Publications
An in utero foetus of the Middle Triassic ichthyosaur Besanosaurus leptorhynchus from Monte San Giorgio, Italy
A detailed analysis of a Middle Triassic ichthyosaur fetus from the Besano Formation at Monte San Giorgio, Italy, confirms its prenatal stage and challenges recent interpretations that it might be stomach contents. The fetus, belonging to Besanosaurus leptorhynchus, exhibits features such as tail-first orientation—common in derived ichthyosaurs—and palatine teeth, a rare trait among ichthyosaurs. This discovery provides new insights into the reproductive biology and developmental stages of early-diverging merriamosaurian ichthyosaurs, supporting the original interpretation of the specimen's origin.
K3) From Sacred Landscape to Pilgrimage Environment: The Case of Monte San Giorgio and Mendrisio
A novel process-based approach to pilgrimage landscapes reveals that sacred sites like Monte San Giorgio and Mendrisio can evolve into contemporary pilgrimage environments, even when formal participation declines. This transformation occurs through heritage activation, reconnecting ecological awareness, community memory, and spiritual experience—rather than competitive destination promotion. The study highlights the persistence of ritual practices, slow mobility, and cross-border traditions (e.g., Sacri Monti) in postsecular communities, offering a sustainable model for heritage tourism that balances cultural preservation with experiential engagement.
First subioblattid roachoid (Insecta: Holopandictyoptera) from the Middle Triassic of Monte San Giorgio (Switzerland)
A new species of fossilized roachoid insect, Samaroblattella valmarensis, has been identified from the Middle Triassic period at Monte San Giorgio (Switzerland), marking it as the oldest known representative of its genus. This discovery extends the temporal and geographical range of Samaroblattella and establishes a connection between species from South Africa and Kazakhstan. The fossil exhibits unique wing traits, including elongated ellipsoidal forewings with sigmoidal radial vein stems, and a hind leg morphology resembling that of extant jumping cockroaches, suggesting possible jumping behavior indicative of convergent evolution in Eoblattodea. Additionally, the elongate ovipositor differs significantly from those in crown group Dictyoptera, implying that Subioblattidae likely laid eggs in sediment or plant tissues without hardened ootheca. This study provides significant insights into the evolutionary history and behavioral adaptations of this ancient insect lineage.
Tetrapod Remains from the Ladinian (Middle Triassic) Seltrich Beds of Monte San Giorgio UNESCO Site
Paleontologists have uncovered rare tetrapod remains from the Ladinian (Middle Triassic) Sceltrich beds of Monte San Giorgio. The findings include isolated teeth and bones, revealing the presence of large to mid-sized eusauropterygians and the terrestrial tanystropheid Macrocnemus, providing the first documented evidence of reptile fauna in these strata. The research suggests that the tetrapod composition of the Sceltrich beds mirrors that of the upper Cassina beds, with taphonomic conditions likely involving disarticulation during a floating phase or prolonged residence allowing soft tissue decomposition before current removal of isolated elements.
The first specimen with skin preserved of Lariosaurus (Eusauropterygia) from the Middle Triassic of Monte San Giorgio (Switzerland) allows inferences about its swimming method
A virtually complete specimen of Lariosaurus valceresii, the first of its kind with preserved skin, has been discovered in the UNESCO World Heritage Site of Monte San Giorgio. This rare find reveals that the hands and feet were webbed, suggesting a paraxial, otariid-like swimming method for rapid acceleration. The carbon-film-preserved skin outlines the body and limbs, providing insights into the muscular structure and swimming mechanics of this eosauropterygian nothosauroid from the Middle Triassic. This discovery sheds new light on the evolutionary adaptations of aquatic reptiles during the Triassic period.
