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  • Sun, Xiaole
    et al.
    Stockholm University.
    Mörth, Carl-Magnus
    Stockholm University.
    Porcelli, Don
    Oxford University.
    Kutscher, Liselott
    Swedish Museum of Natural History, Department of Geology.
    Hirst, Catherine
    Swedish Museum of Natural History, Department of Geology.
    Murphy, Melissa
    Oxford University.
    Maximov, Trofim
    Institute for Biological Problems in the Cryolithozone, Yakusk.
    Petrov, Roman
    Institute for Natural Sciences of North Federal University, Yakutsk.
    Humborg, Christoph
    Stockholm University.
    Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Andersson, Per
    Swedish Museum of Natural History, Department of Geology.
    Stable Silicon Isotopic Compositions of the Lena River and its Tributaries: Implications for Silicon Delivery to the Arctic Ocean2018In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 241, p. 120-133Article in journal (Refereed)
    Abstract [en]

    Silicon isotope values (δ30SiDSi) of dissolved silicon (DSi) have been analyzed in the Lena River and its tributaries, one of the largest Arctic watersheds in the world. The geographical and temporal variations of δ30SiDSi range from +0.39 to +1.86 ‰ with DSi concentrations from 34 to 121 μM. No obvious patterns of DSi concentrations and δ30SiDSi values were observed along over 200 km of the two major tributaries, the Viliui and Aldan Rivers. In summer, the variations of DSi concentrations and δ30SiDSi values in the water are either caused by biological uptake by higher plants and phytoplankton or by mixing of water masses carrying different DSi concentrations and δ30SiDSi values. DSi in tributaries from the Verkhoyansk Mountain Range seems to be associated with secondary clay formation that increased the δ30SiDSi values, while terrestrial biological production is likely more prevalent in controlling δ30SiDSi values in Central Siberian Plateau and Lena Amganski Inter-River Area. In winter, when soils were frozen, the δ30SiDSi values in the river appeared to be controlled by weathering and clay formation in deep intrapermafrost groundwater. During the spring flood, dissolved silicate materials and phytoliths were flushed from the upper thawed soils into rivers, which reset δ30SiDSi values to the values observed prior to the biological bloom in summer. The results indicate that the Si isotope values reflect the changing processes controlling Si outputs to the Lena River and to the Arctic Ocean between seasons. The annual average δ30SiDSi value of the Lena Si flux is calculated to be +0.86±0.3 ‰ using measured δ30SiDSi values from each season. Combined with the estimate of +1.6±0.25 ‰ for the Yenisey River, an updated δ30SiDSi value of the major river Si inputs to the Arctic Ocean is estimated to be +1.3±0.3 ‰. This value is expected to shift towards higher values in the future because of the impacts from a variety of biological and geochemical processes and sources under global warming.

     

  • Hybertsen, Frida
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Kiel, Steffen
    Swedish Museum of Natural History, Department of Paleobiology.
    A middle Eocene seep deposit with silicified fauna from the Humptulips Formation in western Washington State, USA2018In: Acta Palaeontologica Polonica, ISSN 0567-7920, E-ISSN 1732-2421, Vol. 63, p. 751-768Article in journal (Refereed)
  • Snape, Joshua
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Curran, Natalie
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Nemchin, Alexander
    Joy, Katherine
    Hopkinson, Tom
    Mahesh, Anand
    Bellucci, Jeremy
    Swedish Museum of Natural History, Department of Geology.
    Kenny, Gavin
    Swedish Museum of Natural History, Department of Geology.
    Ancient volcanism on the Moon: Insights from Pb isotopes in the MIL 13317 and Kalahari 009 lunar meteorites2018In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 502, p. 84-95Article in journal (Refereed)
    Abstract [en]

