Search

Graduate medical education programs must ensure residents and fellows acquire skills needed for independent practice. Workplace-based observational assessments are informative but can be time- and resource-intensive. In this study we sought to gather "relations-to-other-variables" validity evidence for scores generated by the Electromyography Direct Observation Tool (EMG-DOT) to inform its use as a measure of electrodiagnostic skill acquisition.Scores on multiple assessments were compiled by trainees during Clinical Neurophysiology and Electromyography rotations at a large US academic medical center. Relationships between workplace-based EMG-DOT scores (n = 298) and scores on a prerequisite simulated patient exercise, patient experience surveys (n = 199), end-of-rotation evaluations (n = 301), and an American Association of NeuromuscularElectrodiagnostic Medicine (AANEM) self-assessment examination were assessed using Pearson correlations.Among 23 trainees, EMG-DOT scores assigned by physician raters correlated positively with end-of-rotation evaluations (r = 0.63, P = .001), but EMG-DOT scores assigned by technician raters did not (r = 0.10, P = .663). When physician and technician ratings were combined, higher EMG-DOT scores correlated with better patient experience survey scores (r = 0.42, P = .047), but not with simulated patient or AANEM self-assessment examination scores.End-of-rotation evaluations can provide valid assessments of trainee performance when completed by individuals with ample opportunities to directly observe trainees. Inclusion of observational assessments by technicians and patients provides a more comprehensive view of trainee performance. Workplace- and classroom-based assessments provide complementary information about trainee performance, reflecting underlying differences in types of skills measured.

Titanopterans are spectacular, giant, predatory insects mainly known from the Triassic, but they are known from a few localities in Central Asia (including European Russia) and Australia. The Nampo Group is a nonmarine sequence, located on the southwestern Korean Peninsula, the age of which has remained controversial, due to lack of proper age-constraining fossils. Here, we report a new titanopteran Magnatitan jongheoni n. gen. n. sp. from the Amisan Formation, Nampo Group. The division of the radius anterior and radius posterior beyond the distal half of the fossil wing is a characteristic of the family Paratitanidae. This is the first discovery of a titanopteran fossil outside of Central Asia and Australia, suggesting a possible circum-Tethys oceanic distribution. Given the possibly widespread distribution of titanopterans, this group might have played a critical role as giant predatory insects in Triassic terrestrial ecology. Because titanopterans have never been found beyond the Triassic-Jurassic boundary, the occurrence of a titanopteran corroborates the Triassic age of the Nampo Group.UUID: http://zoobank.org/10177029-0044-424f-9816-e3fb057cfe85

In mammals, the gut microbiome is vertically transmitted during maternal lactation at birth. In this study, we investigated the gut microbiome and diets of muskox, a large herbivore inhabiting in the high Arctic. We compared the microbiota composition using bacterial 16S rRNA gene sequencing and diets using stable isotope analysis of muskox feces of six female adults and four calves on Ella Island, East Greenland. Firmicutes were the most abundant bacterial phylum in both the adults and calves, comprising 94.36% and 94.03%, respectively. Significant differences were observed in the relative abundance of the two Firmicutes families. The adults were primarily dominated by Ruminococcaceae (73.90%), and the calves were dominated by both Ruminococcaceae (56.25%) and Lachnospiraceae (24.00%). Stable isotope analysis of the feces in the study area revealed that both adults and calves had similar ranges of

Titanopterans are well-known as giant predatory insects in the Triassic, but not only their rare occurrences have been limited to Central Asia and Australia, but also their phylogenetic affinity remains unresolved. The age of the nonmarine sequences of the Nampo Group at the southwestern Korean Peninsula is unclear, and the tectonic affinity of the surrounding area is contentions. Here we report a new titanopteran Magnatitan jongheoni gen. et sp. nov. the Amisan Formation, Nampo Group, which marks the first discovery of the titanopteran fossil from outside Central Asia and Australia, presenting a possible circum-Tethys Ocean distribution, at least, during the Late Triassic. The new fossil shows a clearly divided CuPb, which will help understand the evolution of titanopterans in the future. Moreover, the occurrence of a titanopteran finally confirms the Late Triassic age of the Nampo Group. In China, similar Late Triassic non-marine sequences are widespread in the Cathaysia Block, in which various geological features similar to those in the southwestern Korean Peninsula, such as a Paleozoic magmatism and an eclogite facies with Neoproterozoic protoliths, have been recently documented as in the southeastern Korean Peninsula. Such similarities may suggest a close tectonic affinity between the northeastern Cathaysia Block and the southwestern Korean Peninsula.