A new suction feeder and miniature teleosteomorph, Marcopoloichthys mirigioliensis, from the lower Besano Formation (late Anisian) of Monte San Giorgio
Paleontologists have identified Marcopoloichthys mirigioliensis, a miniature suction-feeding fish from the late Anisian period, as the smallest known stem teleost. This discovery, derived from fossil records in Monte San Giorgio's lower Besano Formation (southern Switzerland), distinguishes it from its larger relative, Marcopoloichthys furreri, through differences in caudal endoskeleton and fin structures. Measuring approximately 32 mm in standard length, M. mirigioliensis challenges the understanding of early teleost evolution, suggesting a potential link between size reduction and ecological specialization. The study employed comparative anatomical analysis to highlight its unique morphological traits, contributing new insights into Triassic marine biodiversity at this UNESCO World Heritage Site.
Postcranial anatomy of Besanosaurus leptorhynchus (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio (Italy/Switzerland), with implications for reconstructing the swimming styles of Triassic ichthyosaurs
A detailed analysis of the postcranial anatomy of Besanosaurus leptorhynchus, a Middle Triassic ichthyosaur from Monte San Giorgio, reveals a unique swimming style intermediate between anguilliform and shastasaur-grade ichthyosaurs. The study identifies diagnostic features, including rounded forelimb elements and pedal phalanges with rudimentary shafts, suggesting forefins embedded in fibrocartilage-rich connective tissue akin to modern cetaceans. By comparing Besanosaurus with related taxa like Pessopteryx and Pessosaurus, the research confirms its distinct status while proposing convergent evolution of body profiles in mixosaurids and Parvipelvia. The findings support niche partitioning among ichthyosaurs from the Besano Formation, enhancing our understanding of their locomotory adaptations.
Special Issue: 100 years of scientific excavations at UNESCO World Heritage Site Monte San Giorgio and global research on Triassic marine Lagerstätten
Monte San Giorgio, a globally significant UNESCO World Heritage Site spanning Switzerland and Italy, has emerged as a pivotal locality for understanding Triassic marine ecosystems. The site's remarkable fossil record, particularly its Konservat-Lagerstätten, preserves articulated skeletons of marine reptiles and other vertebrates and invertebrates, offering unprecedented insights into ancient biodiversity. Over the past century, systematic excavations led by Bernhard Peyer from the University of Zurich have yielded a wealth of data, including groundbreaking discoveries that gained international relevance with the identification of similar fossil-rich sites in China. Advanced methodologies, such as computed tomography (CT), have further enriched research, particularly by revealing intricate details of endocranial anatomy in tetrapods. This special issue commemorates these centennial efforts and their profound impact on global paleontological research.
The contribution of the Middle Triassic fossil assemblage of Monte San Giorgio to insect evolution
A remarkable fossil assemblage from Monte San Giorgio, Switzerland, offers unprecedented insights into insect evolution during the critical transition from Paleozoic to Mesozoic eras. Dating back 239 million years, the collection of 248 exceptionally preserved fossils represents 15 major insect clades, including dragonflies, caddisflies, true bugs, and wasps, revealing a diverse paleocommunity dominated by monurans—thought to have perished during the end-Permian mass extinctions. Notably, the discovery of a blattodean-like fossil with an external ootheca provides key evidence for understanding the transition from Paleozoic roachoids to modern cockroaches and the evolution of maternal brood care. Additionally, the youngest complete specimen of †Permithonidae and the oldest sawfly fossils were identified, along with round-shaped bodies on midge-like individuals, potentially representing seminal capsules or lycophyte spores. These findings challenge previous assumptions about early entomophilous plants and significantly advance our understanding of insect evolution and faunal turnover during this pivotal period.
The history of palaeontological research and excavations at Monte San Giorgio
Monte San Giorgio has yielded exceptionally well-preserved Middle Triassic vertebrate fossils over centuries of palaeontological research. Initial discoveries in the mid-19th century during black shale mining near Besano, Italy, sparked international interest and systematic excavations from 1863 onwards, with peak activity between 1924 and 1968. Modern excavations continue to focus on six distinct fossiliferous horizons—Besano Formation, Meride Limestone (including Cava inferiore, Cava superiore, Cassina, Sceltrich, and Kalkschieferzone beds)—revealing a rich archive of Triassic life. This study chronicles the history of these excavations, detailing locations, methodologies, and recovered material, highlighting Monte San Giorgio's significance as a key site for understanding Triassic biodiversity.