    Lunar meteorites provide a potential opportunity to expand the study of ancient (>4000 Ma) basaltic volcanism on the Moon, of which there are only a few examples in the Apollo sample collection. Secondary Ion Mass Spectrometry (SIMS) was used to determine the Pb isotopic compositions of multiple mineral phases (Ca-phosphates, baddeleyite K-feldspar, K-rich glass and plagioclase) in two lunar meteorites, Miller Range (MIL) 13317 and Kalahari (Kal) 009. These data were used to calculate crystallisation ages of 4332 ± 2 Ma (95% confidence level) for basaltic clasts in MIL 13317, and 4369 ± 7 Ma (95% confidence level) for the monomict basaltic breccia Kal 009. From the analyses of the MIL 13317 basaltic clasts, it was possible to determine an initial Pb isotopic composition of the protolith from which the clasts originated, and infer a 238 U/204 Pb ratio (μ-value) of 850 ± 130 (2σ uncertainty) for the magmatic source of this basalt. This is lower than μ-values determined previously for KREEP-rich (an acronym for K, Rare Earth Elements and P) basalts, although analyses of other lithological components in the meteorite suggest the presence of a KREEP component in the regolith from which the breccia was formed and, therefore, a more probable origin for the meteorite on the lunar nearside. It was not possible to determine a similar initial Pb isotopic composition from the Kal 009 data, but previous studies of the meteorite have highlighted the very low concentrations of incompatible trace elements and proposed an origin on the farside of the Moon. Taken together, the data from these two meteorites provide more compelling evidence for widespread ancient volcanism on the Moon. Furthermore, the compositional differences between the basaltic materials in the meteorites provide evidence that this volcanism was not an isolated or localised occurrence, but happened in multiple locations on the Moon and at distinct times. In light of previous studies into early lunar magmatic evolution, these data also imply that basaltic volcanism commenced almost immediately after Lunar Magma Ocean (LMO) crystallisation, as defined by Nd, Hf and Pb model ages at about 4370 Ma.

  • Bouvier, Laura
    et al.
    Costa, Maria
    Connelly, James
    Jensen, Ninna
    Wielandt, Daniel
    Storey, Michael
    Nemchin, Alexander
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Snape, Joshua
    Swedish Museum of Natural History, Department of Geology.
    Bellucci, Jeremy
    Swedish Museum of Natural History, Department of Geology.
    Moynier, Frederic
    Agranier, Arnaud
    Gueguen, Bleuenn
    Schonbachler, Maria
    Bizzarro, Martin
    Evidence for extremely rapid magma ocean crystallization and crust formation on Mars2018In: Nature, ISSN 1476-4687, Vol. 558, p. 586-589Article in journal (Refereed)
    Abstract [en]

    The formation of a primordial crust is a critical step in the evolution of terrestrial planets but the timing of this process is poorly understood. The mineral zircon is a powerful tool for constraining crust formation because it can be accurately dated with the uranium-to-lead (U–Pb) isotopic decay system and is resistant to subsequent alteration. Moreover, given the high concentration of hafnium in zircon, the lutetium-to-hafnium (176Lu–176Hf) isotopic decay system can be used to determine the nature and formation timescale of its source reservoir (1,2,3) Ancient igneous zircons with crystallization ages of around 4,430 million years (Myr) have been reported in Martian meteorites that are believed to represent regolith breccias from the southern highlands of Mars (4,5) These zircons are present in evolved lithologies interpreted to reflect re-melted primary Martian crust4, thereby potentially providing insight into early crustal evolution on Mars. Here, we report concomitant high-precision U–Pb ages and Hf-isotope compositions of ancient zircons from the NWA 7034 Martian regolith breccia. Seven zircons with mostly concordant U–Pb ages define 207Pb/206Pb dates ranging from 4,476.3 ± 0.9 Myr ago to 4,429.7 ± 1.0 Myr ago, including the oldest directly dated material from Mars. All zircons record unradiogenic initial Hf-isotope compositions inherited from an enriched, andesitic-like crust extracted from a primitive mantle no later than 4,547 Myr ago. Thus, a primordial crust existed on Mars by this time and survived for around 100 Myr before it was reworked, possibly by impacts (4,5) to produce magmas from which the zircons crystallized. Given that formation of a stable primordial crust is the end product of planetary differentiation, our data require that the accretion, core formation and magma ocean crystallization on Mars were completed less than 20 Myr after the formation of the Solar System. These timescales support models that suggest extremely rapid magma ocean crystallization leading to a gravitationally unstable stratified mantle, which subsequently overturns, resulting in decompression melting of rising cumulates and production of a primordial basaltic to andesitic crust (6,7).

