• Deep-time biodiversity patterns and the dinosaurian fossil record of the Late Cretaceous Western Interior, North America

      Maidment, Susannah; Dean, Christopher; Mansergh, Robert I; Butler, Richard J (The Royal Society, 2021-06-30)
      In order for palaeontological data to be informative to ecologists seeking to understand the causes of today's diversity patterns, palaeontologists must demonstrate that actual biodiversity patterns are preserved in our reconstructions of past ecosystems. During the Late Cretaceous, North America was divided into two landmasses, Laramidia and Appalachia. Previous work has suggested strong faunal provinciality on Laramidia at this time, but these arguments are almost entirely qualitative. We quantitatively investigated faunal provinciality in ceratopsid and hadrosaurid dinosaurs using a biogeographic network approach and investigated sampling biases by examining correlations between dinosaur occurrences and collections. We carried out a model-fitting approach using generalized least-squares regression to investigate the sources of sampling bias we identified. We find that while the raw data strongly support faunal provinciality, this result is driven by sampling bias. The data quality of ceratopsids and hadrosaurids is currently too poor to enable fair tests of provincialism, even in this intensively sampled region, which probably represents the best-known Late Cretaceous terrestrial ecosystem on Earth. To accurately reconstruct biodiversity patterns in deep time, future work should focus on smaller scale, higher resolution case studies in which the effects of sampling bias can be better controlled.
    • Prediction of shoreline–shelf depositional process regime guided by palaeotidal modelling

      Collins, Daniel S; Avdis, Alexandros; Wells, Martin R; Dean, Christopher; Mitchell, Andrew J; Allison, Peter A; Johnson, Howard D; Hampson, Gary J; Hill, Jon; Piggott, Matthew D (Elsevier BV, 2021-10-29)
      Ancient shoreline–shelf depositional systems are influenced by an unusually wide array of geological, biological and hydrodynamic processes, with sediment transport and deposition primarily determined by the interaction of river, wave (including storm) and tidal processes, and changes in relative sea level. Understanding the impact of these processes on shoreline–shelf morphodynamics and stratigraphic preservation remains challenging. Numerical modelling integrated with traditional facies analysis provides an increasingly viable approach, with the potential to quantify, and thereby improve understanding of, the impact of these complex coastal sedimentary processes. An integrated approach is presented here that focuses on palaeotidal modelling to investigate the controls on ancient tides and their influence on sedimentary deposition and preservation – one of the three cornerstones of the ternary process classification scheme of shoreline-shelf systems. Numerical tidal modelling methodology is reviewed and illustrated in three palaeotidal model case studies of different scales and focus. The results are synthesised in the context of shoreline–shelf processes, including a critique and modification of the process-based classification scheme. The emphasis on tidal processes reflects their global importance throughout Earth’s history. Ancient palaeotidal models are able to highlight and quantify the following four controls on tidal processes: (1) the physiography (shape and depth) of oceans (1000s km scale) determines the degree of tidal resonance; (2) the physiography of ocean connections to partly enclosed water bodies (100–1000s km scale) determines the regional-scale flux of tidal energy (inflow versus outflow); (3) the physiography of continental shelves influences shelf tidal resonance potential; and (4) tides in relatively local-scale embayments (typically 1–10s km scale) are influenced by the balance of tidal amplification due to funnelling, shoaling and resonance effects versus frictional damping. In deep time, palaeogeographic and palaeobathymetric uncertainty can be accounted for in palaeotidal models by performing sensitivity analyses to different scenarios, across this range of spatial scales. These tidal process controls are incorporated into an updated predictive decision tree for determining shoreline–shelf process regime in terms of the relative interaction of wave, fluvial and tidal processes. The predictive decision tree considers the effects of basin physiography, shelf width and shoreline morphology on wave, fluvial and tidal processes separately. Uncertainty and ambiguity in applying the widely used three-tier process classification scheme are reduced by using the decision tree in conjunction with a proposed two-tier classification of process regime that is limited to primary and secondary processes. This two-tier classification scheme is illustrated in the three case studies, showing how integration of numerical modelling with facies analysis of the preserved stratigraphic record improves confidence in prediction of tide-influenced shoreline-shelf process regimes. Wider application of this approach will further improve process-based classifications and predictions of modern and ancient shoreline–shelf systems.
    • Formation binning: a new method for increased temporal resolution in regional studies, applied to the Late Cretaceous dinosaur fossil record of North America

