DOI: 10.15468/sk9ja7
title: The Late Devonian placoderm Aspidichthys Newberry, 1873 from the Holy Cross Mountains, Poland

description: This dataset contains the digitized treatments in Plazi based on the original journal article Dworczak, Patrycja G., Szrek, Piotr (2016): The Late Devonian placoderm Aspidichthys Newberry, 1873 from the Holy Cross Mountains, Poland. Fossil Record 20 (1): 9-19, DOI: 10.5194/fr-20-9-2016, URL: http://dx.doi.org/10.5194/fr-20-9-2016Abstract. The reported placoderm remains from the Holy Cross Mountains, Poland, belong to the species Aspidichthys ingens Koenen, 1883. This study focuses on the material described in the past from Wietrznia Quarry but the new specimens were also collected form Kowala and Płucki localities. All specimens presented here differ from others described in the past, mainly by having smaller tubercles and possessing a distinctive crest in the anterior median part of the median dorsal plate, but did not allow the erection of a new taxon. Based on conodont assemblage, all specimens are attributed to a Frasnian age. Aspidichthys occurs in the middle to the upper part of the Frasnian (Palmatolepis punctata to P. linguiformis conodont zone) and is not found in the Famennian boundary. Described specimens also occur in a stepwise deepening environment caused by local synsedimentary tectonics.1 IntroductionThe genus Aspidichthys has an uncertain systematic position and is traditionally placed within the Arthrodira and closely related to the holonematids (e.g. Kulczycki, 1957; Schultze, 1973; Denison, 1978). It comprises large and medium-size placoderms with a distinctive elongated median dorsal plate, and well-marked large tubercles cover dermal bones. The tubercles are closely spaced and irregularly arranged. They may form rows paralleling the plate outline, usually at the margins. Plates are relatively thick (reach several centimetres). Due to these features, it is easy to recognize even partially preserved specimens of Aspidichthys, which has noticed very often by many authors, in several areas of the former Laurussia and Gondwana. Remains of Aspidichthys are known from the USA (Newberry, 1873; Sinclair and Walker, 1956; Miles, 1965); north-eastern Iran (Schultze, 1973); Morocco (e.g. Rücklin, 2010), Bad Wildungen, Germany (e.g. Gross, 1932); and the Holy Cross Mountains, Poland (Kulczycki, 1957; Ivanov and Ginter, 1997; Janiszewska et al., 2007; Szrek, 2006, 2007, 2008; Szrek and Ginter, 2007, 2008).The main goal of this paper is to describe placoderms previously assigned to the genus Aspidichthys from the Upper Devonian of the Holy Cross Mountains and check whether they belong to this genus. First information about the occurrence of the genus of Aspidichthys in the Holy Cross Mountains was reported by Gorizdro-Kulczycka (1934) and was later published by Kulczycki (1957). Kulczycki (1957) described a median dorsal plate and nuchale plate from the Frasnian deposits of the Kadzielnia Chain (Kielce) and reported the exceptional prominent semidentine tubercles reaching more than 10 mm in diameter as the most important feature. He also ascertained that Aspidichthys and Anomalichthys differ from each other in size and morphology of ornamentation, and these differences are the result of the North American extent of Aspidichthys and the European extent of Anomalichthys. Nevertheless, all specimens formerly belonging of the genus Anomalichthys are assigned to the genus Aspidichthys (Denison, 1978).The stratigraphic occurrence of Aspidichthys is limited to the Upper Devonian. Most remains have been discovered in the Frasnian, although a few specimens have been dated as Famennian (Denison, 1978). However, the Holy Cross Mountains deposits yielding Aspidichthys material are confined to the Frasnian (Kulczycki, 1957; Narkiewicz et al., 2006).Institutional abbreviations: WNaZ – Faculty of Earth Sciences, University of Silesia, Sosnowiec; MWG UW – Faculty of Geology, University of Warsaw; Muz. PGI-NRI – Geological Museum of the Polish Geological Institute-National Research Institute, Warsaw.Anatomical abbreviations: lc – main lateral lines; MD – median dorsal plate; PDL – posterolateral plate.