In the late Lochkovian a regression is documented in several areas of the world, followed by a transgression in the early Pragian. Connected with the eustatic variation, a minor extinction event occurred ("Lochkovian-Pragian Event"), affecting several fossil groups, a strong reduction of carbonate production and sedimentary facies changes. The Carnic Alps are a key area for studying this event, because Lower Devonian rocks are widely exposed, representing diverse sedimentary environments from shallow water to relatively deep shelf. Fourteen sections were measured along the Carnic Alps across the Lochkovian-Pragian boundary. In the shallower part of the basin, both the Polinik and the Seekopf formations span the boundary, but evident erosional surfaces are observable in the field at the Lochkovian-Pragian boundary. Above the unconformity, at places the so-called megaclast horizon is present in the Seekopf Formation. In intermediate settings the Rauchkofel Fm. is unconfomably followed by the Kellerwand Fm., and different parts of the upper Lochkovian and lower Pragian are missing in the various sections. In the deeper parts of the basin the transition from the La Valute Fm. to the Findenig Fm. is slightly diachronous from the latest Lochkovian to the earliest Pragian; however, conodonts and tentaculitids are rare in the marly boundary beds, preventing a precise chronostratigraphic calibration of these levels. At places, evidence of subaerial exposure at the formational boundary is documented. In general, the hiatus seems to be larger in the western part of the Carnic Alps, in correspondence with the shallower parts of the succession, suggesting a sea level drop in the late Lochkovian, followed by a transgression in the Pragian. Data from the Carnic Alps are compared with those of other regions of North Gondwana to demonstrate that the sea- level variation at the Lochkovian-Pragian boundary are of global importance

The end of the Ordovician witnessed major perturbations in the ecosystem, seriously affecting global marine biodiversity. Nevertheless, some marine organism groups and their crisis -bound palaeogeographic distribution are still understudied. Among the outliers are eunicid polychaetes, even though they flourished and diversified extensively during the Ordovician. A collection of seven genera of jaw-bearing polychaetes, including the new ramphoprionid genus Spitiprion Tonarov & aacute;, Suttner, & Hints, with type new species of Spitiprion khannai Tonarov & aacute;, Suttner, & Hints, is described here from Katian (Upper Ordovician) deposits of Spiti, northern India. The new species is preserved as isolated maxillae and a jaw cluster, and 3D models of the maxillary apparatus are reconstructed based on submicron-CT. Along with the scolecodonts, a low -diversity assemblage of chitinozoans was recovered, comprising five genera. The most common chitinozoan species are Acanthochitina cf. cancellata and Spinachitina suecica .

The Late Devonian-early Carboniferous aged Indert Formation near Shine Jinst (southern Mongolia) is subdivided into the Heermorit and Shombon members. A systematic collection of the few marine carbonaterich levels from the Heermorit Member resulted in a low-diverse conodont assemblage indicating the late Famennian Bispathodus ultimus conodont Biozone at the Tsagaankhaalga-2 section. Supplemental conodont data from the Yamaan Us section support early Tournaisian age for the lowermost limestone beds of the above deposited Shombon Member. In total, twelve species in seven genera are identified and include Apatognathus, Mehlina, Pandorinellina, Polygnathus (including the new taxon Polygnathus communis tomurtogooi n. ssp.), Pseudopolygnathus, transitional forms of Polygnathus-Siphonodella and Siphonodella. The significance and palaeogeographic distribution of the markedly increased occurrence of intergeneric transitional forms before and during the Late Devonian Hangenberg Event and regionally lacking evidence of the end-Famennian Protognathodus kockeli conodont Biozone and associated early protognathodid assemblage below the Devonian/ Carboniferous boundary are discussed.