      Dean, Christopher D; Chiarenza, A Alessandro; Maidment, Susannah (Wiley, 2020-06-11)
      The advent of palaeontological occurrence databases has allowed for detailed reconstruction and analyses of species richness through deep time. While a substantial literature has evolved ensuring that taxa are fairly counted within and between different time periods, how time itself is divided has received less attention. Stage-level or equal-interval age bins have frequently been used for regional and global studies in vertebrate palaeontology. However, when assessing diversity at a regional scale, these resolutions can prove inappropriate with the available data. Herein, we propose a new method of binning geological time for regional studies that intrinsically incorporates the chronostratigraphic heterogeneity of different rock formations to generate unique stratigraphic bins. We use this method to investigate the diversity dynamics of dinosaurs from the Late Cretaceous of the Western Interior of North America prior to the Cretaceous–Palaeogene mass extinction. Increased resolution through formation binning pinpoints the Maastrichtian diversity decline to between 68 and 66 Ma, coinciding with the retreat of the Western Interior Seaway. Diversity curves are shown to exhibit volatile patterns using different binning methods, supporting claims that heterogeneous biases in this time-frame affect the pre-extinction palaeobiological record. We also show that the apparent high endemicity of dinosaurs in the Campanian is a result of non-contemporaneous geological units within large time bins. This study helps to illustrate the utility of high-resolution, regional studies to supplement our understanding of factors governing global diversity in deep time and ultimately how geology is inherently tied to our understanding of past changes in species richness.
    • Re-evaluating the phylogenetic position of the enigmatic early Cambrian deuterostome Yanjiahella

      Zamora, Samuel; Wright, David F; Mooi, Rich; Lefebvre, Bertrand; Guensburg, Thomas E; Gorzelak, Przemysław; David, Bruno; Sumrall, Colin D; Cole, Selina R; Hunter, Aaron W; et al. (Springer Science and Business Media LLC, 2020-03-09)
    • 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.
    • 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 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.
    • The atmospheric entry of fine-grained micrometeorites: The role of volatile gases in heating and fragmentation

      Suttle, Martin; Genge, MJ; Folco, L; Van Ginneken, M; Lin, Q; Russell, SS; Najorka, J (Wiley, 2019-03)
      The early stages of atmospheric entry are investigated in four large (250–950 lm) unmelted micrometeorites (three fine-grained and one composite), derived from the Transantarctic Mountain micrometeorite collection. These particles have abundant, interconnected, secondary pore spaces which form branching channels and show evidence of enhanced heating along their channel walls. Additionally, a micrometeorite with a doublewalled igneous rim is described, suggesting that some particles undergo volume expansion during entry. This study provides new textural data which links together entry heating processes known to operate inside micrometeoroids, thereby generating a more comprehensive model of their petrographic evolution. Initially, flash heated micrometeorites develop a melt layer on their exterior; this igneous rim migrates inwards. Meanwhile, the particle core is heated by the decomposition of low-temperature phases and by volatile gas release. Where the igneous rim acts as a seal, gas pressures rise, resulting in the formation of interconnected voids and higher particle porosities. Eventually, the igneous rim is breached and gas exchange with the atmosphere occurs. This mechanism replaces inefficient conductive rim-to-core thermal gradients with more efficient particle-wide heating, driven by convective gas flow. Interconnected voids also increase the likelihood of particle fragmentation during entry and, may therefore explain the rarity of large fine-grained micrometeorites among collections.
    • Hydrothermal activity on the CV parent body: New perspectives from the giant Transantarctic Mountains minimeteorite TAM 5.29

      Nava, J; Suttle, Martin; Spiess, R; Folco, L; Najorka, J; Carli, C; Massironi, M (Wiley, 2020-01)
      Abstract TAM5.29 is an extraterrestrial dust grain, collected on the Transantarctic Mountains (TAM). Its mineralogy is dominated by an Fe-rich matrix composed of platy fayalitic olivines and clasts of andradite surrounded by diopside-jarosite mantles; chondrules are absent. TAM5.29 records a complex geological history with evidence of extensive thermal metamorphism in the presence of fluids at T < 300 °C. Alteration was terminated by an impact, resulting in shock melt veins and compaction-orientated foliation of olivine. A second episode of alteration at lower temperatures (<100 °C) occurred postimpact and is either parent body or terrestrial in origin and resulted in the formation of iddingsite. The lack of chondrules is explained by random subsampling of the parent body, with TAM5.29 representing a matrix-only fragment. On the basis of bulk chemical composition, mineralogy, and geological history TAM5.29 demonstrates affinities to the CVox group with a mineralogical assemblage in between the Allende-like and Bali-like subgroups (CVoxA and TAM5.29 are rich in andradite, magnetite, and FeNiS, but CVoxA lacks hydrated minerals, common in TAM5.29; conversely, CVoxB are rich in hydrated phyllosilicates but contain almost pure fayalite, not found in TAM5.29). In addition, TAM5.29 has a slightly different metasomatic history, in between the oxidized and reduced CV metamorphic grades while also recording higher oxidizing conditions as compared to the known CV chondrites. This study represents the third CV-like cosmic dust particle, containing a unique composition, mineralogy, and fabric, demonstrating variation in the thermal metamorphic history of the CV parent body(-ies).
    • Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites

