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Upper Triassic freshwater oncoids from Silesia (southern Poland) and their microfossil biota
Abstract
Oncoids are rare components of Keuper sediments across Europe. The exceptions are localities linked to the Upper Triassic “Woźniki Limestone” (formally Limestone Member from Woźniki) in Silesia, southern Poland. Numerous oncoids occur in breccia-like deposits in the Lipie Śląskie claypit at Lisowice. The oncoid-bearing level is underlying by organic-rich carbonaceous mudstone and siltstone and covered by non-carbonaceous sandstone and greywacke sandstone-mudstone heterolithic deposits. The oncoids are of various shapes and are built by agglutinated or skeletal stromatolites composed of a rhythmically grown dendroid micropeloidal framework. The agglutinated stromatolites are poor in microfabrics. The oncoids consist of a smooth or granular outer part and distinct core (carbonate, carbon-rich or phosphate), which may be a fossil (bivalve shell, wood fragment, charcoal piece, carbon-rich coprolite or bone fragment). Dark laminae of the cortex are carbonate-rich, whereas the light ones are silica-rich. They exhibit remains of bacterial/cyanobacterial filaments, as well as some rare and not well-discernible palynomorphs. Ostracods (cf. Darwinula sp.), small fragments of vertebrate bones (mainly fish remains), fragments of wood, plant cuticles and fragments of unionoid bivalves are associated with the oncoid accumulations. Thus, they may have been formed in a shallow
freshwater environment and were buried by rapid flood events or mud runoff.
... Tectonic projection based on Young et al. (2019) model. Stromatolite/microbialite occurrences (circles) coloured according to age: Cisuralian (lower Permian) (Chuvashov, 1983;Cross & Klosterman, 1981a, 1981bFreytet et al., 1996;Kerp et al., 1996;Sch€ afer & Stapf, 1978;Shapiro & West, 2007;Szulc & Cwizewicz, 1989), Guadalupian (middle Permian) (Newell, 1955), Lopingian (late Permian) (Adachi et al., 2017;Angiolini et al., 2010;Freytet et al., 1992;Gaetani et al., 2009;Maurer et al., 2009;Peryt & Piatkowski, 1977;Taraz et al., 1981;Wescott, 1988;Wescott & Diggens, 1998;Wignall & Hallam, 1992), Early Triassic (Angiolini et al., 2007(Angiolini et al., , 2010Adachi et al., 2017;Baud et al., 1997Baud et al., , 2005Baud & Bernecker, 2010;Chen et al., , 2014Escher & Watt, 1976;Ezaki et al., 2003Ezaki et al., , 2008Ezaki et al., , 2012Groves et al., 2007;Groves & Calner, 2004;Heydari et al., 2000;Hips & Haas, 2006;Insalaco et al., 2006;Kalkowsky, 1908;Kershaw et al., 1999Kershaw et al., , 2002Kershaw et al., , 2007Kershaw et al., , 2011Kershaw et al., , 2012Lehrmann, 1999;Lehrmann et al., 2003;Luo et al., 2016;Marenco et al., 2012;Mary & Woods, 2008;Paul & Peryt, 2000;Perch-Nielsen et al., 1972;Peryt, 1975;Pruss et al., 2006;Pruss & Bottjer, 2004;Richoz et al., 2005Richoz et al., , 2010Sano & Nakashima, 1997;Taraz et al., 1981;Wang et al., 2005;Wignall & Twitchett, 2002;Yang et al., 2011), Middle Triassic (Buser et al., 1982;Clemmensen, 1978;Clemmensen & Andreasen, 1976;Grasm€ uck & Tr€ umpy, 1969;Luo et al., 2014;Mary & Woods, 2008;Perch-Nielsen et al., 1974;Tałanda et al., 2017), Late Triassic (Arp et al., 2005;Baud et al., 2001;Gore, 1988;Hamilton, 1961;Mastandrea et al., 2006;Perri et al., 2003;Perri & Tucker, 2007;Tałanda et al., 2017;Tucker, 1978;. The Western Australian occurrence discussed herein is marked by a white star. ...
... Tectonic projection based on Young et al. (2019) model. Stromatolite/microbialite occurrences (circles) coloured according to age: Cisuralian (lower Permian) (Chuvashov, 1983;Cross & Klosterman, 1981a, 1981bFreytet et al., 1996;Kerp et al., 1996;Sch€ afer & Stapf, 1978;Shapiro & West, 2007;Szulc & Cwizewicz, 1989), Guadalupian (middle Permian) (Newell, 1955), Lopingian (late Permian) (Adachi et al., 2017;Angiolini et al., 2010;Freytet et al., 1992;Gaetani et al., 2009;Maurer et al., 2009;Peryt & Piatkowski, 1977;Taraz et al., 1981;Wescott, 1988;Wescott & Diggens, 1998;Wignall & Hallam, 1992), Early Triassic (Angiolini et al., 2007(Angiolini et al., , 2010Adachi et al., 2017;Baud et al., 1997Baud et al., , 2005Baud & Bernecker, 2010;Chen et al., , 2014Escher & Watt, 1976;Ezaki et al., 2003Ezaki et al., , 2008Ezaki et al., , 2012Groves et al., 2007;Groves & Calner, 2004;Heydari et al., 2000;Hips & Haas, 2006;Insalaco et al., 2006;Kalkowsky, 1908;Kershaw et al., 1999Kershaw et al., , 2002Kershaw et al., , 2007Kershaw et al., , 2011Kershaw et al., , 2012Lehrmann, 1999;Lehrmann et al., 2003;Luo et al., 2016;Marenco et al., 2012;Mary & Woods, 2008;Paul & Peryt, 2000;Perch-Nielsen et al., 1972;Peryt, 1975;Pruss et al., 2006;Pruss & Bottjer, 2004;Richoz et al., 2005Richoz et al., , 2010Sano & Nakashima, 1997;Taraz et al., 1981;Wang et al., 2005;Wignall & Twitchett, 2002;Yang et al., 2011), Middle Triassic (Buser et al., 1982;Clemmensen, 1978;Clemmensen & Andreasen, 1976;Grasm€ uck & Tr€ umpy, 1969;Luo et al., 2014;Mary & Woods, 2008;Perch-Nielsen et al., 1974;Tałanda et al., 2017), Late Triassic (Arp et al., 2005;Baud et al., 2001;Gore, 1988;Hamilton, 1961;Mastandrea et al., 2006;Perri et al., 2003;Perri & Tucker, 2007;Tałanda et al., 2017;Tucker, 1978;. The Western Australian occurrence discussed herein is marked by a white star. ...
