Comparative Actualistic Study Hints at Origins of Intriguing Miocene “Coprolites” of Poland Tomasz Brachaniec University of Silesia in Katowice Dorota Środek University of Silesia in Katowice Dawid Surmik University of Silesia in Katowice Robert Niedźwiedzki Wrocław University Georgios L. Georgalis University of Zurich Bartosz J. Płachno Jagiellonian University in Kraków Piotr Duda University of Silesia in Katowice Alexander Lukeneder Natural History Museum Vienna Przemysław Gorzelak Polish Academy of Sciences Mariusz A. Salamon ( [email protected] ) University of Silesia in Katowice Research Article Keywords: Intriguing Miocene , Coprolites, Poland Posted Date: September 7th, 2021 DOI: https://doi.org/10.21203/rs.3.rs-864768/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License 1 Comparative actualistic study hints at origins of intriguing Miocene “coprolites” of 2 Poland 3 4 Tomasz Brachaniec1, Dorota Środek1, Dawid Surmik1, Robert Niedźwiedzki2, Georgios 5 L. Georgalis3, Bartosz J. Płachno4, Piotr Duda5, Alexander Lukeneder6, Przemysław 6 Gorzelak7, Mariusz A. Salamon1* 7 8 1University of Silesia in Katowice, Faculty of Natural Sciences, Będzińska 60, 41-200 9 Sosnowiec, Poland, [email protected] (MAS - corresponding author) 10 2 Institute of Geological Sciences, Wrocław University, Borna 9, 50-204 Wrocław, Poland 11 3Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, 8006 12 Zurich, Switzerland 13 4Jagiellonian University in Kraków, Faculty of Biology, Institute of Botany, Gronostajowa 14 Street 9, 30-387 Cracow, Poland 15 5University of Silesia in Katowice, Faculty of Science and Technology, Będzińska Street 39, 16 41-200 Sosnowiec, Poland 17 6Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria 18 7Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warszawa, 19 Poland 20 21 Abstract 22 Excrement-shaped siderite masses have been the subject of much controversy. They have 23 been variously interpreted either as being coprolites, cololites or pseudofossils created by 24 mechanical deformation of plastic sediment. Here we report excrement-shaped ferruginous 25 masses recovered from the Miocene of the Turów mine in south-western Poland. 26 Mineralogical, geochemical, petrographic and microtomographical analyses indicate that 27 these masses consist of siderite and iron oxide rather than phosphate, and rarely contain 28 recognizable food residues, which may suggest abiotic origins of these structures. On the 29 other hand, evidence in support of a faecal origin include: (i) the presence of two distinct 30 morphotypes differing in size and shape, (ii) the limited quantity of specimens, (iii) the 31 presence of rare hair-like structures or coalified inclusions and (iv) the presence of fine 32 striations on the surface. Importantly, comparative actualistic studies of Recent vertebrate 33 feces show overall resemblance of the first morphotype (sausage-shaped with rare coalified 34 debris) to excrements of testudinoid turtles (Testudinoidea), whose shell fragment was found 35 in the investigated locality. The second morphotype (rounded to oval-shaped with hair-like 36 structures), in turn, is similar to the feces of some snakes (Serpentes), the remains of which 37 were noted in the Miocene of the neighborhood areas. 38 39 40 Introduction 41 42 Incontrovertible examples of the Miocene coprolites are known from only a few localities in 43 Europe, North and South America1-7. Rodents, notoungulates, hathliacynid and borhyaenoid 44 marsupials, indeterminate carnivorans, sirenians, and crocodilians were commonly invoked as 45 potential producers of these coprolites3,5-6. The majority of described Miocene vertebrate 46 coprolites were produced by carnivores. This is not surprising because faeces of herbivorous 47 tetrapods are commonly composed of a large quantity of undigested plant residues attracting 48 microbial decomposition. On the other hand, the calcium phosphate derived from undigested 49 bones in the faeces of carnivores acts as important permineralizing agent5,8-9. 50 Excrement-shaped ferruginous masses have been considered (based on morphological 51 grounds) by some authors as being coprolites or cololites (intestinal casts)10-11. These objects 52 are commonly reported from clay-rich sediments ranging in age from Permian to Holocene. 53 However, given their ferruginous composition, significant variation in size, lack of internal 54 inclusions, and scarcity of associated vertebrate remains, most authors rejected the coprolite 55 nature12-24. Different hypotheses have been invoked to explain the origins of these objects 56 (such as soft sediment extrusion triggered by coseismic liquefaction, sediment intrusion into 57 hollow logs, expulsion of sediment in response to gravity, extrusion of siderite related to 58 methanogenesis). 