The marine conservation deposits of Monte San Giorgio (Switzerland, Italy): the prototype of Triassic black shale Lagerstätten
Monte San Giorgio's marine conservation deposits, renowned for their exceptional fossil preservation, have been classified as the prototype of Triassic black shale Lagerstätten. A comparative analysis of 45 global Phanerozoic and Ediacaran black shale-type Lagerstätten, using principal component and hierarchical cluster analyses, revealed four distinct groups: Burgess type (early Palaeozoic), Monte San Giorgio type (Triassic), Holzmaden type (pyrite-rich black shales), and Solnhofen type (platy limestones). This study highlights the unique characteristics of Monte San Giorgio's deposits, including sedimentary facies, genesis, and fossil content, setting a new benchmark for understanding Triassic marine ecosystems. The findings underscore the significance of these deposits in paleobiological research.
The Middle Triassic palaeontomofauna of Monte San Giorgio with the description of Merithone laetitiae (†Permithonidae) gen. et sp. nov.
A new species of Permithonid insect, Merithone laetitiae gen. et sp. nov., has been described from the Middle Triassic palaeontomofauna of Monte San Giorgio, a UNESCO World Heritage Site and one of the world's nine main insect Fossillagerstätten. This discovery is significant as it contributes to understanding the evolutionary impact of the end-Permian mass extinction on insects. The study reviews 273 fossil insects from five localities at Monte San Giorgio, notable for their exceptional preservation, including extraordinary sizes and phosphatisation revealing fine internal details. Among these, Val Mara site VM 12 contains 248 specimens, many of which are small to medium-sized and nearly intact, preserving intricate features like setae on wings and compound eyes. These fossils represent critical first or last occurrences for their lineages, providing valuable data to calibrate phylogenomic dating analyses. This has led to the backdating of origins for several insect lineages, including Diptera and Heteroptera.
The research history of the Middle Triassic fishes of Monte San Giorgio: getting out of the shadow of aquatic reptiles
A rich and diverse fish fauna from the Middle Triassic period, previously overshadowed by more spectacular aquatic reptiles, has been brought to the forefront through systematic research on fossils from Monte San Giorgio. This study reveals a species-rich ecosystem with six distinct fossiliferous beds, dating back to the Anisian and Ladinian ages. The findings include well-preserved chondrichthyans, coelacanths, and numerous actinopterygian taxa, offering new insights into their taxonomy, palaeobiology, palaeoecology, and palaeobiogeography. Ongoing work not only identifies taxonomic novelties but also sheds light on the ecological and geographical distribution of these ancient fishes.
A new Mesozoic scorpion from the Besano Formation (Middle Triassic, Monte San Giorgio UNESCO WHL), Italy
Researchers have identified and named Protobuthus ziliolii, the first Mesozoic scorpion from Italy, discovered in the Besano Formation of Monte San Giorgio, a UNESCO World Heritage Locality (WHL). This fossil, analyzed using optical, UV, and SEM microscopy, provides critical insights into the species' morphology and confirms its assignment to the family Protobuthidae. The discovery marks the first arachnid reported from the Besano Formation and the Mesozoic of Italy, reinforcing previous hypotheses about the nearshore depositional environment of this geological unit.
Käfer aus Lichtfängen am Monte San Giorgio bei Serpiano, Kanton Tessin (Coleoptera)
A biodiversity study at Monte San Giorgio, a UNESCO World Heritage Site near Serpiano, canton of Ticino, Switzerland, uncovered 366 species of beetles (Coleoptera) from 56 families using light traps between 1995 and 1997. Notably, the research identified one species, Malthodes vincens, as new to Switzerland and 22 others as new records for Ticino. The study, conducted over three years at an elevation of 630 meters, highlights the site's rich beetle diversity, contributing valuable data to regional biodiversity inventories.
