German Triassic Research Articles

Synopsis on the temnospondyls from the German Triassic

Synopsis on the temnospondyls from the German Triassic

Illite and chlorite cementation of siliciclastic sandstones influenced by clay grain cutans

The distribution and amount of clay rim cements are different for Permian Rotliegend and Lower Triassic Bunter sandstones in the Southern Permian and German Triassic Basins, respectively. Both are similar fluvial-aeolian deposits in hot-arid endorheic basins. In both Permian and Triassic sandstones clay grain cutans can be present, but clay rim cement is often lacking or rare in Bunter sandstones. At first sight it would appear that the presence of cutans is thus not relevant for the development of clay cementation. However, at closer inspection, it appears that authigenic clay is indeed present in both cases. In Rotliegend sandstones, the authigenic clay mainly developed as rims around the clay grain cutans, which are often thin and well microlaminated with few intra-micropores and composed of platy particles. The clay crystals in the rim decrease the pore interconnectivity and lower permeability significantly. In Bunter sandstones, most of the authigenic clay developed within the cutans. These cutans are less well microlaminated, have ample micropores, and are composed of more equant-shaped particles. The latter looser structure facilitated clay authigenesis within the cutans and their micropores. This often led to exfoliation of the cutan laminae and expansion of the entire cutan. These expanded cutans also lower pore connectivity. The presence and thickness of clay rim cement on top of cutans and grains is thus not correlated with the thickness of the cutans but with the texture of the cutans. The latter determined where authigenic clays precipitated and the thickness of cutans is partly the result of clay authigenesis within the cutans. This demonstrates that the composition and the texture of sedimentary components constrained and controlled burial diagenesis.

The KALKOWSKY Project - Chapter I. Ooid - stromatoid relationship in a stromatolite from the Maiz Gordo Fm (Argentina)

The comparative study of oolites and stromatolites demonstrates striking similarities between KALKOWSKY's German Triassic material (drawn from the scientific literature) and our Argentinian Paleogene material. However, the latter better illustrates that ooids and stromatoids, hence oolites and stromatolites, which share the same dual (i.e., organic and mineral) nature, are merely the end-members of a continuum of microbial carbonate structures.

Macroecological patterns of the terrestrial vegetation history during the end-Triassic biotic crisis in the central European Basin: A palynological study of the Bonenburg section (NW-Germany) and its supra-regional implications

Abstract The end-Triassic mass extinction is often linked to environmental and climate change triggered by the activity of the Central Atlantic Magmatic Province ca. 201 Mya. In the German Triassic Basin, the transition from pre-extinction to the so-called extinction interval is documented from the fossil-rich Contorta Beds to the mostly barren Triletes Beds. However, despite the lack of macrofossils, plant microfossils are present and studying palynomorph diversity and assemblages still give us a detailed insight into the impact of environmental changes on the flora. Here, we present data from 64 samples taken from the new Triassic-Jurassic section ‘Bonenburgʼ, which originates from a brick quarry in North Rhine-Westphalia (Germany), and encompasses the Triassic–Jurassic transition in the Germanic Basin. Using palynofacies analysis, we document changes in the depositional environment. Based on terrestrial and marine palynological analysis, we also document quantitative changes in four assemblage zones for correlation with other European sections. Further, we discuss the vegetation history with special focus on the transition from the pre-extinction to extinction interval (Contorta to Triletes Beds). Additionally, we investigate palynofloral diversity patterns especially prior to the Triassic-Jurassic transition, to evaluate the ecological impact of environmental upheaval on the flora. Furthermore, we document intraspecific palynomorph variability, indicating a variety of aberrant spore, pollen, and tetrad formation, in the middle Rhaetian, the lowermost upper Rhaetian, and the lowest Hettangian. Our study supports existing paleogeographical reconstructions for the region and reveals, that vegetation underwent gradual changes with intermediate successional stages rather than dramatic extinction or drastic turnover as documented for animals. Diversity patterns coinciding with aberrant palynomorph occurrences, potentially associated with episodes of increased environmental stress, suggest three disturbances pulses of probably increasing severity. Although environmental stress in the context of diversity patterns seems a likely explanation for the occurrence of aberrant palynomorphs, further investigations are needed to better understand the underlying mechanisms and their evolutionary significance and temporal connection with biotic crises.

