• The locomotion of extinct secondarily aquatic tetrapods

      Gutarra, Susana; Rahman, Imran (Wiley, 2021-09-06)
      The colonisation of freshwater and marine ecosystems by land vertebrates has repeatedly occurred in amphibians, reptiles, birds and mammals over the course of 300 million years. Functional interpretations of the fossil record are crucial to understanding the forces shaping these evolutionary transitions. Secondarily aquatic tetrapods have acquired a suite of anatomical, physiological and behavioural adaptations to locomotion in water. However, much of this information is lost for extinct clades, with fossil evidence often restricted to osteological data and a few extraordinary specimens with soft tissue preservation. Traditionally, functional morphology in fossil secondarily aquatic tetrapods was investigated through comparative anatomy and correlation with living functional analogues. However, in the last two decades, biomechanics in palaeobiology has experienced a remarkable methodological shift. Anatomy-based approaches are increasingly rigorous, informed by quantitative techniques for analysing shape. Moreover, the incorporation of physics-based methods has enabled objective tests of functional hypotheses, revealing the importance of hydrodynamic forces as drivers of evolutionary innovation and adaptation. Here, we present an overview of the latest research on the locomotion of extinct secondarily aquatic tetrapods, with a focus on amniotes, highlighting the state-of-the-art experimental approaches used in this field. We discuss the suitability of these techniques for exploring different aspects of locomotory adaptation, analysing their advantages and limitations and laying out recommendations for their application, with the aim to inform future experimental strategies. Furthermore, we outline some unexplored research avenues that have been successfully deployed in other areas of palaeobiomechanical research, such as the use of dynamic models in feeding mechanics and terrestrial locomotion, thus providing a new methodological synthesis for the field of locomotory biomechanics in extinct secondarily aquatic vertebrates. Advances in imaging technology and three-dimensional modelling software, new developments in robotics, and increased availability and awareness of numerical methods like computational fluid dynamics make this an exciting time for analysing form and function in ancient vertebrates.
    • Petrological and geochemical characterisation of the sarsen stones at Stonehenge

      Nash, David J; Ciborowski, T Jake R; Darvill, Timothy; Parker Pearson, Mike; Ullyott, J Stewart; Damaschke, Magret; Evans, Jane A; Goderis, Steven; Greaney, Susan; Huggett, Jennifer M; et al. (Public Library of Science (PLoS), 2021-08-04)
      Little is known of the properties of the sarsen stones (or silcretes) that comprise the main architecture of Stonehenge. The only studies of rock struck from the monument date from the 19th century, while 20th century investigations have focussed on excavated debris without demonstrating a link to specific megaliths. Here, we present the first comprehensive analysis of sarsen samples taken directly from a Stonehenge megalith (Stone 58, in the centrally placed trilithon horseshoe). We apply state-of-the-art petrographic, mineralogical and geochemical techniques to two cores drilled from the stone during conservation work in 1958. Petrographic analyses demonstrate that Stone 58 is a highly indurated, grain-supported, structureless and texturally mature groundwater silcrete, comprising fine-to-medium grained quartz sand cemented by optically-continuous syntaxial quartz overgrowths. In addition to detrital quartz, trace quantities of silica-rich rock fragments, Fe-oxides/hydroxides and other minerals are present. Cathodoluminescence analyses show that the quartz cement developed as an initial <10 μm thick zone of non-luminescing quartz followed by ~16 separate quartz cement growth zones. Late-stage Fe-oxides/hydroxides and Ti-oxides line and/or infill some pores. Automated mineralogical analyses indicate that the sarsen preserves 7.2 to 9.2 area % porosity as a moderately-connected intergranular network. Geochemical data show that the sarsen is chemically pure, comprising 99.7 wt. % SiO2. The major and trace element chemistry is highly consistent within the stone, with the only magnitude variations being observed in Fe content. Non-quartz accessory minerals within the silcrete host sediments impart a trace element signature distinct from standard sedimentary and other crustal materials. 143Nd/144Nd isotope analyses suggest that these host sediments were likely derived from eroded Mesozoic rocks, and that these Mesozoic rocks incorporated much older Mesoproterozoic material. The chemistry of Stone 58 has been identified recently as representative of 50 of the 52 remaining sarsens at Stonehenge. These results are therefore representative of the main stone type used to build what is arguably the most important Late Neolithic monument in Europe.
    • Petrographic and chemical studies of the Cretaceous-Paleogene boundary sequence at El Guayal, Tabasco, Mexico: Implications for ejecta plume evolution from the Chicxulub impact crater

