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Here we report and describe a new assemblage of Thylacocephala (Crustacea) from the Early Ladinian Buchenstein Fm. (Middle Triassic) of Grigna, Northern Italy. The assemblage consists of at least four species from three different genera: Ankitokazocaris lariensis sp. n., Ankitokazocaris sp., Austriocaris sp., Stoppanicaris grignaensis gen. et sp. n. This thylacocephalan assemblage is rather diverse compared to the others of the Triassic. The largest size and ornamentation type of thylacocephalan species is compared among different periods of the Triassic and indicates that taxa with ridges on the carapace are generally smaller than those with smooth carapaces. This may be related to their different modes of life, such as inside or above the sediment with low oxygen levels. Large and smooth taxa were possibly more adapted to a life above sandy bottoms in shallow waters, under a somewhat high wave energy, while small, ornamented taxa are better suited for deeper environments with muddy bottoms, inside which they could move freely. The EDS analysis of Austriocaris sp. reveals that the cuticle mainly consists of apatite, which is in accordance with previous interpretations. [ABSTRACT FROM AUTHOR] more...

Copyright of Rudarsko-Geolosko-Naftni Zbornik is the property of Faculty of Mining, Geology & Petroleum Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Acta Petrologica et Mineralogica / Yanshi Kuangwuxue Zazhi is the property of Acta Petrologica et Mineralogica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Abstract Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 was originally described on the basis of a single complete fossil specimen excavated near Besano (Italy). However, a recent taxonomic revision and re-examination of the cranial osteology allowed for the assignment of five additional specimens to the taxon. Here, we analyse, describe and discuss the postcranial anatomy of Besanosaurus leptorhynchus in detail. The size of the specimens examined herein ranged from slightly more than one meter to eight meters. Overall, several diagnostic character states for this taxon are proposed, demonstrating a mosaic of plesiomorphic and derived features. This is best exemplified by the limbs, which show very rounded elements in the forelimbs, and pedal phalanges with retained rudimentary shafts. We suggest that the widely spaced phalanges in the forefins of Besanosaurus leptorhynchus were embedded in a fibrocartilage-rich connective tissue, like in modern cetaceans. We also review the similarities of Besanosaurus with Pessopteryx and Pessosaurus, allowing us to conclude that Besanosaurus is not a junior synonym of either of the two taxa. Lastly, to test the swimming capabilities of Besanosaurus leptorhynchus, we expanded on a previously published study focussing on reconstructing the swimming styles of ichthyosaurs. Besanosaurus leptorhynchus was found to possess a peculiar locomotory mode, somewhat intermediate between anguilliform swimmers, such as Cymbospondylus and Utatsusaurus, and some shastasaur-grade (e.g., Guizhouichthyosaurus) and early-diverging euichthyosaurian (e.g., Californosaurus) ichthyosaurs. Based on our results, we furthermore suggest that mixosaurids acquired their characteristic body profile (dorsal fin and forefins that are distinctly enlarged compared to the hindfins) independently and convergently to the one that later appeared in Parvipelvia. Moreover, the different swimming styles inferred for Cymbospondylus, Mixosauridae, and Besanosaurus strengthen the earlier hypothesis of niche partitioning among these three distinct ichthyosaur taxa from the Besano Formation. more...

Abstract Our new study of the species originally included in the genus Allolepidotus led to the taxonomic revision of the halecomorph species from the Triassic of Perledo, Italy. The morphological variation revealed by the analysis of the type material is sufficient to confirm four different taxa represented in the Perledo Formation. We correct the misunderstanding about the type species of Allolepidotus, which is A. ruppelii and not “A.” bellottii as considered in the literature over the past two decades. The latter species was originally placed in the genus Semionotus. Fossils from the Kalkschieferzone of Besnasca/Ca' del Frate (Viggiù-Varese, Italy) and Meride (Ticino, Switzerland) which were referred to Allolepidotus, rather represent a species of Eoeugnathus. Therefore, we transfer the species Semionotus bellottii to that genus and propose the new combination E. bellottii. The second and only other species originally included in the genus Allolepidotus is transferred here to the new genus Perledovatus. The holotype of P. nothosomoides new comb. has been mechanically prepared, revealing additional anatomical information that allows to place this taxon in the halecomorph family Subortichthyidae. The other halecomorph species named from the Perledo Formation, Pholidophorus oblongus and Pholidophorus curionii, have been treated as junior synonyms of E. bellottii, but our analysis indicates that they represent distinct separate taxa. However, due to the loss of the type specimens, it is not possible to decide whether they might have been conspecific with other ray-finned fishes from the Middle Triassic of the Alps. more...

Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 was originally described on the basis of a single complete fossil specimen excavated near Besano (Italy). However, a recent taxonomic revision and re-examination of the cranial osteology allowed for the assignment of five additional specimens to the taxon. Here, we analyse, describe and discuss the postcranial anatomy of Besanosaurus leptorhynchus in detail. The size of the specimens examined herein ranged from slightly more than one meter to eight meters. Overall, several diagnostic character states for this taxon are proposed, demonstrating a mosaic of plesiomorphic and derived features. This is best exemplified by the limbs, which show very rounded elements in the forelimbs, and pedal phalanges with retained rudimentary shafts. We suggest that the widely spaced phalanges in the forefins of Besanosaurus leptorhynchus were embedded in a fibrocartilage-rich connective tissue, like in modern cetaceans. We also review the similarities of Besanosaurus with Pessopteryx and Pessosaurus, allowing us to conclude that Besanosaurus is not a junior synonym of either of the two taxa. Lastly, to test the swimming capabilities of Besanosaurus leptorhynchus, we expanded on a previously published study focussing on reconstructing the swimming styles of ichthyosaurs. Besanosaurus leptorhynchus was found to possess a peculiar locomotory mode, somewhat intermediate between anguilliform swimmers, such as Cymbospondylus and Utatsusaurus, and some shastasaur-grade (e.g., Guizhouichthyosaurus) and early-diverging euichthyosaurian (e.g., Californosaurus) ichthyosaurs. Based on our results, we furthermore suggest that mixosaurids acquired their characteristic body profile (dorsal fin and forefins that are distinctly enlarged compared to the hindfins) independently and convergently to the one that later appeared in Parvipelvia. Moreover, the different swimming styles inferred for Cymbospondylus, Mixosauridae, and Besanosaurus strengthen the earlier hypothesis of niche partitioning among these three distinct ichthyosaur taxa from the Besano Formation. [ABSTRACT FROM AUTHOR] more...

Copyright of Geology & Exploration is the property of Geology & Exploration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Our new study of the species originally included in the genus Allolepidotus led to the taxonomic revision of the halecomorph species from the Triassic of Perledo, Italy. The morphological variation revealed by the analysis of the type material is sufficient to confirm four different taxa represented in the Perledo Formation. We correct the misunderstanding about the type species of Allolepidotus, which is A. ruppelii and not "A." bellottii as considered in the literature over the past two decades. The latter species was originally placed in the genus Semionotus. Fossils from the Kalkschieferzone of Besnasca/Ca' del Frate (Viggiù-Varese, Italy) and Meride (Ticino, Switzerland) which were referred to Allolepidotus, rather represent a species of Eoeugnathus. Therefore, we transfer the species Semionotus bellottii to that genus and propose the new combination E. bellottii. The second and only other species originally included in the genus Allolepidotus is transferred here to the new genus Perledovatus. The holotype of P. nothosomoides new comb. has been mechanically prepared, revealing additional anatomical information that allows to place this taxon in the halecomorph family Subortichthyidae. The other halecomorph species named from the Perledo Formation, Pholidophorus oblongus and Pholidophorus curionii, have been treated as junior synonyms of E. bellottii, but our analysis indicates that they represent distinct separate taxa. However, due to the loss of the type specimens, it is not possible to decide whether they might have been conspecific with other ray-finned fishes from the Middle Triassic of the Alps. [ABSTRACT FROM AUTHOR] more...