Zircon size-age sorting and source-area effect: The German Triassic Buntsandstein Group

This study stresses how zircon-grain length versus age correlation significantly can improve provenance interpretations. Hence, taking sedimentary sorting effects into account, we present a detrital-zircon provenance study for continental deposits of the Central European, Lower Triassic Buntsandstein Group in Germany. The Buntsandstein Group was deposited in an extended intracontinental sag basin of Pangea under arid climate conditions. It included several intrabasinal tectonic swells, some of which have been assumed topographic highs acting as detrital source areas. This study of the Lower and Middle Buntsandstein subgroups in Central Germany indicates that particularly the Massif Central and the Bohemian Massif contributed to the basin fill of the central part of the Central European Basin. The Rhenish Massif, an assumed highland, was submerged. This interpretation is based on >1000 zircon grains from 12 sandstone beds. The unbroken grains in seven of the zircon separates have mean lengths of 190–220μm and five are composed 100–140μm long grains in average. All have a main population of 340–320Ma Carboniferous ages, representative of granitic, probably zircon-rich, rocks from the Variscan Orogen of the Massif Central and the Bohemian Massif. This first-cycle detritus was mixed with recycled, abraded zircon grains from Ediacaran to Palaeozoic metasedimentary units feeding the basin with 610–460Ma (Ediacaran to Ordovician) and 2Ga age grains, as is typical for Gondwana-derived material. The Ediacaran to Ordovician age population is common only in five samples with mean grain lengths of 100–140μm. Grains of such ages mainly are <130μm in the east, but equally common in all grain sizes in western sandstone beds. A western group was fed from the Massif Central and an eastern group derived from the Bohemian Massif. However, abrasion, age-population variations for pre-Variscan grains, and dominating wind directions indicate that two different fluvial systems delivered the Bohemian material and that this was combined with aeolian and alongshore lacustrine transport from the south and west. We conclude that interpretation of detrital zircon ages preferably are separately for different size classes, because zircon studies performed on broad grain-size intervals without considering possible size-age correlations may disguise sorting effects that potentially can lead to a misleading source-area interpretation.

Provenance of the Lunz Formation (Carnian) in the Western Carpathians, Slovakia: Heavy mineral study and in situ LA–ICP–MS U–Pb detrital zircon dating

The Middle Carnian (Julian) detritic sediments of the Lunz Formation were deposited during of the so-called Carnian Pluvial Event. They are the only siliciclastic sediments embedded in purely carbonatic formations. The paper brings the first provenance analysis of this formation from the Western Carpathians (Slovakia), where it occurs in the Hronic, Fatric and Veporic zones. Sandstones of the Lunz Formation belong to feldspatic greywackes and less to lithic greywackes. Modal analyses indicate that the sand material was derived from dissected arc and less from a recycled orogen. The heavy mineral assemblage is dominated by zircon and by apatite, slightly lesser amount of garnet, Cr-spinels and tourmaline. Analysis of tourmalines (schorl and dravite) shows their primary provenance mainly from the metapelites and metapsammites coexisting, or not coexisting with an Al-saturating phase; some were also derived from Fe3+-rich quartz–tourmaline rocks, calc-silicate rocks and metapelites, and a slightly smaller group of grains was derived from Li-poor granitoid rocks and their associated pegmatites and aplites. Most of the garnet grains belong to almandine, less to spessartine. All of them have a wide spectrum of potential primary source rocks from low- to medium-grade metamorphic rocks and magmatites. The analysed spinel grains (Cr-rich spinel, chromite and magnesiochromite) match mostly the podiform chromitites, harzburgite and cumulate fields or supra-subduction zone peridotites field, whereas Al-depleted spinel best match the arc volcanic field. Some spinels were affected by alteration or metamorphism. The in-situ LA–ICP–MS isotopic U–Pb dating shows a wide age interval of detrital zircon crystals in the Lunz Formation. Concordant zircon data show a wide interval of Late Triassic (Carnian) to Early Proterozoic ages (~230–2500Ma). Majority of zircons shows Paleozoic (pre-Variscan and Variscan) ages, whereas Neoproterozoic to Paleoproterozoic age populations are relatively scarce. Age populations and chemical composition of zircon reveal their dominant primary provenance from various suites of magmatic rocks, including Variscan granitic rocks and pre-Variscan metaigneous lithologies. Characteristic is big scatter in zircon ages and the dominance of ultrastable minerals, as zircon, tourmaline, rutile and Cr-spinels, and quite a good correlation between zircons and Cr-spinels. This indicates that most of the heavy minerals were not directly derived from some distinct primary magmatic or metamorphic sources, but as recycled particles from older sediments, or metasediments. In the context with the previously published palaeogeographic reconstructions, the provenance analysis indicates that the source area was most likely situated outside the Alpine-Carpathian shelf. They are most likely related to the coeval, mostly fluvial Stuttgart Formation in the Central European Basin (Germanic Triassic Basin).