      Suttle, Martin; Folco, L; Genge, MJ; Russell, SS; Najorka, J; Van Ginneken, M (Elsevier BV, 2019-01)
      This study explores the petrology of five giant (>400μm) hydrated fine-grained micrometeorites from the Transantarctic Mountain (TAM) micrometeorite collection. For the first time, the extent and mechanisms of aqueous alteration in unmelted cosmic dust are evaluated and quantified. We use a range of criteria, previously defined for use on hydrated chondrites, including phyllosilicate fraction, matrix geochemistry and micro textures. Collectively, these micrometeorites represent ~2.22mm2 of intensely altered hydrated chondritic matrix (with petrologic subtypes of <1.2 in the scheme of Howard et al., [2015]) and reveal a range of alteration styles. Two particles are found to contain pseudomorphic chondrules with thick fine-grained rims, while another micrometeorite contains several aqueously altered CAIs. Their outlines range from well-defined to indistinct, demonstrating that the advanced stages of aqueous alteration progressively remove evidence of coarse-grained components. The remaining two micrometeorites entirely lack coarse-grained components but are similarly altered. Thus, the combined chondrule-to-matrix ratio among these giant micrometeorites is extremely low (6.45 area%), and significantly below the average ratio found in typical CM or CR chondrites (~20%, Weisberg et al., 2006). Our findings are consistent with previous analyses from smaller Antarctic micrometeorites, which suggest that chondrules (and CAIs) derived from hydrated carbonaceous chondrite parent bodies are underrepresented among the micrometeorite flux, even when considering contributions from coarse-grained micrometeorites. Therefore, to explain the relative paucity of anhydrous material, we propose that the flux of fine-grained micrometeorites is primarily derived from intensely aqueously altered, primitive C-type asteroids, which have lost the majority of their refractory coarse-grained components by replacement with secondary phyllosilicate minerals.
    • Flying too close to the Sun – The viability of perihelion-induced aqueous alteration on periodic comets

      Suttle, Martin; Folco, L; Genge, MJ; Russell, SS (Elsevier BV, 2020-11)
      Comets are typically considered to be pristine remnants of the early solar system. However, by definition they evolve significantly over their lifetimes through evaporation, sublimation, degassing and dust release. This occurs once they enter the inner solar system and are heated by the Sun. Some comets (e.g. 1P/Halley, 9P/Tempel and Hale-Bopp) as well as chondritic porous cosmic dust – released from comets – show evidence of minor aqueous alteration resulting in the formation of phyllosilicates, carbonates or other secondary phases (e.g. Cu-sulphides, amphibole and magnetite). These observations suggest that (at least some) comets experienced limited interaction with liquid water under conditions distinct from the alteration histories of hydrated chondritic asteroids (e.g. the CM and CR chondrites). This synthesis paper explores the viability of perihelion-induced heating as a mechanism for the generation of highly localised subsurface liquid water and thus mild aqueous alteration in periodic comets. We draw constraints from experimental laboratory studies, numerical modelling, spacecraft observations and microanalysis studies of cometary micrometeorites. Both temperature and pressure conditions necessary for the generation and short-term (hour-long) survival of liquid water are plausible within the immediate subsurface (<0.5m depth) of periodic comets with small perihelia (<1.5 A.U.), low surface permeabilities and favourable rotational states (e.g. high obliquities and/or slow rotational periods). We estimate that solar radiant heating may generate liquid water and perform aqueous alteration reactions in 3-9% of periodic comets. An example of an ideal candidate is 2P/Encke which has a small perihelion (0.33 A.U.), a high obliquity and a short orbital period. This comet should therefore be considered a high priority candidate in future spectroscopic studies of comet surfaces. Small quantities of phyllosilicate generated by aqueous alteration may be important in cementing together grains in the subsurface of older dormant comets, thereby explaining observations of unexpectedly high tensile strength in some bodies. Most periodic comets which currently pass close to the Sun are dormant, having experienced surface heating, significant cometary activity and dust release in the past. These bodies may be responsible for the partially hydrated cometary micrometeorites we find at the Earth’s surface and their aqueous alteration histories may have been produced by perihelion-induced subsurface heating. This is in contrast to radiogenic and impact heating that operated during the early solar system on asteroids. This study has implications for the alteration history of the active asteroid Phaethon, the target of JAXA’s DESTINY+ mission.
    • Phylogeny of Lithobiidae Newport, 1844, with emphasis on the megadiverse genus Lithobius Leach, 1814 (Myriapoda, Chilopoda)