Ginglymodians (e.g. gars) are a group of holostean fishes with a rich fossil history in the Mesozoic. The resolution of interrelationships among extinct ginglymodians is central to the problem of understanding the origin of this clade. Here, a new fossil ginglymodian, Diandongichthys ocellatus gen. et sp. nov. is described based on 13 well-preserved specimens from the Early-Middle Triassic (Anisian) marine deposits exposed in Luoping, eastern Yunnan, China. The discovery documents one of the oldest and smallest ginglymodians hitherto known from the Middle Triassic, with a maximum standard length of 41 mm. Diandongichthys , although displaying several synapomorphies of ginglymodians, retains some primitive states with respect to other early ginglymodians (e.g. a short snout without anterior infraorbitals, a maxilla ending below the orbit, and a median gular); consequently, it is nested at the base of the Ginglymodi in this phylogenetic study. Besides body shape, some autapomorphies on the cranial bones and caudal fin easily distinguish Diandongichthys from other members of this clade. The discovery provides new insights into the origin and early diversification of ginglymodian fishes. [ABSTRACT FROM AUTHOR] more...

Large volumes of Early Mesozoic intermediate to basic igneous rocks related to the evolution of the Paleo-Tethys Ocean are exposed in the East Kunlun Orogenic Belt (EKOB). The petrography, geochemistry, and results of zircon U-Pb dating of Defusheng intermediate to basic rocks from the eastern segment of the EKOB are presented in this report. Zircon U–Pb dating of the intermediate to basic rocks yields ages of 239–245 Ma (Middle Triassic). Defusheng intermediate to basic rocks have low TiO2 contents (0.80–1.47 wt.%) and widely varying MgO (3.14–6.08 wt.%), and are enriched in large ion lithophile elements and light rare earth elements, having a geochemical composition similar to that of island arc basalts. The variation diagrams of major elements indicate that the Defusheng intermediate to basic rocks underwent fractional clinopyroxene and olivine crystallization. Depletion of the high-field-strength elements Nb, Ta, and Ti may have been caused by the mantle wedge having been infiltrated by fluids derived from the subducted slab. The Defusheng intermediate to basic rocks represent magmatic records of the Early Mesozoic oceanic crust subduction in Eastern Kunlun. This indicates that the final closure of the Paleo-Tethyan Ocean and the beginning of collisional orogeny occurred after the Middle Triassic. [ABSTRACT FROM AUTHOR] more...

Abstract A new species (Marcopoloichthys mirigioliensis) of the stem teleosteomorph genus Marcopoloichthys is described from the lower Besano Formation (late Anisian at Monte San Giorgio, southern Switzerland), making this new species distinct from Marcopoloichthys furreri from the Prosanto Formation (early Ladinian at Ducanfurgga, southeastern Switzerland). Marcopoloichthys mirigioliensis n. sp. is smaller (ca. 32 mm standard length) than M. furreri (ca. 40 mm standard length), and in addition, the two species have some important differences in the caudal endoskeleton and fin, e.g., number of epaxial and hypaxial basal fulcra, uroneural structure, size of hypurals, and presence versus absence of urodermals. Marcopoloichthys mirigioliensis n. sp. is the smallest member of Marcopoloichthyidae which is currently known from at least five species living in the Triassic of China (one species), Italy (two and others that remain undescribed), and Switzerland and according to current information, with its ca. 32 mm standard length is candidate to be considered a miniature fish. Additionally, this size makes it the smallest known stem teleost. As in other marcopoloichthyids, the buccal and suspensorium anatomy of M. mirigiolensis n. sp. corresponds to that of suction-feeder fishes. more...

A Ladinian – Carnian volcano-sedimentary succession from western Slovenia, paleogeographically belonging to the western Slovenian Basin, is presented in 17 sections. Except for the lowermost part, which is dominated by volcanics and volcaniclastics, most of the succession is dominated by shale, sandstone, and micritic limestone. Various authors use the name Pseudozilja and/or Amphiclina formation for this part, which is dominated by clastics, but they disagree on the differences between the formations. The lower Pseudozilja formation, represented by the Malenski Vrh section, comprises diabase, tuf and shale. No substantial differences in lithological composition have been observed between the upper Pseudoziljaformation and the Amphiclina formation, which are predominantly composed of shale, sandstone, and limestone. The shale and sandstone are largely composed of quartz, feldspar, and lithic grains (especially volcanics), which vary in proportions. Limestone varieties comprise hemipelagic limestones and resedimented carbonates deposited by gravity-flows. Deposition of the Ladinian – Carnian volcano-sedimentary succession took place on or near the continental slope that was generally inclined to the S, with the direction of transport mainly from N to S. more...

Abstract There is a long history of palaeontological excavations at Monte San Giorgio (Switzerland) and the adjoining Monte Pravello—Monte Orsa (Italy), aimed at finding well-preserved skeletons of Middle Triassic vertebrates. The first fossils were discovered in the mid-Nineteenth Century during mining of black shales (scisti bituminosi) near Besano, Italy, with further finds in the early Twentieth Century through industrial-scale mining. Studies of the material generated international interest and prompted formal palaeontological excavations on both sides of the border. The earliest excavations took place in 1863 and 1878, with the most extensive between 1924 and 1968. Systematic excavations have continued up to the present day, focusing on six distinct fossiliferous horizons: the Besano Formation and the overlying Meride Limestone with the Cava inferiore, Cava superiore, Cassina, Sceltrich and Kalkschieferzone beds. All these have provided material for study and display, with Monte San Giorgio itself recently designated a UNESCO World Heritage Site. The workers and organisations involved, locations excavated and material recovered are described herein. more...

Abstract During the Middle Triassic, intensive volcanic activity took place along the eastern margin of Pangea, including the Greater Adria promontory, due to the Neotethyan oceanization. This resulted in the formation of various volcanic and volcaniclastic rock types. The region of NW Croatia, acting as a transition zone between the Southern Alps and the Dinarides, showcases the outcrops of these rocks. The present study investigates the facies of volcaniclastic rocks, the distribution of those facies, formation processes, as well as the genesis of the primary magma to gain a better understanding of the complex geodynamics of this region during the Middle Triassic. Six profiles across the Vudelja quarry front were surveyed using drone imaging and samples were collected for detailed petrographic and geochemical analyses. Two groups of volcaniclastic rocks were identified—mafic and intermediate/felsic. The former is represented by (I) autoclastic effusive facies and (II) resedimented autoclastic facies, while the latter is represented by (III) secondary pyroclastic facies. Mafic volcaniclastics were generated through basaltic effusions in marine environments, fragmentation in contact with seawater, mixing with shallow marine carbonate clasts, and subsequent redeposition in deeper marine areas. The secondary pyroclastic facies (III) consists of a regionally distributed felsic Pietra Verde tuff whose deposits may be related to pyroclastic density currents and syn-eruptive resedimentation by turbidite-like currents. Geochemical data indicate that parental magmas responsible for generating the mafic volcaniclastics had a calc-alkaline composition and originated in ensialic and mature arc settings of an active continental margin. The observed chemical composition is likely inherited from older, arc-related lithologies, associated with the subduction of the Paleotethys Ocean. Parental magmas are thought to have formed during continental rifting of the passive Middle Triassic margins of the Greater Adria through (i) partial melting of the heterogeneous lithospheric mantle, which had been metasomatized during an earlier Hercynian subduction, and (ii) subordinate processes related to the melting of the upper continental crust and subsequent fractionation. Ar/Ar dating on plagioclase separates yielded an age of 244.5 ± 2.8 Ma for mafic volcaniclastics. This aligns well with biostratigraphic ages of felsic tuffs which crop out on a broader regional scale of the Dinarides, the Southern Alps, and the Transdanubian Range. The overlapping ages obtained from radiometric dating of mafic volcaniclastics and biostratigraphic ages of the felsic Pietra Verde tuffs strongly suggest that the Greater Adria region experienced concurrent bimodal volcanism during the Middle Triassic. more...