... Colours are reflective of geological time using the same scheme as The Geological Time Scale. References: early Permian (Chuvashov, 1983;Cross & Klosterman, 1981a, 1981bFreytet et al., 1996;Kerp et al., 1996;Sch€ afer & Stapf, 1978;Shapiro & West, 2007;Szulc & Cwizewicz, 1989), middle Permian- (Newell, 1955), late Permian (Adachi et al., 2017;Angiolini et al., 2010;Freytet et al., 1992;Gaetani et al., 2009;Maurer et al., 2009;Peryt & Piatkowski, 1977;Taraz et al., 1981;Wescott, 1988;Wescott & Diggens, 1998;Wignall & Hallam, 1992), Early Triassic (Adachi et al., 2017;Angiolini et al., 2007;Baud et al., 1997Baud et al., , 2001Baud et al., , 2005Baud & Bernecker, 2010;Chen et al., , 2014Escher & Watt, 1976;Ezaki et al., 2003Ezaki et al., , 2008Ezaki et al., , 2012Groves et al., 2007;Groves & Calner, 2004;Heydari et al., 2000;Hips & Haas, 2006;Insalaco et al., 2006;Kalkowsky, 1908;Kershaw et al., 1999Kershaw et al., , 2002Kershaw et al., , 2007Kershaw et al., , 2011Kershaw et al., , 2012Lehrmann, 1999;Lehrmann et al., 2003;Luo et al., 2016;Marenco et al., 2012;Mary & Woods, 2008;Paul & Peryt, 2000;Perch-Nielsen et al., 1972;Peryt, 1975;Pruss et al., 2006;Pruss & Bottjer, 2004;Richoz et al., 2005Richoz et al., , 2010Sano & Nakashima, 1997;Taraz et al., 1981;Wang et al., 2005;Wignall & Twitchett, 2002;Yang et al., 2011), Middle Triassic (Buser et al., 1982;Clemmensen, 1978;Clemmensen & Andreasen, 1976;Grasm€ uck & Tr€ umpy, 1969;Luo et al., 2014;Mary & Woods, 2008;Perch-Nielsen et al., 1974;Tałanda et al., 2017), Late Triassic (Arp et al., 2005;Baud et al., 2001;Gore, 1988;Hamilton, 1961;Mastandrea et al., 2006;Perri et al., 2003;Perri & Tucker, 2007;Tałanda et al., 2017;Tucker, 1978;. The full data table may be found in the Supplemental data Table A. ...
Throughout geological history, biodiversity trends have been punctuated by sharp declines coinciding with mass extinction events. Certain organisms—known as disaster forms—flourish during the extinction aftermath from a lack of ecological competition and predation. Microbialites (in particular, stromatolites) are known to increase in environmental diversity following these biotic crises. However, it remains important to identify whether individual microbialite occurrences are a result of globally driven competition reduction or favourable local conditions. Here, we reconsider stromatolites from the northern Perth Basin of Western Australia, previously reported as Smithian (late Olenekian) in age and part of a biotic rebound following the end-Permian mass extinction and re-evaluate their paleodepositional setting and age. Detailed mapping, macro-analysis and meso-analysis of the Perth Basin locality have identified a well-preserved and diverse morphological assemblage of stromatolites that are intimately associated with a coarse siliciclastic facies. The characteristics of, and relationships between the stromatolitic and coarse siliciclastic facies support a restricted aquatic paleodepositional environment with fluvial/alluvial influences. In the Perth Basin, such depositional environments occurred most commonly during the Permian (Guadalupian to Lopingian). The robustness of previous age constraints interpreted from overlying strata (Kockatea Shale) are questioned by the identification of a depositional hiatus and onlapping relationship of the Kockatea Shale on the stromatolitic sequence. Therefore, we suggest that the mid-Phanerozoic northern Perth Basin Stromatolitic Sequence cannot be unequivocally associated with the end-Permian mass extinction and may have instead thrived owing to a favourable paleodepositional setting. The mid-Phanerozoic northern Perth Basin stromatolites are not a unique case. A compilation of reported Permian and Triassic microbialite occurrences shows that stromatolites, although most common following the end-Permian mass extinction, also occur before and after the extinction event in a range of environmental settings.
• KEY POINTS
• Ten microbialite forms were described and mapped out over 30 km in the northern Perth Basin.
• Perth Basin Stromatolitic Sequence formed in a restricted aquatic depositional setting with fluvial and/or alluvial influences.
• Stromatolites from the northern Perth Basin are unlikely to be associated with the end-Permian mass.
... tens of kilometres wide across the main current direction). These low-gradient systems develop in a variety of geodynamic settings, involving foreland, rift and semi-graben basins (Leinfelder et al., 1985;Zamarreño et al., 1997;Parcerisa et al., 2006;Arenas et al., 2000Arenas et al., , 2015bTalanda et al., 2017). ...
... The size and shape of these elements greatly depend on the shape of the nuclei and on the hydrodynamics ( Figure 11B) (Verrecchia et al., 1997;Arenas et al., 2003Arenas et al., , 2007Astibia et al., 2012). Commonly the laminae have varied thicknesses, continuity and shape, with the undulate laminae being most abundant (Zamarreño et al., 1997;Arenas et al., 2000Arenas et al., , 2007Hägele et al., 2006;Talanda et al., 2017). Typically, these laminated deposits show conspicuous evidence of microbial activity, through the presence of shrub-shaped, fan-shaped and tabular structures formed of radially arranged and straight bodies, which resemble the shape of the organism, but also through varied lamina shapes and lamination styles. ...
... Most of these systems are characterised by having rapid lateral changes of facies, as shown in Figure 19. Examples that fit this profile have been investigated by Mäcker (1997), Meléndez and Gómez-Fernández (2000), Astibia et al. (2012), Vázquez-Urbez et al. (2013),Arenas et al. (2000Arenas et al. ( , 2007Arenas et al. ( , 2015b andTalanda et al. (2017).Thick aggrading units can be preserved in areas subject to high subsidence. For instance, synsedimentary subsidence due to evaporite dissolution caused the thick accumulation of lenticular-shaped carbonate units during the upper Miocene in the Montolar hill area, in the Ebro ...
This contribution focusses on stromatolites and oncolites as tools to seek diverse environmental and climate information at different temporal scales. The scales are i) Low frequency, dealing with macroscopic and megascopic scales. ii) High frequency, involving calendar and solar cycles. Two depositional environments are used for this purpose: 1) Fluvial and fluvial‐lacustrine, which can develop under high to moderate‐gradients, and in low‐gradient conditions, and 2) Lacustrine, subject to low gradient, hydrologically closed lake conditions. Several current and ancient examples in the Iberian Peninsula allow high and low frequency analyses. Within the wedge‐shaped depositional units that fill the high to moderate‐gradient, stepped fluvial systems, stromatolites form half domes and lenticular bodies, commonly at the wedge front. Oncolites are uncommon. These stromatolites developed in moderate to fast‐flowing water in stepped‐cascades and rapids. Their geometry and extent reflect the topography of the bedrock and later ongoing growth. In low‐gradient fluvial and fluvial‐(open) lacustrine systems the depositional units are tabular, low‐angle wedge‐shaped and lenticular and have great spatial facies variability. The dominant oncoid and coated‐stem limestones form gently lenticular stacked bodies, developed in wide, low to high‐sinuosity channels within wide tufaceous palustrine areas and small lakes. In the Ebro Basin saline carbonate lacustrine systems, stromatolites form thin planar to domed and stratiform bodies and are associated with muddy‐grainy laminated carbonates and very rare oncolites, together forming ramp‐shaped units that represent the inner fringes of high lake‐level deposits. This geometry reflects low‐gradient lake surface and shallow water conditions. Textural and structural features allow different ranks of laminae and types of lamination to be distinguished. Texture, together with the δ13C and δ18O values of consecutive laminae, are useful in distinguishing environmental and climate changes operating over different time spans. Periodicity analysis of lamination can help to discern any temporal significance in the lamination.
... The dating of the Lipie succession, however, is still debated (see Brański et al. 2015;Szczygielski and Sulej 2016;Racki 2017;Tałanda et al. 2017;Sulej et al. 2018). In this supplementary note, to test once more the stratigraphic inference, paired with the general disparity concerning the dicynodont demise, we address the rationale of Georges Cuvier in the study of the fossil record (paraphrased as 'fossilized large tetrapods are the best documents of Earth's past'). ...
