• The Lyell Collection at the Earth Sciences Department, Natural History Museum, London (UK)

      Sendino, MCSL (Pensoft Publishers, 2019-02-19)
      This paper provides a quantitative and general description of the Lyell Collection kept in the Department of Earth Sciences at the Natural History Museum of London. This collection started to be built by the eminent British geologist Sir Charles Lyell (1797-1875) in 1846 when the first specimen reached the Museum. The last one entered in 1980 donated by one of Lyell’s heirs. There are more than 1700 specimens, mainly hand specimens with 93% of the fauna and flora from the Cenozoic of the Macaronesian archipelagos of the Canaries and Madeira. Those specimens that belong to the Lyell Collection with certainty have been databased and imaged. Currently they are being geo-referred automatically with the rest of the site geo-references at the NHM. This collection could be increased by a couple of dozen more specimens with those specimens located in the same drawers, but they do not have collector details. The work of data collection of these specimens was implemented over a year from 2016 to 2017, including annelids; brachiopods; bryozoans; echinoderms; scyphozoans; bivalves; gastropods; scaphopods; trilobites; plants; reptiles; fishes; and mammals. Access to the specimen-level data is available through the NHM data portal with the images associated. This is the first time that a description of the Fossil Lyell Collection dataset is available in the literature.
    • “Perspectives in Animal Phylogeny and Evolution”: A decade later

      Giribet, G; Edgecombe, GD; Fusco, G (University of Padova PressPadova, 2019-01-15)
      Refinements in phylogenomic methods and novel data have clarified several controversies in animal phylogeny that were intractable with traditional PCR-based approaches or early Next Gen analyses. An alliance between Placozoa and Cnidaria has recently found support. Data from newly discovered species of Xenoturbella contribute to Xenacoelomorpha being placed as sister group of Nephrozoa rather than within the deuterostomes. Molecular data reinforce the monophyly of Gnathifera and ally the longenigmatic chaetognaths with them. Platyzoa was an artefactual grouping, and deep relationships within Spiralia now depict Rouphozoa (= Gastrotricha + Platyhelminthes) as sister group to Lophotrochozoa, and Gnathifera (plus Chaetognatha) their immediate sister group. A “divide and conquer” strategy of subsampling clades to optimize gene selection may be needed to simultaneously resolve the many disparate clades of the animal tree of life
    • Glastonbury Lake Village Revisited: A Multi-proxy Palaeoenvironmental Investigation of an Iron Age Wetland Settlement

      Hill, T; Hill, G; Brunning, R; Banerjea, R; Fyfe, R; Hogg, A; Jones, J; Perez, M; Smith, D (Taylor & Francis, 2019-01-14)
      Glastonbury Lake Village is one of the most iconic late prehistoric wetland settlements in Europe. A new excavation in the core of Glastonbury Lake Village, for the first time since 1907, provided the opportunity for sampling of deposits associated with occupation of the site and for reconstructing the environmental conditions before the settlement was constructed. The results of a detailed multiproxy study are presented, including palaeoecological proxies (Coleoptera, plant macrofossils, diatoms, pollen, non-pollen palynomorphs), geoarchaeological methods (soil micromorphology), supported by new radiocarbon determinations. The results highlight how the difficult process of creating a settlement in a wetland was achieved, both within structures and in the spaces around them. Evidence for grain storage within the macrofossil assemblages, and the presence of animals on the settlement reflected in coleopteran assemblages and non-pollen palynomorphs has refined our understanding of the interaction between the settlement and the neighbouring dryland.
    • The molecularization of centipede systematics

      Edgecombe, GD; Giribet, G; Fusco, G (Padova University Press, 2019-01)
      The injection of molecular data over the past 20 years has impacted on all facets of centipede systematics. Multi-locus and transcriptomic datasets are the source of a novel hypothesis for how the five living orders of centipedes interrelate but force homoplasy in some widely-accepted phenotypic and behavioural characters. Molecular dating is increasingly used to test biogeographic hypotheses, including examples of ancient vicariance. The longstanding challenge of morphological delimitation of centipede species is complemented by integrative taxonomy using molecular tools, including DNA barcoding and coalescent approaches to quantitative species delimitation. Molecular phylogenetics has revealed numerous instances of cryptic species. “Reduced genomic approaches” have the potential to incorporate historic collections, including type specimens, into centipede molecular systematics.
    • The alteration history of the Jbilet Winselwan CM carbonaceous chondrite: An analog for C-type asteroid sample return

