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19 February 2010 A New Tannuolinid Problematic from the Lower Cambrian of the Sukharikha River in Northern Siberia
Artem Kouchinsky, Stefan Bengtson, Duncan J.E. Murdock
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Abstract

A new species of tannuolinid, Tannuolina pavlovi, is reported from the basal Krasnoporog Formation cropping out along the Sukharikha River at the northwestern margin of the Siberian Platform. The new material expands the geographic range of tannuolinids onto the Siberian Platform and extends their stratigraphic range into the basal Tommotian Stage of the traditional Lower Cambrian. The oldest appearance of tannuolinids in the fossil record is shown herein to have occurred as early as the oldest appearance of the linguliformean brachiopods, of which tannuolinids have been suggested to be a stem group. The sellate sclerites of T. pavlovi sp. nov. are different from those of the other known species of Tannuolina in the consistent absence of a pronounced sella and duplicature on the respective sides of sclerites, as well as in having regularly distributed large setal pores on the lateral edges. The mitral sclerites of T. pavlovi sp. nov. do not clearly show asymmetry of left and right forms, manifested in other species by the presence of the carina on the interior surface. Large pores aligned along the lateral margins of sellate sclerites regularly coalesce below the wall surface from an apically and an aperturally directed basal branch, forming a nearly right angle.

Artem Kouchinsky, Stefan Bengtson, and Duncan J.E. Murdock "A New Tannuolinid Problematic from the Lower Cambrian of the Sukharikha River in Northern Siberia," Acta Palaeontologica Polonica 55(2), 321-331, (19 February 2010). https://doi.org/10.4202/app.2009.1102
Received: 23 October 2009; Accepted: 1 February 2010; Published: 19 February 2010
KEYWORDS
Brachiopoda
Cambrian
Siberia
Tannuolina
Tommotian
Tommotiida
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