In order to maximize the utility of future studies of trilobite ontogeny, we propose a set of standard practices that relate to the collection, nomenclature, description, depiction, and interpretation of ontogenetic series inferred from articulated specimens belonging to individual species. In some cases, these suggestions may also apply to ontogenetic studies of other fossilized taxa.

Conodonts and microbrachiopods of latest Cambrian–earliest Ordovician age are documented from the Handler Formation of northern Victoria Land, Antarctica. Five spot samples from allochthonous limestone clasts collected during expeditions conducted by the Korean Polar Research Institute in 2013–2014 yielded the conodonts Cordylodus proavus, C. lindstromi, Hirsutodontus simplex, and Teridontus nakamurai, associated with four species of brachiopods (two indeterminate acrotretides, a zhanatellid lingulide, and a siphonotretide tentatively referred to Schizambon reticulatus). The four conodont species are distinctive taxa occurring in the widely distributed Cordylodus lindstromi Biozone of the latest Cambrian and the Iapetognathus Biozone at the base of the Ordovician. The allochthonous limestone clasts in the Handler Formation were likely derived from now-lost carbonate shelves developed locally (in the Bowers Arc) or transported from further north. Fossil evidence from the Handler Formation indicates that the final episode of the Ross Orogeny that uplifted and deformed the Robertson Bay Group was no older than early Tremadocian (earliest Ordovician). Striking similarities in fossil content, ages and depositional settings between the limestone olistoliths in the Handler Formation and latest Cambrian–earliest Ordovician autochthonous and allochthonous carbonates of the post-Delamerian Orogen recognized in the Koonenberry Belt (Gnalta Shelf) in far western New South Wales support the depositional model considering the Robertson Bay Group as the synorogenic deposits of the Ross Orogeny.

This study reports diverse spiriferellid brachiopods from the Permian rocks of Svalbard and adjacent areas (Arctic Canada and Subpolar Urals of Russia) located at the northern margin of Pangaea. In...

Tardigrades constitute one of the most important group in the challenging Antarctic terrestrial ecosystem. Living in various habitats, tardigrades play major roles as consumers and decomposers in the trophic networks of Antarctic terrestrial and freshwater environments; yet we still know little about their biodiversity. The Eutardigrada is a species rich class, for which the eggshell morphology is one of the key morphological characters. Tardigrade egg morphology shows a diverse appearance, and it is known that, despite rare, intraspecific variation is caused by seasonality, epigenetics, and external environmental conditions. Here we report Dactylobiotus ovimutans sp. nov. from King George Island, Antarctica. Interestingly, we observed a range of eggshell morphologies from the new species, although the population was cultured under controlled laboratory condition. Thus, seasonality, environmental conditions, and food source are eliminated, leaving an epigenetic factor as a main cause for variability in this case.

A collection of spiders from the Cretaceous (Albian) Jinju Formation of Korea is described. These finds increase the number of known spiders from the Jinju Formation from one to 11. There is considerable diversity of mygalomorphs and araneomorphs, including palpimanoids (including lagonomegopids), as well as cribellate and ecribellate entelegynes. Such diversity among so few specimens hints that an even greater range of families will come to light as more specimens are discovered in the future. The first non-amber Lagonomegopidae are described, with the first preservation of a spider eye tapetum in the fossil record, providing evidence for lagonomegopid enlarged eyes being posterior medians. The female-biased sex ratio of lagonomegopids is discussed and it is concluded that the bias is fortuitous.http://zoobank.org/urn:lsid:zoobank.org:pub:7926A54F-1B64-417E-91B4-027FAFCC8C0A

Satellite remote sensing imagery is especially useful for geological investigations in Antarctica because of its remoteness and extreme environmental conditions that constrain direct geological survey. The highest percentage of exposed rocks and soils in Antarctica occurs in Northern Victoria Land (NVL). Exposed Rocks in NVL were part of the paleo-Pacific margin of East Gondwana during the Paleozoic time. This investigation provides a satellite-based remote sensing approach for regional geological mapping in the NVL, Antarctica. Landsat-8 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) datasets were used to extract lithological-structural and mineralogical information. Several spectral-band ratio indices were developed using Landsat-8 and ASTER bands and proposed for Antarctic environments to map spectral signatures of snow/ice, iron oxide/hydroxide minerals, Al-OH-bearing and Fe, Mg-OH and CO3 mineral zones, and quartz-rich felsic and mafic-to-ultramafic lithological units. The spectral-band ratio indices were tested and implemented to Level 1 terrain-corrected (L1T) products of Landsat-8 and ASTER datasets covering the NVL. The surface distribution of the mineral assemblages was mapped using the spectral-band ratio indices and verified by geological expeditions and laboratory analysis. Resultant image maps derived from spectral-band ratio indices that developed in this study are fairly accurate and correspond well with existing geological maps of the NVL. The spectral-band ratio indices developed in this study are especially useful for geological investigations in inaccessible locations and poorly exposed lithological units in Antarctica environments.

