Cyrtogomphoceratidae

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(par 1 modification, link for Phragmoceratidae)
(changed to characters of the Cyrtogomphoceratidae,)
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The Middle Ordovician to Lower Devonian cyrtogomphoceratid lineage of discosorid cephalopods includes the paraphyletic Cyrtogomphoceratidae and later [[Phragmoceratidae]]. The Phragmoceratidae have strongly constricted shell apertures.
The Middle Ordovician to Lower Devonian cyrtogomphoceratid lineage of discosorid cephalopods includes the paraphyletic Cyrtogomphoceratidae and later [[Phragmoceratidae]]. The Phragmoceratidae have strongly constricted shell apertures.
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'''Characters''' (from Teichert 1964): Conchs dominantly medium-sized to large, compressed endogastric cyrtocones; aperture strongly contracted in Phragmoceratidae; siphuncle close to ventral side. Siphuncular segments broadly expanded; connecting rings thick, apical ends expanded into markedly swollen bullettes in early forms, small to vestigial bullettes in Phragmoceratidae.
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'''Characters''' (from Teichert 1964): M [[Ordovician]] to L [[Silurian]] dominantly medium-size to large, compressed, endogastric, cyrtoconic, [[Discosorida]] with the siphuncle close to the ventral side. Siphuncle segments short, broadly expanded. Connecting rings thick, expanded at the adapical end into thick swollen bulletts that reinforce the septal openings.
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The Cyrogomphoceratidae differ from the later Phragmoceratidae in having simple, open, apertures and swollen bulletts, and from the coeval Westonoceratidae in being endogastric rather than exogastric.
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==Taxonomy==
==Taxonomy==
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[[User:Christopher|Christopher]] 23:19, 21 January 2011 (UTC)
[[User:Christopher|Christopher]] 23:19, 21 January 2011 (UTC)
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[[User:John M|John M]] Apr 26, 2012

Revision as of 17:33, 26 April 2012

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