Cyrtogomphoceratidae

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(par 1 modification, link for Phragmoceratidae)
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The Middle Ordovician to Lower Devonian cyrtogomphoceratid lineage of discosorid cephalopods included the paraphyletic Cyrtogomphoceratidae and the later Phragmoceratidae. The Phragmoceratidae had the shell aperture strongly constricted by encroaching lappets.
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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.
'''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.
'''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.

Revision as of 17:10, 26 April 2012

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