The submarine channel-fill system of the Cambrian Spurs Formation exhibits unique metre-scale cycles of breccia and diamictite. The studied sections, Eureka Spurs, are located at the Mariner Glacier in the central-eastern part of northern Victoria Land, Antarctica. A facies analysis of the channel-fill deposit has led to the recognition of four main lithofacies: breccia, diamictite, thin-bedded sandstone and mudstone. The channel-fill deposit consists of two architectural elements: hollow-fill (HF) and sheet-like (SL) elements. The SL has wide convex-up geometry and consists solely of a very thick bed of diamictite, and is interpreted as a submarine channel lobe. The HF has a concave-up erosional base and flat upper surface. The HF consists of nine cyclic alternations of underlying breccia (cohesionless debris flow) and overlying diamictite (cohesive debris flow). The deposition of breccia is interpreted to have been controlled by repeated allogenic processes such as earthquakes. In contrast, the abrupt vertical transition from breccia to diamictite in each cycle is interpreted to have resulted from an autogenic, slope instability-related process. The interaction of the allogenic and autogenic factors recorded in the metre-scale unique cyclic deposits provides new criteria to interpret cycles of submarine debris flow.

Recent discoveries of fossil nervous tissue in Cambrian fossils have allowed researchers to trace the origin and evolution of the complex arthropod head and brain based on stem groups close to the origin of the clade, rather than on extant, highly derived members. Here we show that Kerygmachela from Sirius Passet, North Greenland, a primitive stem-group euarthropod, exhibits a diminutive (protocerebral) brain that innervates both the eyes and frontal appendages. It has been surmised, based on developmental evidence, that the ancestor of vertebrates and arthropods had a tripartite brain, which is refuted by the fossil evidence presented here. Furthermore, based on the discovery of eyes in Kerygmachela, we suggest that the complex compound eyes in arthropods evolved from simple ocelli, present in onychophorans and tardigrades, rather than through the incorporation of a set of modified limbs., The arthropod head is complex and its evolution has been difficult to reconstruct. Here, Park et al. describe new specimens of the Cambrian stem-group euarthropod Kerygmachela that preserve evidence of primitive compound eyes and a unipartite brain, providing insight into the structure of the early arthropod head.

Trilobites are among the most diverse and abundant fossil groups in Korea and occur in the Cambrian–Ordovician Joseon Supergroup of the Taebaeksan Basin. The Cambrian–Ordovician trilobites of the Joseon Supergroup have been intensively studied during the last quarter century, with emphasis on taxonomic revision, refining biostratigraphic zonation, paleogeographic implications, and ontogeny and phylogeny. A total of 243 species have hitherto been known to occur in the Joseon Supergroup of the Taebaeksan Basin: 118 and 110 species were reported in the Taebaek and Yeongwol groups, respectively, whilst 15 species were described from the Mungyeong Group. Contrasting trilobite faunal contents of the Taebaek and Yeongwol/Mungyeong groups resulted in two separate biostratigraphic schemes for the Cambrian–Ordovician of the Taebaeksan Basin: 22 biozones or fossiliferous horizons were recognized in the Taebaek Group; 19 zones were established in the Yeongwol Group; and four biozones were known from the Mungyeong Group. These trilobite biozones of the Taebaeksan Basin can be correlated well with those of North China, South China, and Australia. The distribution of some of the Cambrian and Ordovician endemic trilobites and the detrital zircon spectra of the pertinent areas suggest that the Sino-Korean Craton was located at the margin of east Gondwana and was separated from the South China Craton by an oceanic basin, and that the Taebaeksan Basin was a part of an epeiric sea in east Gondwana. Focus of the ontogenetic research of Korean trilobites was initially on the Cambrian trilobites from the Machari Formation of the Yeongwol Group, and then, was shifted to the silicified sclerites dissolved out of the carbonates of the Guzhangian to Tremadocian strata of the Taebaek Group, which have played a crucial role in resolving the trilobite phylogeny. Still, much of the carbonate strata of the Taebaek Group containing silicified trilobites has remained unstudied. The future ontogenetic research on the trilobites from the middle Cambrian (Cambrian Series 3) and the Furongian strata of the Taebaek Group would significantly contribute to elucidating the muddled trilobite phylogeny.