... The clay pit in Lipie Śląskie at Lisowice village near Lubliniec was active, with some interruptions, from 1928 to 2013, and was known in the geological literature since 1980. The ca. 8 m thick fluvial succession includes mostly greenish, reddish, and grey claystones and siltstones, interbedded with stratified sandstones and limestone (oncoid-bearing; Tałanda et al. 2017) intercalations (Figure 1(b)). Pieńkowski et al. (2014, p. 272) interpreted the bone-bearing facies of Lipie as: '(. . ...
... As documented in boreholes, these strata at the clay pit are sandwiched between the redcolored Ozimek Mudstone-Evaporite Member (= the Upper Gypsum Keuper) and Woźniki Limestone Member, a marker unit in the local stratigraphy (Szulc et al. 2015b; Figure 1(b)). This locality was thought of as the locus typicus of the Lisowice bone-bearing level, which likely encompasses at least five vertebrate sites, including Zawiercie, widely distributed in the Upper Silesian region (see Figure 1(b); Racki (2017), Tałanda et al. (2017)). ...
Dicynodont therapsids are prominent elements of Triassic continental faunas, but the date of their demise is controversial, linked either to end-Carnian faunal turnover or to end-Triassic mass extinction. The second timing is based on a unique, giant dicynodont-theropod dinosaur fauna from Lipie Śląskie, Poland, thought to be Rhaetian in age, due to conjectural botanical and conchostracan (but not tetrapod) evidence. On the other hand, an age assignment for the Lipie fauna to the mid-Norian (Revueltian) has been demonstrated recently by regional integrative stratigraphic data. To test once more this still debated age assignment, we recall the rationale of Georges Cuvier in the study of the fossil record ('the best documents of Earth's past are fossilized large tetrapods'). This approach was applied successfully 200 years ago to the species extinction dilemma. In light of the worldwide distribution of dicynodonts, the alleged compositional paradox of the 'Rhaetian' fauna from Poland can be significantly reduced by its recognition as a more 'normal' early-middle Norian assemblage. The simple megafaunal correlation appears to be conclusive. Thus, there was a major pulse of dicynodont extinction at the end of the Carnian, with the final extinction of the few remaining species happening in the Norian. ARTICLE HISTORY
... This suggests a relatively short transport and no redeposition (Behrensmeyer, 1982;Holz and Barberna, 1994). The oncoids are small and poorly developed if compared with similar structures from the Lisowice and Poreba localities (see Szulc et al., 2006Szulc et al., , 2015aSzulc et al., , 2015bSulej et al., 2012;Tałanda et al., 2017;Bornemann, 1887, also described oncoids from the 'Lisów Breccia' of Koszecin). They are also much less common at Kocury. ...
... Both fossil associations were discovered inside poorly sorted conglomerates Szczygielski and Sulej, 2016). The coarse-grained sediments are also present in Wozńiki, Lisowice, and Krasiejów (Szulc, 2005;Szulc et al., 2006;Sulej et al., 2011a;Tałanda et al., 2017). However, most of bones found in these three localities come from the fine-grained beds, thus from completely different depositional regimes than the high energy environments represented in Poreba and Kocury. ...
Since 1990, several localities within the Keuper (upper Middle to Upper Triassic) strata in southern Poland have yielded remains of numerous terrestrial vertebrate species. Here we report a new Upper Triassic vertebrate assemblage from the rediscovered Kocury locality. An incomplete theropod dinosaur fibula named Velocipes guerichi described in 1932 was found there. The site was then forgotten and not explored until our excavations began in 2012, that yielded material of a lungfish, a proterochersid turtle, and a new typothoracin aetosaur Kocurypelta silvestris gen. et sp. nov. The new taxon is characterized by autapomorphies of the maxilla: an elongated edentulous posterior portion longer than 80% of the posterior maxillary process, a short medial shelf restricted to the posterior portion of the bone, an anteriorly unroofed maxillary accessory cavity, and lack of a distinct groove for choanal recess on the anteromedial surface of the bone. These new finds improve our knowledge on the vertebrate diversity of the Germanic Basin in the Late Triassic, evidencing the presence of yet unrecognized taxa. Additionally, the partial cranial aetosaur material emphasizes the issues with the aetosaurian taxonomy that is focused mostly on the osteoderm morphology
... As with typical microbialites, the formation of oncoids is controversial (Tucker and Wright 1990;Beraldi-Campesi et al. 2004;Baumgartner et al. 2006;Altermann 2008;Bontognali et al. 2008;Azerêdo et al. 2009;Škrinjar et al. 2012). A microbial genesis for oncoids in different regions and environments has been discussed in the literature (Reolid et al. 2007;Védrine et al. 2007;Schlagintweit and Gawlick 2009;Reolid and Nieto 2010;Peryt and Peryt 2012;Zhang et al. 2015a, b;Du et al. 2016;Tałanda et al. 2017;Zhou et al. 2017). However, there are few reports of the Ordovician oncoids in the Tarim Basin, Northwest China. ...
This study examines oncoids and their diagenetic structures in the lower Ordovician (Katian Stage) Lianglitage Formation in the Tarim Basin, Northwest China. Oncoid morphologies range from spherical and sub-spherical to irregular. Individual oncoids generally range from 4 to 10 mm in diameter, with an average of 8 mm and a maximum of 18 mm. Microbial fossils, including gastropods, sponges, trilobite skeletons, and bryozoans, are abundant in oncoid nuclei. Densely packed, calcified microbial clumps are also observed in some nuclei. Microbial remnants in oncoid cortices appear mainly as filaments. Alternating light and dark laminae are obvious in the oncoid cortices, and both sets of laminae contain extracellular polymeric substances, nanoparticles, and microcrystalline calcite. This suggests that oncoid formation was the result of interaction between microbial chemical processes and the external environment. Microbes and heterotrophic organisms provide the building material for oncoid nuclei formation, and frequent fluctuations in sea level provide favorable hydrodynamic conditions.
... The Marciszów site is relatively rich in fossils, with variegated terrestrial strata that preserve microbial structures , plant remains (palynomorphs, charcoal and wood remains; Fijałkowska-Mader et al. 2015;Kubik et al. 2015;Philippe et al. 2015), invertebrates (freshwater bivalves; Skawina and Dzik 2011; ostracods and conchostracans; GN personal observations), vertebrate remains including sharks, actinopterygians, dipnoan fish, large dicynodonts (Budziszewska-Karwowska et al. 2010;Szulc et al. 2015; GN personal observations) and tetrapod trace fossils (Sadlok and Wawrzyniak 2013). This site is especially interesting because it yields a biota which is very similar to that described from the Lipie Śląskie clay-pit at Lisowice (Dzik et al. 2008;Niedźwiedzki et al. 2011Niedźwiedzki et al. , 2012Niedźwiedzki 2013;Pieńkowski et al. 2014;Tałanda et al. 2017) and shows a mixture of two different environments (terrestrial and aquatic). Together with the large collection from an exceptionally fossil-rich locality at Lisowice, the Marciszów fossil collection stands out as one of the most important from the Polish Upper Triassic because it contains a unique record of the tetrapod megafauna which is still unknown in other parts of the Keuper strata of the Germanic Basin (Dzik et al. 2008). ...