      King, A; Russell, S; Schofield, P; Humphreys-Williams, E; Strekopytov, S (Wiley, 2018-12-13)
      Jbilet Winselwan is one of the largest CM carbonaceous chondrites available for study. Its light, major, and trace elemental compositions are within the range of other CM chondrites. Chondrules are surrounded by dusty rims and set within a matrix of phyllosilicates, oxides, and sulfides. Calcium‐ and aluminum‐rich inclusions (CAIs) are present at ≤1 vol% and at least one contains melilite. Jbilet Winselwan is a breccia containing diverse lithologies that experienced varying degrees of aqueous alteration. In most lithologies, the chondrules and CAIs are partially altered and the metal abundance is low (<1 vol%), consistent with petrologic subtypes 2.7–2.4 on the Rubin et al. (2007) scale. However, chondrules and CAIs in some lithologies are completely altered suggesting more extensive hydration to petrologic subtypes ≤2.3. Following hydration, some lithologies suffered thermal metamorphism at 400–500 °C. Bulk X‐ray diffraction shows that Jbilet Winselwan consists of a highly disordered and/or very fine‐grained phase (73 vol%), which we infer was originally phyllosilicates prior to dehydration during a thermal metamorphic event(s). Some aliquots of Jbilet Winselwan also show significant depletions in volatile elements such as He and Cd. The heating was probably short‐lived and caused by impacts. Jbilet Winselwan samples a mixture of hydrated and dehydrated materials from a primitive water‐rich asteroid. It may therefore be a good analog for the types of materials that will be encountered by the Hayabusa‐2 and OSIRIS‐REx asteroid sample‐return missions.
    • Biesiespoort revisited: a case study on the relationship between tetrapod assemblage zones and Beaufort lithostratigraphy south of Victoria West

      Day, M; Rubidge, BS (University of the Witwatersrand Johannesburg, 2018-12)
      The relationship between the tetrapod assemblage zones of the South African Karoo Basin and the lithostratigraphic divisions of the Beaufort Group is well-established, and provides an independent means of dating fossil occurrences. However, this relationship may not be consistent across the basin; a discrepancy exists between the historical tetrapod assemblages in the vicinity of Victoria West, Northern Cape Province, and the expected tetrapod assemblage zones based on mapped geology. In order to examine this disconnect, we collected fossils at two localities close to Biesiespoort railway station, a locality that was visited on a number of occasions by Robert Broom. Our fossil samples support the biostratigraphic determinations of Broom and thus confirm that the stratigraphic extent of the biozones at these localities differs from their type areas further south. The reasons for this are unclear but could be related to the northward younging of the lithological units, implying complex depositional processes, or result from difficulties in mapping. Nevertheless, caution should be exercised when using mapped geology near Victoria West as a guide to the age of fossils found there.
    • Assessing Thallium Elemental Systematics and Isotope Ratio Variations in Porphyry Ore Systems: A Case Study of the Bingham Canyon District

      Fitzpayne, A; Prytulak, J; Wilkinson, JJ; Cooke, DR; Baker, MJ; Wilkinson, CC (MDPI AG, 2018-11-26)
      The Bingham Canyon porphyry deposit is one of the world’s largest Cu-Mo-Au resources. Elevated concentrations of thallium (Tl) compared to average continental crust have been found in some brecciated and igneous samples in this area, which likely result from mobilization of Tl by relatively low temperature hydrothermal fluids. The Tl-enrichment at Bingham Canyon therefore provides an opportunity to investigate if Tl isotope ratios reflect hydrothermal enrichment and whether there are systematic Tl isotope fractionations that could provide an exploration tool. We present a reconnaissance study of nineteen samples spanning a range of lithologies from the Bingham district which were analysed for their Tl content and Tl isotope ratios, reported as parts per ten thousand (ε205Tl) relative to the NIST SRM997 international standard. The range of ε205Tl reported in this study (−16.4 to +7.2) is the largest observed in a hydrothermal ore deposit to date. Unbrecciated samples collected relatively proximal to the Bingham Canyon porphyry system have ε205Tl of −4.2 to +0.9, similar to observations in a previous study of porphyry deposits. This relatively narrow range suggests that high-temperature (>300 °C) hydrothermal alteration does not result in significant Tl isotope fractionation. However, two samples ~3–4 km away from Bingham Canyon have higher ε205Tl values (+1.3 and +7.2), and samples from more distal (~7 km) disseminated gold deposits at Melco and Barneys Canyon display an even wider range in ε205Tl (−16.4 to +6.0). The observation of large positive and negative excursions in ε205Tl relative to the mantle value (ε205Tl = −2.0 ± 1.0) contrasts with previous investigations of hydrothermal systems. Samples displaying the most extreme positive and negative ε205Tl values also contain elevated concentrations of Tl-Sb-As. Furthermore, with the exception of one sample, all of the Tl isotopic anomalies occur in hydrothermal breccia samples. This suggests that ε205Tl excursions are most extreme during the migration of low-temperature hydrothermal fluids potentially related to sediment-hosted gold mineralization. Future investigation to determine the host phase(s) for Tl in breccias displaying both chalcophile element enrichment and ε205Tl excursions can potentially provide new information about hydrothermal fluid composition and could be used to locate sites for future porphyry exploration.
    • A global assessment of Zn isotope fractionation in secondary Zn minerals from sulfide and non-sulfide ore deposits and model for fractionation control

