124 results on '"McNamara, Maria"'
Search Results
102. Organic preservation of fossil musculature with ultracellular detail
- Author
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McNamara, Maria, primary, Orr, Patrick J., additional, Kearns, Stuart L., additional, Alcalá, Luis, additional, Anadón, Pere, additional, and Peñalver-Mollá, Enrique, additional
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- 2009
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103. Exceptionally preserved tadpoles from the Miocene of Libros, Spain: ecomorphological reconstruction and the impact of ontogeny upon taphonomy
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MCNAMARA, MARIA E., primary, ORR, PATRICK J., additional, KEARNS, STUART L., additional, ALCALÁ, LUIS, additional, ANADÓN, PERE, additional, and PEÑALVER-MOLLÁ, ENRIQUE, additional
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- 2009
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104. Australian Health and Safety Inspectors’ Perceptions and Actions in Relation to Changed Work Arrangements
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Quinlan, Michael, primary, Johnstone, Richard, additional, and McNamara, Maria, additional
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- 2009
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105. Coordination of pentaammineruthenium to RNA: spectra, equilibria, kinetics and electrochemistry
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McNamara, Maria A., primary and Clarke, Michael J., additional
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- 1992
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106. Exceptionally preserved tadpoles from the Miocene of Libros, Spain: ecomorphological reconstruction and the impact of ontogeny upon taphonomy.
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MCNAMARA, MARIA E., ORR, PATRICK J., KEARNS, STUART L., ALCALÁ, LUIS, ANADÓN, PERE, and PEÑALVER-MOLLÁ, ENRIQUE
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- *
TADPOLES , *FRESHWATER animals , *TAPHONOMY , *FISH anatomy - Abstract
McNamara, M.E., Orr, P.J., Kearns, S.L., Alcalá, L., Anadón, P. & Peñalver-Mollá, E. 2010: Exceptionally preserved tadpoles from the Miocene of Libros, Spain: ecomorphological reconstruction and the impact of ontogeny upon taphonomy. Lethaia, Vol. 43, pp. 290–306. The Libros exceptional biota from the Upper Miocene of NE Spain includes abundant frog tadpoles ( Rana pueyoi) preserved in finely laminated lacustrine mudstones. The tadpoles exhibit a depressed body, short tail, low tail fins, dorso-laterally directed eyes and jaw sheaths; these features identify the Libros tadpoles as members of the benthic lentic ecomorphological guild. This, the first ecomorphological reconstruction of a fossil tadpole, supports phylogenetic evidence that this ecology is a conserved ranid feature. The soft-tissue features of the Libros tadpoles are characterized by several modes of preservation. The space occupied previously by the brain is defined by calcium carbonate, the nerve cord is defined by calcium phosphate, and jaw sheaths and bone marrow are preserved as organic remains. Gut contents (and coprolites adjacent to specimens) comprise ingested fine-grained sedimentary detritus and epiphyton. The body outline and the eyespots, nares, abdominal cavity, notochord, caudal myotomes and fins are defined by a carbonaceous bacterial biofilm. A similar biofilm in adult specimens of R. pueyoi from Libros defines only the body outline, not any internal anatomical features. In the adult frogs, but not in the tadpoles, calcium phosphate and calcium sulphate precipitated in association with integumentary tissues. These differences in the mode of preservation between the adult frogs and tadpoles reflect ontogenetic factors. □ Anuran, ecology, soft-tissue, tadpoles, taphonomy. [ABSTRACT FROM AUTHOR]
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- 2010
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107. Allometric Analysis Sheds Light on the Systematics and Ontogeny of Anurognathid Pterosaurs
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Yang, Zixiao, Benton, Michael J., Hone, David W. E., Xu, Xing, McNamara, Maria E., and Jiang, Baoyu
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- 2022
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108. Fossilized skin reveals coevolution with feathers and metabolism in feathered dinosaurs and early birds
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McNamara, Maria E., Zhang, Fucheng, Kearns, Stuart L., Orr, Patrick J., Toulouse, André, Foley, Tara, Hone, David W. E., Rogers, Chris S., Benton, Michael J., Johnson, Diane, Xu, Xing, Zhou, Zhonghe, McNamara, Maria E., Zhang, Fucheng, Kearns, Stuart L., Orr, Patrick J., Toulouse, André, Foley, Tara, Hone, David W. E., Rogers, Chris S., Benton, Michael J., Johnson, Diane, Xu, Xing, and Zhou, Zhonghe
- Abstract
Feathers are remarkable evolutionary innovations that are associated with complex adaptations of the skin in modern birds. Fossilised feathers in non-avian dinosaurs and basal birds provide insights into feather evolution, but how associated integumentary adaptations evolved is unclear. Here we report the discovery of fossil skin, preserved with remarkable nanoscale fidelity, in three non-avian maniraptoran dinosaurs and a basal bird from the Cretaceous Jehol biota (China). The skin comprises patches of desquamating epidermal corneocytes that preserve a cytoskeletal array of helically coiled α-keratin tonofibrils. This structure confirms that basal birds and non-avian dinosaurs shed small epidermal flakes as in modern mammals and birds, but structural differences imply that these Cretaceous taxa had lower body heat production than modern birds. Feathered epidermis acquired many, but not all, anatomically modern attributes close to the base of the Maniraptora by the Middle Jurassic.