How Deep Can Surface Signals Be Traced in the Critical Zone? Merging Biodiversity with Biogeochemistry Research in a Central German Muschelkalk Landscape

The Earth’s Critical Zone (CZ) is a thin living layer connecting atmosphere and geosphere, including aquifers. Humans live in the CZ and benefit from the vital supporting services it provides. However, the CZ is increasingly impacted by human activities including land and resource use, pollution and climate change. Recent interest in uniting the many disciplines studying this complex domain has initiated an international network of research infrastructure platforms that allow access to the CZ in a range of geologic settings. In this paper a new such infrastructure platform associated with the Collaborative Research Center AquaDiva is described, that uniquely seeks to combine CZ research with detailed investigation of the functional biodiversity of the subsurface. Overall, AquaDiva aims to test hypotheses about how water connects surface conditions set by land cover and land management to the biota and biogeochemical functions in the subsurface. With long-term and continuous observations, hypotheses about how seasonal variations and extreme events at the surface impact subsurface processes, community structure and function, are tested. AquaDiva has established the Hainich Critical Zone Exploratory (CZE) in central Germany in an alkaline geological setting of German Triassic Muschelkalk formations. The Hainich CZE includes specialized monitoring wells to access the vadose zone and two main groundwater complexes in limestone and marlstone parent materials along a ~6 km transect spanning forest, pasture and agricultural land uses. Initial results demonstrate fundamental differences in the biota and biogeochemistry of the two aquifer complexes that trace back to the land uses in their respective recharge areas. They also show the importance of antecedent conditions on the impact of precipitation events on responses in terms of groundwater dynamics, chemistry and ecology. Thus we find signals of surface land use and events can be detected in the subsurface CZ. Future research will expand to a second CZE in contrasting siliciclastic parent rock, to evaluate the relative importance of parent material lithology versus surface conditions for the emergent characteristics of the subsurface CZ and biodiversity. The Hainich CZE is open to researchers who bring new questions that the research platform can help answer.

The Triassic-Jurassic strata of the Newark Basin, USA: Acomplete and accurate astronomically-tuned timescale?

