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Paleomagnetic data from the Middle Devonian are typically difficult to interpret. Directions and paleointensities often do not fit with dipolar field behavior or expected paleogeography. The reason why the geomagnetic field cannot be reconstructed with traditional methods has been topic of debate, but no consensus has been reached. We would like to understand what happened to the geomagnetic field during the Middle Devonian and why the configuration of the field was potentially unusual.We aim to expand the existing paleomagnetic record for the Middle Devonian by sampling a site in Braunfels, Germany. This site consists of relatively unaltered pillow lavas. Petrographic and rockmagnetic analyses indicate the presence of magnetite and minor maghemite in the samples. We obtained paleomagnetic directions using alternating field (AF) and thermal demagnetization experiments. The directions are scattered and do not cluster around paleomagnetic directions that are expected for Germany in the Devonian.Paleointensity data were acquired using the ZIIZP-Thellier method, resulting in a field intensity of approximately 6 µT, which equals a VADM of 8-15 ZAm2. The latter is in line with very low field intensities generally reported for the Devonian.Various mechanisms have been suggested to explain the typically scattered and ambiguous Devonian paleomagnetic data, such as significant overprinting, tectonic rotations and a non-dipolar field configuration. Our results confirm an extremely weak magnetic field, but this alone does not explain the scattered directions. To exclude the possibility that the scattered directions are related to (partial) overprinting we use Quantum Diamond Microscope imaging to assess the magnetizations of individual magnetic grains instead of the bulk magnetic signal of the sample. With this method, a distinction can be made between e.g., different generations of magnetizations, revealing information on the Middle Devonian geomagnetic field that was previously inaccessible by considering the magnetic moments of bulk samples alone.

The Devonian/Carboniferous (D/C) transition is characterized by a major transgressive/regressive cycle which led to a widespread ocean anoxia known as the Hangenberg Black Shale Event (HBSE), as well to a major sea-level fall (Hangenberg Sandstone Event, HSSE), recognized around the world. Both events are known as the Hangenberg Crisis. In order to examine the D/C transition in shallow water environment, the Mighan section in eastern Alborz was studied in terms of conodont biostratigraphy and stable isotope geochemistry. Twenty-five conodont species belonging to seven genera were identified and 5 conodont zones discriminated; namely, the Bispathodus aculeatus aculeatus Zone, Bispathodus costatus Zone, Bispathodus ultimus Zone, Siphonodella praesulcata Zone, costatus-kockeli Interregnum, and the sulcata Zone. Below the Devonian–Carboniferous boundary (DCB), the Hangenberg Black Shale and Hangenberg Sandstone equivalents were recognized, representing the Hangenberg Crisis that highly affected trilobite, ammonoid, brachiopod and conodont faunas at Mighan and worldwide. The kockeli Zone of the latest Famennian is missing at Mighan due to the lack of conodonts, probably related with the major environmental changes linked with the Hangenberg Crisis recognizable worldwide. Carbon isotopes measured of micrites from Mighan indicate a proximal depositional environment of a shallow shelf with terrestrial input and the oxygen isotope values from conodont apatite suggest warm seawater temperatures of tropical and subtropical setting in the study area.

The lower/upper Emsian boundary witnessed prominent diversification of biostratigraphically important genera Polygnathus Hinde, Caudicriodus Bultynck, and Latericriodus Muller. In contrast, conodonts previously reported around this boundary from the South China Block were characterized by relatively low species or subspecies diversity, and only a few widely distributed and extensively studied zone-defining taxa were recorded. In this paper, conodonts from the Daliantang Formation at the Daliantang section (Guangnan, southeastern Yunnan), one of the representative sections of the transitional facies between the benthic Xiangzhou facies and the pelagic Nandan facies, are investigated. The conodont fauna shows a remarkably high species or subspecies diversity, with fourteen taxa that are assignable to the notoperbonus Zone and inversus Zone. Five polygnathid species are described: P. gronbergi Klapper and Jonson, P. inversus Klapper and Jonson, Polygnathus sp. B, P. luciae Martinez-Perez and Valenzuela-Rios, and P. mashkovae Bardashev. The latter two are reported for the first time from the South China Block. Additionally, three icriodontid taxa are also described, of which L. guangnanensis n. sp. is characterized by distinctly chevron-shaped transverse rows in the anterior part and a well-developed process branching off to the outer side. The new conodont record increases our understanding of the diversification and faunal composition around the lower/upper Emsian boundary in the South China Block. It contributes to the regional and inter-regional biostratigraphical correlation between shallower- and deeper-water facies and also furnishes important South China material for future discussion and deliberation on the position of the lower/upper Emsian boundary.

Upper Devonian carbonates deposited through the Frasnian/Famennian (F/F) stage boundary in the Xom Nha Formation, Central Vietnam, were studied. The section is mainly composed of fossiliferous, brecciated, and laminated limestone beds, while shale beds occur in a subordinate number. Microfacies generally suggests a hemipelagic setting on an outer shelf environment with low sedimentation rates. A sediment accumulation rate of 0.217 cm/kyrs for this section is calculated. The Xom Nha section does not exhibit characteristic black shales or black limestones through the F/F boundary, but instead shows a similar lithology in comparison to other F/F sections in Southeast Asia. The carbonates yielded abundant conodonts, which represent mainly cosmopolitan species but the section differs from most sections in Europe in showing relatively high numbers of Palmatolepis linguiformis species. Deposition through the F/F boundary interval reported here for the Xom Nha section appears to have occurred during a ~1.2 Ma, and shows well-defined climate cyclicity.

A middle Famennian shallow-water vertebrate assemblage is described from the shallow-water shelf deposits exposed in the western Mongolia Hushoot Shiveetiin gol section from the Baruunhuurai Terrane of the Central Asian Orogenic Belt (CAOB). The low diversity, yet abundant chondrichthyan fauna represents a typical shallow-water shark biofacies but lacks the expected protacrodont and phoebodont species, instead comprising almost exclusively of ctenacanthiform shark teeth and a new genus and species Junggarensis ambiguus gen. et sp. nov. This new species appears highly derived, likely occupying the shallow-water niche protacrodont and orodont sharks typically inhabit. The identification of tooth variation in Junggarensis ambiguus gen. et sp. nov. has allowed for the synonymy of previous indeterminate Famennian shark teeth and in turn confirms vertebrate faunal connections between the Central Asian Orogenic Belt and areas along the northern margins of Gondwana.

