The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction

The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle–late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.     

A late-surviving Triassic protomonaxonid sponge from the Paris Biota (Bear Lake County,Idaho, USA)

Protomonaxonid sponges are a major group of Cambrian and Ordovician fossils in exceptionally preserved (especially Burgess Shale-type) faunas, but are rare thereafter. Rare examples of apparent surviving lineages are known from the late Palaeozoic and Mesozoic, but by this time more derived groups of sponges have generally displaced them in at least shallow-water (shelf depth) ecosystems. The early Spathian (Early Triassic) Paris Biota includes abundant material of a new leptomitid protomonaxonid, Pseudoleptomitus advenus Botting nov. gen., nov. sp., distinguished by having an unbundled longitudinal skeleton and very weak transverse component. This is the first post-Ordovician leptomitid known, and indicates long-term survival of the group in unknown environments. Its occurrence near storm wave base is similar to the preferred environment of earlier examples of the family, suggesting either ecological rarity or taphonomic reasons for their ∼200-million-year absence from later Palaeozoic rocks.     

Chondrichthyan teeth from the Early Triassic Paris Biota (Bear Lake County,Idaho, USA)

A new, diverse and complex Early Triassic assemblage was recently discovered west of the town of Paris, Idaho (Bear Lake County), USA. This assemblage has been coined the Paris Biota. Dated earliest Spathian (i.e., early late Olenekian), the Paris Biota provides further evidence that the biotic recovery from the end-Permian mass extinction was well underway ca. 1.3 million years after the event. This assemblage includes mainly invertebrates, but also vertebrate remains such as ichthyoliths (isolated skeletal remains of fishes). Here we describe first fossils of Chondrichthyes (cartilaginous fishes) from the Paris Biota. The material is composed of isolated teeth (mostly grinding teeth) preserved on two slabs and representing two distinct taxa. Due to incomplete preservation and morphological differences to known taxa, the chondrichthyans from the Paris Biota are provisionally kept in open nomenclature, as Hybodontiformes gen. et sp. indet. A and Hybodontiformes gen. et sp. indet. B, respectively. The present study adds a new occurrence to the chondrichthyan fossil record of the marine Early Triassic western USA Basin, from where other isolated teeth (Omanoselache, other Hybodontiformes) as well as fin spines of Nemacanthus (Neoselachii) and Pyknotylacanthus (Ctenachanthoidea) and denticles have been described previously.     

A New Genus of Rhynchonellid Brachiopod from the Lower Triassic of South China and Implications for Timing the Recovery of Brachiopoda After the End-Permian Mass Extinction

A new genus, Meishanorhynchia , is proposed based on new material from the Lower Triassic of the Meishan section, South China. It is of a late Griesbachian age based on both associated biozones (ammonoids and bivalves) and radiometric dates of the intercalated volcanic ash beds. Comparison with both Palaeozoic and Mesozoic–Cenozoic-related genera suggests that it may represent the first radiation of progenitor brachiopods in the aftermath of the end-Permian extinction. The lowest brachiopod horizon that contains the genus is estimated to be about 250.1 ± 0.3 Ma. This implies that the initial stage of recovery of Brachiopoda in the Early Triassic was probably about 1.3 ± 0.3 myr after the major pulse of the end-Permian mass extinction (dated as 251.4 ± 0.3 Ma). This is in agreement with Hallam's expectancy that biotic recovery typically begins within one million years or so of major mass extinctions, in contrast to current views on the end-Permian extinction event which propose that the recovery of most if not all biotic groups in the Early Triassic was severely delayed and only began about five million years after the end-Permian extinction.     

