An enigmatic lower jaw from the Lower Muschelkalk (Anisian, Middle Triassic) of Winterswijk provides insights into dental configuration, tooth replacement and histology

In the aftermath of the Permo-Triassic mass extinction event, several reptile lineages radiated to form major components of marine faunas during the entire Mesozoic. The Lower Muschelkalk, which was deposited within a shallow inland sea in the Germanic Basin during the Middle Triassic, is one of the most important regions for understanding the early evolution of Mesozoic marine reptiles. Here, we present a new specimen from the Lower Muschelkalk of Winterswijk in the Netherlands, comprising an isolated left dentary that is morphologically distinct from any well-known Triassic vertebrate. We provide a detailed description of the jaw and the teeth using histological and micro-computed tomographic analyses. The anterior teeth are fang-like and curved, whereas the posterior teeth are wider and triangular-shaped. Tooth implantation is thecodont and teeth are ankylosed to the base of the alveolus. Replacement teeth are developed directly lingual to the functional teeth, starting with the formation of a resorption cavity on the dorsal surface of the alveolar margin. The replacement pattern cannot be observed in detail but is regular in the posterior part of the dentary with each tooth being alternated with an empty alveolus. The specimen can likely be assigned to Eosauropterygia based on its jaw morphology and dental morphology and replacement pattern, and it is remarkably similar to maxillae referred to the enigmatic Lamprosauroides goepperti from the Lower Muschelkalk of Poland. The dentary from Winterswijk lacks enlarged, ‘alveolarised’ crypts and corresponding distinct dental lamina foramina (DLFs) for the replacement teeth, a configuration that is typical of Sauropterygia, but which was likely not omnipresent in this clade. The specimen also exhibits loosely folded plicidentine at the roots of the teeth, likely representing the first identification of this feature in Sauropterygia.

Petrophysical properties of the Muschelkalk from the Soultz-sous-Forêts geothermal site (France), an important lithostratigraphic unit for geothermal exploitation in the Upper Rhine Graben

The Muschelkalk, composed of Triassic limestones, marls, dolomites, and evaporites, forms part of the Permo-Triassic cover of sedimentary rocks that directly overlies the fractured granitic reservoir used for geothermal energy exploitation in the Upper Rhine Graben. Petrophysical data for this lithostratigraphic unit are sparse, but are of value for reservoir prospection, stimulation, and optimisation strategies at existing and prospective geothermal sites throughout the Upper Rhine Graben. To this end, we present here a systematic microstructural, mineralogical, and petrophysical characterisation of the Muschelkalk core (from the Middle to Lower Muschelkalk; from a depth of ~ 930 to ~ 1001 m) from exploration borehole EPS-1 at Soultz-sous-Forêts (France). First, we assessed the microstructure and mineral content of samples from six depths that we consider represent the variability of the available core. The majority of the core is composed of fine-grained, interbedded dolomites and marls; however, anhydrite and a dolomitic sandstone bank were found in the Upper and Lower Muschelkalk core, respectively. A larger suite of samples (from fifteen depths, including the six depths chosen for microstructural and mineral content analysis) were then characterised in terms of their petrophysical properties. The matrix porosity of the measured Muschelkalk samples is low, from ~ 0.01 to ~ 0.1, and their matrix permeability is below the resolution of our permeameter (≪ 10−18 m2). P-wave velocity, thermal conductivity, thermal diffusivity, specific heat capacity per unit volume, Young’s modulus, and uniaxial compressive strength range from 2.60 to 5.37 km/s, 2.42 to 5.72 W/mK, 1.19 to 2.46 mm2/s, 1.63 to 2.46 MJ/m3 K, 9.4 to 39.5 GPa, and 55.1 to 257.6 MPa, respectively. Therefore, and despite the narrow range of porosity, the petrophysical properties of the Muschelkalk are highly variable. We compare these new data with those recently acquired for the Buntsandstein unit (the Permo-Triassic unit immediately below the Muschelkalk) and thus provide an overview of the petrophysical properties of the two sedimentary units that directly overly the fractured granitic reservoir.