The Bayankhoshuu Ruins section in southern Mongolia is characterized by strongly thrusted and folded sequences. Overall, three sections ranging from Ordovician to Carboniferous rocks were studied. Facies analysis combined with stratigraphic data provide improved lithostratigraphic descriptions of Palaeozoic successions in the Mushgai region. The overall marine sedimentary sequence is punctuated by volcanic rocks–basaltic lava of Silurian and Middle Devonian age and volcaniclastic bentonite and tuff in the Middle to Late Devonian and Mississippian suggesting an island arc setting. The Minjin Member of the Botuulkhudag Formation (Middle Devonian to Late Devonian) is primarily composed of thick basaltic and subaerial volcanic rocks with minor silicified siltstone and chert inclusions. Thicker successions of limestone occur in the Ordovician/Silurian, Early Devonian, and the Mississippian. The macrofauna is scarce, except distinct limestone horizons where different fossil groups were recognized. Microfossils, such as radiolarians and conodonts, are scarce and generally poorly preserved. However, based on the re-study of collections from earlier publications and new conodont data, a more detailed biostratigraphic record of the Khoyormod, Botuulkhudag, and Arynshand formations of the Bayankhoshuu Ruins section can be developed. For instance, the Arynshand Formation likely ranges from the late Bispathodus ultimus conodont biozone to the Scaliognathus anchoralis–Doliognathus latus conodont biozone. A tectonic breccia occurs in the early Mississippian and is overlain by a red shale of remarkable thickness at the top of this formation which points to subaerial exposure in the early Mississippian (near the Tournaisian/Visean transition). Due to strong tectonic overprint and/or facies, some unconformities/hiatuses occur. Most strata are intensively folded and faulted, ranging from centimeter to meter scale. Overall, deposition likely occurred on either the Mandalovoo or Gurvansayhan Terrane.

A conodont fauna from the uppermost part of the Beiliu Formation at the Nalai section (Guangxi, South China) is studied. Four species of Bipennatus Mawson are described, of which B. hemilevigatus n. sp. is differentiated by a short sulcus flanked by a smooth left margin and a nodose right margin, and B. planus n. sp. is characterized by a distinctly flat, smooth, and narrow platform in the middle part of the blade above the basal cavity. Another species in open nomenclature, Bipennatus? sp., is distinguished by an extremely primitive sulcus or a totally fused and adenticulate ridge above the basal cavity. This paper also reports occurrences of ‘Ozarkodina’? sp. B, Polygnathus nalaiensis n. sp., and P. costatus costatus Klapper. The conodont fauna situates the investigated samples in the lower Eifelian costatus Zone. Taking specimens of Bipennatus from the Hillesheimer Mulde and Bergischen Land (Germany) into consideration, the conodont material furnishes new data on the diversification and phylogeny of this genus. A taxonomic revision of Bipennatus is conducted, and this genus includes B. bipennatus (Bischoff and Ziegler), B. hemilevigatus, B. montensis (Weddige), B. planus, B. scalaris (Mawson), and B. mayri (Uyeno), the latter two are raised herein to species level. More importantly, the prominent diversification of Bipennatus in the costatus Zone cannot be interpreted by previously proposed hypotheses on the phylogeny of Bipennatus, which specifically focus on the development of a characteristic sulcus on the upper margin above the basal cavity. It is apparent that the ornamentation of the narrow or wide platform above the basal cavity is more complicated and variable than previously estimated, and that this genus needs further investigation, especially on the lowest occurrences of its assigned species.

An Upper Devonian to (?)Lower Mississippian section at Hushoot Shiveetiin gol in the Baruunhuurai Terrane of the Central Asian Orogenic Belt (CAOB) was investigated. A generally well-preserved and diverse ostracod fauna was collected from the Late Devonian (Famennian) Samnuuruul Formation in western Mongolia. It is the first rich assemblage described from this area. The ostracod fauna consists of 19 genera and 25 species. Two of the species are proposed new species, and 13 species are described in open nomenclature. The Mongolian ostracod fauna is similar to coeval faunas in western China and Laurussia, but also contains new, endemic species. Two new taxa are described: Beyrichiopsis hushootensis and Ampuloides beckeri. Ostracod findings are characterized by the Eifelian Mega-Assemblage (I-III) representing a nearshore, variable palaeoenvironment which is in accordance with facies analysis provided by other studies.

Herein we report on the most abundant and diverse fauna of Palaeozoic crinoids and blastoids collected from Mongolia to date. The fauna is from the Late Devonian (Famennian) Samnuuruul Formation in western Mongolia. The fauna consists of two genera of blastoids and twelve genera of crinoids—four genera of camerates, three genera of flexibles, one disparid genus, and four genera of cladids. The crinoids and blastoids were living on an active island arc complex in the Central Asian Orogenic Belt (CAOB) in a high physical stress environment with frequent and often voluminous pyroclastic eruptions. The Mongolian fauna is similar to coeval faunas collected from the Hongguleleng Formation in western China and supports the hypothesis that the CAOB was a biodiversity hotspot for Famennian echinoderms and a precursor to the very successful echinoderm communities that dominated Mississippian shallow-marine ecosystems globally. Three new taxa are described. Mongoliacrinus minjini, new genus and species, is the oldest member of the Acrocrinidae, previously known from the Mississippian and Pennsylvanian and the first occurrence of the family outside North America. Eutaxocrinus ariunai and Eutaxocrinus sersmaai are new species of the flexible crinoid Eutaxocrinus, a genus with a widespread distribution during the Early and Middle Devonian, which survived into the Lower Mississippian. It is restricted to the CAOB in the Late Devonian.

The early Famennian phacopid trilobites Feistops mongoliensis gen. nov. sp. nov., Feistops khovdensis gen. nov. sp. nov., ?Feistops sp. A, and ?Houseops olonbulagensis sp. nov. are recorded and illustrated from the western Mongolia Hushoot Shiveetiin gol section from the Baruunhuurai Terrane of the Central Asian Orogenic Belt (CAOB). In this section, exposing large parts of cyclic Famennian shallow-water siliciclastic shelf deposits, Feistops mongoliensis gen. nov. sp. nov., Feistops khovdensis gen. nov. sp. nov., ?Feistops sp. A, and ?Houseops olonbulagensis sp. nov. are the first known and described representatives of trilobites from Late Devonian deposits of western Mongolia. Their affinities with known other sighted species of the same age are discussed.

