Publications by authors named "Vincent Fernandez"

43 Publications

Functional constraints during development limit jaw shape evolution in marsupials.

Proc Biol Sci 2021 04 28;288(1949):20210319. Epub 2021 Apr 28.

Department of Life Sciences, The Natural History Museum, London SW7 5DB, UK.

Differences in jaw function experienced through ontogeny can have striking consequences for evolutionary outcomes, as has been suggested for the major clades of mammals. By contrast to placentals, marsupial newborns have an accelerated development of the head and forelimbs, allowing them to crawl to the mother's teats to suckle within just a few weeks of conception. The different functional requirements that marsupial newborns experience in early postnatal development have been hypothesized to have constrained their morphological diversification relative to placentals. Here, we test whether marsupials have a lower ecomorphological diversity and rate of evolution in comparison with placentals, focusing specifically on their jaws. To do so, a geometric morphometric approach was used to characterize jaw shape for 151 living and extinct species of mammals spanning a wide phylogenetic, developmental and functional diversity. Our results demonstrate that jaw shape is significantly influenced by both reproductive mode and diet, with substantial ecomorphological convergence between metatherians and eutherians. However, metatherians have markedly lower disparity and rate of mandible shape evolution than observed for eutherians. Thus, despite their ecomorphological diversity and numerous convergences with eutherians, the evolution of the jaw in metatherians appears to be strongly constrained by their specialized reproductive biology.
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http://dx.doi.org/10.1098/rspb.2021.0319DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8079998PMC
April 2021

Ontogenetic development of the holocephalan dentition: Morphological transitions of dentine in the absence of teeth.

J Anat 2021 Apr 25. Epub 2021 Apr 25.

Department of Earth Sciences, Natural History Museum, London, UK.

Among the cartilaginous fishes (Chondrichthyes), the Holocephali are unique in that teeth are absent both in ontogeny and adult regenerative growth. Instead, the holocephalan dentition of ever-growing nonshedding dental plates is composed of dentine, trabecular in arrangement, forming spaces into which a novel hypermineralized dentine (whitlockin) is deposited. These tissue features form a variety of specific morphologies as the defining characters of dental plates in the three families of extant holocephalans. We demonstrate how this morphology changes through ontogenetic development with continuity between morphologies, through successive growth stages of the dentition represented by the dental plate. For example, rod-shaped whitlockin appears early, later transformed into the tritoral pad, including a regular arrangement of vascular canals and whitlockin forming with increasing mineralization (95%-98%). While the tritoral pads develop lingually, stacks of individual ovoids of whitlockin replace the rods in the more labial parts of the plate, again shaped by the forming trabecular dentine. The ability to make dentine into new, distinctive patterns is retained in the evolution of the Holocephali, despite the lack of teeth forming in development of the dentition. We propose that developmentally, odontogenic stem cells, retained through evolution, control the trabecular dentine formation within the dental plate, and transition to form whitlockin, throughout lifetime growth. Our model of cellular activity proposes a tight membrane of odontoblasts, having transformed to whitloblasts, that can control active influx of minerals to the rapidly mineralizing dentine, forming whitlockin. After the reduced whitloblast cells transition back to odontoblasts, they continue to monitor the levels of minerals (calcium, phosphate and magnesium) and at a slower rate of growth in the peritubate 'softer' dentine. This model explains the unique features of transitions within the holocephalan dental plate morphology.
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http://dx.doi.org/10.1111/joa.13445DOI Listing
April 2021

Gaseous environment modulates volatile emission and viability loss during seed artificial ageing.

Planta 2021 Apr 17;253(5):106. Epub 2021 Apr 17.

Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Wakehurst Place, Ardingly, UK.

Main Conclusion: Modulation of the gaseous environment using oxygen absorbers and/or silica gel shows potential for enhancing seed longevity through trapping toxic volatiles emitted by seeds during artificial ageing. Volatile profiling using non-invasive gas chromatography-mass spectrometry provides insight into the specific processes occurring during seed ageing. Production of alcohols, aldehydes and ketones, derived from processes such as alcoholic fermentation, lipid peroxidation and Maillard reactions, are known to be dependent on storage temperature and relative humidity, but little is known about the potential modulating role of the gaseous environment, which also affects seed lifespan, on volatile production. Seeds of Lolium perenne (Poaceae), Agrostemma githago (Caryophyllaceae) and Pisum sativum (Fabaceae) were aged under normal atmospheric oxygen conditions and in sealed vials containing either oxygen absorbers, oxygen absorbers and silica gel (equilibrated at 60% RH), or silica gel alone. Seeds of A. githago that were aged in the absence of oxygen maintained higher viability and produced fewer volatiles than seeds aged in air. In addition, seeds of A. githago and L. perenne aged in the presence of silica gel were longer lived than those aged without silica, with no effect on seed moisture content or oxygen concentration in the storage containers, but with silica gel acting as a volatile trap. These results indicate that the use of inexpensive oxygen absorbers and silica gel could improve seed longevity in storage for some species and suggests a potential, and previously unidentified, role for silica gel in ultra-dry storage.
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http://dx.doi.org/10.1007/s00425-021-03620-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8053187PMC
April 2021

The emergence of a complex pore-canal system in the dermal skeleton of Tremataspis (Osteostraci).

J Morphol 2021 Apr 13. Epub 2021 Apr 13.

Department of Organismal Biology, Uppsala University, Uppsala, Sweden.