The final part of the Ordovician Period was characterised by major perturbations in climate, environments and ecosystems, as proved by numerous studies. These changes resulted in one of the biggest extinctions in Earth’s history. Most research in early Palaeozoic biogeography is based on data derived from extensively studied localities in North America and Europe, and much less information is available from other parts of the world. Here, we present the first results of our study on Katian/Hirnantian scolecodonts from the Spiti region, India. This area was part of the Tethyan Himalaya of the Gondwana palaeocontinent, located at low palaeolatitudes. Various representatives of algae, bryozoans, corals, cephalopods, conodonts, ostracods and other groups have already been described from this region. Palaeontological data and facies analysis indicate shallow-water conditions within the subtropical–tropical realm. In addition, the specific carbon isotope (δ13Ccarb) trend suggests that late Ordovician carbonate deposits in the region occurred during the pre-Hirnantian global warming interval, the so-called Boda Event. The migration pathways of bryozoan communities have shown that those from Spiti were very similar to the faunas of Laurentia, Baltica, Siberia and southern China during the early Late Ordovician. It is assumed that taxa originating in Laurentia, crossed the Tornquist Sea from Baltica to Avalonia, then to southern Europe, and subsequently extended along the shelf of northern Gondwana, including India and Australia. The organic-walled microfossils of the Spiti region have previously received much less attention than the shelly faunas and conodonts. In the present study, we have focused on scolecodonts – the jaws of polychaete worms, a group that has been abundant since the Cambrian, playing an important role in various marine ecosystems. Polychaetes are a vital part of the food chain and play an essential role in organic matter decomposition and nutrient cycling processes within sediments. The jawed polychaetes are also known for their high resistance to ecological stress. In Spiti, scolecodonts are mainly found in silty limestones containing 60–70% of carbonate minerals. The majority of scolecodonts were recovered from the lithological units 8 and 13 of the studied section, representing well-stabilised shallow-shelf carbonate environments close to the top of a transgressive system tract in otherwise relatively nearshore to shoreline settings. Our results show that at least seven jawed polychaete genera are present in the assemblage. A new endemic ramphoprionid species belonging to the genus Megaramphoprion has been recorded. Other taxa include representatives of Oenonites, Mochtyella, Vistulella, Atraktoprion, Xanioprion and paulinitids, which occur in both scolecodont-rich units. The same genera occur in coeval strata in Baltica and Laurentia. On the other hand, some genera such as Pistoprion and Kalloprion are missing in the Spiti samples and also in other Gondwanan collections. In Laurentia, the family Hadoprionidae is already present in the Late Ordovician, but in Gondwana it appears in the late Silurian. Paulinitids are common in late Katian and Hirnantian strata (Amorphognathus ordovicicus conodont Zone) in Laurentia and Gondwana, as well as in Baltica. Similarly to coeval Laurentian polychaete faunas, labidognath and prionognath taxa outnumber the species with a placognath-type jaw apparatus. The distinct and abundant genus Pteropelta in Baltica and Laurentia has so far not been recorded in the latest Ordovician of Gondwana. In addition to scolecodonts, the studied organic-walled microfossil assemblage contains chitinozoans belonging to the genera Acanthochitina, Conochitina, Spinachitina, and possibly Tanuchitina. The diversity is lower than presented by previous authors and reported from other regions.

The Middle Devonian Epoch, ~ 393–383 million years ago, is known for a peak in diversity and highest latitudinal distribution of coral and stromatoporoid reefs. About 388 million years ago, during the late Eifelian and earliest Givetian, climax conditions were interrupted by the polyphased Kačák Episode, a short-lived period of marine dys-/anoxia associated with climate warming that lasted less than 500 kyr. Reconstruction of the seawater temperature contributes to a better understanding of the climate conditions marine biota were exposed to during the event interval. To date, conodont apatite-based paleotemperatures across the Eifelian–Givetian boundary interval have been published from Belarus, France, Germany and North America (10–36° S paleolatitude). Here we provide new δ18Oapatite data from the Carnic Alps (Austria, Italy) and the Prague Synform (Czech Republic). For better approximation of the paleotemperature record across the Kačák Episode, a latitude-dependent correction for Middle Devonian seawater δ18O is applied. Because δ18Oapatite data from shallow marine sections are influenced by regional salinity variations, calculated mean sea surface temperatures (SST) are restricted to more open marine settings (22–34° S paleolatitude). Water temperatures reach ~ 34 °C in the Prague Synform and ~ 33 °C in the Carnic Alps and suggest that SSTs of the southern hemisphere low latitudes were ~ 6 °C higher than previously assumed for this time interval.