Ten embedded fossil logs sampled in situ from the middle Eocene volcano-sedimentary rocks close to Suffield Point in the Fildes Peninsula, King George Island,Antarctica, are assigned to Protopodocarpoxylon araucarioides Schultze-Motel ex Vogellehner, Phyllocladoxylon antarcticum Gothan, Agathoxylon antarcticum (Poole & Cantrill) Pujana et al., A. pseudoparenchymatosum (Gothan) Pujana et al. andan unidentified angiosperm wood. Differences in the taxonomic representation and growth-ring characters of the Eocene woods on King George Island and coeval assemblages from Seymour Island, on the western and eastern sides of the Antarctic Peninsula respectively, are interpreted to result from environmental and climatic gradients across the Peninsula Orogen during the early Palaeogene. In particular, a precipitation gradient inferred across the Peninsula at that time might have been induced by a rain-shadow effect. This research is a part of the project ‘Long-Term Ecological Researches on King George Island to Predict Ecosystem Responses to Climate Change (PE15020)’ funded by the Korea Polar Research Institute, KOREA. Also funded by National Science Foundation (project #1636625)

The remote lower reaches of the Rennick Glacier in the far north of Victoria Land hold some of the least-explored outcrop areas of the Transantarctic basin system. Following recent international field-work efforts in the Helliwell Hills, we here provide a comprehensive emendation to the regional stratigraphy. Results of geological and palaeontological reconnaissance and of petrographic, geochemical and palynostratigraphic analyses reveal a stack of three previously unknown sedimentary units in the study area: the Lower Triassic Van der Hoeven Formation (new unit, 115+ m thick) consists mainly of quartzose sandstone and non-carbonaceous mudstone rich in continental trace fossils. The Middle to Upper Triassic Helliwell Formation (new unit, 235 m thick) consists of coal-bearing overbank deposits and volcaniclastic sandstone and yielded typical plant fossils of the Gondwanan Dicroidium flora together with plant-bearing silicified peat. The succession is capped by c. 14 m of the sandstone-dominated Section Peak Formation (uppermost Triassic–Lower Jurassic). Our results enable more detailed correlation of the Palaeozoic–Mesozoic successions throughout East Antarctica and into Tasmania. Of particular interest is one section that spans the end-Permian mass extinction interval, which promises to allow detailed reconstructions of high-latitude vegetation dynamics across this critical interval in Earth history. Supplementary material: A Supplementary Data File containing supplementary information, figures S1–S7, and additional references is available at https://doi.org/10.6084/m9.figshare.c.5118431

The lower Albian Jinju Formation has produced various fossils of invertebrates. Of them, insect fossils have remained understudied, and especially, orthopteran fossils have never been described from the Jinju Formation. Here we report a new species of the Elcanidae (Orthoptera: Elcanoidea), Panorpidium spica sp. nov. based on three specimens from the Jinju Formation. Notably, we have applied Wavelength Dispersive Spectrometer (WDS) analysis for the first time on insect fossils, and discovered that the carbon elemental maps are helpful in recognizing crucial morphology. The presence of pterostigmata in forewing supports that elcanids evolved a unique flight mechanism distinct from other extant orthopterans. Based on a detailed morphological comparison with the paddles of the extant tridactylids, it is inferred that the leaf-shaped spurs on the metatibiae of elcanids were used for jumping on the water, although other possible functions cannot be ruled out. Diving into the water and jumping on the water surface must have been an effective way of escaping from predators, both for the flightless nymphs and the short-range flying adults.

Shumardiid trilobites had a small, unique morphology, and formed a key constituent in trilobite faunas during the Cambrian–Ordovician. Because of their unusual morphology, they have been the subject of research s, into various aspects such as their life habit, functional morphology, evolutionary origin and ontogeny. Originally, a flat, adult-like protaspid morphology was suggested for shumardiids, but subsequently a bulbous protaspid morphology interpreted to be associated with metamorphosis was also suggested for this unique trilobite group. This article documents the ontogeny of the two co-occurring shumardiid trilobites, Akoldinioidia latus Park and Kihm and Koldinioidia choii Park and Kihm, from the middle Furongian Hwajeol Formation, Taebaeksan Basin, Korea. Interestingly, protaspides of the two shumardiids have a bulbous morphology. Given the stratigraphic occurrences of the two shumardiids, it can be inferred that commutavi protaspis appeared quite early in the shumardiid evolution. The co-occurrence of the two closely related trilobites is reminiscent of sexual dimorphism, although further evidence is required to prove it. The appearance of metamorphosis-undergoing protaspides in the Furongian shumardiids may have been due to the onset of increasing ecological pressure in the early phase of the Great Ordovician Biodiversification Event.