For decades, scientists have tried to obtain paleomagnetic data from Devonian rocks, but acquiring accurate data from this time period remains problematic. The lack of data has traditionally been interpreted as caused by overprinting during the Kiaman reverse superchron, but recent studies have suggested that the field could have had a non-dipolar configuration. Either way, overprinting is a common problem, although an overprinting mechanism is sometimes lacking. In other cases, data is not interpretable due to large scatter, and a clear explanation has not been found to date.The lack of paleomagnetic data from the Devonian significantly hampers the fundamental understanding of long-term (>100 Myr) magnetic field behaviour and the creation of geodynamo models. However, paleointensities can sometimes be successfully determined, and show that the field was weak to extremely weak during the Late Devonian, with values similar to the Ediacaran.To further constrain the onset of the weak field period, we sampled a succession of Middle Devonian pillow lavas that outcrop in the Philippstein Quarry near Braunfels, Germany. These lavas are subject to some faulting, but are fresh looking and consist of unaltered, unmetamorphosed igneous rock. Pillow lavas cool quickly, which leads to stable magnetic behavior, making them well-suited for magnetic analyses.Here we present our results of traditional paleomagnetic analyses to determine the direction and intensity of the Devonian paleomagnetic field.

The Devonian has long been a problematic period for paleomagnetism. Devonian paleomagnetic data are generally difficult to interpret and have complex partial or full overprints– problems that arise in data obtained from both sedimentary and igneous rocks. As a result, the reconstruction of tectonic plate motions, largely performed using apparent polar wander paths, has large uncertainty. Similarly, the Devonian geomagnetic polarity time scale is very poorly constrained. Paleointensity studies from volcanic units suggest that the field was much weaker than the modern field, and it has been hypothesised that this was accompanied by many polarity reversals (a hyperreversing field). We sampled Middle to Upper Devonian sections in Germany, Poland and Canada which show low conodont alteration indices, implying low thermal maturity. We show that there are significant issues with these data, which are not straightforward to interpret, even though no significant heating or remineralisation appears to have caused overprinting. We compare our data to other magnetostratigraphic studies from the Devonian and review the polarity pattern as presented in the Geologic Time Scale. Combined with estimates for the strength of the magnetic field, we suggest that the field during the Devonian might have been so weak, and in part non-dipolar, that obtaining reliable primary paleomagnetic data from Devonian rocks is challenging. Careful examination of all data, no matter how unusual, is the best way to push forward our understanding of the Devonian magnetic field. Paleointensity studies show that the field during the Devonian had a similar low strength to the Ediacaran. Independent evidence from malformed spores around the Devonian-Carboniferous boundary suggests that the terrestrial extinction connected to the Hangenberg event was caused by increased UV-B radiation, supporting the weak field hypothesis. A fundamentally weak and possibly non-dipolar field during the Devonian could have been produced, in part, by true polar wander acting to maximise core-mantle heat flow in the equatorial region. It may also have influenced evolution and extinctions in this time period. There are a large number of paleobiological crises in the Devonian, and we pose the question, did the Earth’s magnetic field influence these crises?

The Middle to Upper Devonian Kuh-e-Bande-Abdol-Hossein section in eastern Central Iran is an overall shallow marine, nearshore to open marine facies setting that contains a highly variable conodont record generally characterised by an Icriodid-Polygnathid biofacies. The lithology and the palaeoenvironmental setting is similar to other localities in Central Iran and exhibits numerous hiatuses. A continuous biostratigraphic record could not be established, but the section preserves the Givetian/Frasnian boundary. Based on the conodont record, major gaps also occur in the Famennian which confirms earlier results reported from other sections of similar palaeoenvironments in Central Iran.

The Devonian-Carboniferous transition (359 Ma) was a time of extreme climate and faunal change and is associated with the end-Devonian biodiversity crisis. The transition is characterized by transgressive/regressive cycles, which culminated in the onset of widespread ocean anoxia (the Hangenberg Black Shale event) and a remarkable sea-level fall close to the Devonian-Carboniferous boundary (the Hangenberg Sandstone event); together these are known as the Hangenberg Crisis. The Hangenberg Crisis has been documented around the globe, but the trigger mechanisms for its onset remain unknown. The Pho Han Formation on Cat Ba Island in northeastern Vietnam preserves the Devonian-Carboniferous transition and Hangenberg Crisis in a sediment- starved basinal facies on the South China carbonate platform. Although the Hangenberg Black Shale event is generally preserved as a discrete anoxic interval in Devonian-Carboniferous boundary sections of North America and Europe, the Pho Han Formation records sustained dysoxic/anoxic conditions from the Famennian (Upper Devonian) through the Tournasian (early Carboniferous), with severe anoxia (approaching euxinia) throughout the Hangenberg Black Shale event interval (as determined by trace element proxies, increased total organic carbon, and framboidal pyrite distributions). There is also significant mercury enrichment corresponding to the Hangenberg Crisis in the Pho Han Formation. The isolated paleogeography of the region suggests that the mercury is most likely sourced from distal volcanic emissions. It is therefore possible that large-scale volcanic activity acted as a trigger mechanism for the Hangenberg Crisis and biodiversity drop at the Devonian- Carboniferous transition, similar to other major mass extinction events.

Within the Rhenohercynian Zone of the Central European Variscides, the southeastern Rhenish Massif (Germany) contains Paleozoic greywackes and sandstones of uncertain origin and correlation. Herein, detrital zircons from a selection of these rocks are analysed for their U-Pb ages and Lu-Hf values: the Late Ordovician “Andreasteich Quartzite” and the Early Devonian “Dalmanites Sandstone” from the Lindener Mark nappe as well as the “Erbsloch Greywacke” from its type locality in the southern Kellerwald. In addition, the latter greywacke and the “Damm-Muhle Greywacke” from the Steinhorn nappe in the Lahn-Dill area were investigated petrographically. We present a data set for U-Pb ages of 542 detrital zircon grains together with Lu-Hf isotope systematics of 202 dated zircons. U-Pb zircon ages, eHf ratios, and model ages point to an exotic provenance for the sedimentary rock units relative to the Rhenohercynian Zone. The rocks were thrust as top-NW nappe complexes onto the southern Rhenohercynian Zone during Laurussia-Gondwana-collision following the closure of the Rheic Ocean. Potential source areas are identified in the Armorican (Cadomian) part of the Variscan orogen. In terms of paleogeography, the sedimentary rocks were most likely deposited along the southern margin of the Rheic Ocean, presumably on a shelf marginal to the Saxo-Thuringian Zone. This provenance is consistent with the presence of Devonian faunal elements in respect to the surrounding Rhenohercynian Zone and have northern Gondwana biogeographic affinity. Thin section analysis in conjunction with provenance data give rise to the interpretation that andesitic volcanoes existed in the southern Rheic Ocean at the time of sedimentation. Recent publications about revised biostratigraphy and paleobiogeography of Lower Devonian provide grounds for discussion about the age of these sediments.

