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Parakionoceras
Parakionoceras is an extinct nautiloid that lived during the Silurian and Devonian in what is now Europe; included in the orthoceratoid family Kionoceratidae in the Treatise part K, 1964 but removed to the Arionoceratidae in Kröger 2008. Parakionoceras has a long, faintly curved, exogastric shell with relatively long camerae and straight transverse sutures. The surface is lined with sharp-edged longitudinal ribs separated by broader concave inner areas. The siphuncle is slightly eccentric; necks short and loxochoantitic, directed slightly inward; connecting rings slightly inflated. Cameral deposits well developed. References
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