109. The taphonomy of dinosaurs and birds of the Jehol Biota
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Rogers, Chris S., Kearns, Stuart, Orr, Patrick J., Mcnamara, Maria E., and Benton, Mike
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550 - Abstract
Some of the more outstanding fossils from the Early Cretaceous Jehol Biota of NE China are the early birds and feathered dinosaurs. Any interpretation of the biology of the birds and dinosaurs from the Jehol Biota inherently depends on a full understanding of their taphonomy, which must be investigated. We explore the taphonomy of the Jehol birds and dinosaurs from different deposits. In particular, we determine the likelihood that volcaniclastic flows were responsible for the death transport and burial of these animals. Field observations and analysis of Psittacosaurus fossil matrices from the fossil-rich volcaniclastic deposits of the Lujiatun Unit reveals animals were not killed by a previously hypothesised single volcanic event and were instead buried within remobilised volcaniclastic material. Using semi-quantitative skeletal taphonomy metrics we test the hypothesis that all allochthonous components of the Jehol Biota were killed, transported and deposited in a lake by a pyroclastic density current. Analysis of the skeletal taphonomy of the early bird Confuciusornis and feathered microraptorine dinosaurs reveals that these animals were not transported in a pyroclastic or turbulent flow of any other kind. The decay process in the skin of birds and squamates is documented for the first time at an ultrastructural level. Results show that decay of skin progresses differently between individuals and within the same individual over short distances. From this, we develop a predictive model for the likelihood of the various components of the skin being available or unavailable for preservation in the fossil record at different points in the decay process. We also employ micro-computed tomography to image decayed bird skin and muscle. The advantages of imaging decay on non-biomineralized tissues using each method in isolation and as part of an integrated approach are then discussed.
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- 2017
110. The taphonomy of feathers
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Slater, Tiffany S., McNamara, Maria, and Orr, Patrick J.
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Keratin ,Pigmentation ,Taphonomy ,Melanin ,Fossil ,Corneous beta proteins ,Feathers ,Fossil colour - Abstract
Fossil feathers harbour key information for understanding the evolution of feathers through deep time. The ability of fossil feathers to inform on the biochemical evolution of feathers is, however, restricted due to an incomplete understanding of feather taphonomy. Accurate interpretation of data from fossil feathers requires a comprehensive understanding of the fate of key feather components – melanosomes, melanins and feather corneous beta proteins (CBPs) – during fossilization, but this is not fully characterized. Further, whether the preservation of different feather components is inter-dependent, and whether certain components impact preservation of others, is unknown. Unsurprisingly, reports of preserved feather chemistry in fossils are controversial. This thesis addresses these issues using taphonomic experiments incorporating decay, sulfurisation, oxidation, thermal maturation and high temperature-high pressure maturation on black, white and orange feathers from extant birds. The results resolve the controls on the preservation of melanosomes and melanins (in decreasing order of importance: oxidation, maturation and decay) and the proteinaceous component of feathers (in decreasing order of importance: maturation, oxidation and decay). The experimental results also support new fossil evidence for the preservation of disulfides and amides, which are indicative of feather CBPs, in Mesozoic fossil feathers and the preservation of phaeomelanin molecular residues in Miocene fossil frogs. Collectively, the results form the basis for a new integrated model for feather preservation that is firmly grounded in quantitative empirical data and encompasses all major feather components. This model explains variations in the preservation of fossil feathers and represents a major advance in our understanding of the preservation of feathers and of structural proteins. Critically, the model highlights the power of combining systematic and quantitative taphonomic experiments with a holistic, whole-tissue approach, to resolve long-standing issues relating to the preservation of soft tissues in the fossil record.