59 Until recently, a detailed study on excrement-shaped ferruginous masses from the Miocene of 60 Poland has been lacking. In this paper we analyse the Miocene excrement-shaped specimens 61 collected from the coal mine of Turów for the first time. According to our results, we favour 62 the hypothesis that the specimens from Poland represent true coprolites and more particularly 63 pertaining to two different reptile groups. 64 65 Geological setting 66 67 The Turów lignite mine is located in the south-eastern part of the Lower Silesia Voivodeship 68 (SW Poland) and covers the former village of Turów. It is located in the central part of the 69 mesoregion Żytawa-Zgorzelec Depression located between the state borders of Germany and 70 the Czech Republic (Fig. 1A). Turów lignite deposits are part of the Upper Lusatian Brown 71 Coal Basin. This basin comprises a few tectonic sinkholes25 that developed in Paleogene at 72 the junction of two regional zones of strong activity: Ore Mts. Graben (Ohrza rift) and the 73 Lusatian-Elbe Tectono-Volcanic Zone26. The most southern of these25 is the Zittau Basin (Fig. 74 1A, B), which was filledmainly by limno-fluvial or limnic clays, silts, sands and thick layers 75 of lignites exploited in the Turów mine27-28. Furthermore, there are numerous volcanic rocks 76 of late Eocene, Oligocene and early Miocene age28. The basal part of sedimentary section of 77 the Zittau basin is not older than the early Oligocene, however most sediments were formed in 78 the Miocene28. At the base of the Zittau Basin, Precambrian and Palaeozoic metamorphic and 79 igneous rocks are present29. 80 The lithological profile of the Turów mine is ca. 250 m thick and consists of 7 81 lithostratigraphic units of sedimentary rocks. Apart from the two youngest units (Gozdnica 82 Fm. and glacial tills), all of them are mainly composed of clays and/or muds. Additionally, 83 there are coal seams, especially in Opolno and Biedrzychowice formations, which are the 84 deposits mined at the Turów mine. The oldest Cenozoic sediments of the profile are 85 Oligocene sediments (Egger age), forming the lower part of the Turoszów Fm.28. The 86 youngest in the profile are gravels and sands of the Gozdnica Fm. Pannonian in age and 87 Pleistocene deposits, mainly represented by tills30. 88 The Turoszów Fm. was formed in fluvial and limnofluvial conditions, while the Opolno and 89 Biedrzychowice Fms have been formed in limnotelmatic environments, and Porajów Fm. 90 represents limnofluvial environment. Sediments of the upper part of Miocene profile 91 (Rybarzowice and Gozdnica Fms.) have alluvial origin31. Biedrzychowice Fm., within which 92 excrement-shaped ferruginous masses and a turtle remain have been documented, was formed 93 in vast swamps and rushmarshes32. Especially in the upper part of this formation, there are 94 numerous palaeosols levels with plant roots and trunks preserved in situ33. Marsh forests 95 mainly composed of Cupressaceae and Taxaceae33-34. Based on palaeobotanical analysis of 96 the coal seam it was concluded that there was a humid warm temperate climate similar to that 97 of south-eastern China today32,35. 98 The ferruginous masses and the turtle shell fragment documented in this article were collected 99 in an inactive part of the excavation, within the clays of the higher part of Biedrzychowice 100 Fm. in the uppermost part of early Miocene (Burdigalian; see Fig. 1C). Two distinct 101 morphotypes randomly distributed within clay on the flat surface of the excavation were 102 noted. 103 104 Figure 1 around here 105 106 Fossil content in the Turów area and adjacent areas 107 108 No animal fossil remains have been documented so far from the Oligocene–Miocene of the 109 Zittau Basin with exception of burrows of sediment eating fauna28. In the course of the 110 present research in the clays of Biedrzychowice Fm., apart from the excrement-shaped 111 ferruginous masses, a fragment of a turtle shell was found. This shell fragment (Fig. 2N) can 112 only be identified as an indeterminate testudinoid. This turtle lineage is otherwise abundant in 113 Oligocene and early Miocene localities in Germany and Czech Republic37-38 but had not so far 114 been documented from coeval localities in Poland. In older, Eocene and Oligocene localities 115 in the neighbouring north-western Czech Republic and south-eastern Germany (Saxony and 116 southeastern Saxony-Anhalt), rich assemblages of terrestrial-aquatic tetrapod fauna have been 117 documented, comprising frogs, salamanders, choristoderans, crocodiles (also crocodile 118 coprolites, see28 and literature cited