Thyestiids are a group of osteostracans (sister-group to jawed vertebrates) ranging in time from the early Silurian to Middle Devonian. Tremataspis is unique among thyestiids in having a continuous mesodentine and enameloid cover on its dermal elements, and an embedded pore-canal system divided into lower and upper parts by a perforated septum. The origin of this upper mesh canal system and its potential homology to similar canal systems of other osteostracans has remained a matter of debate. To investigate this, we use synchrotron radiation microtomography data of four species of Tremataspis and three other thyestiid genera. Procephalaspis oeselensis lacks an upper mesh canal system entirely, but Aestiaspis viitaensis has partially enclosed upper canals formed between slightly modified tubercles that generally only cover separate pore fields. Further modification of tubercles in Dartmuthia gemmifera forms a more extensive, semi-enclosed upper mesh canal system that overlies an extensive perforated septum, similar to that found in Tremataspis. Lower mesh canals in P. oeselensis are radially arranged and buried tubercles indicate a continuous growth and addition of dermal hard tissues. These features are lacking to varying degrees in the other investigated thyestiids, and Tremataspis probably had a determinate growth accompanied by a single mineralization phase of its dermal hard tissues. The previously proposed homology between the semi-enclosed upper canal system in Dartmuthia to the pore-canal system in Tremataspis is supported in this study, but the suggested homologies between these canals and other parts of the thyestiid vasculature to those in non-thyestiid osteostracans remain unclear. This study shows that three-dimensional modeling of high-resolution data can provide histological and structural details that can help clarify homology issues and elucidate the evolution of dermal hard tissues in osteostracans. In extension, this can give insights into how these tissues relate to those found among jawed vertebrates.
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http://dx.doi.org/10.1002/jmor.21359DOI Listing
April 2021

Preliminary paleohistological observations of the StW 573 ('Little Foot') skull.

Elife 2021 Mar 2;10. Epub 2021 Mar 2.

School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa.

Numerous aspects of early hominin biology remain debated or simply unknown. However, recent developments in high-resolution imaging techniques have opened new avenues in the field of paleoanthropology. More specifically, X-ray synchrotron-based analytical imaging techniques have the potential to provide crucial details on the ontogeny, physiology, biomechanics, and biological identity of fossil specimens. Here we present preliminary results of our X-ray synchrotron-based investigation of the skull of the 3.67-million-year-old specimen StW 573 ('Little Foot') at the I12 beamline of the Diamond Light Source (United Kingdom). Besides showing fine details of the enamel (i.e., hypoplasias) and cementum (i.e., incremental lines), as well as of the cranial bone microarchitecture (e.g., diploic channels), our synchrotron-based investigation reveals for the first time the 3D spatial organization of the Haversian systems in the mandibular symphysis of an early hominin.
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http://dx.doi.org/10.7554/eLife.64804DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7924941PMC
March 2021

Versailles Project on Advanced Materials and Standards interlaboratory study on intensity calibration for x-ray photoelectron spectroscopy instruments using low-density polyethylene.

J Vac Sci Technol A 2020 Dec 23;38(6):063208. Epub 2020 Nov 23.

Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 44-46, 12203 Berlin, Germany.

We report the results of a Versailles Project on Advanced Materials and Standards interlaboratory study on the intensity scale calibration of x-ray photoelectron spectrometers using low-density polyethylene (LDPE) as an alternative material to gold, silver, and copper. An improved set of LDPE reference spectra, corrected for different instrument geometries using a quartz-monochromated Al Kα x-ray source, was developed using data provided by participants in this study. Using these new reference spectra, a transmission function was calculated for each dataset that participants provided. When compared to a similar calibration procedure using the NPL reference spectra for gold, the LDPE intensity calibration method achieves an absolute offset of ∼3.0% and a systematic deviation of ±6.5% on average across all participants. For spectra recorded at high pass energies (≥90 eV), values of absolute offset and systematic deviation are ∼5.8% and ±5.7%, respectively, whereas for spectra collected at lower pass energies (<90 eV), values of absolute offset and systematic deviation are ∼4.9% and ±8.8%, respectively; low pass energy spectra perform worse than the global average, in terms of systematic deviations, due to diminished count rates and signal-to-noise ratio. Differences in absolute offset are attributed to the surface roughness of the LDPE induced by sample preparation. We further assess the usability of LDPE as a secondary reference material and comment on its performance in the presence of issues such as variable dark noise, x-ray warm up times, inaccuracy at low count rates, and underlying spectrometer problems. In response to participant feedback and the results of the study, we provide an updated LDPE intensity calibration protocol to address the issues highlighted in the interlaboratory study. We also comment on the lack of implementation of a consistent and traceable intensity calibration method across the community of x-ray photoelectron spectroscopy (XPS) users and, therefore, propose a route to achieving this with the assistance of instrument manufacturers, metrology laboratories, and experts leading to an international standard for XPS intensity scale calibration.
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http://dx.doi.org/10.1116/6.0000577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7688089PMC
December 2020

The cranial morphology of (Tanystropheidae, Archosauromorpha) as revealed by synchrotron microtomography.

PeerJ 2020 20;8:e10299. Epub 2020 Nov 20.

University of Zurich, Palaeontological Institute and Museum, Zurich, Switzerland.

The postcranial morphology of the extremely long-necked 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, 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. 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 and now 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.
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http://dx.doi.org/10.7717/peerj.10299DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7682440PMC
November 2020

Reptile-like physiology in Early Jurassic stem-mammals.

Nat Commun 2020 10 12;11(1):5121. Epub 2020 Oct 12.

Institute of Biotechnology, University of Helsinki, Helsinki, Finland.