Two isolated teeth, a dorsal vertebra, fragments of a humerus and femur, a fragmentary pubic “boot” and part of an ischium shaft, identified here as belonging to a large predatory archosaur were discovered in the Upper Triassic site at Marciszów near Zawiercie (southern Poland). Comparisons of the new fossils from Marciszów with the dorsal vertebrae, pubic “boot”, ischium and femur of the theropod-like Smok wawelski from Lisowice (Silesia) reveal that the two taxa are very similar. Nevertheless, due to the lack of more diagnostic elements (e.g., braincase or cranial elements), we prefer to consider all described specimens from Marciszów as Smok sp. Smok sp. shares a low mound-like, anterior trochanter with trochanteric shelf on the femur, a massive pubic “boot” with a distinct depression (= bevelled area), and a transversely lenticular ischium shaft in cross-section with S. wawelski. Some observed characters of the dorsal vertebra (e.g., lack of some lamina, shape and position of zygapophyses), however, are different from S. wawelski and may also suggest that the new findings represent a second species of the genus in the Upper Triassic of Poland. The discovery of Smok sp. at Marciszów is significant because it is the second example of the co-occurrence of this genus with: (i) bones of a large dicynodont; and (ii) record of gnawed tetrapod bones. The discovery of Smok sp. and the lack of significant morphologic divergence from S. wawelski suggest that this taxon is the only large-bodied predator currently known from the Upper Triassic of Poland. This new evidence expands the record of the genus and contributes, in some measure, to our knowledge of the stratigraphical distribution of large predatory archosaurs from the Polish Upper Triassic bone-bearing levels.
... The upper bone-bearing interval consists of dark grey siltstones and claystones containing invertebrate remains, coalfield plant debris, carbonate nodules, stromatolites, oncolites, and dispersed FeS 2 crystals (Szulc and Racki, 2014;Szulc et al., 2015aSzulc et al., , 2015b. These sediments originated on a muddy floodplain, in a swamp, a marshy pond, an ephemeral small lake, and in evolving river channels (Szulc et al., 2006(Szulc et al., , 2015bSzulc, 2007;Pieńkowski et al., 2014;Tałanda et al., 2017). The Patoka Member deposits originated during a period of humid climate with its climax during the deposition of the Lisowice bone-bearing horizon (Szulc et al., 2015b). ...
... The water discharge varied, as indicated by choke-off channel deposits with the Bouma-like sequence (massive sandstone → horizontal laminated sandstone → ripple cross-laminated fine sandstone), implying a relatively rapid sedimentation from sand-loaded flows (Fig. 7A). The presence of variously shaped oncoid beds (low-energy and stagnant water conditions) and stromatolites (Fig. 7K) under breccias (high-energy episodes) also suggests a variable water discharge ( Tałanda et al., 2017). The sandstones are relatively well sorted, and contain rounded sand grains and charcoaled organic matter (see Marynowski and Simoneit, 2009), suggesting a long transport distance ( Kubik et al., 2015). ...
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The numerous discoveries of disintegrated skeletons of large terrestrial vertebrates within several thin levels of the Upper Silesian Keuper initiated broad investigations into the palaeoenvironment and age of the bone-bearing sediments. Despite years of research, the depositional history of the Upper Triassic continental succession and its controlling factors are still poorly recognized. This paper reconstructs the depositional evolution of the Upper Triassic strata in Upper Silesia, Poland, discusses the tectonic and climatic control on deposition, and identifies the sediment provenance. Detailed sedimentological analysis enabled the recognition of three major palaeoenvironments: (1) playa; (2) distal floodplain featured by gilgai micromorphology; (3) fluvial system (sand-dominated meandering, sand- and gravel-dominated braided, and potentially anastomosing river system). The transition from one palaeoenvironment into another reflects climatic changes throughout the late Triassic. The Carnian interval is dominated by gypsum-rich playa mudstones deposited under hot and arid conditions, with only one wet episode recorded as meandering river sandstones (the so-called Carnian Pluvial Event). In contrast, Norian sedimentation was controlled by strong seasonal climatic variations, which is reflected in alternating palaeosol horizons (vertisols and calcisols), thin claystone beds (small water-pond deposits), and conglomerates (rapid flood events). This facies assemblage was formed in a relatively stable floodplain which became the main habitat of numerous vertebrate organisms. The Rhaetian is represented by a gravel-dominated braided river system developed in response to significant climate humidification, with tectonic controls on flow direction. Clast types from Norian and Rhaetian conglomerates revealed that the studied area was fed from the south and south west by the San River and Moesian Massifs. Geochemical analysis of Norian palaeosol horizons suggests mean annual precipitation of ~ 720 mm/yr in agreement with the palaeoclimatic reconstructions for the area, pointing to seasonal sub-humid to semi-arid climate conditions.
Oolitic shoals widely developed in the North China Platform during the Cambrian Miaolingian Epoch, which coincided with the first episode of cyanobacterial calcification. This study reports the co-occurrence of oncoids with ooids in the carbonate sedimentary environment in four different sections. A comprehensive study involving outcrop description, microscopic observation and statistical analysis is carried out to determine the facies, morphology and internal structure of both oncoids with ooids. Field observations show that the co-occurrence of oncoids and ooids developed at the top part of the third-order depositional sequence that represents the depositional products of the relative sea-level decline process. Microscopic observation shows that both oncoids and ooids can be subdivided into five types on the basis of their internal structure and morphological features. The comparative study of oncoids and ooids in different stages shows the influence of microbial activity on the formation of oncoids and ooids. Moreover, the comparison of oncoids from four different sections shows that the paleogeographic position and microbial involvement impacted the deposition and morphological diversity of carbonate grains in this period. In addition, the presence of microbial fossils and constructive micrite envelopes around these ooids confirm a participatory role of microbial mats in carbonate grain formation during the first episode of the cyanobacteria calcification event in the Cambrian.
The stratigraphy of the Upper Silesian Keuper, a continental mudstone-dominated is poorly known, although the already renowned, newly-discovered vertebrate localities highlight a growing demand for a more precise intra-regional correlation and an appropriate stratigraphic context. A major lithostratigraphic unit, preliminarily proposed for the middle Keuper (i.e., above the Schilfsandstein; Stuttgart Formation in “Stratigraphische Tabelle von Deutschland”, 2002) by Szulc and Racki (2015; Przegląd Geologiczny, 63: 103–113), is described in detail. The re-defined Grabowa Variegated Mudstone-Carbonate Formation, based on previously inaccurately presented information, includes the Upper Gypsum Beds and Steinmergelkeuper in traditional scheme from Germany (= Weser and Arnstadt Formations). Three members are formally defined: Ozimek (mudstone-evaporite), Patoka (marly mudstone-sandstone) and Woźniki (limestone). Two significant bone-bearing horizons (Krasiejów and Lisowice) are placed within the Patoka Mbr. The formation thickness in a composite regional reference section of the Upper Silesian Keuper, based on the new Woźniki K1 and Patoka 1 well profiles, is approximately 230 m. The Grabowa Fm generally correlates with the Norian stage, with the base located in an undefined upper Carnian, and it is topped by a major erosive disconformity and sedimentary sequence boundary near the Norian-Rhaetian boundary. However, hiatuses in the Silesian middle Keuper succession are located and paired with a cannibalistic type of sand-mud flat deposition, largely controlled by Early Cimmerian tectonic block movements around the Kraków-Lubliniec shear zone.
