Hemiphragmoceratidae

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<u>Systematic Paleontology</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: '''Hemiphragmoceratidae'''
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The Hemiphragmoceratidae is a rather distinctive family of [[Oncocerida|oncocerid]] cephalopods from the Middle and Upper [[Silurian]], possibly extending to the Middle [[Devonian]]. Derivation is probably from ''[[Oncoceras]]''. However phylogeny within the family is not yet worked out.
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Shells are compressed endogasric brevicones, curved adapically, straight adorally, with a ventral, nummuloidal, actinosiphonate siphuncle and an elaborately visored aperture. Actinosiphonate deposits continuous between segments. The mature peristome has a hyponomic sinus on spoutlike process, paired lateral sinuses and mid-dorsal salient. 
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At maturity the shell's opening became restricted by large lappets that developed at the aperture of the body chamber. Exactly what sort of animal inhabited such a shell and how it lived remain unknown.
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==Taxonomy==
  [[Oncoceratidae|<==]]Hemiphragmoceratidae
  [[Oncoceratidae|<==]]Hemiphragmoceratidae
     |--''Hemiphragmoceras'' Hyatt ''in'' Zittel 1900 [=''Hemiphraygmoceras'' (''l. c.'')] S64
     |--''Hemiphragmoceras'' Hyatt ''in'' Zittel 1900 [=''Hemiphraygmoceras'' (''l. c.'')] S64
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[P68] Purnell, L. R. 1968. Catalog of the Type Specimens of Invertebrate Fossils. Part I: Paleozoic Cephalopoda. ''United States National Museum Bulletin'' 262: 1-198.
[P68] Purnell, L. R. 1968. Catalog of the Type Specimens of Invertebrate Fossils. Part I: Paleozoic Cephalopoda. ''United States National Museum Bulletin'' 262: 1-198.
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[S64] Sweet, W. C. 1964. Nautiloidea – Oncocerida. In ''Treatise on Invertebrate Paleontology'' pt. K. ''Mollusca 3. Cephalopoda – General Features – Endoceratoidea – Actinoceratoidea – Nautiloidea – Bactritoidea'' (R. C. Moore, ed.) pp. K277-K319. The Geological Society of America and the University of Kansas Press.
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[S64] Sweet, W. C. 1964. Nautiloidea – Oncocerida. In ''Treatise on Invertebrate Paleontology pt. K. Mollusca 3 pp. K277-K319''. Geological Society of America and the University of Kansas Press.
'''Credits'''
'''Credits'''
[[User:Christopher|Christopher]] 00:20, 16 January 2011 (UTC)
[[User:Christopher|Christopher]] 00:20, 16 January 2011 (UTC)
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[[User:John M|John]] 30 Sept 2014

Latest revision as of 13:57, 30 September 2014

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