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The fusion crust of the Winchcombe meteorite: A preserved record of atmospheric entry processes
Full text linkAbstract - Fusion crusts form during the atmospheric entry heating of meteorites and preserve a record of the conditions that occurred during deceleration in the atmosphere. The fusion crust of the Winchcombe meteorite closely resembles that of other stony meteorites, and in particular CM2 chondrites, since it is dominated by olivine phenocrysts set in a glassy mesostasis with magnetite, and is highly vesicular. Dehydration cracks are unusually abundant in Winchcombe. Failure of this weak layer is an additional ablation mechanism to produce large numbers of particles during deceleration, consistent with the observation of pulses of plasma in videos of the Winchcombe fireball. Calving events might provide an observable phenomenon related to meteorites that are particularly susceptible to dehydration. Oscillatory zoning is observed within olivine phenocrysts in the fusion crust, in contrast to other meteorites, perhaps owing to temperature fluctuations resulting from calving events. Magnetite monolayers are found in the crust, and have also not been previously reported, and form discontinuous strata. These features grade into magnetite rims formed on the external surface of the crust and suggest the trapping of surface magnetite by collapse of melt. Magnetite monolayers may be a feature of meteorites that undergo significant degassing. Silicate warts with dendritic textures were observed and are suggested to be droplets ablated from another stone in the shower. They, therefore, represent the first evidence for intershower transfer of ablation materials and are consistent with the other evidence in the Winchcombe meteorite for unusually intense gas loss and ablation, despite its low entry velocity.Copyright © 2022 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals LLC on behalf of The Meteoritical Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use,
distribution and reproduction in any medium, provided the original work is properly cited. The attached file is the published version of the article.NHM Repositor
Restructuring of Femoral Cortical Bone During Growth and Locomotor Development of Wild Chimpanzees (Pan troglodytes verus)
Full text linkABSTRACT
Objective - Chimpanzees are altricial in terms of their locomotor development and transition from being carried to engaging in suspensory and arboreal locomotor behaviors to eventually relying on terrestrial quadrupedalism as their main form of locomotion. Here, we consider the mechanical implications of femoral cortical bone restructuring during growth and locomotor development in wild chimpanzees.
Materials and Methods - Cortical bone structure was examined in an ontogenetic sample of wild chimpanzees from a single subspecies (P. t. verus) spanning in age from 2 weeks to 12.6 years. Diaphyseal cross‐sections were extracted from micro‐CT scans of the femur at 35%, 50%, and 65% of total intermetaphyseal length and variation in cortical bone structure was assessed based on bending rigidity (Imax/Imin, Ix/Iy), relative medullary area, and cortical bone porosity.
Results - Diaphyseal shape is relatively circular with a high amount of cortical bone porosity and a large relative medullary area during early infancy. Distinct shifts in cortical bone structure occurred for each studied parameter with the biggest changes occurring within the first 5 years. Values appear to stabilize as quadrupedal walking increases in frequency and is established as the main form of locomotion.
Discussion - Collectively, the results suggest a degree of integration in which cortical bone restructures in response to rapid changes in locomotion in addition to nonmechanical influences such as hormonal, and growth factors, without compromising function and structural integrity. The extent of influence of each factor varies throughout growth and highlights the need for caution in functional interpretations of cortical bone geometry.Copyright © 2024 The Author(s). American Journal of Biological Anthropology published by Wiley Periodicals LLC. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. The attached file is the published version of the article.NHM Repositor
Obsidian clasts as sintered remnants of agglutination processes in volcanic conduits, evidence from the Pepom tephras (Sete Cidades), São Miguel, Azores
No full textThe youngest explosive eruptions of the Sete Cidades volcano, São Miguel, Azores, are recorded by a series of relatively small-volume (<0.03 to 0.13 km3 DRE) trachytic pyroclastic deposits termed the Pepom tephra deposits. While dominated by crystal-poor to crystal-moderate (<10%) pumice clasts, these deposits also contain a suite of dense glassy clasts of broadly similar crystallinity. The obsidian clasts from a single deposit vary in texture from entirely dense to those that are moderately vesicular and typically single clasts will contain multiple textural domains. The majority (∼71%) of these dense clasts have compositions both from bulk rock and in-situ glass measurements that are identical to those of the pumice clasts within the same deposit. We interpret these dense clasts to reflect sintering of previously fragmented magma at shallow levels in the conduit prior to being re-entrained and erupted with the vesicular magma, in agreement with recent studies focussing on textural observations. Notably, across the exposed volcanic stratigraphy of São Miguel obsidian domes, flows/coulees are not preserved, arguing against the idea that the dense glass clasts within the Pepom tephras are sourced from existing surficial rocks. In contrast, the neighbouring island of Terceira exhibits domes and coulees with large obsidian bands that cut through the crystalline groundmass. Most silicic rocks of Santa Bárbara and Pico Alto volcanoes on Terceira are peralkaline, comenditic to pantelleritic in composition, and at similar conditions (e.g., temperature and water content) have lower viscosities than the trachytic Pepom obsidian clasts. However, the Santa Bárbara silicic lavas on Terceira (the less peralkaline suite) have more obsidian than the more peralkaline Pico Alto domes and coulees indicating that while peralkalinity, developed during magmatic evolution in the crust, may play a role, sintering occurring at shallow levels within the conduit likely is more important in producing obsidian.Copyright © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). The linked file is the published version of the article.NHM Repositor
