Ruedemannoceratidae

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Family: '''Ruedemannoceratidae'''
Family: '''Ruedemannoceratidae'''
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Early [[Discosorida]] that first appeared near the beginning of the Middle Ordovician, and restricted to that epoch, that gave rise to the [[Cyrtogomphoceratidae]], probably to the [[Mandaloceratidae]] and possibly to the [[Westonoceratidae]]. Shells (conchs) are endogastric cytrocones and near orthocones with unconstriced apertures that bear a shallow hyponomic sinus. The siphuncle of displaced ventrally from the center, but not on the ventral margin. Connecting rings in early growth stages are expanded as siphuncular bulbs, reminiscent if the Upper Cambrian [[Plectronoceratidae]]. In later growth stages siphuncle segments become broadly expanded with strongly recurved septal necks. Connecting rings are thick, longitudinally zoned. Bulletts are generally thin, but with well defined inner and outer layers.
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Early [[Discosorida]] that first appeared near the beginning of the Middle Ordovician, and restricted to that epoch, that gave rise to the [[Cyrtogomphoceratidae]], probably to the [[Mandaloceratidae]] and possibly to the [[Westonoceratidae]]. Shells (conchs) are endogastric cytrocones and near orthocones with unconstriced apertures that bear a shallow hyponomic sinus. The siphuncle of displaced ventrally from the center, but not on the ventral margin. Connecting rings in early growth stages are expanded as siphuncular bulbs, reminiscent if the Upper Cambrian [[Plectronocerida]]. In later growth stages siphuncle segments become broadly expanded with strongly recurved septal necks. Connecting rings are thick, longitudinally zoned. Bulletts are generally thin, but with well defined inner and outer layers.
The Cyrtogomphoceratidae are a direct off shoot of the Reudemannoceratidae, as most likely are the Mandeloceratidae. The Westonoceratidae are thought to be more likely derived from some early cytogomphoceratid genus, probably ''Ulrichoceras'', rather than directly from the Reudemannoceratidae.
The Cyrtogomphoceratidae are a direct off shoot of the Reudemannoceratidae, as most likely are the Mandeloceratidae. The Westonoceratidae are thought to be more likely derived from some early cytogomphoceratid genus, probably ''Ulrichoceras'', rather than directly from the Reudemannoceratidae.

Latest revision as of 13:52, 29 November 2013

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