      Salge, T; Tagle, Roald; Schmitt, Ralf-Thomas; Hecht, Lutz; Wolf Uwe, Reimold; Chris, Koeberl (Geological Society of America, 2021-06-30)
      A combined petrographic and chemical study of ejecta particles from the Cretaceous-Paleogene boundary sequence of El Guayal, Tabasco, Mexico (520 km SW of Chicxulub crater), was carried out to assess their formation conditions and genetic relation during the impact process. The reaction of silicate ejecta particles with hot volatiles during atmospheric transport may have induced alteration processes, e.g., silicification and cementation, observed in the ejecta deposits. The various microstructures of calcite ejecta particles are interpreted to reflect different thermal histories at postshock conditions. Spherulitic calcite particles may represent carbonate melts that were quenched during ejection. A recrystallized microstructure may indicate short, intense thermal stress. Various aggregates document particle-particle interactions and intermixing of components from lower silicate and upper sedimentary target lithologies. Aggregates of recrystallized calcite with silicate melt indicate the consolidation of a hot suevitic component with sediments at ≳750 °C. Accretionary lapilli formed in a turbulent, steam-condensing environment at ~100 °C by aggregation of solid, ash-sized particles. Concentric zones with smaller grain sizes of accreted particles indicate a recurring exchange with a hotter environment. Our results suggest that during partial ejecta plume collapse, hot silicate components were mixed with the fine fraction of local surface-derived sediments, the latter of which were displaced by the preceding ejecta curtain. These processes sustained a hot, gas-driven, lateral basal transport that was accompanied by a turbulent plume at a higher level. The exothermic back-reaction of CaO from decomposed carbonates and sulfates with CO2 to form CaCO3 may have been responsible for a prolonged release of thermal energy at a late stage of plume evolution.
    • The early death of Colonel Robert C. Tytler and the afterlife of his collection

      Prys-Jones, Robert; Harding, Alison C; Rooke, Kathryn (British Ornithologists' Club, 2021-06-15)
      A letter by Allan Octavian Hume and three by Bertram Bevan-Petman, all written between 1904 and 1911 to Ernst Hartert, bird curator of Rothschild’s Tring Museum, are present in the Rothschild Tring archive, now held by the Natural History Museum. These shed light on both the probable cause of the early death in 1872 of Colonel Robert C. Tytler, British army officer and naturalist in colonial India, and on the somewhat convoluted fate of his collection subsequently.
    • Step by step towards citizen science — deconstructing youth participation in BioBlitzes

      Lorke, Julia; Ballard, Heidi L; Miller, Annie E; Swanson, Rebecca D; Pratt-Taweh, Sasha; Jennewein, Jessie N; Higgins, Lila; Johnson, Rebecca F; Young, Alison N; Ghadiri Khanaposhtani, Maryam; et al. (Sissa Medialab Srl, 2021-06-14)
      BioBlitzes, typically one-day citizen science (CS) events, provide opportunities for the public to participate in data collection for research and conservation, potentially promoting deeper engagement with science. We observed 81 youth at 15 BioBlitzes in the U.S. and U.K., identifying five steps participants use to create a biological record (Exploring, Observing, Identifying, Documenting and Recording). We found 67 youth engaged in at least one of the steps, but seldom in all, with rare participation in Recording which is crucial for contributing data to CS. These findings suggest BioBlitzes should reduce barriers to Recording for youth to increase engagement with science.
    • The easternmost record of Macratriinae LeConte, 1862 (Coleoptera: Anthicidae), with a new species from Fiji and a genus-rank synonymy in Macratriini LeConte, 1862

      Telnov, Dmitry (Magnolia Press, 2021-04-27)
      The easternmost record of Macratria Newman, 1838 from Fiji is presented, and M. fijiana sp. nov. is described and illustrated. Biogeographical patterns and diversity of Pacific Macratriinae are briefly discussed. Additionally, a new genus rank synonymy in Macratriinae is proposed: Thambospasta Werner, 1974 syn. nov. of Salimuzzamania Abdullah, 1968. New combination is made for Salimuzzamania howdeni (Werner, 1974) comb. nov. (from Thambospasta).
    • Exites in Cambrian arthropods and homology of arthropod limb branches