Spectral analyses of apparent cyclicity of Triassic-Jurassic strata in the Newark Basin (New Jersey, USA) have been used to generate peak recurrence intervals within the sequence. When calibrated to sedimentation rates derived from varve counts in lacustrine mudstones, these recurrence intervals yield cycles inferred to correspond to orbital forcing at basic precession, eccentricity and long eccentricity frequencies. Consequently, the Newark basin cyclostratigraphy has been proposed as a floating astrochronology capable of providing a continuous high resolution geochronometry for most of the Late Triassic and part of the Early Jurassic. Indeed, orbitally-forced cyclicity does appear to be the dominant control of some portions of the Newark Basin section, particularly in the Lockatong and lower Passaic formations. But the application of the Newark Basin cyclostratigraphy as chronostratigraphy requires that the stratigraphic record is complete, i.e. no substantial erosional or depositional gaps exist, and cyclical throughout. Several lines of evidence indicate that these requirements are not met. Outcrop and core data demonstrate that portions of the Newark Basin stratigraphic section are non-cyclic, particularly in the fluvial-dominated strata of the upper Passaic Formation and the Stockton Formation. Correlation of available biostratigraphic data, including both pollen and conchostracan zones between the Newark Supergroup and the Germanic Triassic, indicates that most of Rhaetian and a portion of late Norian time is not represented by sediment in the Newark Basin and elsewhere in the Newark Supergroup. This suggests that at least 3 Myr of Late Triassic time is not recorded by strata in the Newark Basin. The inability of the Newark cyclostratigraphy to unambiguously locate and date the base of the Rhaetian or to produce a numerical age for the base of the Norian compatible with independently derived constraints demonstrate that the Newark Basin cyclostratigraphy is not a valid “floating astrochronology.” At best, only the middle late Carnian through early late Norian interval, about 10 Myr in duration, may be sufficiently complete to be useful for astrochronological purposes. In great part, the problems with utilizing the Newark Basin record as the basis for an astrochronology result from an inability to make unambiguous correlations to the marine record. Resolution of these issues and discrepancies could potentially be achieved through the collection of additional data, such as magnetostratigraphic data from continuous Upper Triassic marine sections.

First record of a true coleoid cephalopod from the Germanic Triassic (Ladinian)

First record of a true coleoid cephalopod from the Germanic Triassic (Ladinian)

Cyclostratigraphic record of the Triassic: a critical examination

Abstract High frequency (fourth- and fifth-order) cyclicity is a common feature of sedimentary sequences in all depositional settings. While tectonism and autocyclic processes are clearly responsible for this cyclicity in some instances, many cases are interpreted as resulting from orbitally forced variations in solar insolation at the Milankovitch frequencies, that is, the precession and short and long eccentricity cycles at scales of tens of thousands to hundreds of thousands of years. This forcing is presumed to have controlled sedimentation through periodic changes in climate or sea-level. Examples of interpreted Milankovitch-frequency cyclicity occur throughout the Triassic record, and include much of the German Triassic, the Alpine Triassic and the Newark Supergroup of North America. The cyclostratigraphy of these sections has been used as a tool for intrabasinal and interbasinal correlation, and for chronostratigraphy. These interpretations are not always without controversy, however, as conceptual arguments and radio–isotopic age data have called some of these conclusions into question.

JURACYCLUS POSIDONIAE N. GEN. AND SP., THE FIRST CYCLOID ARTHROPOD FROM THE JURASSIC

The cycloids represent an enigmatic arthropod group of probably crustacean affinity, occurring mostly in the younger Paleozoic, from the early Carboniferous up to the Late Triassic (Schram et al., 1997). Superficially, cycloids strikingly resemble crabs and were thought to have had a similar lifestyle, becoming extinct when crabs started to radiate. Recently, the existence of a Late Cretaceous cycloid, Maastrichtiocaris rostratus Fraaije et al., 2003, from the Maastrichtian of the Netherlands, proved that cycloids did not go extinct at the end of the Triassic as believed for a long time, but survived much longer, co-occurring with crabs. Due to obvious collecting bias and the incompleteness of the fossil record of arthropods with relatively delicate carapaces in general, neither Jurassic nor Early Cretaceous representatives have been reported hitherto. However, from the Lower Jurassic Posidonienschiefer (‘Posidonia Shale’) of southwestern Germany—famous for its excellent fossil preservation, not only of marine vertebrates and large crinoids living on driftwood, but also many other invertebrate groups (Riegraf et al., 1984; Urlichs et al., 1994)—now a single specimen of a cycloid is recorded and described herein. Although this record helps link the bias between the Triassic and the Late Cretaceous occurrences, the characters of the specimen differ strongly from those of other cycloids, thus requiring the erection of a new genus and species. In Europe, cycloids are mainly known from the German Triassic (e.g., Meyer, 1838, 1844, 1847; Seebach, 1857; Bill, 1914; Muller, 1955; Trumpy, 1957; Linck, 1961; Meischner, 1963; Zorn, 1971; Oosterink, 1986), and from the Triassic of the Alps (Schafhautl, 1863; Reuss, 1867; Trauth, 1918; …