  • Snape, Joshua
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Davids, Bart
    Nemchin, Alexander
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Bellucci, Jeremy
    Swedish Museum of Natural History, Department of Geology.
    Constraining the timing and sources of volcanism at the Apollo 12 landing site using new Pb isotopic compositions and crystallisation ages2018In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 482, p. 101-112Article in journal (Refereed)
    Abstract [en]

    The basaltic suites collected at the Apollo 12 landing site have been interpreted as representing a stratigraphic sequence of volcanic flows emplaced in the Oceanus Procellarum region between approximately 3100–3300 Ma. This study presents Secondary Ion Mass Spectrometry (SIMS) Pb isotopic analyses of samples from each of the basaltic suites, which have been used to constrain precise crystallisation ages and initial Pb isotopic composi- tions. The new crystallisation ages are consistent with the three main basaltic suites (olivine, pigeonite and ilmenite) being emplaced over a period of approximately 60 million years, and the improved precision of these ages has made it possible to reinterpret the stratigraphic sequence of basalt flows underlying the Apollo 12 landing site. Contrary to previous studies, the three ilmenite basalts are determined as having the oldest ages (with a weighted average of 3187 ± 6 Ma; 2σ) and are, therefore, interpreted as representing the lowest unit in the sequence, underlying the olivine and pigeonite basalts (with an age range constrained by the oldest and youngest pigeonite basalts; 3176 ± 6 Ma and 3129 ± 10 Ma; 2σ). The initial Pb isotopic compositions have been compared with recalculated initial Sr and Nd isotopic compositions, and are consistent with the three main basaltic suites originating from magmatic sources that incorporated different proportions of a common primitive mafic cumulate and the residual trapped liquid fraction remaining after a majority of the lunar magma ocean had crystallised. Our data also demonstrate that the feldspathic basalt (12038) is unique, both in terms of its crys- tallisation age (3242 ± 13 Ma) and its derivation from a distinct mantle reservoir.

  • Bellucci, Jeremy
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Nemchin, Alexander
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Snape, Joshua
    Swedish Museum of Natural History, Department of Geology.
    Bland, Phil
    Benedix, Gretchen
    Roszjar, Julia
    Pb evolution in the Martian mantle2018In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 485, p. 79-87Article in journal (Refereed)
    Abstract [en]

    The initial Pb compositions of one enriched shergottite, one intermediate shergottite, two depleted shergottites, and Nakhla have been measured by Secondary Ion Mass Spectrometry (SIMS). These values, in addition to data from previous studies using an identical analytical method performed on three enriched shergottites, ALH 84001, and Chassigny, are used to construct a unified and internally consistent model for the differentiation history of the Martian mantle and crystallization ages for Martian meteorites. The differentiation history of the shergottites and Nakhla/Chassigny are fundamentally different, which is in agreement with short-lived radiogenic isotope systematics. The initial Pb compositions of Nakhla/Chassigny are best explained by the late addition of a Pb-enriched component with a primitive, non-radiogenic composition. In contrast, the Pb isotopic compositions of the shergottite group indicate a relatively simple evolutionary history of the Martian mantle that can be modeled based on recent results from the Sm–Nd system. The shergottites have been linked to a single mantle differentiation event at 4504 Ma. Thus, the shergottite Pb isotopic model here reflects a two-stage history 1) pre-silicate differentiation (4504 Ma) and 2) post-silicate differentiation to the age of eruption (as determined by concordant radiogenic isochron ages). The μ-values (238U/204Pb) obtained for these two different stages of Pb growth are μ1 of 1.8 and a range of μ2 from 1.4–4.7, respectively. The μ1-value of 1.8 is in broad agreement with enstatite and ordinary chondrites and that proposed for proto Earth, suggesting this is the initial μ-value for inner Solar System bodies. When plotted against other source radiogenic isotopic variables (Sri, γ187Os, ε143Nd, and ε176Hf), the second stage mantle evolution range in observed mantle μ-values display excellent linear correlations (r2 > 0.85) and represent a spectrum of Martian mantle mixing-end members (depleted, intermediate, enriched).

  • Ge, Rongfeng
    et al.
    Wilde, Simon
    Nemchin, Alexander
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Bellucci, Jeremy
    Swedish Museum of Natural History, Department of Geology.
    Erickson, Timmons
    Frew, Adam
    Thern, Eric
    A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization2018In: Geology, ISSN 0091-7613, E-ISSN 1943-2682, Vol. 46, no 4, p. 303-306Article in journal (Refereed)
    Abstract [en]