Abstract Around the middle of the nineteenth century, Italian palaeontologists began to investigate fossils of fishes and reptiles from the Middle Triassic outcrops in the vicinity of Monte San Giorgio (Canton Ticino, Switzerland). In 1924, researchers from the University of Zurich started their scientific excavations on the Swiss side. The many fish fossils found since then have often stood in the shadow of the more spectacular and mostly larger fossils of various aquatic reptiles. Beginning around 1980 the fish fossils in the collection of the Palaeontological Institute and Museum of Zurich University have subsequently been brought out of this shadow. The picture presently emerging is that of a species rich fish fauna located in six different fossiliferous beds of Anisian and Ladinian age with a few chondrichthyan, some coelacanth and a wealth of different actinopterygian taxa, many of them well preserved. The ongoing work not only results in taxonomic and systematic novelties, but gives also new insights into their palaeobiology, palaeoecology and palaeobiogeography. more...

A new species (Marcopoloichthys mirigioliensis) of the stem teleosteomorph genus Marcopoloichthys is described from the lower Besano Formation (late Anisian at Monte San Giorgio, southern Switzerland), making this new species distinct from Marcopoloichthys furreri from the Prosanto Formation (early Ladinian at Ducanfurgga, southeastern Switzerland). Marcopoloichthys mirigioliensis n. sp. is smaller (ca. 32 mm standard length) than M. furreri (ca. 40 mm standard length), and in addition, the two species have some important differences in the caudal endoskeleton and fin, e.g., number of epaxial and hypaxial basal fulcra, uroneural structure, size of hypurals, and presence versus absence of urodermals. Marcopoloichthys mirigioliensis n. sp. is the smallest member of Marcopoloichthyidae which is currently known from at least five species living in the Triassic of China (one species), Italy (two and others that remain undescribed), and Switzerland and according to current information, with its ca. 32 mm standard length is candidate to be considered a miniature fish. Additionally, this size makes it the smallest known stem teleost. As in other marcopoloichthyids, the buccal and suspensorium anatomy of M. mirigiolensis n. sp. corresponds to that of suction-feeder fishes. [ABSTRACT FROM AUTHOR] more...

Hectometric blocks of Middle Triassic mafic pyroclastic rocks, represented by volcanic agglomerates/breccias and lapilli tuffs, form part of the ophiolitic mélange of Mt. Medvednica, situated in the southwestern segment of the Zagorje-Mid-Transdanubian Zone. These rocks share petrochemical characteristics with pyroclastic derivatives of alkali, within-plate basaltic lavas of Mts. Medvednica, Samoborska Gora, and Kalnik, indicating the occurrence of explosive events preceding the dominant effusive submarine volcanism during the Middle Triassic (Illyrian-Fassanian?) stages. The formation of these pre-ophiolitic pyroclastics is associated with an intracontinental rift setting and reflects melts derived from an OIB-type enriched mantle plume source. These pyroclastics represent uncontaminated melts that erupted through a highly thinned continental crust. In geodynamic terms, the formation of pyroclastites occurred during the Late Anisian-Early Ladinian along the continental margin of Palaeotethys through the proto back-arc rifting of continental lithosphere (Adria Plate), leading to the formation of the Maliak/Balkan Neotethys Rift, in the emerging northwestern segment of Neotethys. The investigated pyroclastic rocks of Mt. Medvednica documents the extension in an evolved intracontinental rift basin, which immediately preceded the generation of the initial Neotethyan oceanic lithosphere during the Upper Triassic. [ABSTRACT FROM AUTHOR] more...

[Display omitted] • U-Pb ages indicate Triassic Argentine strata are much older than previously thought. • New ages question previous pollen and spore-based biostratigraphic correlations. • Statistical analysis indicates Triassic plants track climate more than geologic time. Triassic non-marine strata from Gondwana are dated almost exclusively by biostratigraphic means, given the rarity of precise radioisotopic and magnetostratigraphic datasets. A primary method for constraining the age of these sedimentary sequences is palynomorph biostratigraphy, which implicitly assumes that differences in the presence/absence of taxa between two or more assemblages reflect a difference in geological ages. But without biostratigraphically-independent age data, this assumption often remains untested. The Triassic El Peñasco Group of the Santa Clara sub-basin in the Cuyana Basin of central-west Argentina is an excellent study system to help test these assumptions, because the upper part of the sequence comprises a fluvio-deltaic-lacustrine succession that preserves volcaniclastic horizons and extensive palynomorph assemblages. Previous palynostratigraphic analyses had inferred a Late Triassic (Carnian-Norian) age for the Santa Clara Abajo and overlying Santa Clara Arriba formations, but we present new precise U-Pb CA-TIMS zircon ages that suggest an upper Anisian (Middle Triassic) age for both formations. This makes it the only non-marine Anisian Gondwanan sequence, and one of only a handful globally, to be precisely dated geochronologically. These new ages also constrain the deposition of the >700 m-thick succession of the Santa Clara Abajo and Santa Clara Arriba formations to no more than 2.1 my of time, suggesting it represents a synrift phase of the sub-basin. Combining these and existing geochronologic data with a newly assembled comprehensive presence/absence dataset of palynomorphs from the Anisian-Norian of Gondwana, we demonstrate that paleogeography (paleolatitude) has a significantly stronger correlation with taxonomic composition of assemblages than does geologic time. These results imply that geography is an important null hypothesis in explaining differences in early Mesozoic Gondwanan palynomorph assemblages, and that precise geochronologic age constraints are important for refining the accuracy of Triassic palynomorph biochronology. [ABSTRACT FROM AUTHOR] more...

Around the middle of the nineteenth century, Italian palaeontologists began to investigate fossils of fishes and reptiles from the Middle Triassic outcrops in the vicinity of Monte San Giorgio (Canton Ticino, Switzerland). In 1924, researchers from the University of Zurich started their scientific excavations on the Swiss side. The many fish fossils found since then have often stood in the shadow of the more spectacular and mostly larger fossils of various aquatic reptiles. Beginning around 1980 the fish fossils in the collection of the Palaeontological Institute and Museum of Zurich University have subsequently been brought out of this shadow. The picture presently emerging is that of a species rich fish fauna located in six different fossiliferous beds of Anisian and Ladinian age with a few chondrichthyan, some coelacanth and a wealth of different actinopterygian taxa, many of them well preserved. The ongoing work not only results in taxonomic and systematic novelties, but gives also new insights into their palaeobiology, palaeoecology and palaeobiogeography. [ABSTRACT FROM AUTHOR] more...