Global Taxonomic Diversity of Anomodonts (Tetrapoda,Therapsida) and the Terrestrial Rock Record Across the Permian-Triassic Boundary

The end-Permian biotic crisis (∼252.5 Ma) represents the most severe extinction event in Earth''s history. This paper investigates diversity patterns in Anomodontia, an extinct group of therapsid synapsids (‘mammal-like reptiles’), through time and in particular across this event. As herbivores and the dominant terrestrial tetrapods of their time, anomodonts play a central role in assessing the impact of the end-Permian extinction on terrestrial ecosystems. Taxonomic diversity analysis reveals that anomodonts experienced three distinct phases of diversification interrupted by the same number of extinctions, i.e. an end-Guadalupian, an end-Permian, and a mid-Triassic extinction. A positive correlation between the number of taxa and the number of formations per time interval shows that anomodont diversity is biased by the Permian-Triassic terrestrial rock record. Normalized diversity curves indicate that anomodont richness continuously declines from the Middle Permian to the Late Triassic, but also reveals all three extinction events. Taxonomic rates (origination and extinction) indicate that the end-Guadalupian and end-Permian extinctions were driven by increased rates of extinction as well as low origination rates. However, this pattern is not evident at the final decline of anomodont diversity during the Middle Triassic. Therefore, it remains unclear whether the Middle Triassic extinction represents a gradual or abrupt event that is unique to anomodonts or more common among terrestrial tetrapods. The end-Permian extinction represents the most distinct event in terms of decline in anomodont richness and turnover rates.     

Evolutionary rates of the Triassic marine macrofauna and sea-level changes: Evidences from the Northwestern Caucasus,Northern Neotethys (Russia)

A diverse Triassic marine macrofauna from the Northwestern Caucasus sheds new light on the biotic evolution after the end-Permian mass extinction. In the early Mesozoic, the study area was located on the northern margin of the Neotethys Ocean. Data on stratigraphic ranges of 130 genera of brachiopods, bivalves, ammonoids, corals, and sponges have been used to calculate the changes in two evolutionary rates, namely faunal transformation rate (FTR) and rate of transformation of the taxonomic diversity structure (TTDSR). The FTR demonstrates the changes in the generic composition of assemblages through geologic time, whereas the TTDSR indicates changes in the generic control of the species diversity. The Triassic marine macrofauna of the Northwestern Caucasus was characterized by very high FTR and TTDSR during the Early Triassic through early Late Triassic. The FTR slowed in the Middle Triassic, and accelerated again in the Carnian–Norian. In contrast, the FTR was abnormally slow in the Norian–Rhaetian. A remarkable turnover among macrofauna occurred at the Carnian–Norian transition. Regional sea-level changes were similar to the global eustatic fluctuations. It is difficult to establish their direct connections with changes in the evolutionary rates, although the turnover at the Carnian–Norian boundary coincided with a prominent regressive episode. In general, high evolutionary rates reported for the Triassic marine macrofauna of the Northwestern Caucasus may be explained as a consequence of the devastating end-Permian mass extinction.     

Taphonomic field experiments and the role of the Shelf and Slope Experimental Taphonomy Initiative

Fossilization of organism remains is the result of biological, physical, and chemical processes at work in the environment of deposition. The pathways taken by the remains of organisms through death, decay, burial, and diagenesis (known as taphonomic pathways) affect the fossil record of life in important ways, from complete removal and recycling of remains to preservation of hard parts and sometimes to exceptional preservation of soft tissues. Our understanding of taphonomic processes informs our interpretations of the fossil record and helps in the reconstruction of ancient environments. Research into taphonomic pathways in modern environments provides important insight into the fossilization process. In 1993, a group of paleontologists formed the Shelf and Slope Experimental Taphonomy Initiative (SSETI) and began a long-term comparative study of taphofacies and differential decay of taxonomic groups by placing experimental arrays containing bivalves, gastropods, decapod crustaceans, sea urchins, and wood species at multiple marine shelf and slope sites in the Bahamas and Gulf of Mexico. The goal of SSETI is to observe taphonomic processes over a period of decades to better understand taphonomic pathways for these various groups of taxa in a wide variety of depositional environments beyond the shallow near shore region. This special volume brings together eight studies that are the result of the SSETI program. The focus of this contribution is to first review the body of published work concerned with the fossilization process through the experimental manipulation of the remains of organisms in modern marine environments. We also present the methods of the SSETI project and its contributions to our understanding of taphonomic processes in relation to carbonate and wood recycling and preservation.     