DNA barcodes from over-a-century-old type specimens shed light on the taxonomy of a group of rare butterflies (Lepidoptera: Nymphalidae: Calinaginae)
Full text linkWe analyzed COI barcode sequences from 138 over-a-century old specimens of Calinaga including 36 name-bearing type specimens stored at the Natural History Museum London. These new data, combined with previously available RPS5 sequences, divide the Calinaga samples into four well-supported mitochondrial lineages that together with a novel wing-pattern analysis, support the recognition of six species (lhatso, buddha, brahma, aborica, formosana and davidis), with all other names subsumed either as subspecies or synonyms. One new taxon is described, Calinaga aborica naima Vane-Wright, ssp. n.Copyright: © 2024 Todisco et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article.NHM Repositor
New Species of Grotea (Hymenoptera, Ichneumonidae, Labeninae) from Ecuador, with New Records and a Key to the Neotropical Species
Full text linkAbstract - Here we describe two new Grotea species from Ecuador, G. akakana Mazón & Bordera sp. nov., and G. romeri Mazón sp. nov., as well as the male of G. cundinamarquesa Herrera-Flórez 2018. G. akakana sp. nov. is characterized by the combination of a postgenal process long, a 45-flagellomeres antenna without a white band and a mesopleuron black with two yellow spots separated by a red one. On the other hand, G. romeri sp. nov. is characterized by the combination of a postgenal process very short, a 36-flagellomeres antenna without a white band, a propodeum with a long and narrow area lateralis, uninterrupted yellow-colored orbits and a mesopleuron black with a yellow spot in the middle. The species G. santandereana Herrera-Flórez 2018 and G. surinamese Herrera-Flórez 2019 are recorded from Ecuador for the first time. This brings the total of described Grotea species to 31, all from the New World, with 27 of these exclusively Neotropical. A key for the identification of Neotropical species is included.Copyright © The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated
otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The attached file is the published version of the article.NHM Repositor
Salvation and documentation: additional (probable) type material of South American land-snail species (Gastropoda, Stylommatophora) in the Museum für Naturkunde Berlin
Full text linkType material of some South American species in the Museum für Naturkunde Berlin, belonging to different families is documented. It includes 16 species: Bulimus cuneus L. Pfeiffer, 1854, Bulimus proteus Broderip, 1832, Bulimus scalarioides L. Pfeiffer, 1867, Bulimus similaris J. Moricand, 1856, Andinia (Ehrmanniella) dedicata Weyrauch & Zilch, 1954, Helix hettneriana E. von Martens, 1897, Eurycampta hidalgonis Döring, 1877, Helix aequatoris L. Pfeiffer, 1860, Helix bituberculata L. Pfeiffer, 1853, Helix bourcieri L. Pfeiffer, 1853, Helix neogranadensis L. Pfeiffer, 1845, Cyclostoma (Cyclophorus) bourcieri L. Pfeiffer, 1854, and Helix platygyra Albers, 1857. The concept of the “salvation” of type material is explained.Copyright ©The authors. This work is freely available under the Creative Commons Attribution 4.0 International licence (CC BY 4.0). The attached file is the published version of the article.NHM Repositor
A new leaf inhabiting ascomycete from the Jurassic (ca 170 Mya) of Yorkshire, UK, and insights into the appearance and diversification of filamentous Ascomycota
Full text linkAbstract: Leaf-associated fungi, the fungi that depend on leaves to sporulate, have a rich Cenozoic record, however their earlier diversity is poorly characterized. Here we describe Harristroma eboracense gen. et sp. nov., a Middle Jurassic leaf-associated fungus colonizing the leaf cuticle of Nilssonia tenuicaulis (cycadophyte). To place our newly described species into a picture of the diversification of Mesozoic fungi, we reassess fossils with leaf-associated stromata in the context of fungal molecular phylogeny. Being melanized, with radiate stromata, and on leaves, H. eboracense and other fossils from the Jurassic and earlier periods are probably related to filamentous Ascomycota in the superclass Leotiomyceta. Characters needed for further resolution of leaf-associated fungal biology and classification, such as the presence of an ostiole for spore discharge and appressoria for entry into leaf tissue first appear in the Mesozoic fossil record. Among Early Cretaceous fossils, Spataporthe taylorii represents the oldest unambiguous evidence of perithecial Sordariomycetes while Protographum luttrellii and Bleximothyrium ostiolatum are the oldest Dothideomycetes thyriothecia. Environmental observations show that broad leaved gymnosperms (especially cycadophytes) growing in warm temperate wet forests might have been the first environment for the radiation of Leotiomyceta.Copyright © The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which
permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the
original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or
other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line
to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory
regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this
licence, visit http://creativecommons.org/licenses/by/4.0/. The attached file is the published version of the article.NHM Repositor
Bayesian Methods to Analyze Historical Collections in Time and Space: A Case Study Using Cabo Verde Endemic Flora