      Liu, Yu; Edgecombe, GD; Schmidt, Michel; Bond, Andrew D; Melzer, Roland R; Zhai, Dayou; Mai, Huijuan; Zhang, Maoyin; Hou, Xianguang (Springer Science and Business Media LLC, 2021-04-01)
      Abstract: The last common ancestor of all living arthropods had biramous postantennal appendages, with an endopodite and exopodite branching off the limb base. Morphological evidence for homology of these rami between crustaceans and chelicerates has, however, been challenged by data from clonal composition and from knockout of leg patterning genes. Cambrian arthropod fossils have been cited as providing support for competing hypotheses about biramy but have shed little light on additional lateral outgrowths, known as exites. Here we draw on microtomographic imaging of the Cambrian great-appendage arthropod Leanchoilia to reveal a previously undetected exite at the base of most appendages, composed of overlapping lamellae. A morphologically similar, and we infer homologous, exite is documented in the same position in members of the trilobite-allied Artiopoda. This early Cambrian exite morphology supplements an emerging picture from gene expression that exites may have a deeper origin in arthropod phylogeny than has been appreciated.
    • The conundrum of an overlooked skeleton referable to Imperial Woodpecker Campephilus imperialis in the collection of the Natural History Museum at Tring

      Prys-Jones, Robert; Manegold, Albrecht; White, Judith (British Ornithologists' Club, 2021-03-09)
      The discovery of an overlooked skeleton of Imperial Woodpecker Campephilus imperialis in the bird collection of the Natural History Museum at Tring (NHMUK) is documented, one of very few known to exist worldwide of this almost certainly extinct species. We present evidence that, on balance of probabilities, it is one of two collected by Alphonse Forrer in 1882 near the settlement of La Ciudad in the Sierra Madre Occidental, Durango, western Mexico; the whereabouts of the other, which did not come to NHMUK, appears currently unknown. During research into the NHMUK specimen, we demonstrated that the supposed Imperial Woodpecker skull held in the collection of the Russian Academy of Sciences, St. Petersburg, must in fact be that of an Ivory-billed Woodpecker C. principalis.
    • Synthetic and semi-synthetic fibre ingestion by mesopelagic fishes from Tristan da Cuhna and St Helena, South Atlantic

      McGoran, Alexandra; Maclaine, James; Clark, Paul; Morritt, David (2021-02-12)
      As part of the Blue Belt Programme, a marine survey of British Overseas Territories funded by the UK Government, RRS Discovery trawled at depths of between the surface and 1000m around Tristan da Cuhna and St Helena. Fishes were examined for microplastic ingestion. This work was supported by the National Environmental Research Council [grant number NE/L002485/1] with co-sponsorship from a Fishmongers' Company Fisheries Charity Trust CASE Partnership. Specimens were collected onboard RRS Discover as part of the Blue Belt Programme, which is funded by the UK Government in collaboration with CEFAS and BAS. Mesopelagic fishes were sampled around Tristan da Cunha and St Helena in the South Atlantic from the RRS Discovery at depths down to 1000 m. Sampling was part of the Blue Belt Programme, a marine survey of British Overseas Territories funded by the United Kingdom Government. Thirteen species of mesopelagic fishes identified from 30 specimens were compared with two species (two specimens) collected from rock pools or surface water near the shore. The digestive tracts of all fishes were examined for microplastics. Additionally, one specimen of Opostomias micripnus (Günther, 1878) was analyzed after recovery from the stomach of a commercially fished species, Hyperoglyphe antarctica (Carmichael, 1819). One specimen of Anoplogaster cornuta was found to have ingested a bearded sea devil (Linophryne sp.), a cock-eyed squid (Histioteuthis sp.), a bolitaenid octopus, Japetella diaphana, remains of unidentifiable fish, crustaceans, and possibly salps. These prey items were also examined for microfibres. Both Histioteuthis sp. and Linophryne sp. had ingested fibers and these were considered “ingested particles” for A. cornuta. Neither shallow water dwelling species had ingested microplastics, whilst 11 of the 13 studied mesopelagic species were found to be contaminated. Overall, 66.7% of mesopelagic fishes were found to contain microfibres. Anthropogenic fibers were common especially viscose, a semi-synthetic material which is associated with sanitary products as well as other items.
    • Using natural history collections to investigate changes in pangolin (Pholidota: Manidae) geographic ranges through time