At least three widely separated bone-bearing intervals in the Upper Triassic succession of Upper Silesia, ranging in age from the Carnian to Rhaetian (i.e., in the interval of 25 Ma), are presented in papers of the Warsaw research group, led mostly by Jerzy Dzik and/or Grzegorz Niedźwiedzki. The stratigraphic arguments are reviewed for so far studied vertebrate localities, in particular for well-known middle Keuper sites at Krasiejów and Lisowice-Lipie Śląskie, to show that previously proposed age assignments are still inadequately documented and questionable. This unreliability is exemplified by evolving stratigraphic correlations of the fragmentary Silesian sections (10-18.5 m thick) with informal subsurface units from central-western Poland and with the German standard succession, ultimately not corroborated by comparison with the composite reference succession of the Upper Silesian Keuper, including new Woźniki K1 and Patoka 1 well profiles (ca. 260 m thick). Based on a multidisciplinary stratigraphic study covering consistent litho-, bio-, climato- and chemostratigraphic premises, focused on the relatively complete regional reference section, two bone bed levels only are recognized in the Patoka Marly Mudstone-Sandstone Member (= Steinmergelkeuper) of the Grabowa Formation, not very different in age (Classopollis meyeriana Palynozone; probably IVb Subzone): (1) localized Krasiejów bone breccia level (early Norian in age) in the Opole region, and (2) far more widely distributed Lisowice bone-bearing level (middle Norian) in a vast alluvial plain (braided to anastomosing river system) during the Eo-Cimmerian tectonic-pluvial episode. As a consequence of the principal uncertainties and controversies in Upper Triassic terrestrial stratigraphy, this is still a somewhat preliminary inference. Typical fluvial physical skeletal concentrations of combined hydraulic/sedimentologic type are common in the Upper Silesian Fossil-Lagerstätten, even if a conservation element is probably important as well.
Ferromanganesiferous macro-oncoids are distinctive from the External Subbetic Zone (Betic Cordillera, SE Spain) in relation to a major heterochronic unconformity, with a Middle Bathonian-Lower Oxfordian minimum hiatus and a Lowest Bathonian-Lowest Kimmeridgian maximum hiatus. The Fe-Mn macro-oncoids (43 mm mean-size) consist of microbial laminae with planar and arborescent to dendrolitic morphologies. Under petrographic microscopy, the planar morphologies are made up by condensed fibrillar meshworks whereas the dendrolitic ones are similar to Frutexites. Alternation between these two types of laminae reveals a rhythmic growth in the Fe-Mn macro-oncoids. Bacterial and fungal filaments are observed in SEM analyses as microbial mats constituted by a disperse web of filaments exhibiting a branching tube-like morphology with diameters ranging between 2 and 10 μm. Aggregates of coccoid-shaped forms are also registered by SEM analyses. Taxonomical approximation of the microbiota is complex, though in the thin section the condensed fibrillar meshworks look like cyanobacteria, and in SEM images the morphology of the filaments resembles fungal hyphae and green algae, whereas coccoids are assigned to cyanobacteria. The precipitation of Fe-Mn is related to the chemoorganotrophic behaviour of the benthic microbial communities, probably corresponding to the fungal mats and other chemosynthetic microbes. Inorganic precipitation mechanisms are regarded as insufficient for the accumulation of a significant amount of MnO. An efficient precipitation of Mn from natural water largely depended on the presence of Mn-oxidizing microorganisms. Sediment-starved zones of pelagic swells of the External Subbetic, located in the deep euphotic zone, were the best places for microbially mediated authigenesis.
Triassic discoveries have extended the record of near-mammals (Mammaliaformes) back to the Norian, about 215 Ma, and reveal a significant diversity of Late Triassic (Norian-Rhaetian) forms. We now add to this Late Triassic diversity a nearly complete double-rooted right lower molariform tooth (ZPAL V.33/734) from the Polish Upper Triassic that is significant because it comes from uppermost Norian–lower Rhaetian rocks and is the first discovery of a mammal-like tooth in the Mesozoic of Poland. The described tooth shows transitional dental morphology between advanced cynodonts and mammaliaforms and it appears to represent a basal mammaliaform (Hallautherium genus), probably belonging to Morganucodonta.
It is generally accepted that during the Triassic the composi− tion of tetrapod faunas underwent a series of fundamental transformations, mainly as a result of diversification of archosaurs and decline of therapsids (Benton 1994, 2004, 2006). The last herbivorous basal synapsids, dicynodonts, disappeared from the record in the early Norian of the Americas, about 220 Ma (Langer et al. 2007), being un− known from the Late Triassic of Europe. Here, we report a partially articulated skeleton and isolated bones of a giant rhino−size dicynodont in the Upper Triassic fluvial sedi− ments at Lisowice (Lipie Śląskie clay−pit) in southern Po− land. Paleobotanical data indicate an early Rhaetian age for the fauna (Dzik et al. 2008; Niedźwiedzki and Sulej 2008). The dicynodont bones are associated with bones of carnivo− rous dinosaurs, pterosaurs, as well as capitosaur and plagio− saur amphibians. Dicynodonts were represented in the Ger− manic Basin throughout the Late Triassic, as proven by findings of smaller dicynodonts in older deposits in the same area, associated there with temnospondyl amphibians. It ap− pears, thus, that the fossil record of tetrapod succession in the Late Triassic was strongly controlled by ecological fac− tors and biased by uneven representation of particular envi− ronments. The Lisowice assemblage proves that faunas dominated by dicynodonts did not entirely disappear at least until the end of the Triassic.
We report a new site with an occurrence of isolated bones of a Palaeochersis-like turtle in Norian-Rhaetian fluvial sediments from southern Poland. The turtle remains are associated with bones of a medium-sized aetosaur, a coelo-physoid dinosaur, and a larger carnivorous archosaur, as well as a hybodontid shark, ganoid and dipnoan fishes, and a large temnospondyl.
Facies analysis was applied to the six main facies of the Badenian (Middle Miocene) gypsum deposits exposed along the margin of the Carpathian Foredeep basin, from Moldova to the Czech Republic. These facies, recognised within primary selenite and fine-grained gypsum deposits, are: (i) selenites with vertical crystals; (ii) selenites with horizontal crystals; (iii) selenite debris flow facies; (iv) selenite debris facies; (v) gypsum microbialite facies; and (vi) alabastrine facies. The facies represent various environments (from shallow-brine to subaerial) of a giant salina-type basin without open-water connections with the sea and showing evaporite drawdown. Integration of facies analysis and event stratigraphic studies in the gypsum basin allowed reconstruction of its sedimentary history. The architecture of the gypsum facies suggests that the margin of the basin was occupied by a system of variable perennial saline pans (dominated by selenite deposition) and evaporite shoals (dominated by gypsum microbialite deposition). The basin was infilled
with evaporite deposits by aggradation. After initial evaporite drawdown, the northern margin of the basin evolved from a large perennial saline pan (or system of pans) into an evaporite shoal and then back again into a perennial pan, whereas the east area of the basin was a vast evaporite shoal dominated by gypsum microbialites. Separate selenite pans of oligotrophic-type developed both at the periphery and in the interior of this shoal. Later, predominantly clastic gypsum deposition developed throughout the basin margin, presumably due to a drastic change in the chemistry and salinity of the brine. Evaporite deposition was arrested by a flood of marine waters and rapid deepening.