Revision of the Middle Triassic coelacanth Ticinepomis Rieppel 1980 (Actinistia, Latimeriidae) with paleobiological and paleoecological considerations
A revision of the Middle Triassic coelacanth Ticinepomis peyeri from the UNESCO World Heritage Site Monte San Giorgio reveals a previously unrecognized diversity within this slow-evolving lineage. Researchers identified a new species, Ticinepomis ducanensis, based on morphological differences from the type species, T. peyeri. This discovery, supported by a re-evaluation of fossil material from both the Besano and Prosanto formations, indicates that coelacanth diversity was notably high in the Western Tethys during the Middle Triassic (242–240 million years ago). The study clarifies misunderstood morphological traits and strengthens the paleobiological understanding of these ancient fishes.
A new family, genus and species of fossil scorpion from the Meride Limestone (Middle Triassic) of Monte San Giorgio (Switzerland)
A new family, genus, and species of fossil scorpion has been identified from the Meride Limestone (Middle Triassic) of Monte San Giorgio, Switzerland. This discovery provides significant evidence for the recovery of terrestrial scorpions following the Late-Permian mass extinction, suggesting that modern scorpions may have evolved from lineages present at least 240 million years ago. The fossil belongs to the superfamily Chactoidea, reinforcing the idea that extant scorpion families have ancient roots. The study combines detailed morphological analysis with phylogenetic reconstruction to classify this new taxon within existing familial groups.
A new pachypleurosaur from the Early Ladinian Prosanto Formation in the Eastern Alps of Switzerland
Researchers have identified a new species of pachypleurosaur, Prosantosaurus scheffoldi, from the Early Ladinian Prosanto Formation in eastern Switzerland. This discovery challenges previous migration and diversification models for European pachypleurosaurs, suggesting a more complex evolutionary history within the South Alpine realm. The study, based on six complete skeletons and additional fossil remains, also provides the first detailed description of tooth replacement patterns in a European pachypleurosaur, supporting the monophyly of Sauropterygia. Exceptional fossil preservation enabled comprehensive analysis, including phylogenetic relationships and palaeogeographic distribution mapping.
Middle Triassic Nautilida from the Besano Formation of Monte San Giorgio, Switzerland
A rare discovery of Middle Triassic nautilids from the Besano Formation at Monte San Giorgio, Switzerland, sheds light on these cephalopods' presence in an unusual anoxic intra-platform basin environment. The study documents five specimens, including three well-preserved taxa: Enoploceras rieberi sp. nov., Germanonautilus aff. ellipticus, and Syringonautilus sp. indet., representing the families Tainoceratidae and Syringonautilidae. Notably, this is the first record of Enoploceras in the Middle Triassic, expanding its known distribution. The findings challenge the notion that nautilids were restricted to pelagic environments, as they were found in sediments typically deposited under anoxic conditions. This research contributes to our understanding of nautilid diversity and paleoecology during a critical period in Earth's history.
A New Coelacanth Specimen with Elongate Ribs from the Middle Triassic (Ladinian) Kalkschieferzone of Monte San Giorgio (Canton Ticino, Switzerland)
A new coelacanth specimen from the Middle Triassic (Ladinian) Kalkschieferzone of Monte San Giorgio is the first definitive record of this group with elongate ribs. The incomplete fossil prevents formal taxonomic assignment, but its scale morphology closely resembles that of Heptanema paradoxum from Northern Italy. While elongate ribs were not noted in H. paradoxum's original description, small rib fragments are visible among its scales. This suggests a possible affiliation with the genus Heptanema, tentatively identified as Heptanema cf. H. paradoxum. The discovery provides new insights into coelacanth evolution during the Triassic period.
A New Species of Saurichthys (Actinopterygii: Saurichtydae) from the Middle Triassic of Monte San Giorgio
Researchers have identified a new species of the actinopterygian fish genus Saurichthys from the Middle Triassic Sceltrich beds of Monte San Giorgio. This discovery highlights unique adaptations in its fin structure—unsegmented lepidotrichia and elongated, wide paired fins—which suggest specialized swimming and predatory behaviors distinct from other Saurichthys species. Phylogenetic analysis further indicates a close relationship with the Saurorhynchus species group, expanding our understanding of the genus's evolutionary plasticity and functional diversity during the Triassic period.