Micromorphological,geochemical, and diagenetic characterization of sirenian ribs preserved in the Late Miocene paleontological site of Cessaniti (southern Calabria,Italy)

The site of Cessaniti (Vibo Valentia, Italy) has been well known since the 19th century for the richness and good preservation of its Miocene fauna and flora. The sedimentary succession of the site represents a paralic system that evolved toward an open-marine environment recording the Tortonian transgression. The fossil assemblage contains rich invertebrate (corals, bivalves, gastropods, brachiopods, echinoids, benthic and planktonic foraminifers) and vertebrate faunas (proboscideans, rhinoceroses, giraffids, bovids, sirenids, marine turtles, and fish remains). The fossils recovered at the Cessaniti site have a relevant role in phylogenetic studies and paleogeographic reconstructions of Late Miocene environments of the southern Italy. This research is focused on the microstructure and preservation state of the fossil bones. Samples of Metaxytherium sp. bones have been analyzed to understand the diagenetic profile of the bone assemblages that characterizes the taphonomic history of the Cessaniti site. The analyses provided a comprehensive account of how bone mineral (bioapatite) has been altered and demonstrated that the post-burial processes did not significantly affect the micromorphological and biogeochemical features of the bones. The excellent preservation state of the bones strengthens the importance of the Cessaniti site for studies of the Mediterranean Miocene vertebrate fauna.     

New insights on the palaeobiology and biostratigraphy of the acritarch Trachyhystrichosphaera aimika: A potential late Mesoproterozoic to Tonian index fossil

The late Mesoproterozoic to Tonian (∼1100 Ma to ∼720 Ma) witnessed a critical evolutionary transition in Earth history. Several fossil taxa, including acritarchs and vase-shaped microfossils, have been suggested as potential diagnostic fossils for this time interval. The acanthomorphic acritarch Trachyhystrichosphaera aimika has become a focus of recent biostratigraphic investigations, showing great potential to assist the definition of the Tonian Global Boundary Stratotype Section and Point (GSSP). Although T. aimika has been extensively reported in the Proterozoic sequences, little is known about its phylogenetic interpretation. Its palaeogeographic and stratigraphic distributions need to be critically scrutinized with recently emended diagnosis of the taxon and new published age constraints. In this study, we report new palaeobiological data of T. aimika specimens from the Tonian Liulaobei Formation in the Huainan region, North China, using transmitted light microscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. Our analyses reveal a multilayered ultrastructure from the vesicle wall of T. aimika that has experienced advanced diagenesis to low-grade metamorphism with the peak palaeotemperature of ∼212 °C. In addition, a compilation of palaeogeographic occurrences of T. aimika shows the taxon is preserved in a wide range of palaeoenvironments and has a broad palaeogeographic distribution with a relatively limited stratigraphic range from ∼1150 Ma to ∼720 Ma, suggesting that T. aimika has great potential to become an index fossil for the late Mesoproterozoic to Tonian interval.     

Secular distribution of Burgess-Shale-type preservation

Burgess-Shale-type preservation is defined as a taphonomic pathway involving the exceptional organic preservation of non-mineralizing organisms in fully marine siliciclastic sediments. In the Phanerozoic it occurs widely in Lower and Middle Cambrian sequences but subsequently disappears as a significant taphonomic mode. The hypothesis that this distribution derives solely from a secular increase in the depth of bioturbation is falsified: low bioturbation indices do not prevent the rapid enzymatic degradation of organic structure, nor do they account for the conspicuous absence of comparable preservation during the Vendian. An earlier, Late Riphean (ca. 750–850 Ma), interval of enhanced organic-walled fossil preservation suggests a long-term recurrence in Burgess-Shale-type taphonomy that is independent of metazoan activity. A model based on the potentially powerful anti-enzymatic and/or stabilizing effects of clay minerals on organic molecules is proposed to account for Burgess-Shale-type preservation. Long-term changes in average clay mineralogies and the ocean chemistry that determines their interaction with organic molecules are likely to have induced the pronounced secular distribution of these fossil biotas, while regional variations in tectonism, weathering, etc., explain their non-uniform geographic distribution; the close correlation between exceptional, organic-walled fossil preservation and volcano-genic sedimentation in Tertiary lake deposits provides a compelling analogue. Recognition of a temporal control on Burgess-Shale-type preservation constrains the evolutionary scenarios that can be drawn from such biotas; significantly, neither the initial rate of appearance, nor the ultimate fate of Burgess-Shale-type taxa can be directly assessed. □ Taphonomy, exceptional preservation, organic preservation, fossil Lagerstätten, Burgess Shale, clay mineralogy, clay-organic interactions, secular change, Cambrian, Proterozoic.     