Despite considerable advances in knowledge of the anatomy, ecology and evolution of early mammals, far less is known about their physiology. Evidence is contradictory concerning the timing and fossil groups in which mammalian endothermy arose. To determine the state of metabolic evolution in two of the earliest stem-mammals, the Early Jurassic Morganucodon and Kuehneotherium, we use separate proxies for basal and maximum metabolic rate. Here we report, using synchrotron X-ray tomographic imaging of incremental tooth cementum, that they had maximum lifespans considerably longer than comparably sized living mammals, but similar to those of reptiles, and so they likely had reptilian-level basal metabolic rates. Measurements of femoral nutrient foramina show Morganucodon had blood flow rates intermediate between living mammals and reptiles, suggesting maximum metabolic rates increased evolutionarily before basal metabolic rates. Stem mammals lacked the elevated endothermic metabolism of living mammals, highlighting the mosaic nature of mammalian physiological evolution.
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http://dx.doi.org/10.1038/s41467-020-18898-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7550344PMC
October 2020

Aquatic Habits and Niche Partitioning in the Extraordinarily Long-Necked Triassic Reptile Tanystropheus.

Curr Biol 2020 10 6;30(19):3889-3895.e2. Epub 2020 Aug 6.

University of Zurich, Paleontological Institute and Museum, Karl-Schmid-Strasse 4, Zurich 8006, Switzerland.

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.
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http://dx.doi.org/10.1016/j.cub.2020.07.025DOI Listing
October 2020

Cranial morphology of the tanystropheid Macrocnemus bassanii unveiled using synchrotron microtomography.

Sci Rep 2020 07 24;10(1):12412. Epub 2020 Jul 24.

Palaeontological Institute and Museum, University of Zürich, Karl Schmid-Strasse 4, 8006, Zurich, Switzerland.

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.
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http://dx.doi.org/10.1038/s41598-020-68912-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7381672PMC
July 2020

Evolution of the Dentition in Holocephalans (Chondrichthyes) Through Tissue Disparity.

Integr Comp Biol 2020 09;60(3):630-643

Department of Earth Sciences, Natural History Museum, London, UK.

The Holocephali is a major group of chondrichthyan fishes, the sister taxon to the sharks and rays (Elasmobranchii). However, the dentition of extant holocephalans is very different from that of the elasmobranchs, lacking individual tooth renewal, but comprising dental plates made entirely of self-renewing dentine. This renewal of all tissues occurs at the postero-lingual plate surface, as a function of their statodont condition. The fossil record of the holocephalans illuminates multiple different trends in the dentition, including shark-like teeth through to those with dentitions completely lacking individual teeth. Different taxa illustrate developmental retention of teeth but with fusion in their serial development. Dentine of different varieties comprises these teeth and composite dental plates, whose histology includes vascularized tubes within coronal dentine, merging with basal trabecular dentine. In this coronal vascularized dentine, extensive hypermineralization forms a wear resistant tissue transformed into a variety of morphologies. Through evolution, hypermineralized dentine becomes enclosed within the trabecular dentine, and specialized by reduction into specific zones within a composite dental plate, with these increasing in morphological disparity, all reflecting loss of defined teeth but retention of dentine production from the inherited developmental package.
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http://dx.doi.org/10.1093/icb/icaa093DOI Listing
September 2020

One-to-one befriending for people with intellectual disability and symptoms of depression: protocol for a pilot randomised controlled trial.

BMJ Open 2020 06 21;10(6):e033989. Epub 2020 Jun 21.

Division of Psychiatry, University College London, London, UK.

Introduction: People with intellectual disability (ID) are more likely to experience loneliness and have smaller social networks, which increases vulnerability to depression. Befriending may reduce depressive symptoms in other populations, but randomised controlled trials (RCTs) have not been carried out in this population. This pilot study aims to assess the acceptability and feasibility of carrying out a full RCT of one-to-one befriending by volunteers for people with ID, compared with an active control group.

Methods And Analysis: The trial aims to recruit 40 participants with ID. Participants in the intervention arm will receive weekly visits from a volunteer over 6 months. Community befriending schemes will recruit, train, supervise volunteers and match them to individuals with ID. Both groups will receive a booklet about local activities and have access to usual care. Health and social outcomes will be measured at the end of the intervention and 6 months' follow-up. The following outcomes will be assessed: (1) recruitment and retention of individuals with ID and volunteers in the trial, (2) adverse events related to the intervention, (3) the acceptability of the intervention, (4) whether the intervention is delivered as intended, (5) changes in health and social outcomes and (6) the feasibility of carrying out a cost-effectiveness analysis in a full trial. Qualitative data from participants, volunteers, staff and carers will identify barriers and facilitators of a future full trial.

Ethics And Dissemination: The study has been approved by the London City and East Research Ethics Committee (reference 18/LO/2188). The findings will be presented at conferences and published in a peer-reviewed journal and in the National Institute of Health Research journals library. A public engagement seminar will be held at the end of the study aimed at key stakeholders.

Trial Registration Number: ISRCTN63779614.
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http://dx.doi.org/10.1136/bmjopen-2019-033989DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311030PMC
June 2020

Conflicting evidence for the use of caudal autotomy in mesosaurs.

Sci Rep 2020 04 28;10(1):7184. Epub 2020 Apr 28.

Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany.