    Hadean (≥4.0 Ga) zircon grains provide the only direct record of the first half-billion years of Earth’s history. Determining accurate and precise crystallization ages of these ancient zircons is a prerequisite for any interpretation of crustal evolution, surface environment, and geodynamics on the early Earth, but this may be compromised by mobilization of radiogenic Pb due to subsequent thermal overprinting. Here we report a detrital zircon from the Jack Hills (Western Australia) with 4486–4425 Ma concordant ion microprobe ages that yield a concordia age of 4463 ± 17 Ma (2σ), the oldest zircon age recorded from Earth. However, scanning ion imaging reveals that this >4.4 Ga apparent age resulted from incorporation of micrometer-scale patches of unsupported radiogenic Pb with extremely high 207Pb/206Pb ratios and >4.5 Ga 207Pb/206Pb ages. Isotopic modeling demonstrates that these patches likely resulted from redistribution of radiogenic Pb in a ca. 4.3 Ga zircon during a ca. 3.8 Ga or older event. This highlights that even a concordia age can be spurious and should be carefully evaluated before being interpreted as the crystallization age of ancient zircon.

  • Bellucci, Jeremy
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Nemchin, Alexander
    Swedish Museum of Natural History, Department of Geology.
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ross, Kielman
    Swedish Museum of Natural History, Department of Geology.
    Snape, Joshua
    Swedish Museum of Natural History, Department of Geology.
    Pidgeon, Robert
    Geochronology of Hadean zircon grains from the Jack Hills, Western Australia constrained by quantitative scanning ion imaging2018In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 476, p. 469-480Article in journal (Refereed)
    Abstract [en]

    Five Hadean (> 4 Ga) aged zircon grains from the Jack Hills metasedimentary belt have been investigated by a secondary ion mass spectrometry scanning ion image technique. This technique has the ability to obtain accurate and precise full U-Pb systematics on a scale < 5 μm, as well as document the spatial distribution of U, Th and Pb. All five of the grains investigated here have complex cathodoluminescence patterns that correlate to different U, Th, and Pb concentration domains. The age determinations for these different chemical zones indicate multiple reworking events that are preserved in each grain and have affected the primary crystalized zircon on the scale of < 10 μm, smaller than conventional ion microprobe spot analyses. In comparison to the spot analyses performed on these grains, these new scanning ion images and age determinations indicate that almost half of the spot analyses have intersected several age and chemical domains in both fractured and unfractured parts of the individual crystals. Some of these unfractured, mixed domain spot analyses have concordant ages that are inaccurate. Thus, if the frequency of spot analyses intersecting mixed domains here is even close to representative of all other studies of the Jack Hills zircon population, it makes the interpretation of any trace element, Hf, or O isotopic data present in the literature tenuous. Lastly, all of the grains analysed here preserve at least two distinguishable 207Pb/206Pb ages. These ages are preserved in core-rim and/or complex internal textural relationships in unfractured domains. These secondary events took place at ca. 4.3, 4.2, 4.1, 4.0, 3.7, and 2.9 Ga, which are coincident with previously determined statistically robust age peaks present in this zircon population.

  • Skublov, Sergei
    et al.
    Krasotkina, Anna
    Makayev, Aleksandr
    Rizvanova, Nailya
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    The first data on the U-Pb age (TIMS and LA-ICP-MS) of rutile from the Ichetju polymineral occurrence, The Middle Timan2018In: Journal of Mining Institute, Vol. 232, p. 357-363Article in journal (Refereed)
    Abstract [en]

    A study on the U-Pb age of rutile from the Ichetju polymineral occurrence has been done for the first time by LA-ICP-MS and TIMS methods. It was established that rutile originates from various sources with different ages (presumably, ca. 1000, 1660, 1860 and 1980 Ma), but all the rutile types have undergone a common thermal event at ca. 580 Ma. Obtained results are consistent with U-Pb zircon data for the Ichetju occurrence and the Pizhemskoe deposit. According to modern concepts, the closure temperature for the U-Pb system in rutile is higher than 500 С, which suggests fairly high-temperature conditions of the rutile hydrothermal transformation during the formation of the deposits in Riphean. Obviously, a placer hypothesis of formation of titanium deposits of the Middle Timan which is supported by a number of researchers does not explain such temperature of rutile alteration.

  • Glykou, Aikaterini
    et al.
    Eriksson, Gunilla
    Storå, J.
    Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Lidén, Kerstin
    Intra- and inter-tooth variation in strontium isotope ratios from prehistoric seals by laser ablation multi-collector inductively coupled plasma mass spectrometry2018In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 32, p. 1215-1224Article in journal (Refereed)
    Abstract [en]

    Rationale

    Strontium isotope ratios (87Sr/86Sr) in modern‐day marine environments are considered to be homogeneous (~0.7092). However, in the Baltic Sea, the Sr ratios are controlled by mixing seawater and continental drainage from major rivers discharging into the Baltic. This pilot study explores if variations in Sr can be detected in marine mammals from archaeological sites in the Baltic Sea.               

