncles in which there may be internal deposits. Currently, Orthoceratoidea comprises the orders Dissidocerida, Ascocerida, Pseudorthocerida, Lituitida and Orthocerida.
    • Taxonomy