New early crown-group asteroids (Echinodermata; Triassic of Germany)

Migmaster angularis n. gen. n. sp. (Trichasteropsiidae, Forcipulatacea, Asteroidea) is described from the German Triassic Lower Muschelkalk of Anisian (Pelsonian) age, and new specimens ofTrichasteropsis bielertorum broaden understanding of this species. Phylogenetic events linking the stem groups, known only from Paleozoic rocks, with the crown group, known only from post-Paleozoic rocks, are problematic; the new fossils partially constrain phylogenetic changes associated with emergence of crown-group asteroids.

Les pistes dinosauroïdes du Trias moyen français : interprétation et réévaluation de la nomenclature

Numerous dinosauroid footprints which showing sometimes manus imprint mark were gathered, since 1960, from the lower sandstones Triassic formations of the eastern border of the Massif Central (France). Tracks bearing levels are dated from palynological, micropalaeontological and palichnological data. They belong to the period upper Anisian-lower Ladinian. The paleontological results show bipedal digitigrade reptiles with erected, long hind limbs, having also pentadactyl mani and (II-IV) tridactyl feet. The osteological feet inferred structure is like that of Ceratosauria of Late Triassic age. The skeletons of first Dinosauria, diversified already well, are known in summit Ladinian and lower Carnien and those of their ancestors, Dinosauriformes, in Ladinian. And, for this reason, the aniso-ladinian dinosauroid footprints are ascribed to these last animals which thus appeared earlier, to Anisan even to late Olenekian. The chirotheroid hands show a “pseudosuchian” origin which possibly took place during the late Olenekian; feet modifications of these Crurotarsi being characterized by I and V digits reduction and a meso-tarsal joint. The Anisian-Ladinian dinosauroid footprints are ascribed to the ichnospecies Coelurosaurichnus perriauxi and Anchisauripus bibractensis. The discriminant analysis computed from these latter ichnospecies, and others from the German Triassic, French and USA Hettangian indicate that C. perriauxi and A. bibractensis can not be included into Grallator sensu Lull, 1953 or Coelurosaurichnus of Franconie. By this way, these taxa are well original and till now, there was no reason to change their nomenclature. Nevertheless because the numerous changes of Grallator which gathers now, most of dinosauroid footprints, it could be possible to include them into Grallator for the feet and into Atreipus when the manus trace is connected with the foot.

The oldest Mesozoic nearshore Zoophycos : evidence from the German Triassic

The trace fossil Zoophycos has been described from the Middle Triassic carbonates of the German Basin for the first time. It occurs in a calcilutite bed at the top of a shallowing-upward cycle (parasequence) in the transgressive systems tract of the Middle to Upper Muschelkalk sequence of Thuringia (Germany). Based on sedimentological and palaeontological features, the studied interval is interpreted as deposited in a marine nearshore environment with proximal storm deposits (tempestites). Zoophycos occurs in a very simple planar form with lobate spreiten, which were most likely produced by a worm-like animal by strip mining. The upper tier of the ichnofabric consists of Zoophycos, whereas the lower tier is occupied by cylindrical trace fossils of unknown taxonomic affiliation and with decreasing size towards the bottom. Associated trace fossils such as Rhizocorallium, Balanoglossites and Trypanites indicate a partly firm to hard substrate. No mixed layer is developed at the top of the trace fossil bearing succession. The ichnofabric together with the sedimentological features (disseminated pyrite, blue-grey colour) and palaeontological circumstances (poor benthic fauna, meiofauna with a small body size) support an interpretation of a dysaerobic environment. In the view of evolutionary change, Palaeozoic Zoophycos occurs in both deep and shallow marine deposits, whereas Mesozoic and Cenozoic Zoophycos is only common in shelfal and deeper-marine deposits. The new finding from the shallow-marine Middle Triassic represents the first reliable occurrence of Zoophycos after the end-Permian mass extinction and shows close similarities to its Palaeozoic precursors. It demonstrates that the producer survived the end-Permian mass extinction, became re-established in the nearshore realm and progressively colonized deeper-marine environments during the Mesozoic and Cenozoic.

