Gonioceratidae

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'''Gonioceratidae''' is a family of [[Actinocerida|actinocerid]] cephalopods from the Middle Ordovician that contains but a single genus, ''Gonioceras''. Description of the family is that of the genus.
'''Gonioceratidae''' is a family of [[Actinocerida|actinocerid]] cephalopods from the Middle Ordovician that contains but a single genus, ''Gonioceras''. Description of the family is that of the genus.
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Gonioceratids, i.e. ''Gonioceras'', are generally quite small, reaching lengths of perhaps 40 cm, less than  2 ft. but usually smaller. Shells are flattened with a humped upper side and flat under side, joined with a sharp edge low on the flanks. In plan view the shell is subtriangular, expanding from the apex to a maximum width approximately equal to the length at the front. The apeture is broad.  
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Gonioceratids, i.e. ''Gonioceras'', are generally quite small, reaching lengths of perhaps 40 cm, less than  2 ft. but usually smaller. Shells are flattened with a humped upper side and flat under side, joined with a sharp edge low on the flanks. In plan view the shell is subtriangular, expanding from the apex to a maximum width approximately equal to the length at the front. The aperture is broad.  
Based on the particulars of the siphuncle, ''Gonioceras'' appears to be derived from ''Armenoceras''.  While its habits can only be speculated, it is one of the two convergent "flat fish" varieties of actinocerids that probably spent much of its time resting,  partially  hidden in the sea bottom, moving from tome to time.
Based on the particulars of the siphuncle, ''Gonioceras'' appears to be derived from ''Armenoceras''.  While its habits can only be speculated, it is one of the two convergent "flat fish" varieties of actinocerids that probably spent much of its time resting,  partially  hidden in the sea bottom, moving from tome to time.

Revision as of 14:32, 30 November 2013

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