We describe a new large predatory archosaur, Smok wawelski gen. et sp. nov., from the latest Triassic (latest Norian-early Rhaetian; approximately 205-200 Ma) of Lisowice (Lipie Slaskie clay-pit) in southern Poland. The length of the reconstructed skeleton is 5-6 m and that of the skull 50-60 cm, making S. wawelski larger than any other known predatory archosaur from the Late Triassic and Early Jurassic of central Europe (including theropod dinosaurs and "rauisuchian" crurotarsans). The holotype braincase is associated with skull, pelvic and isolated limb-bones found in close proximity (within 30 m), and we regard them as belonging to the same individual. Large, apparently tridactyl tracks that occur in the same rock unit may have been left by animals of the same species. The highly autapomorphic braincase shows large attachment areas for hypertrophied protractor pterygoideus muscles on the lateral surface and a wide, funnel-like region between the basal tubera and basipterygoid processes on the ventral surface. The skeleton (cranial and postcranial) possesses some features similar to those in theropod dinosaurs and others to those in large crocodile-line archosaurs ("rauisuchians"), rendering phylogenetic placement of S. wawelski difficult at this time.
Conchostracans or clam shrimp (order Conchostraca Sars) are arthropods with a carapace consisting of two chitinous lateral valves. Triassic conchostracans range in size from 2 to 12.5 mm long and are common in deposits that formed in fresh water lakes, isolated ponds and brackish areas. Their dessication-and freeze-resistant eggs can be dispersed by wind over long distances. Therefore many conchostracan species are distributed throughout the entire north-ern hemisphere. In the Late Permian to Middle Triassic interval, several of these forms are also found in Gondwana. Many wide-ranging conchostracan species have short stratigraphic ranges, making them excellent guide forms for subdivision of Triassic time and for long-range correlations. The stratigraphic resolution that can be achieved with conchostracan zones is often as high as for ammonoid and conodont zones found in pelagic marine deposits. This makes con-chostracans the most useful group available for biostratigraphic subdivision and correlation in continental lake deposits. Upper Triassic Gondwanan conchostracan faunas are different from conchostracan faunas of the northern hemisphere. In the Norian, some slight provincialism can be observed even within the northern hemisphere. For example, the Sevatian Redondestheria seems to be restricted to North America and Acadiestheriella n. gen. so far has been found only in the Sevatian deposits from the Fundy Basin of southeastern Canada. Here we establish a con-chostracan zonation for the Changhsingian (Late Permian) to Hettangian (Early Jurassic) of the northern hemisphere that, for the most part, is very well correlated with the marine scale. This zona-tion is especially robust for the Changhsingian to early Anisian, late Ladinian to Cordevolian and Rhaetian to Hettangian intervals. For most of the Middle and Upper Triassic, this zonation is still preliminary. Five new genera, six new species and a new subspecies of conchostracans are described that are stratigraphically important. Half of the eight stage boundaries of the Triassic have been defined by a bio-event within a marine Global Stratotype and Point (GSSP) locality, and these definitions have been accepted by both the International Subcommission on Triassic Stratigra-phy and the International Commission on Stratigra-phy. The remaining four stage boundaries are nearing final definition. In the Lower Triassic, both the base of the Induan (priority: Brahmanian) Stage (¼ base of Triassic) and the base of the next younger Olenekian Stage have been firmly defined. In the Middle Triassic, there is wide agree-ment that the defining species for the base of the Anisian Stage should be Chiosella timorensis in the GSSP candidate site at Desli Caira (Romania), but there has not yet been a formal vote on this. The base of the overlying Ladinian Stage, however, has been firmly defined. In the Upper Triassic, the base of the Carnian has been firmly likewise defined, but there is not yet a final defi-nition for the boundaries of the overlying Norian and Rhaetian stages. A consensus has not been reached on a defining species for the base of the Norian or its GSSP locality, but all of the different proposals under consideration do at least fall within a rather narrow stratigraphic interval. For the base of the Rhaetian, Misikella posthernsteini Kozur & Mock has been chosen as the defining species by the International Working Group on the Rhaetian stage, and the GSSP candidate locality at Steinbergkogel (Austria) has been studied in detail by a group under the leadership of L. Krystyn (Vienna) and presented to the participants of the International Conference on 'Upper Triassic Sub-divisions, Zonations and Events' in Bad Goisern in the autumn of 2008. The base of the overlying Hettangian stage (¼ base of the Jurassic) has been defined (so far only by a working group) as the FAD (First Appearance Datum) of Psiloceras spelae Guex, Taylor, Rakus & Bucher. The final definition of the Triassic stages within marine GSSP sections will be completed in the near future, but more than 50% of known Triassic rocks are of continental origin. Therefore, the main task of Triassic stratigraphers in the future will be subdivid-ing and correlating terrestrial strata, both between
The Early Triassic microvertebrate assemblage from karst deposits of Czatkowice quarry, Krakow Upland, Poland, has been dated as of latest Olenekian age at youngest. The assemblage contains mainly small reptiles: three to four possible genera of procolophonids, a small predatory archosaur of proterosuchid or pre-proterosuchid grade, a prolacertiform, and one or two genera attributable to Lepidosauromorpha, one of them, very small, being a possible stem-lepidosaurian. Furthermore there are some less numerous amphibians, including the first European salientian (stem-frog) - Czatkobatrachus polonicus Evans and Borsuk-Bialynicka, 1998, as well as fishes. The bones are disarticulated but fairly well preserved. The assemblage provides a glimpse of the Early Triassic diversity of small taxa, otherwise poorly known, and has a considerable potential in highlighting the earliest phylogeny of such groups as lepidosauromorphs and salientians which are virtually unknown from other roughly contemporaneous horizons. The Czatkowice microvertebrate community appears to have lived under the mesic conditions of a freshwater oasis within the otherwise arid circumequatorial belt of Scythian Northern Pangea.
Upper Triassic (Norian) freshwater carbonates, up to 30 m in thick, occur in the northern part of Upper Silesian basin. These sediments, called the Woźniki Limestone, form a SE-NW-striking elongate (90 km) and narrow (<10 km) belt. The Woźniki Limestone overlies (mostly discordantly) Carnian gypsiferous red beds and underlies the uppermost Triassic-Lower Jurassic continental clastic deposits. Laterally, the carbonates are replaced by a typically red bed clastic assemblage formed under arid and semiarid climatic conditions. Several limestone types have been recognized within the freshwater facies, including travertines, and fluvial, palustrine and pedogenic carbonates. Palustrine limestones form a major component. Common tepee structures, karst breccia, silici-fied horizons, and weathering breccia indicate that the palustrine carbonates have undergone subaerial exposition and pedogenic alteration. Palustrine carbonate sedimentation has been interrupted and replaced by fluvial sedimentation. The fluvial sediments mark the pluvial climate episodes that inhibited carbonate deposition. The studied basin displays a striking scarcity of lacustrine sediments, which may be explained in terms of hydrological and climatic controls. We infer that the carbonates were deposited within shallow swampy depressions, fed by springs of deep-circulating groundwater, partly of hydrothermal nature, under dry and semidry paleo-climatic conditions in a fault-bounded basin. The travertines precipitated directly near the springs, whereas the remnant solutions formed a broad swamp area where palustrine carbonates formed. It seems very likely that the carbonate-bearing solutions were causally related to the hydrothermal karst that occurs within the Triassic and Paleozoic basement limestones.