Change from shallow to deep-water environment on an isolated carbonate platform in the Middle Triassic of the Transdanubian Range (Hungary)
Research at the UNESCO World Heritage Site Monte San Giorgio reveals critical insights into the transition from shallow to deep-water environments during the Middle Triassic. The study, conducted on the Kádárta section of Hungary's Transdanubian Range, identified a significant gap between Pelsonian (Middle Anisian) shallow-marine carbonates and overlying late Illyrian (latest Anisian) deep-water successions, indicating rapid subsidence following the break-up of the Neotethys. Integrated biostratigraphy and radiometric dating enabled precise correlations with other key sections in the western Neotethys, such as those in the Dinarides and Southern Alps. This work highlights the dynamic paleoenvironmental changes that shaped Monte San Giorgio's geological history.
Cranial anatomy of Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio, Italy/Switzerland: taxonomic and palaeobiological implications
A new analysis of Besanosaurus leptorhynchus, a Middle Triassic ichthyosaur from Monte San Giorgio, reveals it as the earliest large diapsid with extreme longirostry—a specialized skull morphology suggesting a novel ecological niche focused on small, elusive prey. The study re-examines cranial osteology and assigns five additional specimens to this taxon, including four previously undescribed ones, while synonymizing Mikadocephalus gracilirostris. Phylogenetic analysis places it as a basal merriamosaurian, with uncertain relationships within Shastasauridae. This specialization likely contributed to the diversification of ichthyosaurs in the Besano Formation by reducing competition among coexisting species.
A new stem-neopterygian fish from the Middle Triassic (Anisian) of Yunnan, China, with a reassessment of the relationships of early neopterygian clades
A new stem-neopterygian fish, Louwoichthys pusillus, has been identified from Middle Triassic marine deposits in Yunnan, China. This small, tooth-adapted species, measuring up to 39 mm, is closely related to Luopingichthys and Ctenognathichthys, forming the newly described family Louwoichthyidae. The study introduces a novel order, Louwoichthyiformes, to resolve paraphyly in 'Perleidiformes' and supports its monophyly with derived cranial features. Louwoichthys is inferred as a scavenger, likely using its elongated teeth to manipulate prey. This research advances understanding of early neopterygian diversity and evolutionary relationships during the Anisian stage.
Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography
Synchrotron microtomography reveals the first detailed cranial morphology of Macrocnemus bassanii, a tanystropheid archosauromorph from the Middle Triassic Besano Formation at Monte San Giorgio, Switzerland. The study uncovers previously unknown features of the braincase, palatal elements, and atlas-axis complex, while confirming tooth-bearing palatal bones like the pterygoid and palatine with observed heterodonty. The morphology of circumorbital bones aligns with those of Prolacerta broomi and Protorosaurus speneri, providing new insights into the evolutionary relationships of non-archosauriform archosauromorphs.
Gastropods from the Sceltrich beds of Monte San Giorgio (Meride Limestone, Ladinian, Canton Ticino, Switzerland)
A groundbreaking discovery at the UNESCO World Heritage Site Monte San Giorgio reveals the first documented gastropods from the Meride Limestone, dating back to the Ladinian period. The study, focused on the newly identified Sceltrich beds in Valle di Sceltrich, Canton Ticino, Switzerland, uncovers three distinct taxa: Cryptonerita? sp., Coelostylina stotteri, and Omphaloptycha cf. marianii. These findings mark the first identifiable Ladinian gastropods from this renowned fossil site, providing significant insights into the biodiversity of the region during this geological epoch. The research highlights the occurrence of several taxa belonging to the clades Neritimorpha and Caenogastropoda, enriching our understanding of marine life in the Southern Alps during the Middle Triassic.