The Lower Cretaceous marine deposits of the Himachal Himalaya are assigned to the Giumal Formation and best exposed in Spiti Valley (Northern India). To date, three sections near the villages of Chikkim, Domal and Gete are studied concerning its general lithological character and age. However, only the biostratigraphically constrained section near Chikkim exposes a complete succession of approximately 300 m in thickness with both lithostratigraphic boundaries preserved. Thus, it is representative for the entire Spiti area. Although some few lithological details on the siliciclastic sequence of the Giumal Formation are known, a comprehensive study of the regional sedimentary development is missing. A detailed microfacies study is performed for the entire sequence of Lower Cretaceous outer neritic to slope environments of Spiti. The specific sedimentary character of the unit results in discrimination of eleven microfacies types. Furthermore, twenty-three sedimentary sequences are identified which correspond with four major regressive/transgressive cycles. Reconstruction of a relative sea-level curve clearly indicates 10 major and minor sea-level drops which correlate well with eustatically induced megacycles between the latest Tithonian to the late Albian. The depositional environment of the Giumal Formation in Spiti is discussed in view of 16 coeval sedimentary sequences framing the Indian Craton during the Late Jurassic and Cretaceous time slice.

In the Carnic Alps, located across the border between Italy and Austria, several sections span the Silurian/Devonian boundary in different sedimentary settings, from very shallow water to moderately deep shelf. All studied sections yielded conodonts and based on the first and last occurrences of the conodont taxa in the upper part of the Upper Oul. el. detortus Zone and in the lower part of the I. hesperius Zone a detailed conodont biostratigraphic framework was able to be constructed for this interval. Comparison of data from different depositional settings demonstrates that, although the majority of species are documented everywhere in the Carnic basin, a few taxa, mainly represented by coniforms, are limited to shallow water, whereas others, mainly ozarkodinids, occur only in open sea deposits.

Conodont elements, consisting of crown and basal tissue are the well-known fossilized hard parts of Conodonta (extinct marine chordates), but the taphonomic processes leading to decomposition or remineralization of the basal tissue are not well understood. Here we focus on the taphonomy of basal tissue, reviewing the published record and describing new material from Asia and Europe (248 occurrences globally). These include crown and basal tissue in conjunction, and isolated basal bodies showing different stages of preservation. Some isolated specimens resemble phosphate rings similar to those assigned to Phosphannulus universalis. High-resolution biostratigraphy indicates that the lamellar type of conodont basal tissue is found in all facies and depositional environments. Other basal tissue types, described in the literature as tubular, mesodentine, spherulitic or lamellar with canalules, are limited to the early Palaeozoic and found exclusively in siliciclastic deposits (with the exception of spherulitic tissue). Although the stratigraphic record of basal tissue spans the range of Euconodonta (Cambrian-Triassic), this study shows that most of the isolated plate and ring-like structures are derived from early Palaeozoic coniform conodonts. Basal tissue of platform-type elements has a much more fragile shape and is therefore rarely preserved as a recognizable isolated unit.

Upper Devonian marine deposits of the Baruunhuurai Terrane in western Mongolia represent island arc settings, which yielded a diverse conodont assemblage of 30 taxa, including species of Ancyrognathus (as well as one new species), Icriodus, Mehlina, Polygnathus and Palmatolepis. Biodiversity analysis of Ancyrognathus, Pelekysgnathus, Mehlina and Icriodus shows that the Mongolian conodont assemblage consists of two endemic and few cosmopolitan taxa. Representatives of the otherwise globally distributed genus Pelekysgnathus are absent. An important factor influencing the regional distribution of conodont taxa seems to be the siliciclastic-dominated sedimentation of the Baruunhuurai Terrane during the early Famennian.

