Oysters and oyster-like bivalves from the Middle Triassic Muschelkalk of the Germanic Basin

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

Controls on migration of conodont fauna in peripheral oceanic areas. An example from the Middle Triassic of the Northern Peri-Tethys

Middle Triassic conodont assemblages in the semi-closed Peri-Tethyan Germanic Basin comprise endemic forms, which evolved within the basin, and immigrants from the Tethys Ocean. Migration from the Tethys proceeded diachronously through three tectonically predisposed pathways (gates) and was controlled by relative sealevel changes recorded in depositional sequences of the Muschelkalk. In the Early and Middle Anisian predominant were the forms that originated in the Eastern Tethys and in southern basins of the Western Tethys. They migrated through the East Carpathian Gate and Silesian-Moravian Gate. In the late Anisian and early Ladinian forms from the Western Tethyan basins prevailed; their migration pathway led through the Western and East Carpathian Gates. The latter gate was active only at the turn of Illyrian and Fassanian. Episodes of migration of the Tethyan forms and dispersal of conodont fauna throughout the German Basin coincide with the transgressive or highstand phases of a particular depositional sequence (as defined by Szulc, 1999). The most significant proportion of the Tethyan species appears to correlate with the maximum flooding surface of the A₃ sequence, (Lower Muschelkalk) later they decrease in diversity. In the Upper Muschelkalk the most numerous Tethyan species correspond to the transgressive phase of the L₁ sequence. Above the mfs of the L₁ sequence only the Germanic forms remain.     

Millions of reptile tracks—Early to Middle Triassic carbonate tidal flat migration bridges of Central Europe—reptile immigration into the Germanic Basin

Discoveries of vertebrate track sites in Central Europe have occurred in 75 localities in carbonate tidal flats of the Middle Triassic. In the Germanic Basin carbonate tidal flats were wide-span mapped, resulting in the finding of millions of small- to medium-sized reptile tracks. In the west of the basin the sediment of the Lower Muschelkalk to basal Upper Muschelkalk contains at least 21 track horizons, whereas in the eastern part more typically marine conditions were present. Here, tidal flats with additional track beds started earlier during the Upper Bunter and demonstrated marine ingression from the eastern Silesian gate. During low stands these tidal flats comprised inter-peninsula bridges, which allowed migration of reptiles. Only two medium to small prolacertilian reptiles, which were fully adapted to these environments, left any kind of track. A large thecodont reptile such as Euparkeria was the potential predator that may rarely have hunted the main small trackmakers Macrocnemus and Hescherleria.     

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.      

New fossil insects from the Anisian (Lower to Middle Muschelkalk) from the Central European Basin (Germany and The Netherlands)

The Palaeozoic–Mesozoic transition is characterized not only by the most massive Phanerozoic mass extinction at the end of the Permian period, but also its extensive aftermath and a prolonged period of major biotal recovery during the succeeding Middle to Late Triassic. Particularly, Anisian insect species from units of the Lower to Middle Muschelkalk from the Central European Basin are rare. The specimens described here originated from the Anisian Wellenkalk facies (Lower Muschelkalk), Vossenveld Formation of the Winterswijk quarry, The Netherlands, and from the orbicularis Member (lowermost Middle Muschelkalk, Anisian) of Esperstedt near Querfurt (Saxony-Anhalt). Thus, the described insect remains from Winterwijk and Esperstedt expand our knowledge about Middle Triassic terrestrial arthropod communities and their palaeodiversity. A new species of Chauliodites (C. esperstedti sp. nov) is introduced.     

New data on crinoid assemblages from the oldest sedimentary rocks of the Polish Outer Carpathians (Jurassic-Cretaceous)

Crinoids (Crinoidea) preserved in the so-called Cieszyn Beds (Tithonian-Hauterivian; southern Poland) are relatively numerous, especially in some levels, but not highly diversified. They are absent in the Lower Cieszyn Shale (Tithonian) and the Upper Cieszyn Shale (Valanginian-Hauterivian). The Lower Cieszyn Limestone (Tithonian) yielded crinoid remains classified as Isocrinus cf. amblyscalaris (Thurmann) and Isocrinida indet. In the Upper Cieszyn Limestone (Berriasian) crinoids are much more numerous and diversified. The following taxa are recorded: Isocrinus? annulatus (Roemer), Balanocrinus subteres (Münster), B. cf. smithi Hess and Gale, and Hemicrinus sp. The presence of specimens resembling Isocrinus amblyscalaris (Thurmann) in the Tithonian strata is surprising since the last occurrence of this taxon was reported from the Kimmeridgian. The Lower Cieszyn Limestone crinoidal assemblage is dominated by isocrinids (Isocrinida). This probably reflects the much shallower sedimentary environment of these sediments compared to that of the Upper Cieszyn Limestone, where excepting isocrinids, hemicrinids (Hemicrinidae, Cyrtocrinida) typical for deep marine environments were found. It is consistent with the analytical results from the foraminiferal assemblages, among which the benthic forms known from shelfal and paralic epicontinental environments first dominated, and then were supplanted by deep-sea taxa at the turn of the Jurassic and Cretaceous.     