Stratigraphy, lithofacies distribution, and petroleum potential of the Triassic strata of the northern Arabian plate

Triassic strata of the northern part of the Arabian plate mark the establishment of the Neo-Tethys passive margin. This ocean first opened in the western part of the Mediterranean region directly after the Hercynian orogeny. The strata were deposited on a shallow carbonate platform surrounded by clastic-evaporitic lagoons and continental fluvial and eolian settings. The rocks are divided between continental clastics (such as the Budra and the Ga'ara formations), continental-marine clastics and evaporites (such as the Mohilla, Abu Ruweis, Beduh, and Baluti formations) and epicontinental marine facies (such as the Saharonim, Salit, and Kurra Chine formations). These settings are comparable to those of the German Triassic and have matching lithofacies and eustatic sea level changes. The succession has been divided into four high-frequency sequences dominated by highstand systems tract carbonates and highstand systems tractlowstand systems tract evaporites and clastics: the Mulussa Formation, the Kurra Chine dolomite and oolitic limestones, the clastics in the EuphratesAnah graben in Syria and Iraq, and the Triassic buildups in the northern parts of the Levant form attractive hydrocarbon reservoirs when they are overlain by the TriassicJurassic evaporite sequence and are in communication with Silurian source rocks. In Syria, the Kurrachine Formation contains both source and reservoir rocks. On the Aleppo plateau, this formation is believed to lie at the beginning of the thermal maturation window, whereas in the areas of Jebbissa, Soukhne, and Souedie, it is in the mature or overmature windows. The Triassic strata produced fair amounts of light oil, gas, and condensates from some fields in Syria and Iraq with a high potential of gas and condensate accumulations in the Levant region.

THE "GERMANIC" TRIASSIC OF SARDINIA (ITALY): A STRATIGRAPHIC, DEPOSITIONAL AND PALAEOGEOGRAPHIC REVIEW

The collection of new lithostratigraphical and sedimentological data has allowed to re-examine the Triassic sedimentation cycle in Sardinia The most important outcrops have been revisited and their general setting reinterpreted. A detailed and homogeneous depositional, palaeoenvironmental and stratigraphic picture is proposed, pointing to the analogies with both the typical Germanic Triassic of Central Europe, and the Middle Triassic Sephardic domain of Western Europe and North Africa. The lower, essentially siliciclastic, lithostratigraphic units, resting discordantly on the Hercynian Palaeozoic basement, resemble the Buntsandstein facies association. They are generally of Anisian age. Their depositional environments range from high-energy continental to transitional environments to the floodplain, where a shallow, epicontinental sea gradually transgressed. Overlaying these are the carbonate units of the Muschelkalk facies association. They are generally dolomitic at the bottom passing to calcareous at the top. These deposits, generally of Ladinian age, formed in the various subenvironments of a carbonate ramp. The few Upper Triassic successions in Sardinia point to the existence, during this period, of diverse depositional conditions in the North (Nurra) and South (Sulcis) of the island. In southern Sardinia, lagoon to shallow sea carbonate shelf deposition predominates, with minor amounts of evaporites and siliciclastics. By contrast, in Northern Sardinia mixed evaporitic-siliciclastic-carbonate facies of paralic-continental (mudflat), locally restricted lagoonal environments, were deposited. The latter are very similar to the classic Germanic Keuper facies. These data suggest that the Upper Triassic successions in Southern Sardinia can be set in a transitional environmental context between the open Alpine-Tethyan domain and the Germanic Triassic proper. An attempt has been made to correlate these successions with the Middle to Late Triassic eustatic cycles.

