Oymurania Ushatinskaya

Kouchinsky, Artem, Holmer, Lars E., Steiner, Michael & Ushatinskaya, Galina T., 2015, The new stem-group brachiopod Oymurania from the lower Cambrian of Siberia, Acta Palaeontologica Polonica 60 (4), pp. 963-980 : 965

Genus Oymurania Ushatinskaya nov.

Etymology: After the Oy-Muran section, type locality.

Type species: Oymurania gravestocki Ushatinskaya sp. nov.; see below.

Species included: Type species and probably a new, not yet formally described species from Morocco ( Micrina sp. in Skovsted et al. 2014) .

Diagnosis.—Bilaterally symmetrical presumably biconvex organophosphatic shells with circumferential growth. Valves orthoconic to cyrtoconic, with a broad subapical platform. Walls composed of laminae perforated by tiny canals and interconnected by acrotretoid columns. Two types of thicker canals perforate the wall orthogonally vs. parallel to lamination and open on the shell exterior trough the pores situated in a common depression or indentation of growth increments.

Remarks.— Oymurania is different from other bivalved stem-group brachiopods and linguliform brachiopods in a unique combination of features, such as the acrotretoid columnar microstructure of its organophosphatic laminated shell, radial and orthogonal systems of canals having external openings associated with each other, and a broad subapical platform. In Oymurania sp. described by Skovsted et al. 2014 as Micrina sp. from Cambrian Stage 3 of Morocco, a pair of low ridges on the inner surface of the subapical platform is probably homologous to apophyses in mitrals sclerites of Micrina ( Skovsted et al. 2014) .

Stratigraphic and geographic range.— Atdabanian to lower Botoman Stages (~Cambrian Stage 3), Siberian Platform and Gondwana ( Morocco).