      Ganske, Anne‐Sarah; Vahtera, Varpu; Dányi, László; Edgecombe, GD; Akkari, Nesrine (Wiley, 2020-11-04)
      Phylogenetic analyses based on molecular and morphological data were conducted to shed light on relationships within the mostly Palaearctic/Oriental centipede family Lithobiidae, with a particular focus on the Palaearctic genus Lithobius Leach, 1814 (Lithobiidae, Lithobiomorpha), which contains >500 species and subspecies. Previous studies based on morphological data resolved Lithobius as nonmonophyletic, but molecular-based phylogenetic analyses have until now sampled few species. To elucidate species inter-relationships of the genus, test the validity of its classification into subgenera, and infer its relationships with other Lithobiidae, we obtained molecular data (nuclear markers: 18S rRNA, 28S rRNA; mitochondrial markers: 16S rRNA, COI) and 61 morphological characters for 44 species of Lithobius representing four of its eight subgenera and nine other representatives of Lithobiidae. The data were analyzed phylogenetically using maximum-likelihood, parsimony and Bayesian inference. This study suggests that (i) a close relationship between L. giganteus and the pterygotergine Disphaerobius loricatus highlighted in recent morphological analyses is also strongly supported by molecular data, and Pterygoterginae is formally synonymized with Lithobiinae; (ii) the Oriental/Australian genus Australobius is consistently resolved as sister group to all other sampled Lithobiidae by the molecular and combined data; (iii) the subfamily Ethopolyinae may be paraphyletic; (iv) the genus Lithobius is nonmonophyletic; (v) the subgenera Lithobius, Sigibius and Monotarsobius are nonmonophyletic and should not be used in future taxonomic studies; and (vi) there are instances of cryptic species and cases in which subspecies should be elevated to full species status, as identified for some European taxa within Lithobius.
    • Isotopic and textural analysis of giant unmelted micrometeorites – identification of new material from intensely altered 16O-poor water-rich asteroids

      Suttle, Martin; Dionnet, Z; Franchi, I; Folco, L; Gibson, J; Greenwood, RC; Rotundi, A; King, A; Russell, Sara (Elsevier BV, 2020-09-15)
      Bulk oxygen isotope data has the potential to match extraterrestrial samples to parent body sourcesbased on distinctive 𝛿 18O and Δ 17 O ratios. We analysed 10 giant (>500µm) micrometeorites using combined µCT and O-isotope analysis to pair internal textures to inferred parent body groups. We identify three ordinary chondrite particles (L and LL groups), four from CR chondrites and the first micrometeorite from the enstatite chondrite (EH4) group. In addition, two micrometeorites are from hydrated carbonaceous chondrite parent bodies with 16 O-poor isotopic compositions above the terrestrial fractionation line. They experienced intense aqueous alteration, contain pseudomorphic chondrules and are petrographically similar to the CM1/CR1 chondrites. These micrometeorites may be members of the newly established CY chondrites and/or derived from the enigmatic “Group 4” micrometeorite population, previously identified by Yada et al., 2005 [GCA, 69:5789-5804], Suavet et al., 2010 [EPSL, 293:313-320] (and others). One of our 16 O-poor micrometeorite plots on the same isotopic trendline as the CO, CM and CY chondrites – “the CM mixing line” (with a slope of ~0.7 and a 𝛿 17 O intercept of -4.23‰), implies a close relationship and potentially a genetic link to these hydrated chondrites. If position along the CM mixing line reflects the amount of 16 O-poor (heavy) water-ice accreted onto the parent body at formation, then the CY chondrites and these 16 O-poor micrometeorites must have accreted at least as much water-ice as CM chondrites but potentially more. In addition, thermal metamorphism could have played a role in further raising the bulk O isotope compositions through the preferential loss of isotopically light water during phyllosilicate dehydration. The study of micrometeorites provides insights into asteroid belt diversity through the discovery of material not currently sampled by larger meteorites, perhaps as a result of atmospheric entry biases preventing the survival of large blocks of friable hydrated material.
    • 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.
    • Orogen architecture and crustal growth from accretion to collision (IGCP#662): Scientific Activities 2018-2019