The first specimen of the Middle Triassic Phalarodon atavus (Ichthyosauria: Mixosauridae) from South China,showing postcranial anatomy and peri‐Tethyan distribution

Phalarodon atavus from the Germanic Muschelkalk Basin was previously represented only by cranial elements. Here we report a nearly complete and articulated specimen of P. atavus from the Middle Triassic Luoping Biota, Yunnan, South China. This is the first specimen of P. atavus from outside the Germanic Basin. This discovery demonstrates a peri‐Tethyan distribution of P. atavus. The new specimen is also the first one preserving the postcranial anatomy of this species, providing the opportunity to evaluate its sustained swimming ability. Inferences made on its functional morphology suggest that this species was probably adapted for active foraging. Tooth crown morphology suggests that P. atavus may have preferred externally soft prey.     

Postcranial morphology and growth of the pachypleurosaur Anarosaurus heterodontus (Sauropterygia) from the Lower Muschelkalk of Winterswijk, The Netherlands

Sauropterygia from the Muschelkalk are only found in lag deposits known as bone beds, and most of the material consists of isolated bones. Alpha taxonomy of Sauropterygia from the Germanic Basin which include Pachypleurosauria is thus based mainly on skull morphology of a few specimens. Articulated or associated postcranial material of pachypleurosaurs, associated with diagnostic skull material, is very rare in the Germanic Basin and currently occurs in larger numbers only in the Lower Muschelkalk of Winterswijk (Gelderland Province, The Netherlands), which continuously produces new material. For the first time, the morphology of several partially articulated skeletons of the pachypleurosaur Anarosaurus heterodontus is described and compared. Some of those specimens have skull material attached; others were identified as pachypleurosaurs on the basis of their long bone histology. The current study revealed that postcranial bones of A.?heterodontus feature a diverse morphology reflecting differences during ontogeny. Thus, A.?heterodontus specimens could be assigned to size classes (I?CIII). However, on the basis of morphology, histology, and maximal known size of isolated skulls and humeri, none of these specimens represent fully grown individuals. Growth mark counts of midshaft-femur samples, morphologically assigned to size class?III, document that this size class was reached within the first year of life. Size class?III continued into the second year of life, and then afterwards skeletal maturity was reached. Thus, a juvenile A.?heterodontus grew very fast, which is also indicated by its bone tissue type, composed of a high number of radial vascular canals and a fast-deposited bone matrix. The assignment of isolated bones from Lower to Middle Muschelkalk localities to A.?heterodontus is now possible with an extensive amended diagnosis of this taxon. This largely contributes to the understanding of taxonomical diversity and distribution. Morphological comparison of the postcranial skeleton of A.?heterodontus with that of the two other valid pachypleurosaurs from the Germanic Basin, Anarosaurus pumilio and Dactylosaurus, supports their close phylogenetic relationship. Furthermore, the skeleton of A.?heterodontus has no morphological or histological aquatic adaptation such as pachyostosis or pachyosteosclerosis and thus represents the least degree of aquatic adaptation within Pachypleurosauria.     

Annalepis, a pioneering lycopsid genus in the recovery of the Triassic land flora in South China

Fossil plants are scarce in the Earliest Triassic marine deposits of western Guizhou and eastern Yunnan. Only Annularia shirakii, Lobatannularia sp., Paracalamites stenocostatus, Gigantopteris sp., Pecopteris sp. were reported from the base of the Kayitou Formation dated as Early Induan by marine fauna. Recently, we discovered numerous representatives of the genus Annalepis in the same Lowermost Triassic beds: A. latiloba, A. brevicystis, A. angusta, Annalepis spp. occur associated with a basal Triassic marine fauna. This discovery fills the biostratigraphic gap between the Late Permian “Gigantonoclea guizhouensis-Ullmannia cf. bronnii-Annularia pingloensis” and the late Lower Triassic “Neuropteridium–Albertia–Voltzia” assemblages reported from South China. It represents an important datum dealing with the very beginning of a new terrestrial flora installation after the Permian flora disappearance following the Permian–Triassic boundary mass extinction. This “starting point” of a new vegetal cover in South China is to be taken into account in reconstructing through space and time the settlement process of the Mesozoic floristic provinces.     