During the Middle Triassic, intensive volcanic activity took place along the eastern margin of Pangea, including the Greater Adria promontory, due to the Neotethyan oceanization. This resulted in the formation of various volcanic and volcaniclastic rock types. The region of NW Croatia, acting as a transition zone between the Southern Alps and the Dinarides, showcases the outcrops of these rocks. The present study investigates the facies of volcaniclastic rocks, the distribution of those facies, formation processes, as well as the genesis of the primary magma to gain a better understanding of the complex geodynamics of this region during the Middle Triassic. Six profiles across the Vudelja quarry front were surveyed using drone imaging and samples were collected for detailed petrographic and geochemical analyses. Two groups of volcaniclastic rocks were identified—mafic and intermediate/felsic. The former is represented by (I) autoclastic effusive facies and (II) resedimented autoclastic facies, while the latter is represented by (III) secondary pyroclastic facies. Mafic volcaniclastics were generated through basaltic effusions in marine environments, fragmentation in contact with seawater, mixing with shallow marine carbonate clasts, and subsequent redeposition in deeper marine areas. The secondary pyroclastic facies (III) consists of a regionally distributed felsic Pietra Verde tuff whose deposits may be related to pyroclastic density currents and syn-eruptive resedimentation by turbidite-like currents. Geochemical data indicate that parental magmas responsible for generating the mafic volcaniclastics had a calc-alkaline composition and originated in ensialic and mature arc settings of an active continental margin. The observed chemical composition is likely inherited from older, arc-related lithologies, associated with the subduction of the Paleotethys Ocean. Parental magmas are thought to have formed during continental rifting of the passive Middle Triassic margins of the Greater Adria through (i) partial melting of the heterogeneous lithospheric mantle, which had been metasomatized during an earlier Hercynian subduction, and (ii) subordinate processes related to the melting of the upper continental crust and subsequent fractionation. Ar/Ar dating on plagioclase separates yielded an age of 244.5 ± 2.8 Ma for mafic volcaniclastics. This aligns well with biostratigraphic ages of felsic tuffs which crop out on a broader regional scale of the Dinarides, the Southern Alps, and the Transdanubian Range. The overlapping ages obtained from radiometric dating of mafic volcaniclastics and biostratigraphic ages of the felsic Pietra Verde tuffs strongly suggest that the Greater Adria region experienced concurrent bimodal volcanism during the Middle Triassic. [ABSTRACT FROM AUTHOR] more...

During the Late Palaeozoic to Early Mesozoic, the eastern segment of the Palaeo–Tethys Ocean closed, resulting in the collision and amalgamation of the South and North Hainan Islands. However, the exact location of the collision and amalgamation remains controversial. The main collision locations are the Baisha, Jiusuo–Lingshui and Changjiang–Qionghai faults. The U–Pb age of detrital zircons was used to determine the main source area of the Middle Triassic basin in the eastern part of Hainan Island and the closed position of the eastern section of the Palaeo‐Tethys Ocean. The U–Pb dating of detrital zircons revealed that the Middle Triassic Lingwen Formation contains four age groups: 235–258, 335–446, 766–986 and >1000 Ma. Notably, rock masses aged 248–252 Ma that were formed in a post‐orogenic tension setting have been identified in the western region of Hainan Island, whereas no igneous rocks from this period have been discovered in the eastern region. The detrital zircon samples from the Lingwen Formation revealed a peak at 249 ± 2 Ma U–Pb age, which is important evidence indicating that the Changjiang–Qionghai Fault is the product of collision between the southern and northern Hainan terranes. Affected by the bipolar subduction of the eastern segment of the Palaeo‐Tethys Ocean, the collision and amalgamation of the South and North Hainan terranes occurred, and experienced a post‐collision (extensional) process at ca. 249 ± 2 Ma. [ABSTRACT FROM AUTHOR] more...

Shallow marine carbonates of the Anisian Hámor Dolomite Formation in the Bükk Mountains, NE Hungary were studied to determine the mechanism and controlling factors of the dolomitization. Petrographic features, along with C and O stable isotope properties of the investigated rocks, indicate near-surface/shallow burial dolomitization of the shallow, subtidal-peritidal carbonate succession. This occurred via long-term circulation of relatively low-temperature fluid of sea-water origin. Geothermal convection may have been the driving force of this circulation. For application of this model, we need to assume that segmentation of a previously-established shallow ramp had already initiated in the Western Neotethys earlier in the middle Anisian. Unfortunately, we have only indirect evidence of this in the studied area. Still, the structural evolution and the related paleogeographic setting may have been the basic controlling factors of the pervasive early diagenetic near-surface/shallow burial dolomitization of the Hámor Formation. The coarse crystalline dolomite cement in the fractures and pores was precipitated from relatively high temperature (cc. 170 °C) water. Comparing the stable isotope values of the bulk rock and the fracture-occluding dolomite cement phase suggests a host-rock buffered fluid flow probably in the Late Cretaceous deformation phase. [ABSTRACT FROM AUTHOR] more...

Abstract Some of the earliest members of the archosaur-lineage (i.e., non-archosauriform archosauromorphs) are characterised by an extremely elongated neck. Recent fossil discoveries from the Guanling Formation (Middle Triassic) of southern China have revealed a dramatic increase in the known ecomorphological diversity of these extremely long-necked archosauromorphs, including the fully marine and viviparous Dinocephalosaurus orientalis. These recent discoveries merit a reinvestigation of enigmatic Triassic diapsid fossils from contemporaneous European deposits housed in historical collections. Here, we provide a redescription of Trachelosaurus fischeri, represented by a single, disarticulated specimen first described in 1918. Due to its unique morphology, which includes short, bifurcating cervical ribs, and a high presacral vertebral count, this taxon has been referred to either as a “protorosaurian” archosauromorph or a sauropterygian. Our revision clearly shows that Trachelosaurus represents the first unambiguous Dinocephalosaurus-like archosauromorph known from outside the Guanling Formation. Our finding has important systematic implications. Trachelosauridae Abel, 1919 represents the senior synonym for the recently identified Dinocephalosauridae Spiekman, Fraser and Scheyer, 2021. Based on our phylogenetic analyses, which employ two extensive datasets, we also corroborate previous findings that tanystropheids and trachelosaurids represent two families within a larger monophyletic group among non-crocopodan archosauromorphs, which is here named Tanysauria (clade nov.). Trachelosauridae is minimally composed of Trachelosaurus fischeri, Dinocephalosaurus orientalis, Pectodens zhenyuensis, and Austronaga minuta, but one of our analyses also found a probably taxonomically broader clade that may also include Gracilicollum latens and Fuyuansaurus acutirostris. Trachelosaurus fischeri considerably expands the known spatial and temporal range of Trachelosauridae to the earliest Anisian and the Central European Basin. Our findings add to the growing evidence for the presence of a diverse group of fully marine reptiles during the Middle Triassic among Tanysauria. These trachelosaurids possess flipper-like limbs, high vertebral counts, and elongate necks, thus superficially resembling long-necked Jurassic and Cretaceous plesiosaurs in some regards. more...

Two new species of dasycladal algae are described from the Anisian limestones of the Lika region in Croatia. Griphoporella? speleoluka n. sp. is characterized by very small cylindrical thallus and vesiculiform laterals arranged in close whorls. In consecutive whorls, laterals are positioned one above the other. It differs from other species by smaller dimensions and the arrangement of the laterals. Palaeodasycladus primus n. sp. has cylindrical thallus with whorls of inclined laterals up to the third order. Primary laterals are not completely calcified, producing so-called intusannulation. Trichoform or tubular secondary laterals bear bundles of thin, probably trichoform, tertiary laterals. Both of the new species have been found within typical Anisian microfossil assemblage. more...

Middle Triassic beds exposed along the road between Mišji Dol and Poljane pri Primskovem (Posavje Hills) comprise marlstone, tuff, volcaniclastic sandstone, and thin- to medium-bedded limestone and dolostone. The succession was logged and sampled for conodonts. A relatively rich conodont assemblage was determined, consisting of Budurovignathus gabrielae Kozur, Budurovignathus sp., Cratognathodus kochi (Huckriede), Gladigondolella malayensis Nogami, Gladigondolella tethydis Huckriede, Gladigondolella sp., Neogondolella balkanica Budurov & Stefanov, Neogondolella cf. excentrica Budurov & Stefanov, Neogondolella constricta (Mosher & Clark), Neogondolella cornuta Budurov & Stefanov, Neogondolella sp., Paragondolella excelsa Mosher, Paragondolella liebermani (Kovacs & Kozur), Paragondolella trammeri (Kozur), Paragondolella cf. alpina (Kozur & Mostler), and Paragondolella sp. The assemblage correlates with the upper Anisian and lowermost Ladinian assemblages from the Global Boundary Stratotype Section and Point (GSSP) of the Ladinian at Bagolino in the Southern Alps in northern Italy. Along with conodonts, numerous specimens of benthic foraminifera Nodobacularia? vujisici Urošević & Gaździcki were recovered from the lowermost part of the succession. Previous research on this taxon is critically evaluated. more...