      Buckingham, Emily; Curry, Jake; Emogor, Charles; Tomsett, Louise; Cooper, N (PeerJ, 2021-02-11)
      Pangolins, often considered the world’s most trafficked wild mammals, have continued to experience rapid declines across Asia and Africa. All eight species are classed as either Vulnerable, Endangered or Critically Endangered by the International Union for Conservation of Nature (IUCN) Red List. Alongside habitat loss, they are threatened mainly by poaching and/or legal hunting to meet the growing consumer demand for their meat and keratinous scales. Species threat assessments heavily rely on changes in species distributions which are usually expensive and difficult to monitor, especially for rare and cryptic species like pangolins. Furthermore, recent assessments of the threats to pangolins focus on characterising their trade using seizure data which provide limited insights into the true extent of global pangolin declines. As the consequences of habitat modifications and poaching/hunting on species continues to become apparent, it is crucial that we frequently update our understanding of how species distributions change through time to allow effective identification of geographic regions that are in need of urgent conservation actions. Here we show how georeferencing pangolin specimens from natural history collections can reveal how their distributions are changing over time, by comparing overlap between specimen localities and current area of habitat maps derived from IUCN range maps. We found significant correlations in percentage area overlap between species, continent, IUCN Red List status and collection year, but not ecology (terrestrial or arboreal/semi-arboreal). Human population density (widely considered to be an indication of trafficking pressure) and changes in primary forest cover, were weakly correlated with percentage overlap. Our results do not suggest a single mechanism for differences among historical distributions and present-day ranges, but rather show that multiple explanatory factors must be considered when researching pangolin population declines as variations among species influence range fluctuations. We also demonstrate how natural history collections can provide temporal information on distributions and discuss the limitations of collecting and using historical data.
    • Phylogenetic analyses suggest centipede venom arsenals were repeatedly stocked by horizontal gene transfer

      Undheim, Eivind AB; Jenner, Ronald (Springer Science and Business Media LLC, 2021-02-05)
      Abstract: Venoms have evolved over a hundred times in animals. Venom toxins are thought to evolve mostly by recruitment of endogenous proteins with physiological functions. Here we report phylogenetic analyses of venom proteome-annotated venom gland transcriptome data, assisted by genomic analyses, to show that centipede venoms have recruited at least five gene families from bacterial and fungal donors, involving at least eight horizontal gene transfer events. These results establish centipedes as currently the only known animals with venoms used in predation and defence that contain multiple gene families derived from horizontal gene transfer. The results also provide the first evidence for the implication of horizontal gene transfer in the evolutionary origin of venom in an animal lineage. Three of the bacterial gene families encode virulence factors, suggesting that horizontal gene transfer can provide a fast track channel for the evolution of novelty by the exaptation of bacterial weapons into animal venoms.
    • The alteration history of the CY chondrites, investigated through analysis of a new member: Dhofar 1988