      Wang, Tao; Seltmann, Reimar; Huang, He; Tong, Ying; Gladkochub, Dmitry; O'Reilly, Suzanne Y.; van Staal, Cees; Hou, Zengqian; Safonova, Inna; Xiao, Wenjiao (International Union of Geological Sciences, 2020-07-15)
      The scientific board of the International Geoscience Programme (IGCP), jointly sponsored by IUGS and UNESCO, approved for funding in March 2018 the IGCP-662 project (2018-2023) entitled “Orogenic architecture and crustal growth from accretion to collision”. Four meetings and field excursion, as well as training courses, have been successfully held respectively in 2018 and 2019. The first workshop was held during 21th - 22nd September 2018 in Beijing, China, with a 5-day (15th - 19th September) preworkshop field trip and one-day (23 September 2018) post-conference training course on “Using isotopes in zircon and sulfides to understanding crust-mantle evolution”. The second workshop and field trip of the IGCP-662 project were held in Mongolia from July 4th - 10th, 2019. Besides, the IGCP-662 project joined as co-sponsor the organization of an international symposium “The Geology of Eurasia” held at the Helmholtz-Centre Potsdam - German Research Centre for Geosciences (GFZ) during 26th June - 1st July 2019.
    • Aquatic Habits and Niche Partitioning in the Extraordinarily Long-Necked Triassic Reptile Tanystropheus

      Spiekman, Stephan NF; Neenan, James M; Fraser, Nicholas C; Fernandez, Vincent; Rieppel, Olivier; Nosotti, Stefania; Scheyer, Torsten M (Elsevier BV, 2020-08-06)
      Tanystropheus longobardicus is one of the most remarkable and iconic Triassic reptiles. Mainly known from the Middle Triassic conservation Lagerstätte of Monte San Giorgio on the Swiss-Italian border, it is characterized by an extraordinarily long and stiffened neck that is almost three times the length of the trunk, despite being composed of only 13 hyper-elongate cervical vertebrae [1-8]. Its paleobiology remains contentious, with both aquatic and terrestrial lifestyles having been proposed [1, 9-12]. Among the Tanystropheus specimens, a small morphotype bearing tricuspid teeth and a large morphotype bearing single-cusped teeth can be recognized, historically considered as juveniles and adults of the same species [4]. Using high-resolution synchrotron radiation microtomography (SRμCT), we three-dimensionally reconstruct a virtually complete but disarticulated skull of the large morphotype, including its endocast and inner ear, to reveal its morphology for the first time. The skull is specialized toward hunting in an aquatic environment, indicated by the placement of the nares on the top of the snout and a "fish-trap"-type dentition. The SRμCT data and limb bone paleohistology reveal that the large morphotype represents a separate species (Tanystropheus hydroides sp. nov.). Skeletochronology of the small morphotype specimens indicates that they are skeletally mature despite their small size, thus representing adult individuals of Tanystropheus longobardicus. The co-occurrence of these two species of disparate size ranges and dentitions provides strong evidence for niche partitioning, highlighting the surprising versatility of the Tanystropheus bauplan and the complexity of Middle Triassic nearshore ecosystems.
    • Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography

      Miedema, Feiko; Spiekman, Stephan NF; Fernandez, Vincent; Reumer, Jelle WF; Scheyer, Torsten M (Springer Science and Business Media LLC, 2020-07-24)
      The genus Macrocnemus is a member of the Tanystropheidae, a clade of non-archosauriform archosauromorphs well known for their very characteristic, elongated cervical vertebrae. Articulated specimens are known from the Middle Triassic of Alpine Europe and China. Although multiple articulated specimens are known, description of the cranial morphology has proven challenging due to the crushed preservation of the specimens. Here we use synchrotron micro computed tomography to analyse the cranial morphology of a specimen of the type species Macrocnemus bassanii from the Besano Formation of Monte San Giorgio, Ticino, Switzerland. The skull is virtually complete and we identify and describe the braincase and palatal elements as well the atlas-axis complex for the first time. Moreover, we add to the knowledge of the morphology of the skull roof, rostrum and hemimandible, and reconstruct the cranium of M. bassanii in 3D using the rendered models of the elements. The circumorbital bones were found to be similar in morphology to those of the archosauromorphs Prolacerta broomi and Protorosaurus speneri. In addition, we confirm the palatine, vomer and pterygoid to be tooth-bearing palatal bones, but also observed heterodonty on the pterygoid and the palatine.
    • 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.
    • 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.
    • 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.