Taphonomy of dense ophiuroid accumulations from the Middle Triassic of Poland

The taphonomy of three Middle Triassic (Muschelkalk) monospecific ophiuroid taphocoenoses, comprising Aspiduriella similis (Eck), from different regions in Poland (Holy Cross Mountains, Upper Silesia and North-Sudetic Basin) has been investigated. The majority of specimens (88.5% of a total of 428 individuals) are partially disarticulated, having only proximal and median portions of their arms preserved (Taphonomic Group 2). Pristine specimens, with only faint traces of disarticulation (Taphonomic Group 1), as well as those that preserve the disc only, or which have only proximal stumps of arms preserved (Taphonomic Group 3), are much rarer (6.5% and 5%, respectively). Moreover, most specimens (76.4%) are oral side up. Only 19.2% of specimens are preserved in life position, and a small fraction (4.4%) are preserved oblique to bedding. All ophiuroids studied occur in thin, pelitic layers devoid of any trace fossils. Associated body fossils, such as bivalves, gastropods or crinoids, are very rare. Taking into account ophiuroid taphonomy, as well as sedimentological characteristics of the thin layer (burial layer), it is clear that all assemblages were transported prior to burial. The predominance of articulated skeletons indicates that the burial event (obrution event) was not only rapid, but also single – subsequent events would have destroyed the previously buried ophiuroids. Storm-related resuspension of fine-grained material from nearshore environments which covered the ophiuroids is the most likely burial agent. The fact that in all regions the ophiuroid taphofacies studied is identical suggests that the three assemblages underwent the same burial history, and that a single event might have been responsible.     Muschelkalk , ophiuroids , Poland , taphonomy , Triassic .     

Die Wirbeltierfährtenfundstelle Borgholzhausen (Teutoburger Wald, NW-Deutschland) aus der Oolith-Zone (Unterer Muschelkalk, Mitteltrias)

At a new Middle Triassic vertebrate track site, Borgholzhausen sports field in the central Teutoburger Wald (NW Germany), 36 superimposed track horizons were discovered in the Graue Zwischenmittel beds of the Oolith Member (Lower Muschelkalk Formation, Bithynian substage, Middle Triassic). The track-bearings beds consist of micritic laminites with a variety of sediment surface marks. They document extensive tidal flat facies along the northern margin of the Rhenish Massif. The track inventory consists ofRhynchosauroides peabodyi (Faber) andProcolophonichnium haarmuehlensis (Holst, Smit &; Veenstra), as well as scratch marks, drag marks, and an unidentified tetrapod track. TheR. peabodyi ichnofacies is associated with the moist carbonates of intertidal ponds. The tracks in this facies show a variety of preservational types and were left by reptiles such as prolacertilians.P. haarmuehlensis, on the other hand, was produced by small terrestrial reptiles, and theP. haarmuehlensis ichnofacies originated in the partially dry intertidal to supratidal carbonates. Borgholzhausen sports field and other new localities indicate that tracks of both ichnotaxa are widespread in several stratigraphic units of the Lower and Middle Muschelkalk along the northern margin of the Rhenish Massif and represent megatracksites.     

The status of the sauropterygian reptilePartanosaurus zitteli Skuphos from the Middle Triassic of the Austrian Alps,with comments onMicroleptosaurus schlössen Skuphos

Partanosaurus zitteli Skuphos 1893 from the Ladinian (Partnachschichten) of the northern Alps (Vorarlberg, Austria) is identified as a junior synonym ofSimosaurus gaillardoti Meyer 1832. Its occurrence in the Germanic Basin (Upper Muschelkalk) predates its appearance in the Alpine Triassic, and suggests faunal interchange between these two faunal provinces during Middle and Upper Ladinian times.Microleptosaurus schlossen Skuphos 1893 is represented by very incomplete material only and must be treated as a nomen dubium.     