      Suttle, Martin; Greshake, A; King, A; Schofield, PF; Tomkins, A; Russell, Sara (Elsevier BV, 2021-02)
      We provide the first detailed analysis of the carbonaceous chondrite Dhofar (Dho) 1988. This meteorite find was recovered in 2011 from the Zufar desert region of Oman and initially classified as a C2 ungrouped chondrite. Dho 1988 is a monomict breccia composed of millimetre-sized clasts, between which large (~50-250µm) intermixed sulphide-Ca-carbonate veins formed. It has high sulphide abundances (~14 vol%), medium-sized chondrules (avg. 530µm, N=33), relatively low chondrule/CAI abundances (<20 area%), a heavy bulk O-isotope composition (δ17O=9.12‰, δ18O=19.46‰) and an aqueously altered and then dehydrated alteration history. These characteristics are consistent with the newly defined Yamato-type (CY) carbonaceous chondrite group, suggesting this meteorite should be reclassified as a CY chondrite. Dho 1988 experienced advanced aqueous alteration (petrologic subtype 1.3 in the scheme of Howard et al., [2015]). Alteration style and extent are similar to the CM chondrite group, with the matrix having been replaced by tochilinite-cronstedtite intergrowths and chondrules progressively pseudomorphed by phyllosilicates, sulphides and in one instance Ca-carbonates. However, departures from CM-like alteration include the replacement of chondrule cores with Al-rich, Na-saponite and upon which Cr-spinel and Mg-ilmenite grains precipitated. These late-stage aqueous alteration features are common among the CY chondrites. Fractures in Dho 1988 that are infilled by phyllosilicates, sulphides and carbonates attest to post-brecciation aqueous alteration. However, whether aqueous alteration was also active prior to brecciation remains unclear. Veins are polymineralic with a layered structure, allowing their relative chronology to be reconstructed: intermixed phyllosilicate-sulphide growth transitioned to sulphide-carbonate deposition. We estimate temperatures during aqueous alteration to have been between 110ºC<T<160ºC, based on the co-formation of Na-saponite and tochilinite. Dho 1988 was later overprinted by thermal metamorphism. Peak temperatures are estimated between 700ºC and 770ºC, based on the thermal decomposition of phyllosilicates (both serpentine and saponite) combined with the survival of calcite. As temperatures rose during metamorphism the thermal decomposition of pyrrhotite produced troilite. Sulphur gas was liberated in this reaction and flowed through the chondrite reacting with magnetite (previously formed during aqueous alteration) to form a second generation of troilite grains. The presence of both troilite and Ni-rich metal in Dho 1988 (and other CY chondrites) demonstrate that conditions were constrained at the iron-troilite buffer.
    • Calathus: A sample-return mission to Ceres

      Gassot, Oriane; Panicucci, Paolo; Acciarini, Giacomo; Bates, HC; Caballero, Manel; Cambianica, Pamela; Dziewiecki, Maciej; Dionnet, Zelia; Enengl, Florine; Gerig, Selina-Barbara; et al. (Elsevier BV, 2021-01-12)
      Ceres, as revealed by NASA's Dawn spacecraft, is an ancient, crater-saturated body dominated by low-albedo clays. Yet, localised sites display a bright, carbonate mineralogy that may be as young as 2 Myr. The largest of these bright regions (faculae) are found in the 92 km Occator Crater, and would have formed by the eruption of alkaline brines from a subsurface reservoir of fluids. The internal structure and surface chemistry suggest that Ceres is an extant host for a number of the known prerequisites for terrestrial biota, and as such, represents an accessible insight into a potentially habitable “ocean world”. In this paper, the case and the means for a return mission to Ceres are outlined, presenting the Calathus mission to return to Earth a sample of the Occator Crater faculae for high-precision laboratory analyses. Calathus consists of an orbiter and a lander with an ascent module: the orbiter is equipped with a high-resolution camera, a thermal imager, and a radar; the lander contains a sampling arm, a camera, and an on-board gas chromatograph mass spectrometer; and the ascent module contains vessels for four cerean samples, collectively amounting to a maximum 40 g. Upon return to Earth, the samples would be characterised via high-precision analyses to understand the salt and organic composition of the Occator faculae, and from there to assess both the habitability and the evolution of a relict ocean world from the dawn of the Solar System.
    • Evolution of reproductive strategies in the species-rich land snail subfamily Phaedusinae (Stylommatophora: Clausiliidae)

      Mamos, Tomasz; Uit de Weerd, Dennis; von Oheimb, Parm Viktor; Sulikowska-Drozd, Anna (Elsevier, 2020-12-28)
      Most of the present knowledge on animal reproductive mode evolution, and possible factors driving transitions between oviparity and viviparity is based on studies on vertebrates. The species rich door snail (Clausiliidae) subfamily Phaedusinae represents a suitable and unique model for further examining parity evolution, as three different strategies, oviparity, viviparity, and the intermediate mode of embryo-retention, occur in this group. The present study reconstructs the evolution of reproductive strategies in Phaedusinae based on time-calibrated molecular phylogenetics, reproductive mode examinations and ancestral state reconstruction. Our phylogenetic analysis employing multiple mitochondrial and nuclear markers identified a well-supported clade (including the tribes Phaedusini and Serrulinini) that contains species exhibiting various reproductive strategies. This clade evolved from an oviparous most recent common ancestor according to our reconstruction. All non-oviparous taxa are confined to a highly supported subclade, coinciding with the tribe Phaedusini. Both oviparity and viviparity occur frequently in different lineages of this subclade that are not closely related. During Phaedusini diversification, multiple transitions in reproductive strategy must have taken place, which could have been promoted by a high fitness of embryo-retaining species. The evolutionary success of this group might result from the maintenance of various strategies.
    • Female aristocrats in the natural history world before the establishment of the Geological Society of London