      Mondillo, N; Wilkinson, JJ; Boni, M; Weiss, DJ; Mathur, R (Elsevier, 2018-11-15)
      We investigated extent and direction of Zn isotope fractionation in secondary zinc minerals formed during low temperature hydrothermal and/or supergene oxidation of primary sulfide deposits. Zinc isotope data have been obtained from non-sulfide zinc mineral separates (willemite - Zn2SiO4, smithsonite - ZnCO3, hemimorphite - Zn4(Si2O7)(OH)2·H2O, hydrozincite - Zn5(CO3)2(OH)6, and sauconite - Na0.3Zn3(Si,Al)4O10(OH)2·4H2O) collected from several Zn deposits in Ireland, Belgium, Poland, Namibia, Peru, Yemen and Zambia. The data are compared with Zn isotope compositions measured on Zn sulfides collected in the same areas and/or derived from the existing literature, to establish the controls of direction and likely extent of any fractionations. We find that willemite has the greatest compositional variability, with measured δ66ZnJCM-Lyon values ranging from −0.42 to 1.39‰, spanning the entire range of terrestrial variation in Zn isotopes recorded to date. Overall, significant fractionations in positive and negative directions are recorded relative to the precursor phase (primary sphalerite or an earlier secondary phase), with primary sphalerite falling in a relatively narrow range of isotopic values (approximately −0.1 to +0.4‰). Most of the data observed on willemite, hemimorphite and hydrozincite can be explained with a model of isotopic fractionation, in which partial dissolution of primary sphalerite is followed by precipitation of an initial secondary phase that preferentially incorporates heavy Zn isotopes. Smithsonite, instead, preferentially incorporates light Zn isotopes. This reflects the variation in the Zn-x bond strengths of these secondary phases with respect to the original sulfides. We also observed that isotope compositions do not depend only on the difference between the fractionation factors of the involved phases but also on the amount of the secondary mineral precipitated after dissolution of primary sulfide, and that the greatest fractionations occur when only small amounts of secondary mineral are precipitated. Progressive precipitation from migrating fluids that form phases enriched in heavy zinc isotopes would lead to a gradual decrease in the δ66Zn values of such phases, and the fluids involved, in time and space. Strong negative isotopic shifts are almost only observed for late crystallizing phases, such as those in vugs. These are interpreted to reflect precipitation from residual, isotopically-light fluids that are the inevitable highly-fractionated product of the above-described process. Where a more complete replacement of primary sulfide has occurred, such as in the high-grade core of non-sulfide zinc orebodies, there is limited net isotopic fractionation because dissolved primary zinc is nearly quantitatively reprecipitated locally. In addition, in only one case (Yanque, Peru) we observed that the fringes of non-sulfide zinc deposit were characterized by isotopically fractionated compositions, with highly negative values implying extensive precipitation (earlier, or elsewhere) of isotopically heavy secondary phases. The higher-grade ore zones, where complete breakdown of primary sulfides and quantitative reprecipitation of zinc have occurred, show instead less fractionated compositions.
    • Cerromojonite, CuPbBiSe3, from El Dragon (Bolivia): A New Member of the Bournonite Group

      Foerster, H-J; Bindi, L; Grundmann, G; Stanley, CJ (2018-09-21)
    • The Hypanis Valles delta: The last highstand of a sea on early Mars?

      Davis, Joel M.; Fawdon, Peter; Gupta, Sanjeev; Warner, Nicholas H.; Adler, Jacob B.; Balme, Matthew R.; Bell, James F., III; Grindrod, Peter M.; Sefton-Nash, Elliot (2018-08-24)
    • Thalhammerite, Pd9Ag2Bi2S4, a New Mineral from the Talnakh and Oktyabrsk Deposits, Noril'sk Region, Russia

      Vymazalova, A; Laufek, F; Sluzhenikin, SF; Kozlov, VV; Stanley, CJ; Plasil, J; Zaccarini, F; Garuti, G; Bakker, R (2018-08)
    • A new Middle Jurassic diplodocoid suggests an earlier dispersal and diversification of sauropod dinosaurs

      Xu, X; Upchurch, P; Mannion, PD; Barrett, PM; Regalado-Fernandez, OR; Mo, J; Ma, J; Liu, H (2018-07-24)
    • Rapid mixing and short storage timescale in the magma dynamics of a steady-state volcano

      Petrone, CM; Braschi, E; Francalanci, L; Casalini, M; Tommasini, S (2018-06)
    • Reconstruction of the diapsid ancestral genome permits chromosome evolution tracing in avian and non-avian dinosaurs

      O'Connor, RE; Romanov, MN; Kiazim, LG; Barrett, PM; Farré, M; Damas, J; Ferguson-Smith, M; Valenzuela, N; Larkin, DM; Griffin, DK (2018-05-21)
    • Chronology of martian breccia NWA 7034 and the formation of the martian crustal dichotomy

      Cassata, WS; Cohen, BE; Mark, DF; Trappitsch, R; Crow, CA; Wimpenny, J; Lee, MR; Smith, CL (2018-05)