The early Permian mesosaurs were the first amniotes to re-invade aquatic environments. One of their most controversial and puzzling features is their distinctive caudal anatomy, which has been suggested as a mechanism to facilitate caudal autotomy. Several researchers have described putative fracture planes in mesosaur caudal vertebrae - unossified regions in the middle of caudal vertebral centra - that in many extant squamates allow the tail to separate and the animal to escape predation. However, the reports of fracture planes in mesosaurs have never been closely investigated beyond preliminary descriptions, which has prompted scepticism. Here, using numerous vertebral series, histology, and X-ray computed tomography, we provide a detailed account of fracture planes in all three species of mesosaurs. Given the importance of the tail for propulsion in many other aquatic reptiles, the identification of fracture planes in mesosaurs has important implications for their aquatic locomotion. Despite mesosaurs apparently having the ability to autotomize their tail, it is unlikely that they actually made use of this behaviour due to a lack of predation pressure and no record of autotomized tails in articulated specimens. We suggest that the presence of fracture planes in mesosaurs is an evolutionary relic and could represent a synapomorphy for an as-yet undetermined terrestrial clade of Palaeozoic amniotes that includes the earliest radiation of secondarily aquatic tetrapods.
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http://dx.doi.org/10.1038/s41598-020-63625-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7189235PMC
April 2020

Conserved in-ovo cranial ossification sequences of extant saurians allow estimation of embryonic dinosaur developmental stages.

Sci Rep 2020 04 9;10(1):4224. Epub 2020 Apr 9.

Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, Gauteng, South Africa.

Dinosaur embryos are among the rarest of fossils, yet they provide a unique window into the palaeobiology of these animals. Estimating the developmental stage of dinosaur embryos is hindered by the lack of a quantitative method for age determination, by the scarcity of material, and by the difficulty in visualizing that material. Here we present the results of a broad inquiry, using 3D reconstructions from X-ray computed tomography data, into cranial ossification sequences in extant saurian taxa and in well-preserved embryos of the early branching sauropodomorph dinosaur Massospondylus carinatus. Our findings support deep-time conservation of cranial ossification sequences in saurians including dinosaurs, allowing us to develop a new method for estimating the relative developmental percentage of embryos from that clade. We also observe null-generation teeth in the Massospondylus carinatus embryos which get resorbed or shed before hatching, similar to those of geckos. These lines of evidence allow us to confidently estimate that the Massospondylus carinatus embryos are only approximately 60% through their incubation period, much younger than previously hypothesized. The overall consistency of our results with those of living saurians indicates that they can be generalized to other extinct members of that lineage, and therefore our method provides an independent means of assessing the developmental stage of extinct, in-ovo saurians.
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http://dx.doi.org/10.1038/s41598-020-60292-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7145871PMC
April 2020

Three-dimensional characterization of osteocyte volumes at multiple scales, and its relationship with bone biology and genome evolution in ray-finned fishes.

J Evol Biol 2020 06 20;33(6):808-830. Epub 2020 Mar 20.

European Synchrotron Radiation Facility, Grenoble, France.

Osteocytes, cells embedded within the bone mineral matrix, inform on key aspects of vertebrate biology. In particular, a relationship between volumes of the osteocytes and bone growth and/or genome size has been proposed for several tetrapod lineages. However, the variation in osteocyte volume across different scales is poorly characterized and mostly relies on incomplete, two-dimensional information. In this study, we characterize the variation of osteocyte volumes in ray-finned fishes (Actinopterygii), a clade including more than half of modern vertebrate species in which osteocyte biology is poorly known. We use X-ray synchrotron micro-computed tomography (SRµCT) to achieve a three-dimensional visualization of osteocyte lacunae and direct measurement of their size (volumes). Our specimen sample is designed to characterize variation in osteocyte lacuna morphology at three scales: within a bone, among the bones of one individual and among species. At the intra-bone scale, we find that osteocyte lacunae vary noticeably in size between zones of organized and woven bone (being up to six times larger in woven bone), and across cyclical bone deposition. This is probably explained by differences in bone deposition rate, with larger osteocyte lacunae contained in bone that deposits faster. Osteocyte lacuna volumes vary 3.5-fold among the bones of an individual, and this cannot readily be explained by variation in bone growth rate or other currently observable factors. Finally, we find that genome size provides the best explanation of variation in osteocyte lacuna volume among species: actinopterygian taxa with larger genomes (polyploid taxa in particular) have larger osteocyte lacunae (with a ninefold variation in median osteocyte volume being measured). Our findings corroborate previous two-dimensional studies in tetrapods that also observed similar patterns of intra-individual variation and found a correlation with genome size. This opens new perspectives for further studies on bone evolution, physiology and palaeogenomics in actinopterygians, and vertebrates as a whole.
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http://dx.doi.org/10.1111/jeb.13612DOI Listing
June 2020

Enhanced bactericidal activity of brucite through partial copper substitution.

J Mater Chem B 2020 01 27;8(1):100-113. Epub 2019 Nov 27.

Institut des Molécules et Matériaux du Mans (IMMM), UMR-6283 CNRS, Le Mans Université, Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France.

Brucite Mg(OH) belongs to a family of two-dimensional compounds with a CdI-type structure built up from layers of edge-sharing octahedra delineating 2D galleries. In the current study, nanometer-sized platelets of copper substituted Mg(OH) were prepared by co-precipitation at room temperature in mixed alkaline (NaOH/NaCO) medium. Very weak substitution of a few hydroxyl ions by carbonate groups was highlighted at first by infrared spectroscopy and then quantified by thermogravimetric (TG) and mass spectrometric (MS) evolved gas analyses. The presence in a very low amount of water molecules in the galleries induces disorder in the stacking of layers of edge-sharing octahedra along the c-axis. The dehydration of the hydroxides taking place below 225 °C preserves the brucite-type structure of the samples while suppressing the stacking disorder. Copper substitution greatly enhances the bactericidal activity of nanometer-sized platelets of brucite against two bacteria frequently involved in healthcare-associated-infections. 10 mol% of cupric ions in Mg(OH) (a copper loading of 0.102 mg mL in the suspension) were sufficient to induce, after 3 h in contact, 100% and 99.3% reductions in viability of Gram-negative E. coli and Gram-positive S. aureus, respectively (reductions as low as 23% and 48% are reported for the parent compound Mg(OH) in the same conditions). A good compromise between fast bactericidal kinetics and a high reduction in viability is reached by the 15 mol% copper-substituted Mg(OH) hydroxide. Its use gives the opportunity to five-fold reduce the copper loading of the bactericidal agent while being at least equally or even more efficient compared to the conventional CuO (a Cu loading of 0.799 mg mL and 0.154 mg mL in the suspension of CuO and 15 mol% copper substituted Mg(OH) particles, respectively).
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http://dx.doi.org/10.1039/c9tb01927hDOI Listing
January 2020

Multiphase progenetic development shaped the brain of flying archosaurs.