A lamellibranch-stromatolite bioherm in the Lower Keuper (Ladinian, Middle Triassic), South Germany

A unique small bioherm, 0.7 m in diameter and 0.25 m high, is described from the Lower Keuper in South Germany. Its core consists of the attached right valves of the tiny oyster-like lamellibranchPlacunopsis ostracina (Pectinacea). It is overgrown by a cm-thick laminated stromatolitic crust formed by microbial mats and sponges. The bioherm was dolomitized during early diagenesis and represents the temporary transition from restricted marine to more saline depositional environments. It is one of the stratigraphically youngestPlacunopsis bioherms found so far in the Germanic Triassic.

High-resolution sequence interpretation of epeiric shelf carbonates by means of palynofacies analysis: An example from the Germanic Triassic (Lower Muschelkalk, Anisian) of East Thuringia, Germany

The Steudnitz quarry (East Thuringia, Germany) exposes the entire Lower Muschelkalk (Middle Triassic, Anisian) with a thickness of 103 m. In this paper, a primarily palynofacies-based sequence-stratigraphical interpretation supported by lithological investigations is proposed. Palynofacies of the sampled carbonate rocks is dominated by land-derived phytoclasts and pollen grains. Spores are quite rare. Marine plankton reaches its maximum abundance in an interval around the ThuringianSpiriferina-bed and the Terebratel-beds. In accordance with lithological features, this interval may be interpreted as a third-order maximum-flooding zone. Two different third-order interpretations are presented and discussed. Third-order sequences and parasequence sets can be identified by use of palynofacies analysis. Furthermore, palynofacies analysis provides an additional possibility of recognizing partly eroded or originally incomplete cycles (‘missed beats’). In some cases, a resolution down to the level of parasequences is possible. High-resolution palynofacies analysis is a powerful new tool in sedimentology but should always be combined with lithofacies interpretation. It provides very useful, additional information for high-resolution sequence analysis and palaeoenvironmental interpretation. Being a rather young method, high-resolution palynofacies analysis still shows some calibration problems with classical methods. However, these should be solvable by further research.

A Middle Triassic Vertebrate Fauna from the Jilh Formation, Saudi Arabia

A Middle Triassic vertebrate fauna from the Jilh formation in Saudi Arabia is described. Although the material is very fragmentary, the occurrence of a wide taxonomic variety of taxa can be documented, including hybodontiform sharks, actinopterygians, and sauropterygian reptiles such as a pachypleurosaur, Simosaurus, nothosaurs and cyamodontoid placodonts. The fauna compares well with other Middle Triassic faunas from the Germanic and Alpine Triassic, and from the northern Gondwanan shelf, in particular with the fauna from Makhtesh Ramon, Negev, Israel.

The systematic status of Hanosaurus hupehensis (Reptilia, Sauropterygia) from the Triassic of China

ABSTRACT Hanosaurus hupehensis was believed to represent a Middle Triassic thalattosaur from the People's Republic of China. Redescription of the holotype and only known specimen, and cladistic analysis of its interrelationships, shows Hanosaurus to represent a distinct pachypleurosaur. The two Chinese pachypleurosaurs, Keichousaurus and Hanosaurus, form two consecutive sister-groups to European pachypleurosaurs, strengthening the Asiatic affinities of the clade. Addition of Hanosaurus furthermore results in a modification of pachypleurosaur interrelationships as previously reconstructed: the pachypleurosaurs from the Germanic Triassic (Anarosaurus, Dactylosaurus) form a monophyletic clade, which is sister-group to the monophyletic clade of Alpine pachypleurosaurs (Serpianosaurus, Neusticosaurus). Thalattosauria are the sister-group of Sauropterygia, the two clades possibly representing a single invasion of the Mesozoic sea. However, more detailed knowledge of thalattosaur anatomy is required to further test the phylogenetic relationships of thalattosaurs.