FOSSIL IMPRINT • vol. 76 • 2020 • no. 2 • pp. 243–251 (formerly ACTA MUSEI NATIONALIS PRAGAE, Series B – Historia Naturalis) FIRST RECORD OF THE STEM AMNIOTE DISCOSAURISCUS (SEYMOURIAMORPHA, DISCOSAURISCIDAE) FROM THE KRKONOŠE PIEDMONT BASIN (THE CZECH REPUBLIC) JOZEF KLEMBARA1,*, MARIKA MIKUDÍKOVÁ2, STANISLAV ŠTAMBERG3, MIROSLAV HAIN4 1 Department of Ecology, Laboratory of Evolutionary Biology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15 Bratislava, Slovakia; e-mail: [email protected]. 2 State Geological Institute of Dionýz Štúr, Mlynská dolina 1, 817 04 Bratislava, Slovakia. 3 Museum of Eastern Bohemia, Eliščino nábřeží 465, 500 01 Hradec Králové, the Czech Republic. 4 Institute of Measurement Science, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia. * corresponding author Klembara, J., Mikudíková, M., Štamberg, S., Hain, M. (2020): First record of the stem amniote Discosauriscus (Seymouriamorpha, Discosauriscidae) from the Krkonoše Piedmont Basin (the Czech Republic). – Fossil Imprint, 76(2): 243–251, Praha. ISSN 2533-4050 (print), ISSN 2533-4069 (on-line). Abstract: The first record of the seymouriamorph stem amnioteDiscosauriscus from the Krkonoše Piedmont Basin (the Czech Republic) is described. The specimen is identified as D. pulcherrimus on the basis of the following features which are absent in D. austriacus: 1) the pointed tip of the ventrolateral process of the postorbital lies anteriorly to the tip of the wedge-shaped dorsomedial process of the jugal; and 2) the rows of small denticles diverge anteromedially and anterolaterally from the mid- width of the ventral surface of the palatal ramus of the pterygoid. This new record increases our knowledge of the occurrence of this seymouriamorph in the Permo-Carboniferous basins of Europe. Key words: Seymouriamorpha, Discosauriscidae, skeleton, lower Permian, the Czech Republic Received: May 5, 2020 | Accepted: August 11, 2020 | Issued: December 30, 2020 Introduction localities in the Czech Republic (Boskovice Basin: e.g., Klembara 1997, Klembara and Mikudíková 2019), Poland The Krkonoše Piedmont Basin belongs to the Permo- (Intrasudetic Basin: Werneburg and Kiersnowski 1996), Carboniferous freshwater basins of the Bohemian Massif. Germany (Döhlen Basin, Saale Basin, Saar-Nahe Basin: The late Carboniferous and early Permian sediments Werneburg 1985, 1988, 1989, Boy 2007), and probably also contain several fossiliferous horizons with rich findings of from France (Autun, Sarre-Lorraine/Palatinat and Bourbon vertebrate fauna. Fish vertebrates such as chondrichthyans, l’Archanbault Basins: Heyler 1969, Werneburg 1989). The acanthodians and actinopterygians are the most abundant. specimen of D. pulcherrimus described here is the first Amphibians also occur in some localities and most record of this seymouriamorph from the Krkonoše Piedmont abundant are branchiosaurids, while archegosaurids and Basin. stereospondylomorphs are unique. A new discovery of the seymouriamorph tetrapod Discosauriscus pulcherrimus (FRITSCH, 1880) from the lower Permian of the Krkonoše Materials and methods Piedmont Basin significantly complements the composition of tetrapods in the basin and is of great importance for The specimen of Discosauriscus pulcherrimus, G 151, biostratigraphic correlation of the Permian sediments (Text- is deposited in the Museum of Eastern Bohemia, Hradec figs 1, 2a). Králové, the Czech Republic. It consists of the disarticulated The stem amniote Discosauriscus pulcherrimus was skull and postcranial bones (Text-fig. 2a). Several skull first described by Fritsch (1880) from the lower Permian bones and pelvic girdle elements are missing, and several locality Ruprechtice (Ruppersdorf) in the Intrasudetic skeletal elements are damaged. The skeletal elements are Basin (north Bohemia, the Czech Republic), Ruprechtice accumulated on two areas of the slab surface and are more- horizon, zone 5 – upper Autunian (sensu Werneburg 1989). or-less embedded in the sediment. We suppose that all the Later, D. pulcherrimus was described from several other bones represent one specimen. The length of the medial DOI 10.37520/fi.2020.020 243 a c b Text-fig. 1. a: simplified geological map of the Krkonoše Piedmont Basin with position of the locality in Arnultovice (see asterisk; coordinates 50° 33′ 58.599″ N; 15° 43′ 18.873″ E). After Blecha et al. (1997). b: position of the finding locality Arnultovice “Track in ravine on the edge of the forest” in idealised section of the Permian sediments of the Krkonoše Piedmont Basin. Locality Arnultovice and dating of overlying ignimbrites in Tatobity are indicated. After Opluštil et al. (2016), based on data in Prouza and Tásler (2001), modified here. c: detail of the outcrop “Track in ravine on the edge of the forest” near Arnultovice with 40–50 cm thick massive badly cleavable pinkish dolomitic limestone (L) and laminated calcareous claystone (C) with fauna. 