The Devonian has long been a problematic era for paleomagnetism. Devonian data are generally difficult to interpret and have complex partial or full overprints. These problems arise from paleomagnetic data obtained from both sedimentary and igneous rocks. As a result, the reconstruction of motions of tectonic plates is often troubling, as these rely on apparent polar wander paths constructed from Devonian paleomagnetic poles. Also the geomagnetic polarity time scale for this time period is poorly constrained. Paleointensity studies suggest that the field was much weaker than the field of today, and it has been hypothesised that this was accompanied by many polarity reversals (a hyperreversing field). We review studies on Devonian paleopoles, magnetostratigraphy and paleointensity. We tentatively suggest that the field during the Devonian might have been so weak and perhaps of a non-dipolar configuration, that obtaining reliable paleomagnetic data from Devonian rocks is extremely difficult. In order to push forward the understanding of the Devonian field, we emphasise the need for studies to provide fully accessible data down to specimen level demagnetisation diagrams. Incorporating all data, no matter how complex or bad they might seem, is the only way to advance the understanding of the Devonian magnetic field. Recent paleointensity studies appear to suggest that the Devonian and Ediacaran were both extreme weak field intervals. For the Ediacaran, it has been hypothesised that the field had an impact on life on earth. A fundamentally weak and perhaps non-dipolar field during the Devonian might have had an influence on evolution and extinctions. As there is a large number of biological crises in the Devonian, we here pose the question whether the Earth’s magnetic field was a contributing factor to these crises. New independent evidence from the Devonian-Carboniferous boundary suggests that the Hangenberg event was caused by increased UV-B radiation, which is in line with a weak magnetic field.

The global polarity time scale (GPTS) is relatively unconstrained for the Paleozoic, particularly the Devonian. Constraining the GPTS and reversal frequency for the Devonian is crucial for the understanding of the behaviour of Earth’s magnetic field. Furthermore, construction of a GPTS for the Paleozoic could provide a valuable tool for age determination in other studies. However, most paleomagnetic data from the Devonian is problematic. The data are difficult to interpret and don’t have a single easy to resolve (partial or full) overprint. Paleointensity studies suggest that the field was much weaker than the field of today, which could have been accompanied by many reversals (a hyperreversing field). In order to improve the geomagnetic polarity time scale in the Devonian, and quantify the number of reversals in this time, we sampled three Devonian sections in Germany, Poland and Canada. These sections show evidence that the rocks were not significantly heated, and they show little evidence for remineralisation. This minimises the chance the rocks were remagnetised after the Devonian. Our data show that even when rocks are well qualified to have reliably recorded the Devonian field, the interpretation is not straightforward. We also discuss problems with the Devonian GPTS as presented in the geologic timescale.

Non-metamorphic Palaeozoic sedimentary successions without major breaks exist in the Istanbul Zone of the Western Pontides (northern Turkey) and in the Taurides (southern Turkey). Based on different proxies, a Gondwanan affinity has been determined for the Taurides; however, the palaeogeographical position of the Istanbul Zone is still controversial. The aim of this paper is to discuss possible contributions of late Silurian and Devonian ostracods to the palaeogeographical assignment of the Western Pontides (Istanbul Zone). Furthermore, ostracods of the Taurides have also been evaluated in terms of the palaeogeographical setting of this terrane. Late Silurian ostracods of the Istanbul Zone (Western Pontides) show close similarities at the species level with the assemblage from the upper Silurian (Ludlow) rocks of Baltica. This Laurussian affinity indicates a palaeogeographical setting to the north of the Rheic Ocean for the Pontides during the late Silurian. The Devonian ostracod assemblages of both the Taurides and the Istanbul Zone have an affinity to both Laurussia and Gondwana. Therefore, a faunal link should exist during this long period between Laurussia and Gondwana. The faunal link between the two palaeocontinents can be explained on the one hand by a narrow ocean with shallow pathways. On the other hand, a wider ocean with long-shore currents, with broad and shallow shelf areas and/or islands functioning as stepping stones would also allow a faunal link for benthic ostracods. © 2018, Senckenberg Gesellschaft für Naturforschung and Springer-Verlag GmbH Germany, part of Springer Nature. Firat University Scientific Research Projects Management Unit TUR04/009, 01DL12036 111Y179 104Y218 Funding information This study was supported by TÜBİTAK/Turkey (DEVEC-TR, Project No. 104Y218, and DECENT, Project No.111Y179), the International Bureau of the BMBF/Germany (Project Nos. TUR04/009 and 01DL12036) and the Çukurova University Scientific Research Projects Coordination Unit (Project Nos. MMF2009YL56 and MMF2012BAP4).

Middle Devonian conodonts from the Si Phai section in NE Vietnam are described. The section ranges from the Middle Devonian ensensis to timorensis conodont zones to the Late Devonian rhomboidea conodont Zone. A rich overall assemblage is described, including 27 taxa of species or subspecies rank and 11 taxa described in an open nomenclature. Among the dominant Polygnathus forms, four new taxa are described: Polygnathus linguiformis saharicus subsp. nov., Polygnathus linguiformis vietnamicus subsp. nov., Polygnathus rhenanus siphai subsp. nov., and Polygnathus xylus bacbo subsp. nov. Conodont assemblages are attributed to polygnathid, polygnathid-klapperinid, and klapperinid conodont biofacies representing hemipelagic to pelagic environments. The klapperinid biofacies, unreported in the previous literature, are here attributed to offshore areas of the external shelf. The taxonomic compositions of the studied conodont assemblages, as well as their CAI characteristics (CAI 4–5), suggest a palaeogeographic affinity of the studied strata to the Chinese Devonian Guangxi Basin, and the South China Terrane in general. Furthermore, the conodont biofacies and the palaeogeographic distribution of the fauna are discussed.

A bryozoan fauna from the Late Devonian (Frasnian) of the Bahram Formation of the Zefreh section in central Iran contains four species: three trepostomes and one rhabdomesine cryptostome. Two species are new: the trepostome Coeloclemis zefrehensis sp. nov. and the rhabdomesine cryptostome Euthyrhombopora tenuis sp. nov. The trepostome species Cyphotrypa definita Morozova, 1960 and Anomalotoechus ramosus Morozova, 1960 were recorded previously from the Upper Devonian (Frasnian) of the Kuznets Basin. The genera Coeloclemis and Euthyrhombo-pora are recorded from the Devonian for the first time. The fauna is dominated by the erect ramose Euthyrhombopora tenuis sp. nov., with rare occurrences of the massive Cyphotrypa definita Morozova, 1960. The bryozoans indicate low to moderate water energy environment of middle to outer ramp position.