Sci Rep 2019 07 25;9(1):10807. Epub 2019 Jul 25.

European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS-40220, 38043, Grenoble, France.

The growing availability of virtual cranial endocasts of extinct and extant vertebrates has fueled the quest for endocranial characters that discriminate between phylogenetic groups and resolve their neural significances. We used geometric morphometrics to compare a phylogenetically and ecologically comprehensive data set of archosaurian endocasts along the deep evolutionary history of modern birds and found that this lineage experienced progressive elevation of encephalisation through several chapters of increased endocranial doming that we demonstrate to result from progenetic developments. Elevated encephalisation associated with progressive size reduction within Maniraptoriformes was secondarily exapted for flight by stem avialans. Within Mesozoic Avialae, endocranial doming increased in at least some Ornithurae, yet remained relatively modest in early Neornithes. During the Paleogene, volant non-neoavian birds retained ancestral levels of endocast doming where a broad neoavian niche diversification experienced heterochronic brain shape radiation, as did non-volant Palaeognathae. We infer comparable developments underlying the establishment of pterosaurian brain shapes.
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http://dx.doi.org/10.1038/s41598-019-46959-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6658547PMC
July 2019

Enhanced Stability and Band Gap Tuning of α-[HC(NH)]PbI Hybrid Perovskite by Large Cation Integration.

ACS Appl Mater Interfaces 2019 Jun 30;11(23):20743-20751. Epub 2019 May 30.

Univ Rennes, ENSCR, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226 , F-35000 Rennes , France.

We report room-temperature synthesis of lead- and iodide-deficient α-[HC(NH)]PbI perovskites (abbreviated d-α-FAPI, FA = formamidinium), with the general formula (A',FA)[PbI] (with A' = hydroxyethylammonium (HEA) or thioethylammonium (TEA) cations, 0.04 ≤ x ≤ 0.15). These materials retain a 3D character of their perovskite network despite incorporation of large HEA or TEA cations, demonstrating that the Goldschmidt tolerance factor can be bypassed. We found that thin films of (TEA,FA)[PbI] ( x = 0.04 and 0.13) show exceptional α-phase stability under ambient conditions, 1 order of magnitude higher than α-FAPI and α-(Cs,FA)PbI thin films. d-α-FAPI phases are shown to maintain a direct band gap, which increases monotonously for x ranging from 0 up to 0.20, with characteristics of a p-type semiconductor for low concentrations of vacancies ( x ≤ 0.13) and n-type for larger ones. They offer alternatives to reach the methylammonium- and bromine-free stable α-FAPI-type phase and open new avenues in the field of perovskite solar cells, up to band gap tuning desirable for tandem solar cells.
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http://dx.doi.org/10.1021/acsami.9b00210DOI Listing
June 2019

Thermomechanical Polymer Binder Reactivity with Positive Active Materials for Li Metal Polymer and Li-Ion Batteries: An XPS and XPS Imaging Study.

ACS Appl Mater Interfaces 2019 May 8;11(20):18368-18376. Epub 2019 May 8.

Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS , 2 rue de la Houssinière , BP 32229, 44322 Nantes Cedex 3 , France.

The lithium and lithium-ion battery electrode chemical stability in the pristine state has rarely been considered as a function of the binder choice and the electrode processing. In this work, X-ray photoelectron spectroscopy (XPS) and XPS imaging analyses associated with complementary Mössbauer spectroscopy are used in order to study the chemical stability of two pristine positive electrodes: (i) an extruded LiFePO-based electrode formulated with different polymer matrices [polyethylene oxide and a polyvinylidene difluoride (PVdF)] and processed at different temperatures (90 and 130 °C, respectively) and (ii) a Li[NiMnCo]O (NMC)-based electrode processed by tape-casting, followed by a mild or heavy calendering treatment. These analyses have allowed the identification of reactivity mechanisms at the interface of the active material and the polymer in the case of PVdF-based electrodes.
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http://dx.doi.org/10.1021/acsami.9b01761DOI Listing
May 2019

Cranial anatomy of the gorgonopsian Cynariops robustus based on CT-reconstruction.

PLoS One 2018 28;13(11):e0207367. Epub 2018 Nov 28.

Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany.

