Bobellis oliveri gen. et sp. nov. from the Silurian of North Greenland (Laurentia) and the systematic position of pycnomphaline gastropods

 

Authors: Peel JS

Published in: Bulletin of Geosciences, volume 94, issue 2; pages: 125 - 136; Received 23 January 2019; Accepted in revised form 12 April 2019; Online 6 May 2019

Keywords: Silurian, North Greenland, Laurentia, Gastropoda, Pycnomphalidae,

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Abstract

The gastropod Bobellis oliveri gen. et sp. nov. is described from carbonate mounds of the Samuelsen Hoj Formation (early Silurian) within the Washington Land Group of North Greenland (Laurentia). It displays a profound adapertural swing of the growth lines across the upper whorl surface in the multi-whorled trochiform shell; the umbilicus is closed by a prominent funicle. Bobellis oliveri is assigned to the Family Pycnomphalidae (Ordovician-Devonian; nom. transl. Subfamily Pycnomphalinae Peel, 1984) which is transferred to the Euomphaloidea, alongside the morphologically similar Omphalotrochidae (Devonian-Permian). In pycnomphalids the umbilicus is usually partially or completely closed by a prominent circumbilical funicle while the umbilicus of omphalotrochids is generally open.