Valcouroceratidae

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(added section on phylogeny)
(added systematics, diagnosis section)
 
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The Valcouroceratidae are mostly breviconic (short-shelled) [[Oncocerida|oncocerid]] cephalopods from the Middle to Upper Ordovician. In mature individuals, bladelike lamellae called actinosiphonate deposits developed within the siphuncle (Sweet 1964).
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<u>Systematics</u> <br/>
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Class: [[Cephalopoda]]<br/>
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Subclass: [[Nautiloidea]] <br/>
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Order: [[Oncocerida]] <br/>
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Family: Valcouroceratidae <br/>
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'''Characteristics''' (from Sweet 1964): Exogastric cyrtocones and brevicones with ventral, actinosiphonate siphuncle; conch changes during ontogeny from compressed to depressed or subtriangular section.
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The Valcouroceratidae are mostly breviconic (short-shelled) [[Oncocerida|oncocerid]] cephalopods from the Middle to Upper Ordovician.
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==Diagnosis==
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Shells are exogastric cyrtocones and brevicones which during ontogeny change from compressed to depreed or subtiangular in section. The siphuncle is ventral, which in mature individuals have bladelike lamellar actinosiphonate deposits.  
==Taxonomy==
==Taxonomy==

Latest revision as of 19:33, 6 October 2014

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