Gorgonopsia is one of the major clades of non-mammalian synapsids, and includes an array of large-bodied carnivores that were the top terrestrial predators of the late Permian. Most research on the clade has focused on these largest members; small-bodied gorgonopsians are relatively little-studied. Here, we redescribe a small gorgonopsian skull (MB.R.999) from the late Permian (Tropidostoma Assemblage Zone) of South Africa on the basis of neutron and synchrotron CT reconstructions, which yield new data on internal cranial morphology in Gorgonopsia. Because of the largely undistorted nature of MB.R.999, we were also able to reconstruct unossified areas such as the brain endocast and the otic labyrinth. MB.R.999 can be referred to the taxon Cynariops robustus based on its general skull proportions, postcanine tooth count, preparietal morphology, and vomerine morphology. We refer additional small gorgonopsian specimens from the Victoria West area to Cynariops robustus, and consider Cynarioides grimbeeki and Cynarioides laticeps to be synonymous with C. robustus. Inclusion of Cynariops in a phylogenetic analysis of Gorgonopsia recovers it within a large clade of African taxa, more closely related to Lycaenops and rubidgeines than Eriphostoma or Gorgonops.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0207367PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6261584PMC
April 2019

Synchrotron radiation reveals the identity of the large felid from Monte Argentario (Early Pleistocene, Italy).

Sci Rep 2018 05 29;8(1):8338. Epub 2018 May 29.

PaleoFactory, Sapienza University of Rome, I-00185, Rome, Italy.

We describe here a partial skull with associated mandible of a large felid from Monte Argentario, Italy (Early Pleistocene; ~1.5 million years). Propagation x-ray phase-contrast synchrotron microtomography of the specimen, still partially embedded in the rock matrix, allows ascribing it reliably to Acinonyx pardinensis, one of the most intriguing extinct carnivorans of the Old World Plio-Pleistocene. The analysis of images and 3D models obtained through synchrotron microtomography - here applied for the first time on a Plio-Pleistocene carnivoran - reveals a mosaic of cheetah-like and Panthera-like features, with the latter justifying previous attributions of the fossil to the extinct Eurasian jaguar Panthera gombaszoegensis. Similarly, we reassign to A. pardinensis some other Italian materials previously referred to P. gombaszoegensis (sites of Pietrafitta and Ellera di Corciano). The recognition of Panthera-like characters in A. pardinensis leads to reconsidering the ecological role of this species, whose hunting strategy was likely to be different from those of the living cheetah. Furthermore, we hypothesise that the high intraspecific variation in body size in A. pardinensis can be the result of sexual dimorphism, as observed today in all large-sized felids.
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http://dx.doi.org/10.1038/s41598-018-26698-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5974229PMC
May 2018

Endothiodon cf. bathystoma (Synapsida: Dicynodontia) bony labyrinth anatomy, variation and body mass estimates.

PLoS One 2018 14;13(3):e0189883. Epub 2018 Mar 14.

Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.

The semicircular canal (SC) system of the inner ear detects head angular accelerations and is essential for navigation and spatial awareness in vertebrates. Because the bony labyrinth encloses the membranous labyrinth SCs, it can be used as a proxy for animal behavior. The bony labyrinth of dicynodonts, a clade of herbivorous non-mammalian synapsids, has only been described in a handful of individuals and remains particularly obscure. Here we describe the bony labyrinth anatomy of three Endothiodon cf. bathystoma specimens from Mozambique based on digital reconstructions from propagation phase-contrast synchrotron micro-computed tomography. We compare these findings with the bony labyrinth anatomy of their close relative Niassodon. The bony labyrinths of Endothiodon and Niassodon are relatively similar and show only differences in the shape of the horizontal SCs and the orientation of the vertical SCs. When compared to extant mammals, Endothiodon and Niassodon have highly eccentric SCs. In addition, the Endothiodon SCs are nearly orthogonal. An eccentric and orthogonal SC morphology is consistent with a specialization in rapid head movements, which are typical of foraging or feeding behaviors. Furthermore, we estimate the body mass of these Endothiodon specimens at ~116 to 182 kg, based on the average SC radii calculated using a linear regression model optimized by the Amemiya Prediction Criterion. Our findings provide novel insights into the paleobiology of Endothiodon which are consistent with the peculiar feeding mechanism among dicynodonts presumed from their multiple postcanine toothrows.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0189883PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5851538PMC
June 2018

Evolution of facial innervation in anomodont therapsids (Synapsida): Insights from X-ray computerized microtomography.

J Morphol 2018 05 21;279(5):673-701. Epub 2018 Feb 21.

Evolutionary Studies Institute (ESI), School of Geosciences, University of the Witwatersrand, Johannesburg, 2050, South Africa.

Anomodontia was the most successful herbivorous clade of the mammalian stem lineage (non-mammalian synapsids) during the late Permian and Early Triassic. Among anomodonts, Dicynodontia stands apart because of the presence of an osseous beak that shows evidence of the insertion of a cornified sheath, the ramphotheca. In this study, fourteen anomodont specimens were microCT-scanned and their trigeminal canals reconstructed digitally to understand the origin and evolution of trigeminal nerve innervation of the ramphotheca. We show that the pattern of innervation of the anomodont "beak" is more similar to that in chelonians (the nasopalatine branch is enlarged and innervates the premaxillary part of the ramphotheca) than in birds (where the nasopalatine and maxillary branches play minor roles). The nasopalatine branch is noticeably enlarged in the beak-less basal anomodont Patranomodon, suggesting that this could be an anomodont or chainosaur synapomorphy. Our analyses suggest that the presence or absence of tusks and postcanine teeth are often accompanied by corresponding variations of the rami innervating the caniniform process and the alveolar region, respectively. The degree of ossification of the canal for the nasal ramus of the ophthalmic branch also appears to correlate with the presence of a nasal boss. The nasopalatine canal is absent from the premaxilla in the Bidentalia as they uniquely show a large plexus formed by the internal nasal branch of the maxillary canal instead. The elongated shape of this plexus in Lystrosaurus supports the hypothesis that the rostrum evolved as an elongation of the subnarial region of the snout. Finally, the atrophied and variable aspect of the trigeminal canals in Myosaurus supports the hypothesis that this genus had a reduced upper ramphotheca.
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http://dx.doi.org/10.1002/jmor.20804DOI Listing
May 2018

Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs.