The Late Devonian (383-359 Ma) was a time of prolonged climate instability with catastrophic perturbation of global marine ecosystems at the Frasnian-Famennian (F-F) and the Devonian-Carboniferous (D-C) boundaries. The causes and mechanisms of anoxia and extinction at the F-F interval are not clearly delineated, and alternative explanations for virtually every aspect of this interval are still intensely debated. In many (but not all) locations, the F-F interval is characterized by two dark, organic-rich lithologies: the Lower and Upper Kellwasser beds (as originally described in Germany) that represent a stepwise ocean anoxia and extinction sequence. The Upper and Lower Kellwasser anoxia event beds are often collectively termed the Kellwasser Event, and the termination of this sequence is within the Upper Kellwasser Event at the F-F boundary. Current knowledge is limited by significant sampling bias, as most previous studies sampled epicontinental seaways or passive continental shelves, primarily from localities across Europe and North America. Together these formed a single equatorial continent with a rising mountain chain during the Late Devonian. Our understanding of the Kellwasser Event is thus based on data and observations from a restricted set of paleoenvironments that may not represent the complete range of Late Devonian environments and oceanic conditions. In the last decade, new methodologies and research in additional paleoenvironments around the world confirm that the Kellwasser Event was global in scope, but also that its expression varies with both paleoenvironment and paleogeography. Studying the many differing geochemical and lithological expressions of the Kellwasser Event using a) a wide variety of paleoenvironments, b) a multiproxy approach, and c) placement of results into the broader context of Late Devonian marine biodiversity patterns is vital for understanding the true scope of ocean anoxia, and determining the causes of the marine biodiversity crisis at the F-F boundary. Highlights • Bias in existing samples limits understanding of the Frasnian-Famennian biodiversity crisis and the Kellwasser anoxia event. • The Kellwasser Event was global but its expression is highly dependent on paleoenvironment and paleogeography. • The Kellwasser Event was due to "top-down" climate forcing with surface eutrophication not upwelling anoxic bottom water. • The F-F crisis was a lack of species origination in environments with climate stress and changes in sediment/nutrient supply.

The Sarhlef Formation, which hosts the massive sulphide deposits of the Moroccan Meseta, has been considered as Carboniferous in age. Moreover, palynological analysis of the black shales hosting the Draa Sfar deposit (Central Jebilet) has allowed to restrict the age of the Sarhlef Formation to the late Visean (Asbian). However, this age is not compatible with geochronological data of various magmatic intrusions present in Central Jebilet. New biostratigraphic results based on metamorphosed conodonts from 34 samples (three cores, DS170, DF306 and DS125) of the Draa Sfar deposits provide a new biostratigraphic framework of the Sarhlef Formation. The collected fauna is affected by pyritization, silicification and tectonic deformation. Some non-pyritised or partially pyritized conodonts show a conodont color alteration (CAI) change varying from black to translucent (CAI 5 to CAI 8). The conodont fauna comprise representatives of the genera Icriodus, Polygnathus, Ancyrodella, Palmatolepis, Ancyrognathus, Ancyroides, and Palmatolepis showing that age spans from the Frasnian to Late Famennian. This age is more compatible with the radiometric data of the intrusive magmatic rocks. In core DS170, the Upper Kellwasser Horizon at the Frasnian-Famennian boundary has been identified by lithological characteristics and stratigraphy. The proposed Late Devonian age of the Sarhlef Formation provides new insights on the geological evolution and stratigraphy of the entire region.

The Zefreh section in central Iran represents a carbonate ramp succession with a general shallow-marine palaeoenvironment. This section represents most of the Bahram Formation (Givetian to at least Middle falsiovalis Zone) and consists of a very heterogeneous succession of medium- to coarse-grained sandstones, skeletal pack- to grainstones with local biostromes, massive or laminated dolostones, and shales. Microfacies analysis allowed the discrimination of 12 microfacies reflecting supratidal to open marine palaeoenvironments. The shallow-marine environment was investigated using facies analysis and geochemical proxies. Redox conditions in the Zefreh section appear to be primarily oxic and support the facies and sedimentological results. The provenance of the Zefreh sediments using La, Sc, Zr, and Th indicates that they are most likely derived from continental arc volcanics which is consistent with the preliminary tectonic interpretations. Conodonts and brachiopods were used for establishing the biostratigraphical framework. The lack of important zonal index taxa of the widely applied conodont standard zonation requires the application of an alternative shallow-marine conodont zonation. Based on conodont and brachiopod data, the Zefreh section covers sediments ranging from the upper Givetian to lower Frasnian.

A rich assemblage of Middle Devonian (late Eifelian) polychaete jaws (scolecodonts) from the Blankenheimerdorf section in the type Eifel area, western Germany, is described. The top part of the section also reflects the onset of the global Kacak Event. The sediments of the section were deposited in a shallow to deep subtidal environment on the southern Avalonian margin. The habitat was obviously favourable for jaw-bearing polychaetes, which are represented by 18 species belonging to 9 genera. The assemblage is dominated by polychaetaspids, followed by mochtyellids, paulinitids and kielanoprionids. Notably, this study documents one of the oldest records of kielanoprionids, a polychaete family common since the Middle Devonian and closely related to the extant Hartmaniellidae. This may indicate that a prominent change in jawed polychaete evolution occurred during the Early–Middle Devonian transition. Moreover, we present new information on polychaete palaeobiogeography, which when compared with previously described Devonian scolecodonts shows that very similar polychaete faunas with many species in common were widespread in today's Europe and North America.