Abstract In northern Switzerland, Middle Muschelkalk evaporites (Zeglingen Formation) were deposited under arid conditions in the southernmost part of the epicontinental Central European Basin during times of reduced inflow of sea water from the Tethyan realm. Because of their marginal position in the basin, direct and detailed correlation of Muschelkalk sediments of northern Switzerland with equivalent strata in interior parts of the basin is not straightforward. Based on detailed sedimentological logging of 640 m of drill cores from ten wells in northern Switzerland, 22 lithofacies and 10 lithofacies associations were distinguished for the Middle Muschelkalk evaporites. High-resolution regional correlations of gamma-ray logs record substantial thickness variation of the evaporites. Locally, dissolution was recognized by visual core examination that could be dated to Middle Triassic times and that was likely related to subsurface fluid flow along deeper seated faults. In combination with the regional thickness variation, the dissolution phenomena suggest a tectonically active depositional setting in the Middle Triassic. Middle Muschelkalk evaporites consist of nine types of mainly auto-cyclic shallowing- or brining-upward mini-cycles which form a correlatable succession of five distinct 4th order cycle-sets. Despite the tectonically active depositional environment, most lithofacies encountered appear to have nearly flat bounding surfaces. Thus, marine transgressions flooded wide areas nearly simultaneously. The corresponding deposits serve as reference levels to tie the peripheral facies of northern Switzerland into the supra-regional context. more...

Some of the earliest members of the archosaur-lineage (i.e., non-archosauriform archosauromorphs) are characterised by an extremely elongated neck. Recent fossil discoveries from the Guanling Formation (Middle Triassic) of southern China have revealed a dramatic increase in the known ecomorphological diversity of these extremely long-necked archosauromorphs, including the fully marine and viviparous Dinocephalosaurus orientalis. These recent discoveries merit a reinvestigation of enigmatic Triassic diapsid fossils from contemporaneous European deposits housed in historical collections. Here, we provide a redescription of Trachelosaurus fischeri, represented by a single, disarticulated specimen first described in 1918. Due to its unique morphology, which includes short, bifurcating cervical ribs, and a high presacral vertebral count, this taxon has been referred to either as a "protorosaurian" archosauromorph or a sauropterygian. Our revision clearly shows that Trachelosaurus represents the first unambiguous Dinocephalosaurus-like archosauromorph known from outside the Guanling Formation. Our finding has important systematic implications. Trachelosauridae Abel, 1919 represents the senior synonym for the recently identified Dinocephalosauridae Spiekman, Fraser and Scheyer, 2021. Based on our phylogenetic analyses, which employ two extensive datasets, we also corroborate previous findings that tanystropheids and trachelosaurids represent two families within a larger monophyletic group among non-crocopodan archosauromorphs, which is here named Tanysauria (clade nov.). Trachelosauridae is minimally composed of Trachelosaurus fischeri, Dinocephalosaurus orientalis, Pectodens zhenyuensis, and Austronaga minuta, but one of our analyses also found a probably taxonomically broader clade that may also include Gracilicollum latens and Fuyuansaurus acutirostris. Trachelosaurus fischeri considerably expands the known spatial and temporal range of Trachelosauridae to the earliest Anisian and the Central European Basin. Our findings add to the growing evidence for the presence of a diverse group of fully marine reptiles during the Middle Triassic among Tanysauria. These trachelosaurids possess flipper-like limbs, high vertebral counts, and elongate necks, thus superficially resembling long-necked Jurassic and Cretaceous plesiosaurs in some regards. [ABSTRACT FROM AUTHOR] more...

Modelling plumbing systems dynamics of active volcanoes through textural and chemical studies of mineral phases is crucial to unravel their eruptive behaviour, but it is rarely applied in ancient volcanic and volcano-plutonic systems. Here, we present an investigation of the architecture, magma dynamics and pre-eruptive timing of Middle Triassic plumbing systems in the Dolomites area (Southern Alps) through a detailed investigation of textures and compositional zoning of clinopyroxenes in lavas and dykes from Predazzo, Mt. Monzoni, Cima Pape and Sciliar volcano-plutonic complexes. The clinopyroxene composition varies between low-Mg# (67–78), low-Cr augite and high-Mg# (77–91), Cr-rich diopside. Diopside is less frequent and appears as variably thick single or multiple bands between augitic cores and rims or as resorbed homogeneous, or patchy-zoned and mottled cores. Rims are homogeneous or oscillatory zoned, with augitic composition. The mid- to low-crustal plumbing systems of all volcanic centres were characterised by the presence of a mildly evolved trachyandesitic magma (Mg# 45; T = 1044–1118 °C), where augitic clinopyroxene formed. Periodic mafic injections of more primitive and hotter trachybasaltic magma (Mg# 56; T = 1056–1170 °C) caused frequent crystallisation of diopsidic bands around augitic cores. The presence of resorbed or patchy-zoned mottled diopsidic cores in clinopyroxene phenocrysts, as well as of rare clinopyroxenitic xenoliths with analogous diopsidic composition, indicates the recycling and remobilisation of antecrysts from the deeper part of the plumbing system, which was probably located at a depth of 10–17 km. Diffusion chronometry models based on Fe–Mg interdiffusion in clinopyroxene revealed that the time elapsed from the mafic injection into the shallow portion of the plumbing systems to the eruption ranges from decades to < 1 year. Our findings enabled us to resolve the different plumbing system dynamics acting at the local scale beneath each volcanic centre. Our data indicate a striking similarity with magma dynamics and timing of pre-eruptive processes at active volcanoes: therefore, we posit that this work sets a starting point to deepen our knowledge of the volcano-plutonic links and, in turn improves our ability to interpret the main processes acting in active plumbing systems. [ABSTRACT FROM AUTHOR] more...

Holocrinus hagdorni sp. nov. (Crinoidea, Holocrinida) is described based on well-preserved, disarticulated stem remains from latest middle to early late Anisian (early Middle Triassic) deposits of the north-eastern outskirts of Qingyan, Guizhou Province, south-western China. The columnals exhibit a well-differentiated articulation facet sculpture, and the distal nodal facets show a conspicuous variability. They generally are symplectial as typical for Holocrinus, but in many nodals, the distal facet is slightly to distinctly weaker sculptured than the proximal facet, and sometimes cryptosymplectial to more or less synostosial distal nodal facets occur. The morphological variability of the distal nodal facets in the genus Holocrinus is discussed with regard to holocrinid and isocrinid evolution and life mode. Cryptosymplectial to synostosial nodal–infranodal articulations have only been documented in a minority of the Holocrinus species and their occurrence appears to be random with regard to stratigraphical age and ontogenetic stage, whereas the isocrinids, descended from holocrinids and co-existing with them in Triassic times, show always cryptosymplectial to synostosial nodal–infranodal articulations. The predisposition for weaker sculptured nodal–infranodal articulations probably developed in early holocrinids prior to or during the early Olenekian (late Early Triassic) in the far-eastern part of the Palaeotethys. Furthermore, the isocrinid genus Bakonycrinus is documented from China for the first time. [ABSTRACT FROM AUTHOR] more...

This paper is a continuation of a previous one in which I described and revised different Middle Triassic nassellarian Radiolaria from the Alps and Carpathians illustrated with drawings. On the present paper, are described two new groups of Middle Triassic dicyrtid Nassellaria with bell-shaped shell from the same area to enrich the inventory of these microfossils. Two new families (Gorispelidae and Humerocyrtiidae), five new genera (Silicotintinnabulum, Colpotrelus, Gorispela, Pozsvartia and Humerocyrtis) and 30 new species are described from these genera and illustrated with drawings [ABSTRACT FROM AUTHOR] more...