Although trilobites have provided research subjects for more than two centuries, their head segmentation has remained unresolved. Four glabellar furrows (SO and S1–S3) marking the segmental boundaries are generally present in the cephalic axis, but there are trilobites with one more pair of furrows, the so-called S4, in the cephalic axis, causing confusion in understanding trilobite head segmentation. Recent advances in developmental biology and palaeontology have shed light on the arthropod head problem, and thus, trilobite head segmentation can be reviewed in the light of this knowledge. Based on the information from the anatomy of exceptionally preserved trilobites and artiopodans closely related to trilobites, it is inferred that trilobite head contains five segments: the anteriormost ocular segment potentially associated with the hypostome, the antennal segment and the following three segments with walking legs. When present, the S4 furrows are situated where the eye ridges meet the cephalic axis of trilobites, indicating that the furrows are incised ‘within’ the anteriormost segment in trilobites with an anteriorly enlarged frontal lobe. Trilobites of the Order Redlichiida, the most primitive stock, show variable conditions in the frontal glabellar conditions, while in other more derived groups, the condition is rather constant. The frontal glabellar condition, therefore, could provide a clue to elucidate the unresolved Cambrian trilobite phylogeny and the Cambrian roots of the post-Cambrian trilobites.

In Korea, trilobites are among the most intensively studied fossil groups in the past century and provide invaluable information about lower Paleozoic stratigraphy, paleogeography, and tectonics of the Korean Peninsula. Trilobites occur in the lower Paleozoic Joseon Supergroup of the Taebaeksan Basin which was part of the Sino-Korean Craton in the Paleozoic. The Joseon Supergroup is divided into the Taebaek, Yeongwol, and Mungyeong groups. The Taebaek and Yeongwol groups are richly fossiliferous, while the Mungyeong Group is poorly fossiliferous. Contrasting trilobite faunal contents of the Taebaek and Yeongwol groups resulted in two separate biostratigraphic schemes for the Cambrian–Ordovician of the Taebaeksan Basin. A total of 22 biozones or fossiliferous horizons were recognized in the Taebaek Group; 19 zones were established in the Yeongwol Group; and four biozones were known from the Mungyeong Group. These trilobite biozones of the Taebaeksan Basin indicate the Joseon Supergroup ranges in age from the Cambrian Series 2 to Middle Ordovician and can be correlated well with the formations of North China, South China, and Australia.

Mid to late Cambrian thrombolites and maze-like maceriate reefs from the western North China Platform, Wuhai, Inner Mongolia, northwestern China, occur in the middle of a succession dominated by thin-bedded lime mudstone-shale/marlstone alternations, and are laterally surrounded by limestone conglomerate and/or grainstone. Thrombolite, characterized by meter-scale lenticular mounds composed of millimeter- to centimeter-scale mesoclots and wackestone matrix, occurs in the lower middle part of the sequence. Thrombolite mesoclots are composed of microstromatolites with alternating dark gray and light gray micritic laminae. The maze-like maceriate reefs occur in the middle to the upper part of the sequence, commonly forming lenticular mounds up to 1 m thick. They are characterized by centimeter- to decimeter-scale branched maze-like structures, whose biogenic portions (maceria) are selectively dolomitized. The maceriae are composed of poorly preserved microstromatolites and siliceous sponges. Inter-macerial sediments consist of lime mud and scattered bioclasts. These Wuhai reefs are generally similar to but older than various other Cambrian reefs previously reported from the Shandong region, northeastern China.

There were multiple origins of metamorphosis-undergoing protaspides in trilobite evolution: within the superfamilies Remopleuridioidea, Trinucleoidea, and within the Order Asaphida. Recent studies have revealed that the protaspides of the Cambrian representatives of the Remopleuridioidea and the Trinucleoidea did not undergo metamorphosis. However, ontogeny of the Cambrian members of the Order Asaphida has remained unknown. This study documents the ontogeny of the Furongian asaphoidean ceratopygid trilobite, Proceratopyge cf. P. lata Whitehouse, from northern Victoria Land, Antarctica. Two stages for the protaspid phase, five developmental stages for the post-protaspid cranidia, and ten stages for the post-protaspid pygidia have been identified. Interestingly, the protaspis directly developed into a meraspis without metamorphosis. A new cladistic analysis resulted in a single most parsimonious tree, according to which the presence of the bulbous commutavi protaspis turns out to be a synapomorphy for Asaphidae + Cyclopygoidea, not a synapomorphy for the Order Asaphida as previously suggested. In addition, it is inferred that there was convergent evolution of indirectly-developing commutavi protaspides during the Furongian and Early Ordovician. Metamorphosis-entailing planktonic larvae evolved in many different metazoan lineages near the Cambrian–Ordovician transition, due to the escalating ecological pressure of the Great Ordovician Biodiversification Event. Since the bulbous commutavi protaspid morphology is thought to be an adaptation for a planktonic life mode, the convergent evolution of the indirect development in the three trilobite lineages at this period might have been a result of adaptation to the early phase of the Great Ordovician Biodiversification Event.

