Lower Homerian (Silurian) Pristiograptus from the Zdanów section, Bardo Mountains (Sudetes, Poland) and their palaeobiogeographical implications

 

Authors: Radzevičius S, Raczyński P, Whittingham M

Published in: Bulletin of Geosciences, volume 95, issue 2; pages: 231 - 242; Received 5 November 2019; Accepted in revised form 17 April 2020; Online 9 May 2020

Keywords: Homerian, Silurian, Bardo Mountains, Sudetes, Poland, Pristiograptus, Graptoloidea,

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Abstract

Pristiograptus dubius pseudodubius and Pristiograptus lodenicensis were collected from outcrops of black pelagic shales of the Zdanów section of the Bardo Mountains (Sudetes, Poland). The species are easily distinguished from one another in that P. lodenicensis has distinct lobate processes on its thecae, whereas those of P. d. pseudodubius are comparatively unornamented. Our findings indicate that the age of the Lower Graptolitic Shales in the Zdanów is the middle part of the C. lundgreni graptolite Biozone (lower Homerian, upper Wenlock). The presence of P. d. pseudodubius at this site adds another locality to its global range, while the presence and abundance of P. lodenicensis further indicates the restriction of the latter species to the Rheic palaeo-ocean.