Delayed recovery of non-marine tetrapods after the end-Permian mass extinction tracks global carbon cycle

During the end-Permian mass extinction, marine ecosystems suffered a major drop in diversity, which was maintained throughout the Early Triassic until delayed recovery during the Middle Triassic. This depressed diversity in the Early Triassic correlates with multiple major perturbations to the global carbon cycle, interpreted as either intrinsic ecosystem or external palaeoenvironmental effects. In contrast, the terrestrial record of extinction and recovery is less clear; the effects and magnitude of the end-Permian extinction on non-marine vertebrates are particularly controversial. We use specimen-level data from southern Africa and Russia to investigate the palaeodiversity dynamics of non-marine tetrapods across the Permo-Triassic boundary by analysing sample-standardized generic richness, evenness and relative abundance. In addition, we investigate the potential effects of sampling, geological and taxonomic biases on these data. Our analyses demonstrate that non-marine tetrapods were severely affected by the end-Permian mass extinction, and that these assemblages did not begin to recover until the Middle Triassic. These data are congruent with those from land plants and marine invertebrates. Furthermore, they are consistent with the idea that unstable low-diversity post-extinction ecosystems were subject to boom-bust cycles, reflected in multiple Early Triassic perturbations of the carbon cycle.     

An ecologically mixed brachiopod fauna from Changhsingian deep-water basin of South China: consequence of end-Permian global warming

The Late Permian Shaiwa Group of the Ziyun area of Guizhou, South China is a deep-water facies succession characterized by deep-water assemblages of pelagic radiolarians, foraminifers, bivalves, ammonoids and brachiopods. Here we report 20 brachiopod species in 18 genera from the uppermost Shaiwa Group. This brachiopod fauna is latest Changhsingian in age and dominated by productides. The palaeoecologic and taphonomic analysis reveals that the brachiopod fauna is preserved in situ. The attachment modes and substratum preference demonstrate that the Shaiwa brachiopod fauna comprises admixed elements of deep-water and shallow-water assemblages. The presence of the shallow-water brachiopods in the Shaiwa faunas indicates the involuntary settlement of shallow-water brachiopods. The stressed ecologic pressure, triggered by warming surface waters, restricted ecospace and short food sources, may have forced some shallow-water elements to move to hospitable deep-water settings and others to modify their habiting behaviours and exploit new ecospace in deep-water environments. We infer that the end-Permian global warming and subsequent transgression event may have accounted for the stressed environmental pressure in the shallow-water communities prior to the end-Permian mass extinction.     

Survival patterns of macrobenthic marine assemblages during the end-Permian mass extinction in the western Tethys (Dolomites, Italy)