Copyright of Geologija (0016-7789) is the property of Geological Survey of Slovenia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

This paper presents the results of a revision and synthesis of data on Triassic tetrapods of Russia, collected and studied over more than a century and a half. An annotated catalog of the species encountered has been compiled, with information on the systematic position and synonymy provided for each of them, the holotype indicated, and in each case, references to the main works and illustrations are given. The accepted reconstruction of Triassic tetrapod succession of European Russia expressing the recovery of terrestrial biota after the Permian crisis is discussed. The level of resolution available for recognizing the events recorded in this faunal succession has no comparable equivalents for other land areas, so in many respects, the resulting scheme can serve as a kind of standard for intercontinental correlations. Analysis of local distinctions shown by a number of coeval tetrapod communities from different areas of European Russia enabled the identification of three distinct regions, differing in their zoogeographical connections, or, in some cases, in features of the biotopes inhabited, or in the proximity of these biotopes to the diversification centers. A catalog of all Triassic tetrapod localities known on the territory of Russia is provided, with a revised list of taxa found in each of them and collection numbers of all identifiable fossils. [ABSTRACT FROM AUTHOR] more...

The assemblage of oceanic islands and seamounts, arising from the widespread presence of mature oceans, plays a crucial role in reconstructing the evolutionary history of the paleoocean. Oceanic islands or seamounts within the Longmuco-Shuanghu metamorphic complex, a remnant of the Paleo-Tethys Ocean in the central Tibetan Plateau, have seldom been reported due to their remoteness. This study has identified an oceanic island-seamount in the Maoershan area, situated to the west of the Longmuco-Shuanghu metamorphic complex, composed of basalt, diabase, limestone, and siliceous rocks. Based on field observations, petrology, zircon U-Pb dating, whole-rock geochemistry, and Sr-Nd isotopes analyses, we have identified a suite of mafic rocks with OIB affinity. The youngest zircon U-Pb age cluster was concentrated at ~243–241 Ma. The geochemical characteristics of the siliceous rocks indicate a mixture of terrigenous material, suggesting that they formed in a continental margin. In combination with regional geological data, we conclude that the Longmuco-Shuanghu Paleo-Tethys Ocean remained open during the Middle Triassic. Furthermore, a fraction of the oceanic island-seamounts underwent scraping and transformed into a metamorphic complex, while other segments experienced deep subduction, resulting in the formation of high-pressure metamorphic rocks. Collectively, these processes gave rise to the distinctive high-pressure metamorphic complex within the central Qiangtang terrane. [ABSTRACT FROM AUTHOR] more...

Coelacanths form today an impoverished clade of sarcopterygian fishes, which were somewhat more diverse during their evolutionary history, especially in the Triassic. Since the first description of the coelacanth Ticinepomis peyeri from the Besano Formation of the UNESCO World Heritage Site of Monte San Giorgio (Canton Ticino, Switzerland), the diversity of coelacanths in the Middle Triassic of this area of the western Paleo-Tethys has been enriched with discoveries of other fossil materials. At Monte San Giorgio, two specimens of Heptanema paradoxum and several specimens of the unusual coelacanth Rieppeliaheinzfurreri, have been reported from the Meride Limestone and the Besano Formation, respectively. Another unusual coelacanth, Foreyia maxkuhni, and two specimens referred to Ticinepomis cf. T. peyeri have been described from the isochronous and paleogeographical close Prosanto Formation at the Ducanfurgga and Strel sites (near Davos, Canton Graubünden). In the framework of the revision of the coelacanth material from the Besano Formation kept in the collection of the Paläontologisches Institut und Museum der Universität Zürich (Switzerland), we reviewed the genus Ticinepomis on the basis of the holotype and four new referred specimens. Several morphological traits that were little and/or not understood in T. peyeri are here clarified. We re-evaluate the taxonomic attribution of the material of Ticinepomis cf. T. peyeri from the Prosanto Formation. Morphological characters are different enough from the type species, T. peyeri, to erect a new species, Ticinepomis ducanensis sp. nov., which is shown to be also present in the Besano Formation of Monte San Giorgio, where it is represented by fragmentary bone elements. The recognition of a new coelacanth species indicates that the diversity of this slow-evolving lineage was particularly high in this part of the Western Tethys during the Middle Triassic, especially between 242 and 240 million years ago. [ABSTRACT FROM AUTHOR] more...

Articulated natural assemblages contain direct evidence of the element numbers, morphologies, positions and structures for reconstructing the feeding apparatuses of conodont animals, but these kind of materials are very rare in fossil records. Here we report ten new conodont natural assemblages from Member II of the Guanling Formation in Luoping County, eastern Yunnan Province, southwestern China. These assemblages were obtained from the fossil-bearing layers of the Luoping Biota, dated to the early Middle Triassic Anisian stage (Pelsonian substage). These fossiliferous laminated limestones mainly consist of calcites and dolomites, with platy clay minerals and pyrites as subordinate components, indicating that the conodont assemblages were preserved in a lower energy and anoxic sedimentary environment. The new natural assemblages preserve the primary collapse orientations of the Nicoraella feeding apparatus from the Luoping Biota, showing the relative original positions of the S, M and P elements, that could be further used to refine the architecture of this apparatus in space variable M elements and the position unclear P1 elements. Integrating previously reported three-dimensional and bilaterally symmetrical fused clusters, we statistically analyze the size of the positional homogenous elements within different sized materials, in particular S4, S3, or S2 elements, indicates that elements ontogenic changes do not affect the apparatus architecture. Architecture of Nicoraella apparatus remains stable in the process of ontogeny, so our reconstructed model is credible. It is the first time that ample types of materials have been used to restore a conodont apparatus within one genus, namely natural assemblages (articulated and disarticulated), fused clusters (articulated, disarticulated, compressed, and relatively three-dimensional), and abundant discrete elements, respectively. These materials together record the most complete information on architecture in the gondolelloid apparatuses, thus enabling us to reconstruct a reliable fifteen-element apparatus and propose it as a standard template for gondolelloid apparatus reconstruction. [ABSTRACT FROM AUTHOR] more...

Copyright of Acta Scientiarum Naturalium Universitatis Pekinensis is the property of Editorial Office of Acta Scientiarum Naturalium Universitatis Pekinensis and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

In northern Switzerland, Middle Muschelkalk evaporites (Zeglingen Formation) were deposited under arid conditions in the southernmost part of the epicontinental Central European Basin during times of reduced inflow of sea water from the Tethyan realm. Because of their marginal position in the basin, direct and detailed correlation of Muschelkalk sediments of northern Switzerland with equivalent strata in interior parts of the basin is not straightforward. Based on detailed sedimentological logging of 640 m of drill cores from ten wells in northern Switzerland, 22 lithofacies and 10 lithofacies associations were distinguished for the Middle Muschelkalk evaporites. High-resolution regional correlations of gamma-ray logs record substantial thickness variation of the evaporites. Locally, dissolution was recognized by visual core examination that could be dated to Middle Triassic times and that was likely related to subsurface fluid flow along deeper seated faults. In combination with the regional thickness variation, the dissolution phenomena suggest a tectonically active depositional setting in the Middle Triassic. Middle Muschelkalk evaporites consist of nine types of mainly auto-cyclic shallowing- or brining-upward mini-cycles which form a correlatable succession of five distinct 4th order cycle-sets. Despite the tectonically active depositional environment, most lithofacies encountered appear to have nearly flat bounding surfaces. Thus, marine transgressions flooded wide areas nearly simultaneously. The corresponding deposits serve as reference levels to tie the peripheral facies of northern Switzerland into the supra-regional context. [ABSTRACT FROM AUTHOR] more...