Middle Triassic gastropods from the Besano Formation of Monte San Giorgio, Switzerland
A rare discovery of Middle Triassic gastropods from the Besano Formation at Monte San Giorgio, Switzerland, sheds light on the biodiversity and paleoecology of the Anisian/Ladinian boundary. The study documents five taxa—Worthenia (Humiliworthenia)? aff. microstriata, Frederikella cf. cancellata, ? Trachynerita sp., and two ? Omphaloptycha species—representing the clades Vetigastropoda, Neritimorpha, and Caenogastropoda. These specimens, among the best preserved in the formation, suggest that small gastropods may have thrived as pseudoplankton or free-swimming larvae under anoxic conditions, while larger forms were likely transported by sediment disturbances. The findings challenge previous interpretations of the Besano Formation's depositional environment and highlight its significance for understanding Triassic carbonate platform ecosystems.
Placodont remains (Sauropsida, Sauropterygia) from the Triassic of Hungary (Transdanubian Range and Villány Mountains)
New placodont fossils from the Triassic of Hungary reveal significant insights into the distribution and diversity of these marine reptiles. The study describes remains from two tectonic units: the Transdanubian Range, including a maxilla fragment identified as Paraplacodus broilii from the Anisian stage (similar in age to Monte San Giorgio), and a Carnian dentary fragment and teeth assigned to Placochelys placodonta. Additionally, a Rhaetian tooth fragment was found in the Keszthely Mountains. The most notable discovery is a rich Ladinian assemblage from the Villány Mountains, featuring cranial elements and teeth attributed to Cyamodus sp., marking one of the last occurrences of this genus in Europe's Triassic sedimentary basins. This study highlights Hungary as a critical gap locality for understanding placodont evolution during the Late Triassic.
Recalibration of the insect evolutionary time scale using Monte San Giorgio fossils suggests survival of key lineages through the End-Permian Extinction
A groundbreaking recalibration of the insect evolutionary time scale, using exceptionally preserved 240-million-year-old fossils from Monte San Giorgio, reveals that key insect lineages survived the catastrophic End-Permian Extinction. These findings, derived from phylogenomic dating analysis, push back the origins of major groups like Lepidoptera (moths and butterflies), Hemiptera: Heteroptera (true bugs), and Diptera (flies) by up to 200 million years. The study suggests that critical evolutionary innovations, such as flight and metamorphosis, emerged much earlier than previously thought, challenging long-held assumptions about insect resilience during mass extinction events.
New holostean fishes (Actinopterygii: Neopterygii) from the Middle Triassic of the Monte San Giorgio (Canton Ticino, Switzerland)
Paleontologists have uncovered two new species of holostean fish, Ticinolepis longaeva and T. crassidens, from the Middle Triassic carbonate platform deposits of Monte San Giorgio in Switzerland. These findings provide critical insights into the evolutionary history of neopterygian fishes, revealing a mosaic of halecomorph and ginglymodian traits that suggest these species represent basal holosteans. The study highlights distinct habitat partitioning between the two species, with T. longaeva adapting to more restricted environments while T. crassidens exhibited anatomical adaptations indicative of a durophagous diet. Additionally, the research documents intraspecific variation and ontogenetic changes in T. longaeva, offering a nuanced understanding of its ecological adaptability over time.
A New Early Semionotidae (Semionotiformes, Actinopterygii) from the Upper Ladinian of Monte San Giorgio Area Southern Switzerland and Northern Italy)
A new genus of early Semionotidae, Sangiorgioichthys aldae, was discovered from the Upper Ladinian Kalkschieferzone of Monte San Giorgio, a UNESCO World Heritage Site spanning southern Switzerland and northern Italy. This fossil provides critical insights into the poorly understood early history of Semionotiformes, with distinct morphological features such as ganoine-covered dermal skull bones, an unusually large ventral infraorbital, and specialized dentition. The study employed detailed anatomical analysis to classify the specimen within the Semionotidae family, noting shared diagnostic traits while highlighting unique characteristics that differentiate it from other known taxa. This discovery contributes significantly to understanding the evolutionary trajectory of this ancient fish group during the Triassic period.