Small stromatolites and thrombolites occur in Kelly Lake, British Columbia, Canada. Thrombolites appear as welllithified, irregular calcite crusts on hard submerged surfaces, whereas poorly mineralized stromatolites exist on the thrombolite crusts as small laminated hemispherical domes 1.0 to 2.0 cm in diameter and height. Microscopic examination of the thrombolitic crusts reveal the presence of many coccoid and fewer small filamentous cyanobacteria. In contrast, large filamentous cyanobacteria are predominant in the stromatolitic domes. The inorganic carbon and elemental content of the two different microbialites are similar; however, the stromatolites contain more organic carbon (0.5% dry wt) than the thrombolites (0.2% dry wt). This implies that the production rate of organic matter in the stromatolites is higher, relative to the calcification rate, than in the thrombolites. Stable carbon isotope analyses show that the calcite precipitated within the microbialites is enriched in 13C compared to the dissolved inorganic carbon (DIC) source. The enrichments are the result of photosynthetic 12C fractionation by the respective microbial communities. Calcite precipitated within the stromatolites is even more enriched in 13C than that within the thrombolites, corresponding to an enhanced productivity level for the filamentous cyanobacteria in the stromatolites. These data indicate that the degree of mineralization, isotopic fractionation, and morphogenesis of modern microbialites are controlled to a large extent by relative rates of microbial growth and calcification.
Stromatolites are laminated structures that have been previously termed fossil algae. It is now recognized that such structures may be formed by a number of different processes and organisms. Recognizable algal stromatolites are more validly treated as organosedimentary structures than fossil organisms. This paper proposes a new classification of algal stromatolite structures based upon their geometric forms and relates these forms to their sites of growth relative to sea-level environments. The classification uses the arrangement of the basic geometric units (hemispheroids and spheroids) from which common stromatolites and oncolites are built. Three main arrangements of these geometric structures occur in Recent algal stromatolites and oncolites; (1) laterally linked hemispheroids (LLH), (2) discrete, vertically stacked hemispheroids (SH), and (3) discrete spheroids-either as randomly stacked hemispheroids or concentrically arranged spheroids (SS). The abbreviations are used to designate the various stru...
The Lower and Middle Triassic carbonate successions of the Western Tethys domain (Alps, Carpathians, Ger- manic Basin) comprise very particular sponge-microbial stromatolites that formed within the extremely shallow, perilitoral zone (Szulc, 1997). The stromatolites are capping emergent oolitic bars or form the lining of deep (up to 1.5m) karstic fissures. The stromatolites are composed of interfingered, microbial laminites and small (< 0.5 cm), lenticular sponge bodies. They display a variety of morphology, ranging between mm-thin flat laminites to 50 cm-thick columnar fabrics. Internal structures are relatively poorly preserved, nonetheless the dictyid Hexactinellidea seem to be the main sponge component of the Triassic stromatolites. The aphanitic and peloidal automicrite carbonate fabrics typical of the spongean- microbial association are also recognizable. The Lower Triassic sponge-microbial stromatolites could be recognized as a "disaster form" enabling survival and recovery of the sponge buildups after the Permian-Triassic extinction. Regarding the paleoecological context of this interval of the Phanerozoic, the stromatolites represent a "Lazarus form." These Lilliputian metazoan-bacterial buildups most likely enabled a survival and recovery of the reef-forming organisms after the P/T mass extinction. In Middle Triassic times (Pelsonian), the hexactinellid sponges accompanied first by scleractinian corals gave rise to the oldest in situ reefs found in the Western Tethys province. The best developed Pelsonian sponge-coral buildups occur in Upper Silesia (Poland) where they form bioherms of some 2-80 meters across and several meters high (Szulc, 2000). The sponge-coral buildups display a complex vertical succession typical of "catch up reefs" affected by the highstand, shallowing-upward trend in the basin. Generally, the buildup construction began with prostrate colonies of Hexactinellida sponges settled over subequal bioclastic dunes and formed thin (up to 3 cm) veneers perfectly mimick- ing disposition of the dune surface. The contribution of the sponge component grows upsection and they start to first form biostromal fabrics and afterward bioherms. With the further growth and relative shallowing, other organisms contributed to the reef community: crinoids, other species of sponges, brachiopods, serpulids, encrusting forams and scleractinian branched corals. The sponges and branched corals form domes and knobs clustered together. When the reef crest reached the surf zone, the encrusting corals (Pamiroseris silesiaca) became the main reef contributor typical of a highly turbulent environment. The Silesian reefs developed within the storm wave zone and display a possible zooxanthellate association (Morycowa & Szulc, 2006).
Middle Miocene sulfate sediments south of the Holy Cross Mountains, southern Poland, comprise deep- and shallow-water as well as subaerial facies, accompanied by carbonates and siliciclastics. In the gypsum section, 18 lithostratigraphic units have been distinguished. The facies variety reflects distinct sedimentary conditions in the peripheral area of the evaporitic basin, where the maximum water depth never exceeded some tens of meters. The succession of facies is regressive and comprises six sedimentary cycles that reflect relative changes in sea level and in the physicochemical regime of the basin, both of which were controlled by tectonic and climatic factors. Sea level fell five times during sulfate sedimentation; the last sea-level drop led to the almost total desiccation of the sea in the peripheral part of the basin.
Remains of silicified microbial mats composed of benthic colonial coccoid cyanobacteria similar to modern entophysalidaceans and/or pleurocapsaleans have been identified in Lower Silurian black radiolarian cherts from central and southwestern Poland. Contrary to widespread views ascribing the genesis of such deposits to permanently anoxic deep-water marine environments, the abundance of benthic mats of phototrophic cyanobacteria suggests that the water-mat interface must have been located at moderate depth, most probably close to the limit of light penetration (dysphotic zone). Depending on ambient sulfide levels, the mats could intermittently perform anoxygenic (PSI) or oxygenic (PSII) photosynthesis, thriving under anoxic, oxic, or dysoxic (microaerophilic) conditions. The open marine (offshore) character of these cherts is consistent with their paleooceanographic location and with the presence of remains of such planktonic organisms as acritarchs, radiolarians, chitinozoans, and graptolites, entrapped by the cyanobacterial mats.
Exceptionally well-preserved Late Triassic unionoids from Silesia, Poland, show prominently ornamented juvenile shells and umbonal muscle attachments that are similar to Margaritifera, which are anatomically the least derived among extant unionoids. Their phosphatized (originally chitinous and impregnated with calcium phosphate) gill supports lacked transverse connections, and occasionally some of them were separated from others, being thus at the filibranch grade, like their trigonioid ancestors. Several separate small foot elevator attachments in these unionoids indicate Trigonodidae adaptation to marine or brackish water, in which the original trigonioid strong single attachment was already split into two in the Early Triassic. The ribbing of juvenile shells suggests a change to deeper infaunal life for juvenile stages, and generally less efficient near-surface locomotion, with a wedge-like foot, in adults. Much later the unionoids became eulamellibranchial, which promoted the brooding of the fish that their larvae parasitize. To accomodate the classification of the order under this scenario of evolutionary changes, a new suborder Silesunionina is proposed for its filibranch members. It includes the Silesunionidae fam. nov., with the location of umbonal muscles similar to that in the extant underived unionoids, and the Unionellidae fam. nov., with umbonal muscles attached to the external wall of the umbonal cavity. The early Late Triassic (Carnian) Silesunio parvus gen. et sp. nov. and latest Triassic (Rhaetian) Tihkia(?) silesiaca sp. nov. are proposed.
© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, 863–883.
