Comments on distribution and taphonomy of Devonian placoderms in the Holy Cross Mountains, Poland

Abstract

of early jawed vertebrates that appeared in the Silurian period and reached maximum diversification during the Devonian. Placoderms became extinct at the end of the Devonian. Placoderms played an important role in the history of geological studies in the Holy Cross Mountains. Initially, the placoderms were used as stratigraphic tools to distinguish between the Cambrian and Devonian sandstones in the Holy Cross Mountain region (Czarnocki 1919, 1936). Placoderms were used as a biostratigraphic marker for correlation for the first time by Kontkiewicz (1882) and this was applied to the mining activity that occurred between 1893 and 1895 (Kosmowska-Ceranowicz 1973). Gürich (1896), Czarnocki (1919, 1936) and other authors followed Kontkiewiczʼs concept of employing placoderms as index fossils to recognize Early Devonian. By contrast, placoderms served rather limited biostratigraphic value for younger Devonian strata. However they were useful in determining crucial details of the palaeo-environment, especially the sediments deposited under marine conditions (Kulczycka 1933; GorizdroKulczycka 1934, 1949, 1950; Samsonowicz 1934). One could say that the modern study of placoderms from Poland commences with Kulczycki’s investigations in 1956 and 1957, where he provided comprehensive data of the stratigraphical and geographical distribution of placoderms and correlated these occurrences with other areas. However, Kulczycki worked prior to the publication of Wegener’s theory of continental drift, resulting in some erroneous palaeogeographic conclusions, but his correlations of the Late Devonian American, West-European and Polish assemblages are still quite important (Kul czy c ki 1957). So far, other vertebrate remains in the stu died horizons reveal little information. Surprisingly, not much has been published on placoderm taxonomy and their spatial and stratigraphic distribution in the Holy Cross Mountains. Thus, the main goal of this article is to summarize and discuss the placoderm record, their preservation and taphonomy in the Holy Cross Mountains using published data (Kontkiewicz 1882; Gürich 1896; Siemiradzki 1903; Czarnocki 1919, 1936; Kulczycka 1933; Samsonowicz 1934; Gorizdro-Kulczycka 1934, 1949, 1950; Kulczycki 1956, 1957; Liszkowski & Racki 1993; Ivanov & Ginter 1997; Szrek 2000, 2003, 2004, 2006a, b, 2007a, b, c, 2008; Szrek & Ginter 2007; Gorzelak et al. 2010; Szrek et al. 2014, 2015; Dworczak & Szrek 2016; Szrek & Dupret 2017; Szrek & Wilk 2018). This study also includes recent, unpublished discoveries including new material.