Early Ladinian Radiolarian Fauna from the Monte San Giorgio (Southern Alps, Switzerland): Systematics, Biostratigraphy and Paleo(Bio)Geographic Implications
A pioneering study of radiolarian fauna from the UNESCO-listed Monte San Giorgio reveals a unique early Ladinian assemblage, characterized by low diversity and restricted circulation. The research identifies 73 species, including seven new ones, and introduces four novel genera, providing critical insights into the paleo(bio)geography of the Tethys. This first-ever description of radiolarians from Monte San Giorgio supplements knowledge of the uppermost Ladinocampe multiperforata Radiolarian Zone, confirming stability in radiolarian fauna across the Anisian/Ladinian boundary. The findings suggest open-marine connections between the Monte San Giorgio basin and broader Tethyan regions during early Ladinian times.
Two new species ofSaurichthys(Actinopterygii: Saurichthyidae) from the Middle Triassic of Monte San Giorgio, Switzerland, with implications for character evolution in the genus
Two new species of the iconic Triassic fish genus Saurichthys have been identified from the Middle Triassic Besano Formation at Monte San Giorgio, Switzerland: S. breviabdominalis, distinguished by its elongated operculum and reduced abdominal region, and S. rieppeli, notable for its block-like haemal arches and unique fin structures. Phylogenetic analysis reveals that S. rieppeli occupies a basal position among Alpine Triassic saurichthyids, supporting hypotheses of convergent evolution in scale reduction within the genus. Meanwhile, S. breviabdominalis forms a monophyletic group with local congeners, suggesting sympatric divergence—a finding that sheds light on ecomorphological divergence and resource partitioning in Triassic marine ecosystems. The study leverages detailed morphological analysis to elucidate character evolution and ecological adaptations in saurichthyid fishes.
Palaeoenvironmental significance of organic facies and stable isotope signatures: the Ladinian San Giorgio Dolomite and Meride Limestone of Monte San Giorgio (Switzerland, WHL UNESCO)
Monte San Giorgio reveals that its Ladinian carbonate section contains immature organic matter primarily of marine bacterial origin, with increasing land plant-derived contributions upsection. This study links organic-matter accumulation to sea-level changes, productivity, and volcanic activity-induced rainfall. Enhanced productivity during high sea levels contributed to black-shale formation under anoxic-sulphidic conditions, while low sea levels intensified runoff, leading to basin restriction and laminated limestone deposition under dysoxic to anoxic conditions. Benthic microbial activity played a significant role in hydrogen-rich organic matter production, carbonate precipitation, and vertebrate fossil preservation. The research integrates sedimentology, geochemistry, and microscopy to provide insights into palaeoenvironmental dynamics.
Ossification sequences and associated ontogenetic changes in the bone histology of pachypleurosaurids from Monte San Giorgio (Switzerland/Italy)
Pachypleurosaurids from Monte San Giorgio exhibit a transition from 'terrestrial' to more 'aquatic' osteogenetic sequences, as evidenced by increasing heterochronic shifts with decreasing stratigraphic age. This study reveals that forelimb ossification precedes hind limb elements in all stages except initiation, while early phase compaction processes align with the hypothesized plesiomorphic eureptilian condition. The research analyzed bone histology and taphonomic patterns in four pachypleurosaurid species, comparing them to extant terrestrial lizards and secondarily aquatic reptiles to determine evolutionary trends in osteogenesis.
Long bone microstructure gives new insights into the life of pachypleurosaurids from the Middle Triassic of Monte San Giorgio, Switzerland/Italy
A detailed analysis of long bone microstructure in four pachypleurosaurid taxa from Monte San Giorgio reveals distinct adaptations to secondary aquatic lifestyles, supporting earlier findings on habitat diversity and reproductive strategies. The study highlights high compactness values in their bones, characterized by a thick cortex and persistent calcified cartilaginous core, with variations in remodeling processes, growth cycle spacing, and vascularization. These differences suggest varying longevities, ages at sexual maturity, and potential climate-dependent reproductive seasons akin to modern squamates. The research combines histological data with morphological and facies distribution studies, offering new insights into the life history of these Middle Triassic reptiles.
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