Five species, Lipopora lissa Jell and Jell, 1976, Lipopora daseia Jell and Jell, 1976, Tretocylichne perplexa Engelbretsen, 1993 from Australia, Cambroctoconus orientalis Park, Woo, Lee, Lee, Lee, Han and Chough, 2011 from China, and Cambroctoconus kyrgyzstanicus Peel, 2014 from Kyrgyzstan, belonging to the Cambrian stem-group cnidarians have been documented in the fossil record. Cambroctoconus coreaensis sp. nov., interpreted here as a stem-group cnidarian, from the Seokgaejae section in the Daegi Formation, Taebaek Group (Cambrian Series 3), Taebaeksan Basin, central-eastern Korean Peninsula, has a slender cup-shaped skeleton. A cladistic analysis produced 21 most parsimonious trees, which invariably placed the six stem-group cnidarians below the crown-group, but their relationships within the stem-group are unresolved. Nine out of the 21 trees suggest a monophyletic relationship for the Cambrian stem-group cnidarians, whereas in six other trees a monophyly of Cambroctoconus and Tretocylichne appeared as the sister-group to the crown-group cnidarians with Lipopora at the most basal branch. This result may reflect the fact that crown-group cnidarians evolved in the Precambrian, and suggests that the diversity of stem-group cnidarians was a result of an independent radiation in the Cambrian.

The middle to later Cambrian (Drumian-Jiangshanian Ages, 505–490 Ma) was a time of unique evolutionary dynamics that remain enigmatic. This interval records unusually high rates of faunal turnover that produced a “plateau” within the broader trajectory of rapidly increasing biodiversity seen across the Cambrian Explosion and Great Ordovician Biodiversification Event (GOBE). The oceans during this time are generally thought to have been less oxygenated than later in the Phanerozoic, yet knowledge of oceanic redox structure and the influence this exerted upon the biosphere remains limited. Importantly, this interval also encompasses two large carbon cycle perturbations—the DICE and SPICE events— that are thought to involve the expansion of anoxic and, more specifically euxinic regions in the ocean. Despite this supposition, direct characterization of redox conditions across this time remains limited. Here we explore these conditions using new and previously published Fe-speciation data from seven basins distributed across five paleocontinents representing a range of depositional conditions. Our analysis reveals anoxia was a common and persistent feature of deeper-water environments and that it was generally absent from shallower-waters across this timespan. An exception to this broad pattern is seen during the SPICE when these deeper-water anoxic conditions expanded into shallower-water environments. These anoxic conditions were dominantly ferruginous and rare instances of euxinia were spatiotemporally limited to environments of high productivity, low clastic sedimentation and high sulfate availability within a generally low-sulfate ocean. Intriguingly, during these events faunal turnover was concentrated in inner-shelf areas suggesting a mechanistic link to the variable redox conditions characteristic of these environments. More broadly this instability in nearshore environments appears a likely cause of the high rates of faunal turnover seen across the later Cambrian and into the Early Ordovician, but further detailed paleontological and redox investigation of these environments are needed to adequately evaluate this view.

This study reports diverse spiriferellid brachiopods from the Permian rocks of Svalbard and adjacent areas (Arctic Canada and Subpolar Urals of Russia) located at the northern margin of Pangaea. In total, 11 brachiopod species in four genera are recognized and described in detail, including two new species (Spiriferella protodraschei and Arcullina? enokiani). According to our taxonomic investigation, morphological characteristics of the ventral sulcus and dorsal fold are relatively stable within each species, in spite of considerable intraspecific variations in shell outline and macro-ornamentation. In addition, both the arrangement of pustules, as a shell surface micro-ornamentation, and the development of delthyrial coverings are shown to be significant features for inferring phylogenetic relationships and for defining species. The best-known but still questionable taxon, Spiriferella keilhavii, is here identified as an endemic species restricted to Bjørnøya and, possibly, to central East Greenland; it is phylogenetically closest to S. loveni. Following the taxonomic revision, the stratigraphical ranges of the spiriferellids within the Kapp Starostin Formation in Spitsbergen are fully refined: three species, S. protodraschei, A. polaris and Timaniella wilczeki, are confined to the lowermost Vøringen Member (late Artinskian–early Kungurian), whereas S. loveni dominates the overlying members with a much longer stratigraphical range (late Kungurian–Lopingian?). This abrupt compositional change, along with comparable changes in other taxonomic groups, can be explained by a palaeoclimatic shift from cool to cold conditions between the Vøringen Member and the overlying Svenskeegga member. A similar biotic transition is identified between the Hambergfjellet and Miseryfjellet formations in Bjørnøya. On the other hand, S. loveni is abundant in the Late Permian strata of central East Greenland, but there it appears to be more costate in plication compared to its counterpart from Spitsbergen. It is suggested that this alteration in shell ornamentation may represent a possible response (adaptation) to warming arising from the southward migration of the species. http://zoobank.org/urn:lsid:zoobank.org:pub:85B863D2-DB42-4835-940A-2DE852C82178