Nature 2017 12 6;552(7685):395-399. Epub 2017 Dec 6.

Directorate Earth & History of Life, Royal Belgian Institute of Natural Sciences, B-1000 Brussels, Belgium.

Maniraptora includes birds and their closest relatives among theropod dinosaurs. During the Cretaceous period, several maniraptoran lineages diverged from the ancestral coelurosaurian bauplan and evolved novel ecomorphologies, including active flight, gigantism, cursoriality and herbivory. Propagation X-ray phase-contrast synchrotron microtomography of a well-preserved maniraptoran from Mongolia, still partially embedded in the rock matrix, revealed a mosaic of features, most of them absent among non-avian maniraptorans but shared by reptilian and avian groups with aquatic or semiaquatic ecologies. This new theropod, Halszkaraptor escuilliei gen. et sp. nov., is related to other enigmatic Late Cretaceous maniraptorans from Mongolia in a novel clade at the root of Dromaeosauridae. This lineage adds an amphibious ecomorphology to those evolved by maniraptorans: it acquired a predatory mode that relied mainly on neck hyperelongation for food procurement, it coupled the obligatory bipedalism of theropods with forelimb proportions that may support a swimming function, and it developed postural adaptations convergent with short-tailed birds.
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http://dx.doi.org/10.1038/nature24679DOI Listing
December 2017

Endocranial Casts of Pre-Mammalian Therapsids Reveal an Unexpected Neurological Diversity at the Deep Evolutionary Root of Mammals.

Brain Behav Evol 2017 8;90(4):311-333. Epub 2017 Nov 8.

Evolutionary Studies Institute (ESI), School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa.

The origin and evolution of the mammalian brain has long been the focus of scientific enquiry. Conversely, little research has focused on the palaeoneurology of the stem group of Mammaliaformes, the Permian and Triassic non-mammaliaform Therapsida (NMT). This is because the majority of the NMT have a non-ossified braincase, making the study of their endocranial cast (sometimes called the "fossil brain") problematic. Thus, descriptions of the morphology and size of NMT endocranial casts have been based largely on approximations rather than reliable determination. Accordingly, here we use micro-CT scans of the skulls of 1 Dinocephalia and 3 Biarmosuchia, which are NMT with a fully ossified braincase and thus a complete endocast. For the first time, our work enables the accurate determination of endocranial shape and size in NMT. This study suggests that NMT brain size falls in the upper range of the reptilian and amphibian variation. Brain size in the dicynodont Kawingasaurus is equivalent to that of early Mammaliaformes, whereas the Dinocephalia show evidence of a secondary reduction of brain size. In addition, unlike other NMT in which the endocast has a tubular shape and its parts are arranged in a linear manner, the biarmosuchian endocast is strongly flexed at the level of the midbrain, creating a near right angle between the fore- and hindbrain. These data highlight an unexpected diversity of endocranial size and morphology in NMT, features that are usually considered conservative in this group.
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http://dx.doi.org/10.1159/000481525DOI Listing
July 2018

Lead- and Iodide-Deficient (CH NH )PbI (d-MAPI): The Bridge between 2D and 3D Hybrid Perovskites.

Angew Chem Int Ed Engl 2017 12 15;56(50):16067-16072. Epub 2017 Nov 15.

Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue P. et M. Curie, 75005, Paris, France.

3D and 2D hybrid perovskites, which have been known for more than 20 years, have emerged recently as promising materials for optoelectronic applications, particularly the 3D compound (CH NH )PbI (MAPI). The discovery of a new family of hybrid perovskites called d-MAPI is reported: the association of PbI with both methyl ammonium (MA ) and hydroxyethyl ammonium (HEA ) cations leads to a series of five compounds with general formulation (MA) (HEA) [Pb I ]. These materials, which are lead- and iodide-deficient compared to MAPI while retaining 3D architecture, can be considered as a bridge between the 2D and 3D materials. Moreover, they can be prepared as crystallized thin films by spin-coating. These new 3D materials appear very promising for optoelectronic applications, not only because of their reduced lead content, but also in account of the large flexibility of their chemical composition through potential substitutions of MA , HEA , Pb and I ions.
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http://dx.doi.org/10.1002/anie.201710021DOI Listing
December 2017

Synchrotron scanning reveals the palaeoneurology of the head-butting (Therapsida, Dinocephalia).

PeerJ 2017 10;5:e3496. Epub 2017 Aug 10.

Evolutionary Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa.

Dinocephalian therapsids are renowned for their massive, pachyostotic and ornamented skulls adapted for head-to-head fighting during intraspecific combat. Synchrotron scanning of the tapinocephalid reveals, for the first time, numerous anatomical adaptations of the central nervous system related to this combative behaviour. Many neural structures (such as the brain, inner ear and ophthalmic branch of the trigeminal nerve) were completely enclosed and protected by bones, which is unusual for non-mammaliaform therapsids. The nearly complete ossification of the braincase enables precise determination of the brain cavity volume and encephalization quotient, which appears greater than expected for such a large and early herbivore. The practice of head butting is often associated with complex social behaviours and gregariousness in extant species, which are known to influence brain size evolution. Additionally, the plane of the lateral (horizontal) semicircular canal of the bony labyrinth is oriented nearly vertically if the skull is held horizontally, which suggests that the natural position of the head was inclined about 60-65°to the horizontal. This is consistent with the fighting position inferred from osteology, as well as ground-level browsing. Finally, the unusually large parietal tube may have been filled with thick conjunctive tissue to protect the delicate pineal eye from injury sustained during head butting.
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http://dx.doi.org/10.7717/peerj.3496DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5554600PMC
August 2017

The mystery of a missing bone: revealing the orbitosphenoid in basal Epicynodontia (Cynodontia, Therapsida) through computed tomography.