    Methods

    87Sr/86Sr ratios were measured in tooth enamel from three seal species by laser ablation multi‐collector inductively coupled plasma mass spectrometry (LA‐MC‐ICP‐MS). The method enables micro‐sampling of solid materials. This is the first time that the method has been applied to marine samples from archaeological collections.               

    Results

    The analyses showed inter‐tooth 87Sr/86Sr variation suggesting that different ratios can be detected in different regions of the Baltic Sea. Furthermore, the intra‐tooth variation suggests possible different geographic origin or seasonal movement of seals within different regions in the Baltic Sea through their lifetime.               

    Conclusions

    The method was successfully applied to archaeological marine samples showing that: (1) the 87Sr/86Sr ratio in marine environments is not uniform, (2) 87Sr/86Sr differences might reflect differences in ecology and life history of different seal species, and (3) archaeological mobility studies based on 87Sr/86Sr ratios in humans should therefore be evaluated together with diet reconstruction.

  • Drake, Henrik
    et al.
    Ivarsson, Magnus
    Tillberg, Mikael
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Ancient Microbial Activity in Deep Hydraulically Conductive Fracture Zones within the Forsmark Target Area for Geological Nuclear Waste Disposal, Sweden2018In: Geosciences, Vol. 8, no 211Article in journal (Refereed)
    Abstract [en]

    Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of δ13Ccalcite (−36.2 to +20.2‰ V-PDB) and δ34Spyrite (−11.7 to +37.8‰ V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of δ18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded.

  • Norén, Michael
    Swedish Museum of Natural History, Department of Zoology. FishBase.
    The enigmatic Betadevario ramachandrani (Teleostei: Cyprinidae: Danioninae): phylogenetic position resolved by mitogenome analysis, with remarks on the prevalence of chimeric mitogenomes in GenBank2018In: Cogent Biology, ISSN 2331-2025, Vol. 4, no 1, p. 1-8Article in journal (Refereed)
  • Malm, Tobias
    et al.
    Swedish Museum of Natural History, Department of Zoology.
    Rota, Jadranka
    Department of Biology, Lund University, Lund, Sweden.
    Chazot, Nicolas
    Department of Biology, Lund University, Lund, Sweden.
    Peña, Carlos
    HipLead, San Francisco, CA, United States of America.
    Wahlberg, Niklas
    Department of Biology, Lund University, Lund, Sweden.
    A simple method for data partitioning based on relative evolutionary rates2018In: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, p. 1-21, article id 6:e5498Article in journal (Refereed)
    Abstract [en]

    Background. Multiple studies have demonstrated that partitioning of molecular datasets is important in model-based phylogenetic analyses. Commonly, partitioning is done a priori based on some known properties of sequence evolution, e.g. differences in rate of evolution among codon positions of a protein-coding gene. Here we propose a new method for data partitioning based on relative evolutionary rates of the sites in the alignment of the dataset being analysed. The rates are inferred using the previously published Tree Independent Generation of Evolutionary Rates (TIGER), and the partitioning is conducted using our novel python script RatePartitions. We conducted simulations to assess the performance of our new method, and we applied it to eight published multi-locus phylogenetic datasets, representing different taxonomic ranks within the insect order Lepidoptera (butterflies and moths) and one phylogenomic dataset, which included ultra-conserved elements as well as introns.

    Methods. We used TIGER-rates to generate relative evolutionary rates for all sites in the alignments. Then, using RatePartitions, we partitioned the data into partitions based on their relative evolutionary rate. RatePartitions applies a simple formula that ensures a distribution of sites into partitions following the distribution of rates of the characters from the full dataset. This ensures that the invariable sites are placed in a partition with slowly evolving sites, avoiding the pitfalls of previously used methods, such as kmeans. Different partitioning strategies were evaluated using BIC scores as calculated by PartitionFinder.

    Results. Simulations did not highlight any misbehaviour of our partitioning approach, even under difficult parameter conditions or missing data. In all eight phylogenetic datasets, partitioning using TIGER-rates and RatePartitions was significantly better as measured by the BIC scores than other partitioning strategies, such as the commonly used partitioning by gene and codon position. We compared the resulting topologies and node support for these eight datasets as well as for the phylogenomic dataset.