The ecological competition between brachiopods and bivalves is analysed by means of a quantitative palaeoecologic method applied on four assemblages located within a short stratigraphic interval, approximately 2 m thick, in the lower Tesero Member of the Werfen Formation (in the Southern Alps). The assemblages originate from the Tesero, Bulla and Sass de Putia sections. The analysed stratigraphic interval, uppermost Changhsingian in age, is located between the early and heaviest phase of the end-Permian mass extinction, which occurred across the Bellerophon/Werfen formational boundary (Event Boundary), and the Permian/Triassic boundary (Chronological Boundary), when nearly all the Permian stenotopic holdovers disappeared.These assemblages are characterised by small sized skeletons (“Lilliput effect”), which represent an adaptive survival strategy in stressed and harsh habitats resulting from the climatic and palaeoceanographic changes connected with the mass extinction. The Tesero assemblages are dominated by rhynchonelliform brachiopod Orbicoelia (bed CNT10) or Streptorhynchus (bed CNT11A), which were mostly attached at the top of shallow microbialitic mounds. These assemblages are again dominated by Permian stenotopic taxa and show a Palaeozoic structure. The Tesero habitat, which again permitted the survival of brachiopods, represented one of the last refuges in the western Tethys. On the contrary, the Bulla (BU9-10) and Sass de Putia (wPK13A) assemblages are bivalve-dominated, and thus show an ecologic structure typical of Early Triassic post-extinction marine benthic communities or Palaeozoic stressed marine communities. The bivalve-dominated assemblages proliferated in prevailing muddy siliciclastic substrates, with brief episodes of microbial algal growth. The most important environmental limiting factors and leading causes of end-Permian mass extinction are discussed in terms of palaeoautecologic and palaeosynecologic analysis.The different taxonomic composition and ecologic structure of the assemblages is related to palaeogeography, including water depth and connections with the open sea. The brachiopod-dominated assemblage, exclusive of the Tesero section, proliferated in microbial carbonate habitats in near-shore environments. The bivalve-dominated assemblages, which were more widespread than the brachiopod assemblages in the Dolomites and also occurred in other western Tethys localities, occur in more open and deeper marine environments. In the western Tethys margins, the local distribution of mixed faunas suggests that the extinction of Permian stenotopic taxa was caused by the onset of poisonous water on the shelves originating from deep marine environments.This extinction pattern appears to be a regional phenomenon and does not seem be applicable on a global scale. The extinction events were controlled by a complex network of interactive factors and the survival of faunal elements was probably stochastic.     

Wildfires in the Early Triassic of northeastern Pangaea: Evidence from fossil charcoal in the Bogda Mountains,northwestern China

Fires are an integral part of modern and ancient ecosystems, serving as friends for renewal or foes for complete destruction and extinction. Indicators of palaeowildfire were so far absent from the Lower Triassic. Lack of plants in the Early Triassic due to the end-Permian mass extinction event and low atmospheric oxygen levels were proposed as the major reasons for the scarcity of wildfires. We present macroscopic charcoals from the Olenekian (Lower Triassic) in northwestern China, indicating probable ground/smoldering fires occurred on landscapes in mid-latitudes of northeastern Pangaea. Atmospheric oxygen concentration during the Olenekian would have been above 18.5%. These findings demonstrate that wildfires continued to be a source of disturbance of terrestrial ecosystems in Bogda Mountains after the end-Permian marine biotic crisis. There were adequate supplies of fuels and oxygen during this critical time period in the Earth history.     

Paleobiology of a Neoproterozoic tidal flat/lagoonal complex: the Draken Conglomerate Formation, Spitsbergen

Carbonates and rare shales of the ca 700-800 Ma old Draken Conglomerate Formation, northeastern Spitsbergen, preserve a record of environmental variation within a Neoproterozoic tidal flat/lagoon complex. Forty-two microfossil taxa have been recognized in Draken rocks, and of these, 39 can be characterized in terms of their paleoenvironmental distributions along a gradient from the supratidal zone to permanently submerged lagoons. Supratidal to subtidal trends include: increasing microbenthic diversity, increasing abundance and diversity of included allochthonous (presumably planktonic) elements, decreasing sheath thickness of mat-building organisms (with significant taphonomic consequences), and an increasing sediment/fossil ratio in fossiliferous rocks. Five principal and several minor biofacies can be distinguished. The paleoecological resolution obtainable in the Draken Conglomerate Formation rivals that achieved for most Phanerozoic fossil deposits. It documents the complexity and diversity of Proterozoic coastal ecosystems and indicates that both environment and taphonomy need to be taken into explicit consideration in attempts to understand evolutionary trends in early fossil record. Three species, Coniunctiophycus majorinum, Myxococcoides distola, and M. chlorelloidea, are described as new; Siphonophycus robustum, Siphonophycus septatum, and Gorgonisphaeridium maximum are proposed as new combinations.     