      Sendino, Consuelo; Porter, Julian (Geological Society of London, 2020-12-07)
      A fascination with natural history does not recognize class, as is shown through the activities of female aristocrats who, during the eighteenth and nineteenth centuries, contributed significantly by increasing the number of collections at natural history museums. These women were not members of the Geological Society of London because, at that time, women were not even allowed to be members, but they still left their impressive legacy in museums. This paper will focus on three women who made extensive collections that are now incorporated into British museums. The first of these, the Duchess of Portland, made one of the finest collections in England and, possibly, the best collection of shells and fossils in Europe of her time, which was later acquired by the Natural History Museum, London. She was followed by the Countess of Aylesford who made one of the most important mineral collections of her time, which is now at the Natural History Museum, London. Finally, Baroness Brassey collected geological samples during her trips that were used to establish the Brassey Institute in Hastings. These three women used their own income and influence to build collections.
    • The Natural History Museum Fossil Porifera Collection

      Sendino, Consuelo (SAGE Publications, 2020-12-02)
      This article provides updated information about the Porifera Collection at The Natural History Museum (NHM), London. With very little information available regarding fossil sponge digitization or any similar initiative, this paper covers the type and figured specimens and drawer label content data of the Porifera Collection and also describes the collection and its research potential. With approximately 71,000 specimens, of which more than 60% are Mesozoic, the NHM holdings offer the best Mesozoic sponge collection in the world and one of the most important due to its breadth and depth. The Porifera Collection covers all stratigraphic periods and all taxonomic groups and includes almost 3000 cited and figured specimens including types. Although most of the specimens come from the British Isles, worldwide samples are also present, with abundant specimens from other Commonwealth countries and from Antarctica.
    • Disparate compound eyes of Cambrian radiodonts reveal their developmental growth mode and diverse visual ecology

      Paterson, John R; Edgecombe, GD; García-Bellido, Diego C (American Association for the Advancement of Science (AAAS), 2020-12)
      Radiodonts are nektonic stem-group euarthropods that played various trophic roles in Paleozoic marine ecosystems, but information on their vision is limited. Optical details exist only in one species from the Cambrian Emu Bay Shale of Australia, here assigned to Anomalocaris aff. canadensis. We identify another type of radiodont compound eye from this deposit, belonging to ‘Anomalocaris’ briggsi. This ≤4-cm sessile eye has &gt;13,000 lenses and a dorsally oriented acute zone. In both taxa, lenses were added marginally and increased in size and number throughout development, as in many crown-group euarthropods. Both species’ eyes conform to their inferred lifestyles: The macrophagous predator A. aff. canadensis has acute stalked eyes (&gt;24,000 lenses each) adapted for hunting in well-lit waters, whereas the suspension-feeding ‘A.’ briggsi could detect plankton in dim down-welling light. Radiodont eyes further demonstrate the group’s anatomical and ecological diversity and reinforce the crucial role of vision in early animal ecosystems.
    • Cooling and exhumation of the Late Paleozoic Tulasu epithermal gold system, Western Tianshan, NW China: implications for preservation of Pre-Mesozoic epithermal deposits