244 Text-fig. 2. Discosauriscus pulcherrimus (FRITSCH, 1880). a: specimen G 151, cranial and postcranial skeleton (for details of postcranial skeleton, see Text-fig. 4) with highlighted virtual 3D models of postparietal and jugal (cf. Text-fig. 3c, d and 3e, f) originally embedded in sediment, b: frontal, c: frontal and prefrontal, d: intertemporal, e: parietal and postorbital, f: supratemporal and clavicle, g: parasphenoid, h: pterygoid. Abbreviations: ar.s. – articulating surface, CL – clavicle, cult. pr. – cultriform process, DE – dentary, FR – frontal, IT – intertemporal, JU – jugal, l. j. – lower jaw, or.m. – orbital margin, pal. ram. – palatal ramus, pl. pr. – posterolateral process, PO – postorbital, POFR – postfrontal, PP – postparietal, PRFR – prefrontal, ST – supratemporal, TAB – tabular. 245 margins of the frontal, parietal and postparietal is about from the village Arnultovice (3 km north of the town of 15 mm; the nasal and premaxilla are not preserved. The Hostinné). The outcrop Arnultovice “Track in ravine on length of the skull may be estimated to be about 20 mm. the edge of the forest” (coordinates 50° 33′ 58.599″ N, It means that the specimen represents a larval ontogenetic 15° 43′ 18.873″ E; Text-fig. 1c) exposes a 4 m thick set of stage (Klembara 1995, 2009). sediments. The main layer with fossils is 90 cm thick, pinkish We used high-resolution X-ray microcomputed laminated calcareous claystone lying below the massive tomography to access the most detailed anatomy of the dolomitic limestone (Text-fig. 1c). Numerous finds of the individual bones, as well as to locate bones or parts of bones actinopterygian fish Paramblypterus “Type B” (Štamberg embedded in the sediment. The scan of Discosauriscus 2014) and Amblypterus vratislaviensis, chondrichthyan pulcherrimus was performed using X-ray micro CT Xenacanthus decheni, minute branchiosaurid amphibians, tomography system Nanotom 180 (GE Phoenix). The X-ray large stereospondylomorph amphibian, and a new tube was fitted with a tungsten target, microfocusing mode seymouriamorph stem amniote described here form the M0 was used, and no filtering was applied for outgoing X-ray taxonomic composition of the fauna from the locality in radiation. Accelerating voltage was set to U = 160 kV, beam Arnultovice. current to I = 100 µA, and in total 1,800 X-ray projections were recorded. The detector timing was set to 750 ms, no binning was used (1 × 1), and the voxel size was 32 µm. The Systematic palaeontology 3D volume reconstruction was done using Phoenix Datos|x CT software utilising the Feldkamp filtered back-projection Order Seymouriamorpha WATSON, 1917 algorithm. The 3D volume data sets were filtered, rendered, Family Discosauriscidae ROMER, 1947 and segmented using VGStudio MAX 2.1 software package Genus Discosauriscus KUHN, 1933 and AVISO 8.1 software. For the volume data rendering (2D projection of 3D volume data), the isosurface rendering Discosauriscus pulcherrimus (FRITSCH, 1880) algorithm was applied. For the segmentation of volume Diagnosis. Discosauriscus pulcherrimus is chara- data, the region growing method was mostly used along cterized by three diagnostic features: 1) the posterior ramus with opening/closing and erosion/dilation image processing of the prefrontal is anteroposteriorly shorter than the anterior techniques. ramus of the postfrontal and both rami meet at the level of the anterior, middle third of the frontal length; 2) the ventrolateral ramus of the postorbital is narrow and pointed Geological setting and lies anteriorly to the wedge-shaped dorsomedial ramus The Krkonoše Piedmont Basin occupies the north-eastern of the jugal; and 3) the rows of small densely arranged region of the Bohemian Massif (Text-fig. 1a). It belongs to denticles diverge anteromedially and anterolaterally from a system of intramontaneous basins which were formed in the mid-width of the ventral surface of the palatal ramus of the early postorogenic phase during the Westphalian and the pterygoid. Saxonian times (Martínek et al. 2006). Maximum thickness M a t e r i a l . G 151 – disarticulated specimen (Text-fig. of the volcano-sedimentary fill in the central part of the 2a) deposited in the Museum of Eastern Bohemia, Hradec basin is nearly 1,800 m and the area of the basin is more than Králové, the Czech Republic. 1,100 km2. The basin fill consists of continental sediments discontinuously deposited from Westphalian D (Moscovian) Locality and horizon. Krkonoše Piedmont to the earliest Triassic. Basin (the Czech Republic), Upper Kalná Horizon, village Early Permian filling