A new phosphatic‐shelled cirripede (Crustacea,Thoracica) from the Lower Jurassic (Toarcian) of Germany – the oldest epiplanktonic barnacle

A new genus and species of phosphatic‐shelled eolepadid barnacle from the Posidonia Shale (Toarcian, falciferum Zone) of Zell u. Aichelberg, southern Germany, is described as Toarcolepas mutans gen. et sp. nov. Numerous disarticulated individuals, associated with fossil wood, are present in a piece of concretionary limestone, and these are interpreted as having lived epiplanktonically attached to driftwood. The taxonomy of the Late Triassic – Early Cretaceous family Eolepadidae is reviewed, and two further species (T. gaveyi (Withers, 1920) and T. lotharingica (Méchin, 1901)) are referred to Toarcolepas. The chemistry of valve composition of the Carboniferous Praelepas and Triassic–Jurassic eolepadid cirripedes is investigated using X‐ray dispersive analysis, and the ubiquitous presence of abundant phosphorus is taken as evidence that these taxa had a primary phosphatic composition, now preserved as francolite. A significant change in shell chemistry from phosphate to calcium carbonate took place during the evolution of the Thoracica, during the Late Triassic or Early Jurassic. The driving force behind this change may have been related to the reduced predation pressure associated with acquisition of an epiplanktonic mode of life. Calcite is softer, but energetically cheaper to deposit than phosphate mineral phases.     

Paleobiology of the Neoproterozoic Svanbergfjellet Formation, Spitsbergen

A fossil Lagerstätte from the 700–750 Ma old Svanbergfjellet Formation of northeastern Spitsbergen offers a substantially enhanced view of late Proterozoic paleobiology. Fossils occur primarily as Organic-walled compressions in shales and permineralizations in chert: secondary modes of preservation include bedding-plane imprints and mineral replacements in apatite and goethite (?). The depositional setting of all fossiliferous horizons is broadly peritidal with highest taxonomic diversity occurring in shallow subtidal settings; the details of included fossil assemblages contribute to improved paleoecological resolution. The often distinct constituents of shale-and chert-hosted fossil assemblages appear to be a product of both paleoenvironment and fundamentally dissimilar taphonomic pathways, such that only forms with inferred wide ecological tolerance appear in both. Consideration of taphonomic processes also provides a variety of useful taxonomic insights, on the one hand permitting some resolution of so-called wastebasket taxa. such as Chuaria, and on the other acknowledging the taxonomic disparity that can occur in simple forms like Siphonophycus and Oscillatoriopsis. True multicellular (including coenocytic) eukaryotes are a conspicuous Component of the Svanbergfjellet assemblage: of eight distinct taxa, one can be identified as a coenobial/colonial chlorococcalean and three as filamentous siphonocladaleans (Chlorophyta). Other forms are problematic, but several show significant cell, or possibly tissue, differentiation. A review of Proterozoic multicellular organisms reveals that a coenocytic grade of organization was common among early metaphytes and supports the view (that a cellularity is a derived condition in many ‘multicellular’ lineages. Nineteen acritarch taxa are preserved in the Svanbergfjellet sediments. Ten of these show a readily identifiable ornamentation and contribute significantly to Neoproterozoic biostratigraphy; a world-wide and exclusively Late Riphean distribution of the acanthomorph Trachyhystrichosphaera aimika identifies it as a particularly valuable index fossil. The Svanbergfjellel fossil assemblage preserves a total of 63 distinct forms, of which 56 are treated taxonomically. As much as possible, principles of ‘natural’ taxonomy are applied, such that taphonomic and ontogenetic variants are declined separate taxonomy status. Major taxonomic revisions are offered for the acritarchs Trachyhystrichosphaera and Chuaria as well as for the prokaryotic-grade filaments: Cephalonyx, Cyanonema, Oscillatoriopsis, Palaeolyngbya, Rugossopsis, Siphonophycus, Tortunema, and Veteronostocale. Newly erected taxa include 7 new genera: Palaeastrum. Proterocladus, Pseudotawuia, Valkyria, Cerebrosphaera, Osculosphera and Pseudodendron; 14 new species in 12 genera: Palaestrum ***dyptocranum, Proterocladus major, Proterocladus minor, Proterocladus ***hermannae. Pseudodendron birenifera, Valkyria borealis, Cerebrosphaera buickii, Osculosphaera hyaline, Pseudodendron anteridium fullerne, Germinosphaera jankauskasii, Trachyhystrichosphaera polaris, Siphonophycus thulenema and thulenema and Digitus adumbrates 7 new combinations: Leiosphaeridia wimanii, Eoentophysalis croxfordii Cephlonyx geminatus. Oscillatoriopsis amadeus. Siphonophycus typicum, Siphonophycus solidum and Tortunema Wernadskii.     