      Zhao, Xiao-Bo; Xue, Chun-Ji; Zhao, Wei-Ce; Seltmann, Reimar; Symons, David T.A.; Dolgopolova, Alla; Zhang, Yong (Geological Society of London, 2020-11-22)
      Epithermal gold deposits are rarely well preserved in pre-Mesozoic terranes because their low-temperature mineralization in shallow crust levels, and easily destroyed by subsequent erosion or depleted by tectonic events. However, several significant late Paleozoic epithermal gold deposits have been found in the Tulasu volcanic basin in NW China, forming one of the largest gold districts in the western Tianshan orogen. Here, we report new 40Ar/39Ar age from a monzonite porphyry enclave hosted in andesite and apatite fission track (AFT) data for 10 volcanic rocks from the Tulasu basin. These data, combined with the previous dataset, are used to perform inverse thermal modelling to quantify the district's cooling and exhumation history. Our modelling indicates a phase of burial reheating during late Paleozoic sedimentation following the mineralization, and subsequent a rapid exhumation in the Jurassic to Early Cretaceous (∼196–128 Ma), and a slow exhumation until to present. The Mesozoic exhumation is likely related to the far-field effects of the Cimmerian orogeny along the southern Eurasian margin. Therefore, we suggest that the quick burial by thick sediments and the slow protracted exhumation after mineralization were crucial for the preservation of the Paleozoic epithermal gold system at Tulasu.
    • The cranial morphology of Tanystropheus hydroides (Tanystropheidae, Archosauromorpha) as revealed by synchrotron microtomography

      Spiekman, Stephan NF; Neenan, James M; Fraser, Nicholas C; Fernandez, Vincent; Rieppel, Olivier; Nosotti, Stefania; Scheyer, Torsten M (PeerJ, 2020-11-20)
      The postcranial morphology of the extremely long-necked Tanystropheus hydroides is well-known, but observations of skull morphology were previously limited due to compression of the known specimens. Here we provide a detailed description of the skull of PIMUZ T 2790, including a partial endocast and endosseous labyrinth, based on synchrotron microtomographic data, and compare its morphology to that of other early Archosauromorpha. In many features, such as the wide and flattened snout and the configuration of the temporal and palatal regions, Tanystropheus hydroides differs strongly from other early archosauromorphs. The braincase possesses a combination of derived archosaur traits, such as the presence of a laterosphenoid and the ossification of the lateral wall of the braincase, but also differs from archosauriforms in the morphology of the ventral ramus of the opisthotic, the horizontal orientation of the parabasisphenoid, and the absence of a clearly defined crista prootica. Tanystropheus hydroides was a ram-feeder that likely caught its prey through a laterally directed snapping bite. Although the cranial morphology of other archosauromorph lineages is relatively well-represented, the skulls of most tanystropheid taxa remain poorly understood due to compressed and often fragmentary specimens. The recent descriptions of the skulls of Macrocnemus bassanii and now Tanystropheus hydroides reveal a large cranial disparity in the clade, reflecting wide ecological diversity, and highlighting the importance of non-archosauriform Archosauromorpha to both terrestrial and aquatic ecosystems during the Triassic.
    • Extended Pelagic Life in a Bathybenthic Octopus

      Villanueva, Roger; Laptikhovsky, Vladimir V; Piertney, Stuart B; Fernández-Álvarez, Fernando Ángel; Collins, Martin A; Ablett, J; Escánez, Alejandro (Frontiers Media SA, 2020-11-20)
      Planktonic stages of benthic octopuses can reach relatively large sizes in some species, usually in oceanic, epipelagic waters while living as part of the macroplankton. These young octopuses appear to delay settlement on the seabed for an undetermined period of time that is probably longer than for those octopus paralarvae living in coastal, neritic waters. The reason for this delay is unknown and existing information about their biology is very scarce. Here we report on the presence of juvenile and subadult forms of the bathybenthic octopus Pteroctopus tetracirrhus in oceanic waters of the South and North Atlantic and its association with the pyrosomid species Pyrosoma atlanticum, apparently used by the octopus as a refuge or shelter. The relatively large size of the P. tetracirrhus living in oceanic waters as the individuals reported here, together with the morphological characteristics of this bathybenthic species including its gelatinous body, minute suckers embedded in swollen skin and the deep interbrachial web, indicates that P. tetracirrhus may be considered a model of a transitional octopus species that is colonizing the pelagic environment by avoiding descending to the bathyal benthos. This process seems to occur in the same way as in the supposed origin of the ctenoglossan holopelagic octopods of the families Amphitretidae, Bolitaenidae, and Vitreledonellidae, which have arisen via neoteny from the planktonic paralarval stages of benthic octopuses.