This contribution presents a comprehensive study of the unique and rich terrestrial Middle Triassic palynoflora recovered from the Quebrada de los Fósiles Formation, lower unit of the Puesto Viejo Group, San Rafael Depocenter, Mendoza Province, Argentina. The palynoflora was recorded at two sections of the unit (Quebrada de los Fósiles creek and Río Seco de la Quebrada creek), yielding diverse and well-preserved spores, pollen, freshwater algae, and fungal associations. Herein, 259 spore-pollen species are described and/or illustrated, from which eight are new: Baculatisporites magnus sp. nov., Carnisporites microspinous sp. nov., Leschikisporis variabilis sp. nov., Neoraistrickia stricta sp. nov., Limatulasporites rugulatus sp. nov., Aratrisporites circularis sp. nov., Protohaploxypinus bonapartei sp. nov. and P. diazii sp. nov. The following new combinations are proposed: Brevitriletes decorus comb. nov., B. pamelae comb. nov., B. sandrae comb. nov., Cuneatisporites cacheutensis comb. nov., C. salujhai comb. nov., and Pityosporites thoracatus comb. nov. A new emendation for Alisporites cymbatus is instituted, and A. libyaensis nom. nov. is a new name to replace A. plicatus. These microfloras present varied parental vegetation, containing high proportions of spores from Pleuromeiales, Equisetales, Marattiales, and Corystospermales pollen. The grains of Araucariaceae, Cupressaceae, Voltziales, Cordaitales, Gnetales, and Ginkgoales/Cycadales are recorded in smaller proportions. Zygospores of chlorophytic algae and fungi are also recorded in these assemblages. The microflora of the Quebrada de los Fósiles Formation is distinctive, quantitatively and qualitatively, from the rest of the Triassic microfloras, exhibiting the highest similarities in its composition with the associations of the La Veteada (Early Triassic, Olenekian) and Cerro de Las Cabras (Late Anisian-Early Ladinian) formations. [ABSTRACT FROM AUTHOR] more...

In this paper, we present an integrated study of petrology, zircon U–Pb geochronology, whole-rock geochemistry, and zircon Lu–Hf isotopes for the basic–intermediate dykes in the western Gonghe basin, northeastern Qinghai–Tibetan Plateau. LA–MC–ICP–MS zircon U–Pb dating indicates that these dykes were emplaced in the Middle Triassic (240 ± 1.6 Ma). Geochemically, these basic–intermediate dykes are characterized by enrichments in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs; e.g. K, Rb, and Pb), coupled with depletions in high-field-strength elements (HFSEs; e.g. Nb, Ta, and Ti). These geochemical features, along with the relatively low zircon εHf values (−7.2 to 1.6), suggest that these mafic dykes were originated from enriched mantle metasomatized by subduction-related fluids in a back-arc extensional environment. Literature investigations indicate that Middle Triassic mafic dykes are widespread in central China and are geochemically of arc affinities. Therefore, a regional back-arc extensional event occurred in central China during Middle Triassic time, which was likely caused by rollback of the subducting Kunlun–Animaqin Paleo-Tethyan slab. [ABSTRACT FROM AUTHOR] more...

The Middle Triassic Pingtai pluton, which occurs in the southeastern part of Wulonggou gold orefield, East Kunlun orogen, provides new insights into the subduction history of the Paleo-Tethyan ocean. The detailed petrology, whole-rock geochemistry, zircon U-Pb age and Hf isotopic data of granodiorite from Pingtai pluton were conducted. The results show that the granodiorite of Pingtai pluton mainly comprises plagioclase(the volume fraction is 45%-50%), quartz(20%-25%), K-feldspar(20%-25%), hornblende(5%), and biotite(5%), and it yields a zircon U-Pb weighted mean age of(247±1)Ma, suggesting an emplacement age of Middle Triassic; whole-rock geochemistry characteristics show that SiO2 content varies from 64.88% to 65.90%, average ratios of FeOT/MgO and Fe2O3/FeO are 3.70 and 1.48, respectively, and average saturation temperature for zircon is calculated to be 770 ℃. Therefore, it is suggested that the granodiorite belongs to strong peraluminous and high-potassium calcium alkaline series, which is similar to typical I-type granite. Chondrite-normalized REE pattern shows that the granodiorite is enriched in LREEs and depleted in HREEs with weak negative Eu anomaly. The εHf(t)values range from -4.51 to 0.64, and the Hf model age is 1.54-1.22 Ga. In combination with regional geological data, it is suggested that the granodiorite of Pingtai pluton is generated in a continental magmatic arc setting, which is related to the northward subduction of the Paleo-Tethyan ocean, and its parental magma is derived from meta-sandstone of continental crust. It is further indicated that the subduction of the Paleo-Tethyan ocean might have lasted until the late Middle Triassic. [ABSTRACT FROM AUTHOR] more...

Abstract For the first time, nautilids from the Besano Formation (Anisian/Ladinian boundary) are documented. The extremely rare material was collected from two different outcrops at Monte San Giorgio (Southern Alps, Ticino, Switzerland). This material is represented by only five specimens described here. The three best specimens belong to the taxa Enoploceras rieberi sp. nov., Germanonautilus aff. ellipticus and Syringonautilus sp. indet., documenting the presence of the families Tainoceratidae and Syringonautilidae in the middle Besano Formation. Another nautilid specimen is described in open nomenclature, representing an additional taxon. The new species Enoploceras rieberi n. sp. is currently the only occurrence of the genus Enoploceras in the Middle Triassic. Nautilida are poorly known from the Middle Triassic Tethyan region, mostly from sediments deposited in pelagic environments. This is the first record of these nautilids from an usually anoxic depositional paleoenvironment of an intra-platform basin, where the sediments of the Besano Formation were laid down. ZooBank LSID: urn:lsid:zoobank.org:pub:61CF9E69-0F12-4D63-8CD7-0F2C8BA15C7C more...

Pseudobeaconiidae is a South American endemic actinopterygian family recorded in the Middle-Late Triassic Cuyana and Ischigualasto-Villa Unión rift basins. This family has been studied for more than seven decades by several authors. In spite of that, the morphological information about their scales is not complete, especially the one related to micromorphology, which has remained unknown until now. The main goal of this contribution is to provide new macro- and micromorphological information of scales from new material of Pseudobeaconiidae, including a brief revision of the scales of the family based on our own observations from material collections. The new studied specimens were recovered from the center lake facies of the Santa Clara Abajo Formation with detailed stratigraphic control. The macromorphology of isolated scales confirms a peg-and-socket articulation in this newly studied material. New features described also include the squamation general pattern, including the scales of the lateral line, the ventral margin, that is characterized by round or angular scales, and the presence of ganoine ornamentations covering preanal and postanal scutes. Regarding micromorphology, paleohistology shows lepidosteoidtype ganoid scales and; also, possible transitional ganoid scales between lepidosteoid and palaeoniscoid-type. Detailed morphological studies on Triassic fish faunas are necessary to obtain clearer patterns that contribute to the understanding of the evolution of Actinopterygii from Gondwana. [ABSTRACT FROM AUTHOR] more...

