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Stuttgart, Germany

Zaton M.,University of Silesia | Hagdorn H.,Muschelkalkmuseum Ingelfingen | Borszcz T.,Polish Academy of Sciences
Palaeobiodiversity and Palaeoenvironments

In the present paper, the commonly mentioned but poorly recognised microconchid species Microconchus valvatus (Münster in Goldfuss, 1831) is redescribed on the basis of material from the Upper Muschelkalk of Germany. ESEM studies of the microconchid tubes with clear morphological and microstructural characters were compared to the existing known Triassic species. Microconchus valvatus is characterised by fine growth lines and transverse riblets. ESEM analysis shows that tubes which appear smooth under the binocular microscope are in fact abraded. Thus, taphonomy must be taken into account and scanning microscopy must be used during studies of microconchid tubes. Quantitative ecology shows that particular microconchid populations developed various size ranges punctuated by some gaps, have non-normal distributions as expected in time-averaged assemblages, and suggests that differences among populations may reflect distinct hydrologic settings. This study provides a multidimensional investigation of microconchids and offers compelling evidence that microconchids were an important faunal group during the post-recovery Middle Triassic interval. © 2013 The Author(s). Source

Greene S.E.,University of Southern California | Bottjer D.J.,University of Southern California | Hagdorn H.,Muschelkalkmuseum Ingelfingen | Zonneveld J.-P.,University of Alberta
Palaeogeography, Palaeoclimatology, Palaeoecology

Phanerozoic diversity curves illustrate that the transition from taxonomic dominance of the Paleozoic Fauna to taxonomic dominance of the Modern Fauna is coincident with the Permo-Triassic boundary. Although a corresponding transition in ecological dominance must have occurred, its timing is unclear. One way to assess ecological dominance during the Early-Middle Triassic recovery interval is through the study of bioclastic accumulations. Bioclastic accumulations from the Early Triassic are largely dominated by constituents of the Modern Fauna. In this study, we examined bioclastic accumulations from the Middle Triassic, the interval after the environmental stress associated with the end-Permian extinction abated.Bioclastic accumulations from Panthalassan deposits (Ladinian portion of the Liard Formation at Williston Lake, CaČada) and Tethyan deposits (Anisian-Ladinian Muschelkalk Group, Germany) were examined. Although the most common shell bed-producer differed between the two sites (bivalves, constituents of the Modern Fauna, in Germany and brachiopods, constituents of the Paleozoic Fauna, in CaČada), both sites, though geographically disparate, contained significant crinoidal bioclastic accumulations (encrinites).Crinoids, like many constituents of the Paleozoic Fauna, suffered drastic diversity losses at the end-Permian mass extinction and maintained relatively low diversity through the Middle Triassic. Despite reduced diversity, bioclastic accumulations show that crinoids regained some measure of ecologic dominance in the Middle Triassic. In addition, brachiopods, another constituent of the Paleozoic Fauna that suffered severe diversity losses at the end-Permian extinction, regained at minimum local ecological dominance in the Middle Triassic of Panthalassa. These data demonstrate that the transition to Modern faunal taxonomic dominance was decoupled from the transition to Modern faunal ecological dominance. © 2010 Elsevier B.V. Source

Hautmann M.,Palaontologisches Institute und Museum | Hagdorn H.,Muschelkalkmuseum Ingelfingen
Palaontologische Zeitschrift

Middle Triassic marine deposits of the Germanic Basin (Muschelkalk) record a significant proliferation of cementing bivalves from different families. Based on previously undescribed, excellently preserved material from the Willebadessen Member (late Anisian, Illyrian) of the Upper Muschelkalk Trochitenkalk Formation of Willebadessen (Germany), we propose the new genus Noetlingiconcha, type species N. speculostreum sp. nov., for strongly plicate prospondylids lacking auricles. The new genus differs from Terquemia and Enantiostreon in being plicate rather than costate, and from Newaagia in the absence of auricles. We demonstrate that N. speculostreum was invariably attached by its right valve, in contrast to an externally similar species from the Lower Muschelkalk Freudenstadt Formation (lower Anisian, Bithynian) that was exclusively cemented by its left valve and thus represents the geologically oldest known oyster species. Previous reports of amphi-pleurothetic cemented bivalve species from the Muschelkalk probably result from lumping together these two externally similar species. The constancy of sinistral attachment in the geologically oldest Ostreidae suggests that left-pleurothetic valve orientation was already established in the ancestry of this family. Palaeontological data are therefore in accordance with genetic and larval shell morphology analyses that identified Pterioidea as the sister taxon of Ostreoidea, because Pterioidea contains several Permian-Triassic genera with an anatomically lower left valve. © 2012 Springer-Verlag. Source

Menning M.,Helmholtz Center Potsdam | Schroder B.,Behringsweg 6 | Plein E.,Sudliche Hauptstr. 34 | Simon T.,Gehrendshalde 42 | And 9 more authors.
Zeitschrift der Deutschen Gesellschaft fur Geowissenschaften

After the re-unification of Germany on October 3rd 1990, the "Subkommission Perm-Trias" (SKPT) of the German Stratigraphic Commission passed recommendations on 70 applications concerning stratigraphic nomenclature, classification (rank), subdivision of stratigraphic units and items of procedure in Central Europe. Here, the most important 33 of these recommendations are documented, with some additional explanations. A full list of recommendations can be found on the website www.stratigraphie.de/Perm-Trias. The stratigraphic systems of the Federal Republic of Germany and the German Democratic Republic differed significantly and they have now been aligned with each other and with the International Stratigraphic Guide (ISG 1976, 1994). The 33 resolutions given here are listed in five groups by ascending stratigraphic order - Rotliegend, Zechstein, Buntsandstein, Muschelkalk and Keuper - irrespective of when the resolutions were passed. For each unit, the listings include the lower boundary, rank (classification), subdivisions and the results of the voting. Figures are provided to illustrate the position and rank of the stratigraphic units mentioned. After a final resolution fixing the lower boundary of the Rotliegend in 2006, the two groups of the Dyas (Rotliegend and Zechstein = Central European Permian) and the three Germanic Trias groups (Buntsandstein, Muschelkalk and Keuper = Central European Triassic) are now firmly established. The boundaries between the five groups, and those separating the numerous formations within them, are quasi-isochronous across large parts of the Central European Basin (Germanic Basin). This is an extremely valuable geochronological component of the stratigraphy, and to make it fully accessible, the German Stratigraphic Commision has defined 33 "Folgen" (intervals) as "regional geochronological units" (RGU) after thorough discussions. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany. Source

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