    Discussion. We developed a new method of partitioning phylogenetic datasets without using any prior knowledge (e.g. DNA sequence evolution). This method is entirely based on the properties of the data being analysed and can be applied to DNA sequences (protein-coding, introns, ultra-conserved elements), protein sequences, as well as morphological characters. A likely explanation for why our method performs better than other tested partitioning strategies is that it accounts for the heterogeneity in the data to a much greater extent than when data are simply subdivided based on prior knowledge.

  • Kullander, Sven
    et al.
    Swedish Museum of Natural History, Department of Zoology.
    Norén, Michael
    Swedish Museum of Natural History, Department of Zoology.
    Rahman, MD. Mizanur
    University of Dhaka.
    Mollah, Abdur Rob
    University of Dhaka.
    Laubuka tenella, a new species of cyprinid fish from southeastern Bangladesh and southwestern Myanmar (Teleostei, Cyprinidae, Danioninae)2018In: ZooKeys, ISSN 1313-2989, E-ISSN 1313-2970, Vol. 742, p. 105-126Article in journal (Refereed)
    Abstract [en]

    Laubuka tenella is a new species characterized by the colour pattern, consisting of short dark verticalbars anteriorly on the side, and a dark lateral band posteriorly on the side, combined with a relativelyshort pelvic fin and 29–30 lateral-line scales. It is separated from other   analysed by minimum9 % uncorrected p-distance in the mitochondrial COI gene. The type series is composed of specimens from small streams in the Cox’s Bazar District in Bangladesh (the type locality), and the Thandwe River drainage in western Myanmar. Laubuka brahmaputraensis is strongly indicated to be a junior synonymof L. laubuca, the second known species of Laubuka in Bangladesh. Eustira ceylonensis, currently in thes ynonymy of Devario malabaricus, is a valid species of Laubuka.

  • Hålenius, Ulf
    et al.
    Swedish Museum of Natural History, Department of Geology.
    Hatert, Frédéric
    Université de Liège, Belgium..
    Pasero, Marco
    Università di Pisa, Italy..
    Mills, Stuart J.
    Museum Victoria, Melbourne, Australia..
    IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) Newsletter 452018In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 82, no 5, p. 1225-1232Article in journal (Other academic)
  • MARRAMÀ, GIUSEPPE
    et al.
    Department of Paleontology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria..
    ENGELBRECHT, ANDREA
    Department of Paleontology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria..
    Mörs, Thomas
    Swedish Museum of Natural History, Department of Paleobiology.
    REGUERO, MARCELO A.
    Division Paleontologia de Vertebrados, Museo de La Plata, Paseo del Bosque s/n, 81900 FWA La Plata, Argentina.
    KRIWET, JÜRGEN
    Department of Paleontology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria..
    THE SOUTHERNMOST OCCURRENCE OF BRACHYCARCHARIAS (LAMNIFORMES, ODONTASPIDIDAE) FROM THE EOCENE OF ANTARCTICA PROVIDES NEW INFORMATION ABOUT THE PALEOBIOGEOGRAPHY AND PALEOBIOLOGY OF PALEOGENE SAND TIGER SHARKS2018In: Rivista italiana di paleontologia e stratigrafia, ISSN 0035-6883, E-ISSN 2039-4942Article in journal (Refereed)
    Abstract [en]

     The first record of one of the most common and widespread Paleogene selachians, the sand tiger shark Brachycarcharias, in the Ypresian strata of the La Meseta Formation, Seymour Island, Antarctica, is provided herein. Selachians from the early Eocene horizons of this deposit represent the southernmost Paleogene occurrences in the fossil record, and are represented by isolated teeth belonging to orectolobiforms, lamniforms, carcharhiniforms, squatiniforms and pristiophoriforms. The combination of dental characters of the 49 isolated teeth collected from the horizons TELMs 2, 4 and 5 supports their assignment to the odontaspidid Brachycarcharias lerichei (Casier, 1946), a lamniform species widely spread across the Northern Hemisphere during the early Paleogene. The unambiguous first report of this lamniform shark in the Southern Hemisphere in the Eocene of the La Meseta Formation improves our knowledge concerning the diversity and paleobiology of the cartilaginous fishes of this deposit, and provides new insights about the biotic turnovers that involved the high trophic levels of the marine settings after the end-Cretaceous extinction and before the establishment of the modern marine ecosystems.