The Wetteldorf section is the Global Stratotype Section and Point (GSSP) locality of the Lower–Middle Devonian boundary. The section is characterized by an alternation of marls, limestones, and siltstones, with the base of the Eifelian stage defined by the first occurrence of the conodont Polygnathus costatus partitus. The well-established conodont biostratigraphy for this section permits correlations with other time-equivalent sections; however, a cyclostratigraphic framework does not yet exist for this section. Here, we construct such a framework that provides an additional tool for long-distance correlation, and at the same time constrains the amount of geologic time represented by this stratigraphic interval. Microfacies analysis indicates that the entire section has been deposited in an open-marine shelf paleoenvironment, below the storm wave base and under oxygen-rich conditions. We collected high-resolution (5-cm spaced) geochemical data, using a handheld X-ray fluorescence (XRF) spectrometer, and quantified net intensity results for 23 chemical elements. By using factor analysis, we explain 52% of the observed variance in those elements by a model that consists of four factors. The most important factor, factor 1, is driven by geochemical elements related to detrital input (e. g. K, Rb, Si, Ti). Factor 2 is interpreted as a pyrite-indicator, while Factor 3 is driven by Ca and Sr and is thus tied to lithological variations in carbonate content. Factor 1 and 3 are used for cyclo-stratigraphy, as their respective power spectra show similar characteristics. Both factors exhibit a strong 58-cm period, which can be interpreted, according to the available biostratigraphic constraints, either as the imprint of the 18-kyr precession cycle or as the imprint of the 33-kyr obliquity cycle. However, the ratio between different spectral peaks in the different proxies’ power spectra strongly advocates the first option. Our interpretation in terms of astronomical climate forcing implies that the 8.65 meter thick Wetteldorf section (within the Happel Hut) is characterized by an average sedimentation rate of ∼ 3.2 cm/kyr and represents ∼ 250 kyr. From a paleoclimatological point of view, our results indicate that detrital input into the Rhenohercynian Basin was spurred under high-eccentricity configurations, which allowed for strongly enhanced seasonal rainfall. Under astronomical configurations that avoided extremes in seasonality for a prolonged period of time (simultaneously low eccentricity and obliquity), Factor 2 indicates the occurrence of pyrite, which we associate with temporary deteriorations of generally well-oxygenated conditions.

The face of Planet Earth has changed significantly through geological time. Dynamic processes active today, such as plate tectonics and climate change, have shaped the Earth’s surface and impacted biodiversity patterns from the beginning. Organisms, on the other hand, have the capacity to significantly alter Earth’s hydrological and geochemical cycles, its atmosphere and climate, sediments, and even hard rocks deep down under the surface. Abiotic– biotic interactions characterize Earth’s system history and, together with biotic competition and food webs, were the main trigger of evolutionary change, innovations and biodiversity fluctuations. Within the Palaeozoic, the Devonian was an especially interesting time interval as it was characterized by the ‘mid-Paleozoic predator revolution’ (Signor & Brett 1984; Brett 2003) and the related ‘nekton revolution’ (Klug et al. 2010), characterized by the blooms of free-swimming cephalopods, including the oldest ammonoids, and fish groups (e.g. toothed sharks and giant placoderms), the rise of more advanced vertebrates, including the oldest tetrapods (e.g. Blieck et al. 2007, 2010; Niedzwiedzki et al. 2010), the most extensive reef complexes of the Phanerozoic (e.g. Kiessling 2008), and the ‘greening of land’ by the diversification and spread of land plants, including the oldest forests (e.g. Stein et al. 2012; Giesen & Berry 2013), which resulted in new soil types and changing weathering. These major evolutionary trends did not unfold in a long interval of environmental stability, but in times of numerous and repeated, geologically brief, global events that punctuated prolonged periods, up to several million years in duration, of relative stability, termed ecological-evolutionary subunits (EE subunits: Boucot 1990; Brett & Baird 1995; Brett et al. 2009). The bounding events, even those of lesser intensity, produced major re-structuring in local to global ecosystems and are seen as critical drivers of long-term evolutionary patterns (Brett 2012). These linked abiotic and biotic events and extinctions of different magnitude have been summarized by House (1983, 1985, 2002), Walliser (1984, 1996) and, more recently, by Becker et al. (2012). The Devonian event succession is summarized in Figure 1. Two first-order mass extinctions at the Frasnian–Famennian boundary (Kellwasser Crisis) and at the end of the Devonian (Hangenberg Crisis), characterized by the loss of major fossil groups (classes and orders) and complete ecosystems (e.g. metazoan reefs, early forests), have to be viewed in the context of a complex global event sequence. There are important similarities between discrete pulses/phases of the major biotic crises and individual smaller-scale events. In our understanding, second-order global events are characterized by sudden extinctions in many groups and ecosystems, including the complete disappearance of several widespread and diverse organism groups (orders and families). Examples are the basal Emsian atopus Event, where the planktonic graptolites finally died out, the Taghanic Crisis, Frasnes events and Lower Kellwasser Event. Third-order global events show globally elevated extinction rates, often at lower taxonomic level (genera and species), but within many clades and in several ecosystems. Examples are the Silurian–Devonian boundary Klonk Event, and the Daleje, Chotěc, Kacak, Condroz and Annulata events. Fourth-order global extinctions refer to the sudden disappearance of relatively fewer but widespread groups, which implies a global, not regional, trigger. This category may include the Lochkovian–Pragian boundary

Sedimentary organic matter derives from biological precursor material which undergoes systematic, irreversible changes upon burial which mainly reflect increasing diagenetic temperatures, although other factors have also an influence. Several parameters have been established in the last decades to determine the palaeotemperature history of sedimentary rocks based on geochemical or petrographical methods. Organic matter is the most temperature-sensitive solid constituent in sedimentary rocks and vitrinite reflectance (VR), miospore and conodont colour alteration are among the most widely used optical maturity parameters. Despite tremendous interest in estimating maturity parameters in the oil generation zone as well as for high grade diagenesis and metamorphism and despite decades of research only a few of these methods have been well established and compared to each other by now. The focus of this review is on some new aspects with respect to organic matter maturation and optical palaeotemperature parameters, especially for high grade diagenesis and anchimetamorphism. Such a discussion might be a prerequisite for a better understanding of palaeotemperature assessments in different sedimentological and/or geotectonic settings and useful for different fields in applied sciences. Furthermore, suggestions for further research are discussed.

Four sections of mainly Middle Devonian (Givetian) shallow-marine rocks at the northern margin of Gondwana (Central Iran) were investigated with a special focus on the Bahram Formation, as the stratigraphic range of the Bahram Formation is uncertain and still under discussion. Generally, the Bahram Formation is discontinuously underlain by the Lower Devonian Padeha Formation and disconformably overlain by the Permian Jamal Formation. Conodont communities from the four sections in the Soh area (Najhaf and Neqeleh sections) and the Natanz area (Varcamar and North Tar sections) were investigated. The most widely applied conodont standard zonation of the Upper Givetian contain taxa characteristic of deeper shelf facies whereas conodont fauna of the investigated sections mainly show affinities to shallow-marine environments. Shallow-water conodont associations corresponding to the expansus Zone and subterminus Zone are described from Central Iran for the first time, whereas the vast majority of icriodontid and polygnathid faunas were reported from shallow-marine carbonates around Laurussia (e.g. North America, and Europe). Thirty-six species and subspecies were assigned to five genera (Ancyrodella, Bipennatus, Icriodus, Polygnathus and Pandorinellina). The sedimentological record is characterised by remarkable lateral facies changes, but in the upper part of the Givetian, a general transgressive trend is obvious due to the dominance of limestones and small biostromes.