Strontium and Barium in the Triassic Limestone of the Opole Silesia Deposits

This article presents the results of studies of strontium and barium content in Triassic (Muschelkalk) carbonate rock samples taken from the area of the Polish part of the Germanic Basin (the area of Opole Silesia). Sr and Ba were determined in the rocks of all formations of the Lower Muschelkalk - Gogolin Beds, Górażdże Beds, Dziewkowice (Terebratula) Beds and Karchowice Beds. Strontium and barium are chemical elements characteristic for aragonite carbonate phase. Aragonite is unstable calcium carbonate phase which is transformed such as high-Mg calcite into low magnesium calcite during diagenesis. So as Sr and Ba indicate the presence of aragonite in the primary carbonate material. Now these elements concentrate in low-Mg calcite crystal structure. The Triassic rocks of Lower Muschelkalk which are mined in different quarries of the Opole Silesia area are mainly built of low-Mg calcite with lower amounts of high-Mg calcite, protodolomite, ordered dolomite and huntite. There are smaller addition of non-carbonate minerals - quartz, chalcedony, muscovite, feldspars and iron minerals. The presence of Sr and Ba now bound in a structure of low-Mg calcite will indicate the occurrence of aragonite in the primary carbonate material. The Triassic rocks from the area of Opole Silesia were studied to determine the rocks enriched in Sr and Ba. Selected rock samples were examined using ICP AES spectrometry, XRF analysis and microprobe measurements. The results of studies show that strontium and barium occur in rocks of all Lower Muschelkalk formations. The lowest contents of these elements were determined in rocks of Gogolin Beds, higher - in rocks of other formations. The results of studies show that Sr and Ba concentrate in low-Mg calcite which dominates in Lower Muschelkalk rocks. Limestone built mainly of low-Mg calcite or “pure” calcite without substitution of other elements, especially Mg, Fe, Si and Al could be applied in lime industry or in other branches of industry, where pure quality raw material, without substitutions is needed.

Trace fossils from the Lower Muschelkalk of Raciborowice Górne (North Sudetic Synclinorium, SW Poland) and their palaeoenvironmental interpretation

The following trace fossils have been recognised in the Lower Muschelkalk of Raciborowice Gorne (North Sudetic Synclinorium, SW Poland): Archaeonassa fossulata, Balanoglossites triadicus, ?Gastrochaenolites isp., Lockeia isp., Palaeophycus tubularis, Palaeophycus isp., ?Planolites beverleyensis, P. montanus, Planolites isp., ?Protovirgularia isp., Rhizocorallium commune var. auriforme, R. commune var. irregulare, R. jenense, Skolithos linearis, Thalassinoides suevicus and Trypanites weisei. Coprolites and an unidentified trace fossil A are also described. The trace fossils allow the discrimination of five ichnoassociations in the Raciborowice Gorne section: (IA 1) Rhizocorallium- Pholeus, (IA 2) Rhizocorallium-Palaeophycus, (IA 3) Thalassinoides, (IA 4) Trypanites-Balanoglossites and (IA 5) Planolites-Palaeophycus. The Lower Muschelkalk succession was deposited on a shallow carbonate ramp affected by frequent storms. Deposition commenced with sedimentation in a restricted lagoon on the inner ramp with a short episode of sabkha formation. It continued on the middle and outer ramp and then on a skeletal shoal of the outer ramp and in an open basin. Ichnoassociation IA 5 is related to a maximum transgression that commenced with the deposition of the Spiriferina Bed and which probably marked the opening of the Silesian-Moravian Gate. The basin underwent two shallowing episodes, as evidenced by ichnoassociations IA 3-IA 4, resulting in the formation of hardgrounds. Bathymetric changes in the Raciborowice Gorne section correspond well with a general transgressive trend in the Germanic Basin.

Probable remains of jellyfish (Cnidaria, Scyphozoa) from the lower Middle Triassic (Anisian) of Winterswijk, eastern Netherlands

During recent years, regular round structures have been collected from the top of Bed 12 of the Vossenveld Formation (Lower Muschelkalk, lower Middle Triassic, Anisian) in the Winterswijk area, eastern Netherlands. These are here illustrated and described as probable remains of jellyfish.