Actinocerida

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== General Description – what are Actinocerids==
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SYSTEMATIC PALEONTOLOGY <br/>
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'''Phylum''': [[Mollusca]] <br/>
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'''Class''': [[Cephalopoda]]<br/>
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'''Subclass''': [[Nautiloidea]]<br/>
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'''Order''': '''Actinocerida'''<br/>
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The '''Actinocerida''' is an order of Paleozoic [[Cephalopoda|cephalopods]] that comprises those characterized by generally straight shells with siphuncles composed of expanded segments in which there are parietal deposits and a canal system. Cameral deposits are common.
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== General Description ==
'''Actinocrids''' are generally straight shelled cephalopods with a ventral siphuncle composed of expanded segments in which internal deposits form that contain a canal system and in which there is a seam along the inner side of the connecting rings known as a parispatium. Connecting rings are typically thin and septal necks are cytrochoanitic (outwardly curved)  to recumbent. Shells vary is cross section from almost circular to very broad with acutly angles lateral edges. Siphuncles vary in position from resting on the ventral margin to slightly below the center. Cameral deposits, especially in the apical portion, are common.(Flower 1957, Teichert 1964)   
'''Actinocrids''' are generally straight shelled cephalopods with a ventral siphuncle composed of expanded segments in which internal deposits form that contain a canal system and in which there is a seam along the inner side of the connecting rings known as a parispatium. Connecting rings are typically thin and septal necks are cytrochoanitic (outwardly curved)  to recumbent. Shells vary is cross section from almost circular to very broad with acutly angles lateral edges. Siphuncles vary in position from resting on the ventral margin to slightly below the center. Cameral deposits, especially in the apical portion, are common.(Flower 1957, Teichert 1964)   

Revision as of 13:00, 8 December 2012

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