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Ammonoids from the Besano Formation published by Airaghi in 1912 kept at the Museo Kosmos in Pavia. The ammonoids from the Besano Formation described by Airaghi in two works in 1912, belonging to the collections of the Museo di Storia Naturale di Milano, as well as many other historical collections stored in this museum, have been lost during World War II. However, some plaster casts of these specimens were recently found among the material stored in the new Museo Kosmos in Pavia during a reorganization of the deposits. The plaster casts, probably made by Airaghi, were obtained from the original specimens corresponding to some species erected by Airaghi and coming from the mine of Tre Fontane (Mt. San Giorgio, Switzerland). Lacking original specimens and related stratigraphic data, the present material is herein reclassified and considered as complementary for the corresponding neotypes, previously stated by Rieber in 1973. Among the taxa not revised in literature, two new combinations are here proposed: Serpianites marianii (Airaghi 1912) and ?Nevadites bassanii (Airaghi 1912). With these plaster casts we also uncovered some original specimens never described. The majority of the material is paired with the original labels by Airaghi. These ammonoids are characteristic of the lower and upper Secedensis Zone (Upper Anisian, Middle Triassic) of the Besano Formation. It is very likely the herein described specimens were collected in the beds belonging to the Secedensis Zone of the mine Tre Fontane which have been completely removed in the first years of excavation activity. [Article in Italian] more...

The so-called Lange Encrinite, designated as one of two syntypes of Encrinus liliiformis Lamarck, 1801, was regarded as missing or forgotten since the late 1760s. Only recently the specimen was identified as one of Lamarck's syntypes in the collections of the Bergakademie Freiberg (Saxony). The intricate history of finding, ownership, and research of this iconic crinoid leads to the ideas and thoughts in the time of Enlightenment in Central Germany. According to contemporary witnesses the crinoid was found near Schraplau or Farnstädt respectively (Querfurt Depression, Saxony-Anhalt, Central Germany) about 1740 and was obtained by the Halle professor J. J. Lange. In 1755 it was published by G. W. Knorr in Nuremberg in a large-size copper engraving. As early as in the 1770s the Jena professor and expert in fossils J. E. I. Walch was unable to localise the crinoid despite all his enquiries. Lange had already sold the specimen to the Saxony Oberberghauptmann (chief mining director) Baron von Gartenberg. Afterwards, the Muschelkalk slab probably came from his possession into the local collections shortly before the foundation of the Bergakademie Freiberg (Saxony) in 1765. Several individuals of the brachiopod Tetractinella trigonella on the bedding plane allow to unequivocally assign the finding horizon to the Tetractinella Bed close to the base of the Trochitenkalk Formation. The syntype first mentioned by Lamarck from the Trochitenkalk of the Asse Hill (Lower Saxony) was already described and figured as Fig. 1 on Plate 1 by M. R. Rosinus (1719). This specimen was probably obtained with the collection of von Schlotheim in 1833 by the Berlin Natural History Museum but could not yet be located. However, the crown on his Plate 1, Fig. 2, from the same locality that also belonged to Rosinus's collection is still preserved in the Berlin collection (Quenstedt-Katalog E. 4.). [ABSTRACT FROM AUTHOR] more...

A new Triassic small marine reptile has been found in the locality of Cehegín (Murcia, Southeastern Spain). The fossil remains mainly comprise moulds of the bones and some osseous fragments still embedded in the rock. These correspond to an articulated sauropterygian, being distinguishable the cervical vertebrae in one rock, while the other rock preserves the middle-inferior part of the body, being differentiated some dorsal, sacral and caudal vertebrae, the ribs, the gastralia, part of one forelimb, part of the hindlimbs and some pelvic elements that can be also intuited. The moulds of dorsal vertebrae, the ribs and the gastralia are overlapped, but it can be distinguished that the ribs are pachiostotic and the gastral ribs are constituted by different components (partite gastral ribs). The features of this reptile permit to refer it to Eosauropterygia. This discovery constitutes the most complete sauropterygian found, to date, in the SouthIberian Palaeomargin of the Tethys, and adds new information about the diversity and palaeogeographical distribution of Sauropterygia in the Middle Triassic, indicating that it was greater than previously believed. [ABSTRACT FROM AUTHOR] more...

Rhynchosaurs were key herbivores over much of the world in the Middle and Late Triassic, often dominating their faunas ecologically. The anatomy of the Middle Triassic forms is debated in certain phylogenetically important details. Among several genera from the Anisian of England, Bentonyx sidensis is represented by a near-complete skull. New CT scanning of the holotype skull reveals previously concealed details of the palate and braincase in particular, and this allows comparison with other Middle Triassic rhynchosaurs and confirmation that Bentonyx is a distinct taxon from others of similar age including Fodonyx, Rhynchosaurus, Langeronyx, and Stenaulorhynchus. These are part of the first wave of rhynchosaur diversification in the Middle Triassic. [ABSTRACT FROM AUTHOR] more...

The East Kunlun Orogenic Belt is considered as one of the important gold mineralization regions in the Tethys tectonic domain. These orogenic gold deposits are related to intermediate-acid intrusions formed at the end of Paleo-Tethys evolution, but the petrogenesis is controversial. This paper presents a new study on the geochemistry of zircon U-Pb, O, S, and Pb isotopic compositions of Asiha quartz diorite, granite porphyry, and sulfides. The geochemical features of quartz diorite and granite porphyry are consistent with the modern adakite, with high content of Sr but low content of Y, Yb, and MgO. Magmatic zircons from these two types of intrusion yielded U-Pb ages of 238.4 ± 1.4 Ma and 240 ± 1.7 Ma, respectively. The high O isotopic composition of Asiha complex may reflect that crust or crustal derivates were incorporated into the magmatic melt, and the Pb isotope characteristics indicates a lower crust origin. The δ34S values of pyrites range from 4.9‰ to 11.6‰. This study infers that the Asiha complex perhaps formed by partial melting of the Paleo-Tethys subducted oceanic crust with seafloor sediments and is markedly different from the traditional adakite. Asiha deposit is an orogenic gold deposit related to adakite-like rocks, which formed in Triassic in the East Kunlun Orogenic Belt. [ABSTRACT FROM AUTHOR] more...

The tectonic setting of Jiangda-Weixi magmatic belt is still controversy. Two different interpretations include the eastward subduction of Longmucuo-Shuanghu-Changning-Menglian Paleo-Tethys main ocean basin, and the westward subduction and subsequent collision of Jinshajiang Paleo-Tethys main ocean basin. These controversies concern different models for tectonic evolution of Paleo-Tethys. A new set of intrusive complex has been discovered in Pantiange area, the southern part of Jiangda-Weixi magmatic belt. The main components include dioritic, granodioritic and granitic rocks, which have been mylonitized. The zircons from granitic rocks have U-Pb mean age of (243.0±4.8) Ma. The age is considered as crystallization age of granitic rocks. Dioritic rocks have high contents of Na2O and Al2O3, and moderate content of K2O, suggesting they belong to metaluminous and calc-alkaline series. Granodioritic rocks has high contents of K2O and Al2O3, but low content of Na2O, suggesting they belong to peraluminous and shoshonite, high potassium calc-alkaline series. Granitic rocks have moderate content of Na2O and low content of K2O, and belong to metaluminous-peraluminous and low-potassium series. All three types of rocks are enriched in LILEs (such as Rb, Th, U), depleted in HFSEs (such as Nb, Ta, P, Ti) and LILEs (such as Ba, Sr), with high values of LREE/HREE ratio. The dioritic rocks have no obvious Eu anomaly, whereas granodioritic and granitic rocks show weak negative Eu anomaly. The granitic rocks have zircon εHf(t) values of-11.92--8.54, whole rocks initial 87Sr/86Sr ratio of 0.717 229-0.725 994, and εNd(t) values of-14.2--7.8. These characteristics show that dioritic magmatism is formed by partial melting of Paleoproterozoic basaltic lower crust; granodioritic magmatism is formed by partial melting of metamorphic mudstones of Paleoproterozoic upper crust with the addition of mantle material; granitic magmatism originates from partial melting of metamorphic graywacke in Paleoproterozoic upper crust, and then underground crystallization fractionation with the addition of mantle material. Combined with regional tectonic setting and petrogeochemical characteristics, it is proposed that Jiangda-Weixi magmatic belt is formed by the eastwards subduction of Paleo-Tethys. [ABSTRACT FROM AUTHOR] more...