© 2018 by the authors. Geological mapping and mineral exploration programs in the High Arctic have been naturally hindered by its remoteness and hostile climate conditions. The Franklinian Basin in North Greenland has a unique potential for exploration of world-class zinc deposits. In this research, multi-sensor remote sensing satellite data (e.g., Landsat-8, Phased Array L-band Synthetic Aperture Radar (PALSAR) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)) were used for exploring zinc in the trough sequences and shelf-platform carbonate of the Franklinian Basin. A series of robust image processing algorithms was implemented for detecting spatial distribution of pixels/sub-pixels related to key alteration mineral assemblages and structural features that may represent potential undiscovered Zn-Pb deposits. Fusion of Directed Principal Component Analysis (DPCA) and Independent Component Analysis (ICA) was applied to some selected Landsat-8 mineral indices for mapping gossan, clay-rich zones and dolomitization. Major lineaments, intersections, curvilinear structures and sedimentary formations were traced by the application of Feature-oriented Principal Components Selection (FPCS) to cross-polarized backscatter PALSAR ratio images. Mixture Tuned Matched Filtering (MTMF) algorithm was applied to ASTER VNIR/SWIR bands for sub-pixel detection and classification of hematite, goethite, jarosite, alunite, gypsum, chalcedony, kaolinite, muscovite, chlorite, epidote, calcite and dolomite in the prospective targets. Using the remote sensing data and approaches, several high potential zones characterized by distinct alteration mineral assemblages and structural fabrics were identified that could represent undiscovered Zn-Pb sulfide deposits in the study area. This research establishes a straightforward/cost-effective multi-sensor satellite-based remote sensing approach for reconnaissance stages of mineral exploration in hardly accessible parts of the High Arctic environments.

태백산 분지에 분포하는 탄산염 및 규질쇄설성 혼합 퇴적물로 구성된 세송층(late Middle Cambrian to Furongian)은 ${\delta}^{13}C$ 값이 1.14에서 2.81‰을 갖는 SPICE (Steptoean positive carbon excursion)를 15 m 두께의 층서구간에서 보여준다. SPICE는 Fenghuangella laevis대, Prochuangia mansuyi대 그리고 Chuangia대로 구성된 삼엽충 생물대에서 산출되며 이는 Paibian Stage의 하부에 해당된다. 세송층은 엽층리 이암, 단괴상 셰일, 엽층리 사암, 균질사암, 석회역암, 석회암-셰일 쌍을 포함한 6개의 암상으로 구성된다. 세송층은 폭풍파도기저면 아래의 외대륙붕에서 퇴적된 것으로 알려져 있다. 시기적으로 Paibian Stage에 속하는 SPICE는 세송층에서 고수위 퇴적계 다발, 대비 정합면과 해침퇴적계 다발에서 발견된다. SPICE의 최대 안정 탄소 동위원소 값은 상대적인 해수면 하강에 의해 형성된 대비 정합면과 일치한다. 세송층에서 SPICE의 산출은 SPICE가 화석의 산출이 결여된 지층의 전세계적 대비를 위해 사용될 수 있는 도구임을 암시한다. 【The Sesong Formation, mixed carbonate-siliciclastic deposits of late Middle Cambrian (Series 3) to Furongian in age, in the Taebaeksan Basin shows the Steptoean Positive Carbon Isotope Excursion (SPICE) with the ${\delta}^{13}C$ values ranging from 1.14 to 2.81‰ in the approximately 15-m-thick stratigraphic interval. The SPICE in the Sesong Formation occurs in the lower part of the Paibian Stage which contains trilobite biozones of the Fenghuangella laevis Zone, Prochuangia mansuyi Zone and the lower part of the Chuangia Zone. The Sesong Formation is composed of six lithofacies including laminated mudstone, nodular shale, laminated sandstone, massive sandstone, limestone conglomerate, and limestone-shale couplet facies. The Sesong Formation is known to have been deposited in the outer shelf below storm wave base. The SPICE occurs in the stratigraphic interval associated with highstand systems tract, correlative conformity and transgressive systems tract of the Sesong Formation. The peak carbon isotope value in the SPICE may coincide with the correlative conformity formed by relative sea-level fall. The occurrence of the SPICE in the Sesong Formation suggests that the SPICE can be used as a tool of global correlation for the successions of mixed carbonate-siliciclastics which lack fossils.】