Naturwissenschaften 2017 Aug 18;104(7-8):66. Epub 2017 Jul 18.

Evolutionary Studies Institute; School of Geosciences, University of the Witwatersrand, Private Bag 3, WITS, Johannesburg, 2050, South Africa.

The basal non-mammaliaform cynodonts from the late Permian (Lopingian) and Early Triassic are a major source of information for the understanding of the evolutionary origin of mammals. Detailed knowledge of their anatomy is critical for understanding the phylogenetic transition toward mammalness and the paleobiological reconstruction of mammalian precursors. Using micro-computed tomography (μCT), we describe the internal morphology of the interorbital region that includes the rarely fossilized orbitosphenoid elements in four basal cynodonts. These paired bones, which are positioned relatively dorsally in the skull, contribute to the wall of the anterior part of the braincase and form the floor for the olfactory lobes. Unlike procynosuchids and the more basal therapsids in which the orbitosphenoids are well developed, dense, and bear a ventral keel, the basal epicynodonts Cynosaurus, Galesaurus, and Thrinaxodon display cancellous, reduced, and loosely articulated orbitosphenoids, a condition shared with many eucynodonts. The hemi-cylindrical orbitosphenoid from which the mammalian condition is derived re-evolved convergently in traversodontid and some probainognathian cynodonts.
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http://dx.doi.org/10.1007/s00114-017-1487-zDOI Listing
August 2017

Aspects of gorgonopsian paleobiology and evolution: insights from the basicranium, occiput, osseous labyrinth, vasculature, and neuroanatomy.

PeerJ 2017 11;5:e3119. Epub 2017 Apr 11.

Instituto Superior Técnico, Instituto de Plasmas e Fusão Nuclear, Universidade de Lisboa, Lisboa, Portugal.

Synapsida, the clade including therapsids and thus also mammals, is one of the two major branches of amniotes. Organismal design, with modularity as a concept, offers insights into the evolution of therapsids, a group that experienced profound anatomical transformations throughout the past 270 Ma, eventually leading to the evolution of the mammalian bauplan. However, the anatomy of some therapsid groups remains obscure. Gorgonopsian braincase anatomy is poorly known and many anatomical aspects of the brain, cranial nerves, vasculature, and osseous labyrinth, remain unclear. We analyzed two gorgonopsian specimens, GPIT/RE/7124 and GPIT/RE/7119, using propagation phase contrast synchrotron micro-computed tomography. The lack of fusion between many basicranial and occipital bones in GPIT/RE/7124, which is an immature specimen, allowed us to reconstruct its anatomy and ontogenetic sequence, in comparison with the mature GPIT/RE/7119, in great detail. We explored the braincase and rendered various skull cavities. Notably, we found that there is a separate ossification between what was previously referred to as the "parasphenoid" and the basioccipital. We reinterpreted this element as a posterior ossification of the basisphenoid: the basipostsphenoid. Moreover, we show that the previously called "parasphenoid" is in fact the co-ossification of the dermal parasphenoid and the endochondral basipresphenoid. In line with previous descriptions, the anatomy of the osseous labyrinth is rendered in detail, revealing a unique discoid morphology of the horizontal semicircular canal, rather than toroidal, probably due to architectural constraints of the ossification of the opisthotic and supraoccipital. In addition, the orientation of the horizontal semicircular canal suggests that gorgonopsians had an anteriorly tilted alert head posture. The morphology of the brain endocast is in accordance with the more reptilian endocast shape of other non-mammaliaform neotherapsids.
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http://dx.doi.org/10.7717/peerj.3119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5390774PMC
April 2017

Cranial Bosses of Choerosaurus dejageri (Therapsida, Therocephalia): Earliest Evidence of Cranial Display Structures in Eutheriodonts.

PLoS One 2016 22;11(8):e0161457. Epub 2016 Aug 22.

Evolutionary Studies Institute (ESI), School of Geosciences, University of the Witwatersrand, Braamfontein, 2050, Johannesburg, South Africa.

Choerosaurus dejageri, a non-mammalian eutheriodont therapsid from the South African late Permian (~259 Ma), has conspicuous hemispheric cranial bosses on the maxilla and the mandible. These bosses, the earliest of this nature in a eutheriodont, potentially make C. dejageri a key species for understanding the evolutionary origins of sexually selective behaviours (intraspecific competition, ritualized sexual and intimidation displays) associated with cranial outgrowths at the root of the clade that eventually led to extant mammals. Comparison with the tapinocephalid dinocephalian Moschops capensis, a therapsid in which head butting is strongly supported, shows that the delicate structure of the cranial bosses and the gracile structure of the skull of Choerosaurus would be more suitable for display and low energy combat than vigorous head butting. Thus, despite the fact that Choerosaurus is represented by only one skull (which makes it impossible to address the question of sexual dimorphism), its cranial bosses are better interpreted as structures involved in intraspecific selection, i.e. low-energy fighting or display. Display structures, such as enlarged canines and cranial bosses, are widespread among basal therapsid clades and are also present in the putative basal therapsid Tetraceratops insignis. This suggests that sexual selection may have played a more important role in the distant origin and evolution of mammals earlier than previously thought. Sexual selection may explain the subsequent independent evolution of cranial outgrowths and pachyostosis in different therapsid lineages (Biarmosuchia, Dinocephalia, Gorgonopsia and Dicynodontia).
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161457PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4993441PMC
August 2017