Middle Devonian (Eifelian, australis-ensensis zones) conodonts from the Jirásek quarry near Koněprusy (Barrandian area, Czech Republic) with special emphasis on the Polygnathus pseudofoliatus Group and notes on environmental changes related to the Kačák Episode

 

Authors: Vodrážková S, Suttner TJ

Published in: Bulletin of Geosciences, volume 95, issue 1; pages: 81 - 125; Received 14 October 2019; Accepted in revised form 18 February 2020; Online 31 March 2020

Keywords: conodonts, Middle Devonian, Eifelian, australis-ensensis zones, Polygnathus pseudofoliatus Group, Kačák Episode, Barrandian area,

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Abstract

The Jirásek quarry in the Koněprusy area (Barrandian area, Czech Republic) represents a unique section, where the stratigraphic equivalent of the black shales of the Kačák Member (Srbsko Formation) is developed in a carbonate succession. Here we describe conodont faunas of the upper Acanthopyge Limestone (Choteč Formation, australis- kockelianus zones) and the Upper Dark Interval of the Acanthopyge Limestone referred to as UDI (Choteč Formation, ensensis Zone) with special emphasis on the Polygnathus pseudofoliatus Group. The following taxa are discussed in this paper: Polygnathus pseudofoliatus Wittekindt, P. amphora Walliser & Bultynck, P. sp. aff. P. amphora Walliser & Bultynck, P. eiflius Bischoff & Ziegler, P. ensensis Ziegler & Klapper in Ziegler et al., transitional forms among P. pseudofoliatus-P. amphora, P. eiflius-P. amphora, P. pseudofoliatus-P. eiflius and P. eiflius-P. ensensis, P. benderi Weddige, P. abbessensis Savage, P. bagialensis Savage, Tortodus kockelianus (Bischoff & Ziegler), T. australis (Jackson in Pedder et al.), Tortodus sp. A, Tortodus sp. B, Tortodus sp. aff. T. weddigei Aboussalam, Tortodus sp. aff. T. caelatus (Bryant), Polygnathus sp. A, P. kluepfeli Wittekindt, P. trigonicus Bischoff & Ziegler, P. linguiformis Hinde, P. klapperi Clausen, Leuteritz & Ziegler, Polygnathus sp. aff. P. zieglerianus Weddige, Polygnathus sp. aff. P. alveolus Weddige, Polygnathus sp. B, Polygnathus sp. C, Polygnathus sp. D, Polygnathus sp. E and Polygnathus sp. F. The occurrence of P. amphora, P. benderi, P. abessensis and P. bagialensis was recorded for the first time in the Barrandian area. The large morphological variability, occurrence of transitional forms and in most cases unknown ontogenetic variation within the P. pseudofoliatus Group, hampers using particular species of this group as zonally diagnostic taxa. It is emphasized herein that taxonomic and morphometric analysis of large collections with members of P. pseudofoliatus Group is highly needed in order to properly delineate species boundaries. The increased morphological variation within the group is discussed in the light of the contemporary environmental changes related to the Kačák Episode.

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