Full text linkBiological collections, including herbarium specimens, are unique sources of biodiversity data presenting a window on the history of the development and accumulation of knowledge of a specific geographical region. Understanding how the process of discovery impacts that knowledge is particularly important for oceanic islands which are often characterized by both high levels of endemic diversity and high proportions of threatened taxa. The archipelagos of the Macaronesian region (i.e. Azores, Canaries, Savages, Madeira, and Cabo Verde) have been the focus of attention for scientific expeditions since the end of the 17th century. However, there is no integrated study describing the historical process of collecting, discovery and description of its flora. Using as a case study the Cabo Verde endemic angiosperm flora, we review the history of collecting in the flora and apply a Bayesian approach to assess the accumulation of species discovery, through time and space across the nine islands of the archipelago. Our results highlight the central role not only of natural characteristics (e.g. area, age, maximum altitude and average value of the terrain ruggedness index) but also historical factors (i.e. the location of major harbors) for the development of knowledge of the flora. The main factors that have determined the process of species description in the archipelago and how this impact our understanding of diversity patterns across archipelagos are discussed.Copyright © 2020 Romeiras, Carine, Duarte, Catarino, Dias and Borda-de-Água. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not
comply with these terms. The attached file is the published version of the article.NHM Repositor
Quantifying the rise of animals during theEdiacaran–Cambrian using ichnodissimilarity
Full text linkThe trace fossil record provides important insights into the evolution of early animals during the Ediacaran/Cambrian transition, with changes in ichnodiversity through time and between environments informing on the diversification of major body plans, behaviors, and niches. To
quantify variation in the diversity of trace fossils across this critical interval, we propose a measure of trace fossil dissimilarity (ichnodissimilarity) based on vector calculation. Furthermore, by comparing discrepancies between the angular bisector and mean vector of two sets of vectorized fossil data, we are able to weigh the relative contribution of increases and decreases in the variation of occurrences of taxa. We used this metric to analyze an
expansive dataset of Ediacaran/Cambrian trace fossils. The results allowed us to quantify the diversification of traces across this transition, informing on the timing of first appearance of different behaviors (e.g., foraging, grazing, and resting) and functional groups. By interpreting the results in the context of environmental changes and advancements in motility and sensory capabilities, we were able to pinpoint the onset and sequence of the Fortunian diversification event, Cambrian information revolution, and agronomic revolution, shedding light on the evolution of organismal body plans, behaviors, and locomotion during the Ediacaran/Cambrian transition. We identified two phases of origination and expansion during the divergence of
early animal traces. Furthermore, by analyzing shallow- and deep-marine trace fossils, we were able to uncover evidence for a more rapid diversification of traces in shallow-marine environments, with progressive niche partitioning through the Ediacaran to Cambrian.The attached file is the accepted manuscript of the article. You are advised to consult the published version if you wish to cite it.NHM Repositor
Genomics of ecological adaptation in Canary Island Descurainia (Brassicaceae) and comparisons with other Brassicaceae
Full text linkAbstract
Oceanic archipelagos provide striking examples of lineages that have radiated over pronounced ecological gradients. Accompanying this diversification, lineages have evolved adaptations allowing survival in extreme environments. Here, we investigate the genomic basis of ecological adaptation in Canary Island Descurainia (Brassicaceae), an island relative of Arabidopsis. The seven endemic species have diversified in situ along an elevational and ecological gradient, from low‐elevation scrub to high‐elevation sub‐alpine desert. We first generated a reference genome for Descurainia millefolia, phylogenetic analysis of which placed it as sister to D. sophioides. Ninety‐six gene families were found to be specific to D. millefolia and a further 1087 and 1469 gene families have expanded or contracted in size, respectively, along the D. millefolia branch. We then employed genome re‐sequencing to sample 14 genomes across the seven species of Canary Island Descurainia and an outgroup. Phylogenomic analyses were consistent with previous reconstructions of Canary Island Descurainia in resolving low‐ and high‐elevation clades. Using the branch‐site dN/dS method, we detected positive selection for 275 genes on the branch separating the low‐ and high‐elevation species and these positively selected genes (PSGs) were significantly enriched for functions related to reproduction and stress tolerance. Comparing PSGs to those in analyses of adaptation to elevation and/or latitude in other Brassicaceae, we found little evidence of widespread convergence and gene reuse, except for two examples, one of which was a significant overlap between Descurainia and Draba nivalis, a species restricted to high latitudes. The study of Canary Island Descurainia suggests that the transition to high‐elevation environments such as that found in the high mountains of the Canary Islands involves selection on genes related to reproduction and stress tolerance but that repeated evolution across different lineages that have evolved into similar habitats is limited, indicating substantially different molecular trajectories to adaptation.Copyright © 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
provided the original work is properly cited. The attached file is the published version of the article.NHM Repositor