SUMMARY In many marine invertebrates metamorphosis entails a shift from a free-swimming larva to a benthic juvenile or adult. However, how the metamorphosis-entailing “indirect development” in arthropods arose from direct-developing ancestor is poorly understood. Trilobites left a rich fossil record, and some trilobite lineages had a metamorphosis-undergoing early developmental stage, termed the “asaphoid protaspis”-stage, providing a good opportunity to elucidate the rise of indirect development. Among others, the Ordovician representatives of Remopleuridioidea are known to possess a highly bulbous “asaphoid protaspis,” while the Furongian (Late Cambrian) remopleuridioidean genus Haniwa did not possess it. Here we show the post-embryonic development of the remopleuridioidean trilobite, Apatokephalus latilimbatus, from the Tremadocian (485.4 Ma–477.7 Ma) Dongjeom Formation, Korea. The post-embryonic development of A. latilimbatus contains a free-swimming “commutavi protaspis” (a term replacing “asaphoid protaspis”). Interestingly, the earlier protaspid stage shows more similar morphology and size to the meraspis than the commutavi protaspid stage does. This indicates that the commutavi protaspid stage was intercalated into the ancestral direct development as a specialized stage for a better dispersal, and thus the “commutavi protaspis” of A. latilimbatus represents the initial phase of the evolution of indirect development. The duration of the free-swimming phase became longer in more derived remoplueridioidean trilobites, implying that the intercalated free-swimming strategy became emphasized during subsequent evolution. The morphological gap between the commutavi protaspis and the subsequent earliest meraspis provides a convincing case for the “selective independence” of developmental stages, explaining the various morphologies of commutavi protaspides in many trilobite lineages.

A PDF file describing our methods in greater detail, alongside the new opsin family nomenclature

A single PDF file containing Supplemental Figures 1 through 8, as described in the main text, alongside their figure legends

Park, T.-Y.S. & Kihm, J.-H., 3.10.2014. Furongian (late Cambrian) trilobites from the Asioptychaspis subglobosa Zone of the Hwajeol Formation, Korea. Alcheringa 39, xxx–xxx. ISSN 0311-5518The Hwajeol Formation of the Taebaek Group, Korea extends from the Jiangshanian Stage to Cambrian Stage 10. The lower part of the formation incorporates the Asioptychaspis Zone, which is closely correlated to the Asioptychaspis–Tsinania Zone of North China. This study documents silicified trilobites from the lower part of the Hwajeol Formation in the Sagundari section. Asioptychaspis subglobosa occurs throughout the interval; hence the biozone is renamed as the Asioptychaspis subglobosa Zone in this study. The Asioptychaspis subglobosa Zone of the Hwajeol Formation yields 14 polymerid species belonging to 14 genera. Of these, 11 species including three new species are documented for the first time in Korea. Among other taxa, the occurrence of Caznaia is stratigraphically significant because two biozones were established ...

Detailed study on the Lower Ordovician Mungok Formation in the mideastern part of the Korean peninsula has led to recognition of seven lithofacies which can be grouped into seven facies associations (FAs): FA1 (lagoon), FA2 (shoal), FA3 (shoreface), FA4 (inner to mid-ramp), FA5 (inner to outer ramp), FA6 (mid- to outer ramp), and FA7 (outer ramp). Spatio-temporal organization of the FAs represents homoclinal ramp environments with fringing ooidpeloid shoals. Correlation and lateral thickness variation of the FAs suggest that deep part of the basin might have been located toward the northern part of the study area. The relative sea-level curve inferred from the facies analysis suggests that the Mungok Formation evolved through three depositional stages in accordance with 3rd-order sealevel change. The organization of the facies succession indicates that the inner ramp facies associations (FA1 to 3) of the Mungok Formation are characterized by non-cyclic facies succession whereas the midand outer ramp facies associations (FA 4 to 7) have distinct cyclicity except non-cyclic FA 7. The difference in the facies successions between the inner ramp and the mid- to outer ramp area may result from the various depositional regime across a ramp. A non-cyclic facies successions of inner ramp facies (e.g., packstone to grainstone and lime mudstone) are suggestive of mosaic-type distribution that is controlled mostly by wave, storms, tides, currents, and local geomorphology. In contrast, cyclic facies successions (e.g., pebbly limestone conglomerate, limestone-shale alternation, and calcareous shale) represent a simple belt-type distribution of mid- to outer ramp facies that seems to reflect shifts of facies belt caused by sea-level changes. The partitioning of inner and mid- to outer ramp facies is appropriate for understanding the facies development of the Mungok Formation and similar ramp successions with distinct inner and mid- to outer ramp facies.