The Jirasek quarry in the Koneprusy area (Barrandian area, Czech Republic) represents a unique section, where the stratigraphic equivalent of the black shales of the Kacak Member (Srbsko Formation) is developed in a carbonate succession. Here we describe conodont faunas of the upper Acanthopyge Limestone (Choted Formation, australis-kockelianus zones) and the Upper Dark Interval of the Acanthopyge Limestone referred to as UDI (Choted Formation, ensensis Zone) with special emphasis on the Polygnathus pseudofoliatus Group. The following taxa are discussed in this paper: Polygnathus pseudofoliatus Wittekindt, P. amphora Walliser & Bultynck, P. sp. aff. P. amphora Walliser & Bultynck, P. eijhus Bischoff & Ziegler, P. ensensis Ziegler & Klapper in Ziegler et al., transitional forms among P pseudofoliatus-P. amphora, P. eiflius-P P. amphora, P pseudofoliatus- P. eijhus and P. eiflius-P . ensensis, P. benderi Weddige, P. abbessensis Savage, P. bagialensis Savage, Tortodus kockelianus (Bischoff & Ziegler), T. australis (Jackson in Pedder et al.), Tortodus sp. A, Tortodus sp. B, Tortodus sp. alt T. weddigei Aboussalam, Tortodus sp. aff. T. caelatus (Bryant), Polygnathus sp. A, P. kluepfeli Wittekindt, P. trigonicus Bischoff & Ziegler, P. linguifbrmis Hinde, P. klapperi Clausen, Leuteritz & Ziegler, Polygnathus sp. aff. P. zieglerianus Weddige, Polygnathus sp. aff. P. alveolus Weddige, Polygnathus sp. B, Poftnathus sp. C, Polygnathus sp. D, Poftnathus sp. E and Polygnathus sp. F. The occurrence of P. amphora, P. benderi, P. abessensis and P. bagialensis was recorded for the first time in the Barrandian area. The large morphological variability, occurrence of transitional forms and in most cases unknown ontogenetic variation within the P. pseudofoliatus Group, hampers using particular species of this group as zonally diagnostic taxa. It is emphasized herein that taxonomic and morphometric analysis of large collections with members of P. pseudofoliatus Group is highly needed in order to properly delineate species boundaries. The increased morphological variation within the group is discussed in the light of the contemporary environmental changes related to the Kacak Episode.

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.

A new conodont species, Icriodus marieae , is described from pelagic limestone beds of the Carnic Alps (Austria). Specimens are obtained from the upper part of the Valentin Formation (Central Carnic Alps) and range from the latest Eifelian to middle Givetian. Significantly differing from other icriodontid conodonts is that the icriodontan element of the new species develops only three denticles on either lateral denticle row, which are constricted to the central part of the element. The anterior part of the element is free of lateral row denticles and consists of two to four denticles, which have a fan-shaped outline in lateral view. The anterior part as well as the posterior part (consisting of cusp and two to three pre-cusp denticles) is higher than the denticles of the central part of the element. Shape analysis confirms that the parameters chosen for landmarks (element size relation and denticle setting) show little variation between different specimens.

Increasing numbers of conodont discoveries with soft tissue preservation, natural assemblages and fused clusters of the hard tissue have strengthened the hypothesis regarding the function and mechanism of the conodont feeding apparatus. Exceptional fossil preservation serves as a solid basis for modern reconstructions of the conodont apparatus illustrating the complex interplay of the single apparatus elements. Reliable published models concern the ozarkodinid apparatus of Pennsylvanian and Early Triassic conodonts. Recognition of microwear and mammal-like occlusion, especially of platform elements belonging to individuals of the genus Idiognathodus, allows rotational closure to be interpreted as the crushing mechanism of ozarkodinid platform (P1) elements. Here we describe a new icriodontid conodont cluster of Caudicriodus woschmidti that consists of one pair of icriodontan (I) and 10 pairs of coniform (C1–5) elements, with I elements being preserved in interlocking position. The special kind of element arrangement within the fused cluster provides new insights into icriodontid apparatus reconstruction and notation of elements. However, orientation of coniform elements is limited to a certain degree by possible preservational bias. Four possible apparatus models are introduced and discussed. Recognition of specific wear on denticle tips of one of the icriodontan elements forms the basis for an alternative hypothesis of apparatus motion. Analysis of tip wear suggests a horizontal, slightly elliptical motion of opposed, antagonistically operating I elements. This is supported by similar tip wear from much better preserved, but isolated, elements of Middle Devonian icriodontids. More detailed interpretation of the masticatory movement will allow enhanced understanding of anatomical specifications, diet and palaeobiology of different euconodont groups.