Gorzelak, P., Niedźwiedzki, G. & Skawina, A. 2010: Pathologies of non-marine bivalve shells from the Late Triassic of Poland. Lethaia, Vol. 43, pp. 285–289.Shells of Late Triassic non-marine bivalves from Lisowice (Lipie Śląskie clay pit, southern Poland), which co-occur with remains of several vertebrate taxa (mammal-like reptiles, carnivorous dinosaurs, pterosaurs, temnospondyl amphibians, hybodont sharks, dipnoan and ganoid fish), bear evidence of pathologies. Distribution, dimension and shape of some of these injuries (radiate tooth marks) closely match the dental morphology of lungfish (here probably represented by the genus Ceratodus). Thus, we interpret these pathologies as evidence of unsuccessful predatory attack on bivalves by this fish. This interpretation is also consistent with modern examples of such behaviour among lungfish. The feasibility that other culprits caused other pathologies (shell scarring and wedges) on the bivalves analysed is also discussed. Discovery of these traces constitutes important evidence of predator–prey interaction, which provides ‘fingerprints’ of trophic structure within this Late Triassic freshwater ecosystem. □Freshwater bivalves, lungfish, pathologies, predation, Triassic.
Terrestrial oncoids, up to 85 mm long, are common in some of the soil-filled pockets found in the finely crystalline dolostones of the Cayman Formation on Cayman Brac. Each of these coated grains has a nucleus formed of a white, finely crystalline dolostone lithoclast (derived from the Cayman Formation) that is encased by a light brown to tan cortex that is formed largely of micrite and minimicrite, is vaguely laminated, and lacks obvious biogenic structures. The cortex, typically < 10 mm thick, is variable in thickness around individual grains and from grain to grain. On the surfaces of the oncoids there is a diverse microbiota that includes various reticulate filaments that are typically < 1 μm in diameter, cocci, some large-diameter collapsed and calcified filaments, sporangia-like structures, and locally, exopolysaccharides (EPS). In the subsurface parts of the cortices, however, filaments are very rare and there are only scattered cocci. Evidence derived from the surface microbes indicates that they played an active role in the growth of the cortical laminae by binding material to their surfaces, calcification of the microbes, providing substrates on which calcite was precipitated, and forming cavities in which calcite cement was later precipitated. In stark contrast, it is difficult to ascribe a biotic influence to the formation of the subsurface laminae because of the paucity of preserved microbes. The lack of microbes, however, probably reflects the fact that the formative microbes were destroyed during diagenesis. This example clearly demonstrates that the lack of preserved microbes cannot be taken as an indication that the grains formed as a result of abiogenic processes.
Niedźwiedzki, G., Gorzelak, P. & Sulej, T. 2010: Bite traces on dicynodont bones and the early evolution of large terrestrial predators. Lethaia, Vol. 44, pp. 87–92.
Dicynodont (Synapsida: Anomodontia) bones from the Late Triassic (late Norian/early Rhaetian) of Poland yield characteristic tooth marks that can be attributed to three ichnotaxa (Linichnus serratus, Knethichnus parallelum and Nihilichnus nihilicus). The general shape and dimension of these traces perfectly match the dental morphology of a co-occurring carnivorous dinosaur. It is therefore concluded that early carnivorous dinosaurs were feeding on dicynodonts. This discovery constitutes one of the oldest evidence of dinosaur predator–prey interaction. It is suggested that an evolutionary increase in the size of dicynodonts across the Late Triassic may have been driven by selection pressure to reach a size refuge from early dinosaur predators. □Bite traces, dicynodonts, dinosaurs, predation, Triassic.
Spectacular modern freshwater oncoids from the river Alz (Bavaria, Southern Germany) grow in-situ, without being regularly overturned. In order to understand growth processes, properties of Alz river waters such as nutrient balance and pH were analysed and monitored, and the biotic composition of the oncoids was examined. Key features for the understanding of the growth of the Alz oncoids include (1) the presence of subconcentric calcareous laminae; (2) the existence of extracellular polymeric substances (EPS) within the enveloping biofilm that are produced by cyanobacteria and diatoms and cover the entire oncoid except for the contact area with riverbed sediments; (3) a stratified, ‘telescoping’ pattern of cyanobacteria living both intertwined within the soft outer biofilm and in radial arrangement within the partially calcified cortex below; (4) the calcification pattern of individual cyanobacterial colonies; (5) the presence of an oncoidal food web; (6) the occurrence of destructive processes such as boring by endolithic cyanobacteria and EPS-burrowing of animals; (7) a lack of multicellular algae and higher plants owing to pronounced phosphate limitation.Organismic interactions important in the extant Alz oncoids are believed to be important for a more complete understanding of fossil oncoids.
En este trabajo se han caracterizado sedimentológica y geoquímicamente las tres unidades genéticas reconocidas en el sector centro-occidental de la Cuenca del Ebro (Muela de Borja) durante el final del relleno de la misma (intervalo Aragoniense medio-Turoliense?), con el objetivo de establecer las condiciones paleoclimáticas y paleogeográficas que condujeron al desarrollo de esos depósitos y, especialmente, del sistema tobáceo que culmina la muela. Por otro lado, la comparación de los depósitos tobáceos con otros similares cuaternarios formados por los ríos Piedra y Mesa (sector central de la Cordillera Ibérica) permite establecer notables diferencias en las condiciones de sedimentación: un sistema fluvio-lacustre carbonatado amplio, con una red de canales de gran movilidad lateral y pendiente suave y uniforme hacia un cuerpo lacustre situado al este (para la Muela de Borja) frente a un sistema fluvial escalonado, con saltos y represamientos, pero de amplitud lateral restringida (para los ríos Piedra y Mesa).
Lithification in microbial ecosystems occurs when precipitation of minerals outweighs dissolution. Although the formation of various minerals can result from microbial metabolism, carbonate precipitation is possibly the most important process that impacts global carbon cycling. Recent investigations have produced models for stromatolite formation in open marine environments and lithification in shallow hypersaline lakes, which could be highly relevant for interpreting the rock record and searching for extraterrestrial life. Two factors that are controlled by microbial processes and physicochemical characteristics determine precipitation: exopolymeric substances and the saturation index, the latter being determined by the pH, {Ca(2+)} and {CO(3)(2-)}. Here, we evaluate community metabolism in microbial mats and hypothesize why these organosedimentary biofilms sometimes lithify and sometimes do not.
Columnar stromatolites were abundant and widespread in the Proterozoic but are exceedingly rare in modern seas. Consequently, the stromatolites at Hamelin Pool in Shark Bay, Western Australia, have been widely interpreted as unique modern analogs of ancient stromatolites constructed by complex communities of cyanobacteria. However, the Shark Bay columnar stromatolites contain sediment that is unusually coarse for stromatolites both ancient and modern, and the subtidal columnar stromatolites have a significant component of algal eukaryotes dominated by motile diatoms with mucilaginous tubes. This suggests that Shark Bay columnar stromatolites are not strict analogs for most ancient cyanobacterial stromatolites, least of all for those from subtidal environments. We argue that algal eukaryotes may play a substantial role in the formation and maintenance of subtidal columnar stromatolites at Shark Bay and are capable of trapping coarse sediment. In contrast, cyanobacteria have difficulty in trapping coarse sediment and produce essentially fine-grained stromatolites. We propose that there are two major types or end members of Recent marine stromatolites: (i) eualgal-cyanobacterial stromatolites that are generally coarse-grained, and (ii) cyanobacterial stromatolites that are generally fine-grained.
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