Three out of seven institutes belonging to the Senckenberg Gesellschaft fur Naturforschung (SGN) house considerable palaeontological collections: The Senckenberg Research Institute and Natural History Museum in Frankfurt on the Main including the Research Station on Quaternary Palaeontology in Weimar, the Senckenberg Naturhistorische Sammlungen Dresden and the Senckenberg Museum fur Naturkunde in Gorlitz. The palaeontological collections of the SGN comprise a total of more than two million specimens and series. Traditionally the different institutes have different stratigraphic and regional focal points, due to the long history of most collections. Frankfurt has a focus on the Palaeozoic (especially Devonian) of the Rhenish slate mountains and the Eocene of the Messel fossil pit (an UNESCO world-heritage site since 1995), Dresden has a focus on the Cretaceous of Saxony and the Tertiary of Central Germany, whereas the smaller collections in Gorlitz have a focus on Eastern Saxony and the Lausitz.

The record of conodonts related to the Mississippian/Pennsylvanian boundary interval was investigated in four sections in Central Iran from two different structural units. Two sections from the Sanandaj–Sirjan trend zone (Asad-abad, and Darchaleh sections) and two from the East-Central Iran Microplate (Shesh-angosht and Kale-Sardar sections) exhibit a nearly complete record previously described across the Mississippian/Pennsylvanian boundary in Iran. The investigated sections can be subdivided in three formations (Ghaleh-, Absheni-, and Zaluda Formation) which belong to the Sardar Group. The mid-Carboniferous boundary was defined by the occurrence of Declinognathus noduliferus s.l.. Bio-event characteristics of the Carboniferous conodont fauna (Mississippian genera Gnathodus and Lochriea have been replaced by Pennsylvanian genera Declinognathus and Idiognathodus) as well as sedimentological changes within overall shallow water deposits were located approximately 33° S of the paleoequator and suggest sea-level changes within the framework of the Late Paleozoic Ice Age (LPIA). Furthermore, a widespread crinoid marker horizon previously described from two localities in Iran can be subdivided into three units of different ages.

On Cat Ba Island in northeastern Vietnam, the Devonian to Carboniferous (D–C) transition consists mainly of ramp carbonates intercalated with black shale beds (Beds 1 to 176) in the Pho Han Formation and is one of the few records of the D–C transition of the eastern Paleotethys. The three main facies of the sequence are Facies 1 (alternations of whitish gray to gray limestone and marl), Facies 2 (calcirudite, Bed 115b), and Facies 3 (alternations of dark gray limestone and organic-carbon-rich black shale, Beds 115c–120 and 126–129). The latest Famennian (Siphonodella praesulcata Subzone) conodont assemblage of S. praesulcata, Palmatolepis gracilis, Palmatolepis sigmoidalis, and Rhodalepis polylophodontiformis was recognized in Beds 113–115c. Beds 105–112 commonly contain Palmatolepis expansa, P. gracilis, and P. sigmoidalis. Bed 119 yielded a basal Carboniferous index conodont Siphonodella sulcata. In Beds 116–118, solenoporids such as Pseudochaetetes elliotti and Parachaetetes sp. were characteristic species in organic-carbon-rich dark gray limestone. Facies 1 is characterized by bioclastic, peloidal, and intraclastic grainstone and packstone containing massive normal grading and cross-laminations, and is interpreted to represent deep ramp carbonates above storm wave base. Facies 2 is represented by typical lag deposits overlying a transgressive surface. Facies 3 comprises organic-carbon-rich black shale and minor scour-filling bioclastic, peloidal, and intraclastic packstone, and may represent a marginal basin plain environment surrounding a carbonate ramp. The alternations of organic-carbon-rich black shale and dark gray packstone (Facies 3) show no evidence of bioturbation and have high TOC contents (0.18–5.73 wt.%). A minor succession within the transgressive lag deposits (from Bed 115b of Facies 2 to Beds 115c–120 in the lower part of Facies 3) is equivalent to the Hangenberg Black Shale (s. l.) in the middle part of the Siphonodella praesulcata to Siphonodella sulcata zones, because Beds 115b–120 characterized by no evidence of bioturbation and high TOC contents are interpreted to be accumulated in anoxic to dysoxic conditions.

The southern Rheinisches Schiefergebirge, which is part of the Rhenohercynian zone of the Central European Variscides, exhibits several allochthonous units: the Giesen-, and the Horre nappe, and parts of the Frankenbach imbrication zone. These units were thrust over autochthonous and par-autochthonous volcano-sedimentary complexes of the Lahn and Dill–Eder synclines. This paper reports a representative data set of U–Pb LA–SF–ICP–MS ages of 1067 detrital zircon grains from Devonian and Lower Carboniferous siliciclastic sediments of the autochthonous and the allochthonous areas, respectively. The cluster of U–Pb ages from the allochthonous units points to a provenance in the Saxothuringian zone. Zircon populations from the Saxothuringian zone are representative of a Gondwanan hinterland and are characterized by age clusters of ~ 530–700 Ma, ~ 1.8–2.2 Ga, ~ 2.5–2.7 Ga, and ~ 3.0–3.4 Ga. Further samples were taken from the autochthonous and par-autochthonous units of the Lahn–Dill and Kellerwald areas. A Lower Devonian sandstone sample from the Siegen anticline provides a reference for siliciclastic sediments derived from the Old Red Continent. These samples show a provenance representative of Laurussia with debris primarily derived from Baltica and Avalonia. U–Pb zircon age clusters occur at ~ 400–450 Ma, 540–650 Ma, 1.0–1.2 Ga, ~ 1.4–1.5 Ga, ~ 1.7–2.2 Ga, and 2.3–2.9 Ga. Provenance analysis and geochemical data of the Rhenohercynian zone provide new information on the evolution of magmatic arcs in the Mid-Paleozoic. The data set constrains top-SE and top-NW directed subduction of the oceanic crust of the Rheic Ocean. Subduction-related volcanism lasted from the Early Devonian to the Early Carboniferous and thus confirms the existence of the Rheic Ocean until the Early Carboniferous. The tectonic model outlined for the Rhenohercynian zone suggests a wide Rheic Ocean.