Cyclotosaurus cf. PosthumusFraas (Capitosauridae,Stereospondyli) from the Huai Hin Lat Formation (Upper Triassic), Northeastern Thailand: With a note on capitosaurid biogeography

Part of a large capitosaurid skull, similar to that of Cyclotosaurus posthumus from the Upper Triassic of Germany, has been discovered in the upper part of the Huai Hin Lat Formation near Chulabhorn (Nam Phrom) Dam. This discovery is consistent with the presumed Norian age of this formation. Although the phylogeny of the Capitosauridae is still unclear, the group of Upper Triassic Cyclotosaurus species to which C. posthumus belongs is monophyletic and seems to be known only from Laurasia or Northwestern Gondwana (Morocco). The occurrence of C. cf. posthumus in Thailand is consistent with the hypothesis previously put forward, that this part of Southeast Asia was bound to Laurasia in Mesozoic times.     

Taxonomical and palaeoecological investigations of the chondrichthyan and osteichthyan fish remains from the Middle-Late Triassic deposits of the Villány Hills (Southern Hungary)

Two sites in the Villány Hills, Hungary, have yielded rich fish assemblages from Middle to Late Triassic shallow marine deposits. The collected material comes from the Ladinian Templomhegy Dolomite Member and from the Carnian Mészhegy Sandstone Formation. The ichthyofauna is composed of both chondrichthyans (Hybodontidae indet., Palaeobates angustissimus, ‘Polyacrodus’ sp., ?Lissodus sp.) and osteichthyans (Gyrolepis sp., Birgeria sp., and further indeterminate actinopterygians). Despite the large sample size, no remains of neoselachians have been found. The Ladinian Templomhegy Dolomite is dominated by durophagous hybodontiforms (Palaeobates angustissimus, ?Lissodus sp.), but the piscivorous hybodontid and the generalist ‘Polyacrodus’ sp. are missing, while in the fish fauna collected from the Carnian Mészhegy Formation indeterminate piscivorous hybodontids are the most common elements and durophagous forms are much less abundant. The dominance of piscivorous hybodontids in the Carnian Mészhegy Sandstone could be related to the global decrease of diversity of marine fish-eating reptiles (e.g., nothosaurs) or to a change of paleoenvironmental conditions. The present study improves our knowledge on the poorly known Triassic vertebrate faunas of the Tisza Mega-unit, which formed a segment of the passive Neotethys margin of the European Plate and shows an important example of a potential vertebrate faunal shift during the Middle to Late Triassic.     

Traquairaspididae and Cyathaspididae (Heterostraci) from the Lower Devonian of Poland

Lower Devonian strata from the drill cores from Poland have yielded new Heterostraci material. One ventral shield of Toombsaspis (Traquairaspididae, Phialaspidinae) discovered in the Białopole IG-1 drill core, and a fragment of dorsal shield of cf. Paraliliaspis (Cyathaspididae, Anglaspidinae) with the impressions of internal structures from Ciepielów IG-1 are described and provide new information on paleogeographic disparity of these groups.     

Postcranial morphology of a basal Pistosauroidea (Sauropterygia) from the Lower Muschelkalk of Winterswijk,The Netherlands

Two partial postcranial skeletons from the Lower Muschelkalk (early Anisian) of Winterswijk, The Netherlands, are described in detail. The specimens were assigned to basal Pistosauroidea, presumably to cf. Cymatosaurus or a closely related taxon. Cymatosaurus is currently the earliest member of the Pistosauroidea and is only known from skull material. Taxonomical assignment is based on humerus morphology and histology, and on morphological differences from other Sauropterygia (Nothosauria and Pachypleurosauria).     

Fossil reptiles from the Spanish Muschelkalk (mont‐ral and alcover,province Tarragona)

The marine tetrapods from the late Ladinian Spanish Muschelkalk deposits located between the towns of Mont‐ral and Alcover (province Tarragona) are reviewed. The fauna comprises an undetermined thalattosaur, a small cyamodontoid placodont probably referrable to Psephoderma, a possible pachypleurosaur with (if any) affinities to the Serpianosaurus‐Neusticosaurus clade, lariosaur specimens currently referred to Lariosaurus balsami, an incomplete specimen of Lariosaurus calcagnii, an endemic nothosaur (Nothosaurus cymatosauroides), and a possible pistosaur. Collectively, the faunal mix comprises endemic taxa as well as elements with affinities to the fauna of the Alpine and/or Germanic Triassic. The fauna suggests faunal interchange through the Burgundy Gate linking the southern branch of the developing Neotethys to the Germanic Basin.