A new stem-neopterygian fish from the Middle Triassic of China shows the earliest over-water gliding strategy of the vertebrates

Flying fishes are extraordinary aquatic vertebrates capable of gliding great distances over water by exploiting their enlarged pectoral fins and asymmetrical caudal fin. Some 50 species of extant flying fishes are classified in the Exocoetidae (Neopterygii: Teleostei), which have a fossil record no older than the Eocene. The Thoracopteridae is the only pre-Cenozoic group of non-teleosts that shows an array of features associated with the capability of over-water gliding. Until recently, however, the fossil record of the Thoracopteridae has been limited to the Upper Triassic of Austria and Italy. Here, we report the discovery of exceptionally well-preserved fossils of a new thoracopterid flying fish from the Middle Triassic of China, which represents the earliest evidence of an over-water gliding strategy in vertebrates. The results of a phylogenetic analysis resolve the Thoracopteridae as a stem-group of the Neopterygii that is more crown-ward than the Peltopleuriformes, yet more basal than the Luganoiiformes. As the first record of the Thoracopteride in Asia, this new discovery extends the geographical distribution of this group from the western to eastern rim of the Palaeotethys Ocean, providing new evidence to support the Triassic biological exchanges between Europe and southern China. Additionally, the Middle Triassic date of the new thoracopterid supports the hypothesis that the re-establishment of marine ecosystems after end-Permian mass extinction is more rapid than previously thought.     

Marine invertebrate migrations trace climate change over 450 million years

Aim

Poleward migration is a clear response of marine organisms to current global warming but the generality and geographical uniformity of this response are unclear. Marine fossils are expected to record the range shift responses of taxa and ecosystems to past climate change. However, unequal sampling (natural and human) in time and space biases the fossil record, restricting previous studies of ancient migrations to individual taxa and events. We expect that temporal changes in the latitudinal distribution of surviving taxa will reveal range shifts to trace global climate change.

Location

Global.

Time period

Post‐Cambrian Phanerozoic aeon.

Major taxa studied

Well‐fossilized marine benthic invertebrates comprising stony corals, bivalves, gastropods, brachiopods, trilobites and calcifying sponges.

Methods

We track deviations in the latitudinal distribution of range centres of age boundary crossing taxa from the expected distribution, and compare responses across latitudes. We build deviation time series, spanning hundreds of million years, from fossil occurrences and test correlations with seawater temperature estimates derived from stable oxygen isotopes of fossils.

Results

Seawater temperature and latitudinal deviations from sampling are positively correlated over the post‐Cambrian Phanerozoic. Simulations suggest that sampling patterns are highly unlikely to drive this putative signal of range shifts. Systematically accounting for known sampling issues strengthens this correlation, so that climate is capable of explaining nearly a third of the variance in ancient latitudinal range shifts. The relationship is stronger in low latitude taxa than higher latitude taxa, and in warm ages than cool ages.

Main conclusions

Latitudinal range shifts occurred in concert with climate change throughout the post‐Cambrian Phanerozoic. Low latitude taxa show the clearest climate‐migration signal through time, corroborating predictions of their shift in a warming future.