The Brilon-reef complex is one of the biggest Devonian carbonate buildups (*80 km 2 ) of the Rhei- nisches Schiefergebirge. The Burgberg section is located in the southeastern fore-reef area of the Brilon Reef Complex and exposes a succession of strata (117 m thick), which extends from the Middle Givetian (middle varcus conodont Zone) to the Visean (bilineatus cono- dont Zone). Field and microfacies observations led to the definition of nine microfacies that are integrated into a sedimentary model divided into off-reef, intermediate fore-reef, and proximal fore-reef sedimentary domains (SD). The off-reef domain (SD1) is the most distal set- ting observed and is characterized by fine-grained sedi- ments, dominated by pelagic biota and the local occurrence of gravity-flow deposits. The intermediate fore-reef (SD2) is characterized by a mixture of biota and sediments coming from both deeper-water and shallow-water sources and is influenced by storm and gravity-flow currents. In this domain, Renalcis mound- like structures developed locally. Finally, the proximal fore-reef (SD3) corresponds to the most proximal setting that is strongly influenced by gravity-flow currents derived from the Brilon Reef Complex. The temporal evolution of microfacies in the fore-reef setting of the Burgberg section show five main paleoenvironmental trends influenced by the onset, general development, and demise/drowning of the Brilon Reef Complex. Fore-reef to off-reef lithologies and their temporal changes are from the base to the top of the section: (U1)—fine- grained sediments with large reef debris, corresponding to the initial development of the reef building upon submarine volcaniclastic deposits during the Middle Givetian (middle varcus Zone) and first export of reef debris in the fore-reef setting; (U2)—high increase of reef-derived material in the fore-reef area, corresponding to a significant progradation of the reef from the Middle Givetian to the Early Frasnian (maximum extension of the Brilon Reef Complex to the south, disparilis to the falsiovalis conodont biozones); (U3)—progressive decrease of shallow-water derived material and increase of fine-grained sediments and deep-water biota into the fore-reef setting, corresponding to the stepwise with- drawal of the reef influence; from the Middle to the Late Frasnian (jamieae conodont Zone); (U4)—development of a submarine rise characterized by nodular and ceph- alopod-bearing limestones extending from the Late Frasnian to the Late Famennian corresponding to the demise and drowning of the Brilon Reef Complex as a result of the Late Frasnian Kellwasser events (upper rhenana and triangularis conodont biozones); (U5)— significant deepening of the Burgberg area starting in the Late Famennian, directly followed by an aggrading trend marked by pelagic shales overlying the nodular limestone deposits.

Conodonts collected from sections near the small towns of Thong Pha Phum and Mae Sariang in the westernmost part of Thailand are used to reconstruct the neodymium (Nd) isotopic composition of seawater during the Late Devonian. The study provides the first Devonian seawater signatures recognized within the Australian shelf of northeastern Gondwana and the adjacent Paleotethys Ocean. At Thong Pha Phum site, the seawater was characterized by very low e Nd values (from − 13.1 to − 18.2) and very high Sm/Nd ratios (between 0.36 and 0.66). In contrast, the seawater at the Mae Sariang site was characterized by much more radiogenic signatures (e Nd values from − 8.7 to − 11.1) and uniform, low Sm/Nd ratios (between 0.20 and 0.23). Extremely low e Nd values recognized at Thong Pha Phum attest to a passive margin continental setting and a paleogeographic position very close to a continental area where Paleoproterozoic and Neoarchean rocks were eroded. Thus, the isotopic data provide strong evidence that during Late Devonian time the Sibumasu terrane was situated in the proximity to the Archean cratons of Western Australia, presumably adjacent to the Carnarvon intracratonic basin. Moreover, Sibumasu may not have been situated in an outboard position on the shelf, as previously suggested, but could have been directly attached to the Australian continental crust. By contrast, low and uniform Sm/Nd ratios of seawater at Mae Sariang resemble those of the Variscan and the present-day oceanic seawaters. Therefore, a pelagic setting within the Paleotethys Ocean is postulated for the Mae Sariang succession. This conclusion is also constrained by minor temporal changes in e Nd values and suggests that the Paleozoic of Mae Sariang is not part of the Sibumasu terrane but belongs to the Inthanon Zone.

An 11 m thick condensed sequence of Late Devonian limestones in northwestern Thailand exhibits faunal associations and sedimentological-/microfacies data which are indicative of a pelagic facies setting. The entire long-ranging section is completely free from clastic input. Similar successions are known worldwide in a few sections only. The Mae Sariang section is characterised by low sedimentation rates as recognised by a number of hardgrounds, neptunian dikes and Fe/Mn crusts. The succession comprises a number of pelagic faunal elements e.g. conodonts, cephalopods and pelagic ostracodes. The fauna records rare macrofossils and the faunal diversity is low. The very condensed section ranges from the Late rhenana to praesulcata conodont biozones, but contains some global events as undoubtedly shown by biostratigraphical and carbon-isotope results (including major Kellwasser and Hangenberg biotic crises). In terms of plate tectonics this important succession most probably belongs to the Inthanon Zone comprising remnants of the Paleotethys Ocean.

A Middle Devonian section in the Blankenheim Syncline (northern Eifel, Rheinisches Schiefergebirge) contains a rather diverse fauna dominated by bryozoans, brachiopods, corals and other taxa, such as calcimicrobes. The section covers sediments of the Junkerberg Formation and the transition to the Freilingen Formation. The transition between the Junkerberg and Freilingen formations coincides with the base of the otomari Event Interval. The section displays an overall transgressive trend in shallow subtidal and deeper subtidal environments below fair-weather wave base. In contrast to the general transgressive trend, one horizon is interpreted to represent a regressive trend of local origin. Sedimentation rates were quite low, as indicated by the abundant occurrence of suspension-feeding organisms. According to Standard Microfacies Types (SMF), the carbonates represent mainly wackestones and floatstones and can be assigned to SMF 5 and SMF 8, respectively. Complex fossil communities in some horizons suggest excellent living conditions during deposition. Large abundances of calcifying taxa, such as Girvanella, occur in some layers, particularly at the base of the Junkerberg Formation. Other encrusting/calcifying organisms are present in various layers, suggesting deposition during supersaturation of CaCO3 minerals in a calcite sea in a low-energy environment. The studied bryozoan fauna is very diverse throughout the entire section, erect branching colonies being dominant. Five new taxa are described: the trepostomes Trachytoechus globosus sp. n., Multihemiphragma minor sp. n. and Eridotrypella multaeformis sp. n., and the rhabdomesine cryptostomes Isostylus vulgaris n. sp. and Bigeyella prima n. sp. Lenaporidae fam. n. is erected for the genera Lenapora and Bigeyella.

There is a mistake in the caption of Fig. 8m. It should be “Svantovites lethiersi Casier, 1979” instead of “Svantovites lethiersi Becker 1971”.