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- 2022
111. Fossil scales illuminate the early evolution of lepidopterans and structural colors.
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Qingqing Zhang, Mey, Wolfram, Ansorge, Jörg, Starkey, Timothy A., McDonald, Luke T., McNamara, Maria E., Jarzembowski, Edmund A., Wichard, Wilfried, Kelly, Richard, Xiaoyin Ren, Jun Chen, Haichun Zhang, and Bo Wang
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LEPIDOPTERA , *SCALE insects , *DIFFRACTION patterns , *PHOTONICS , *SCATTERING (Physics) - Abstract
The article presents a study on scale architectures from Jurassic Lepidoptera and Tarachoptera. It mentions that Jurassic lepidopterans exhibit a type 1 bilayer scale vestiture which is almost identical to those of some extant Micropterigidae. It states that optical modeling confirms that diffraction related scattering mechanisms dominate the photonic properties of the fossil cover scales, which would have displayed broadband metallic hues as in numerous extant Micropterigidae.
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- 2018
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112. Pterosaur melanosomes support signalling functions for early feathers
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Aude Cincotta, Michaël Nicolaï, Hebert Bruno Nascimento Campos, Maria McNamara, Liliana D’Alba, Matthew D. Shawkey, Edio-Ernst Kischlat, Johan Yans, Robert Carleer, François Escuillié, Pascal Godefroit, D'Alba, Liliana/0000-0002-2478-3455, Cincotta, Aude, Nicolai, Michael, Nascimento Campos, Hebert Bruno, McNamara, Maria, D'Alba, Liliana, Shawkey, Matthew D., Kischlat, Edio-Ernst, Yans, Johan, CARLEER, Robert, Escuillie, Francois, and Godefroit, Pascal
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Multidisciplinary ,Melanosomes ,MELANIN ,Fossils ,Pigmentation ,Biology and Life Sciences ,EVOLUTIONARY ORIGIN ,PALEONTOLOGIA ,Feathers ,Biological Evolution ,Dinosaurs ,COLOR PATTERNS ,PELEONTOLOGY ,Animals ,DIVERSIFICATION ,DINOSAUR ,THEROPOD ,PTEROSAUR MELASONES - Abstract
Remarkably well-preserved soft tissues in Mesozoic fossils have yielded substantial insights into the evolution of feathers(1). New evidence of branched feathers in pterosaurs suggests that feathers originated in the avemetatarsalian ancestor of pterosaurs and dinosaurs in the Early Triassic(2), but the homology of these pterosaur structures with feathers is controversial(3,4). Reports of pterosaur feathers with homogeneous ovoid melanosome geometries(2,5) suggest that they exhibited limited variation in colour, supporting hypotheses that early feathers functioned primarily in thermoregulation(6). Here we report the presence of diverse melanosome geometries in the skin and simple and branched feathers of a tapejarid pterosaur from the Early Cretaceous found in Brazil. The melanosomes form distinct populations in different feather types and the skin, a feature previously known only in theropod dinosaurs, including birds. These tissue-specific melanosome geometries in pterosaurs indicate that manipulation of feather colour-and thus functions of feathers in visual communication-has deep evolutionary origins. These features show that genetic regulation of melanosome chemistry and shape(7-9) was active early in feather evolution. This work was funded by a Fonds National pour la Recherche Scientifique (F.R.S.-FNRS) FRIA grant (F3/5/5-MCF/ROI/BC-2319784), an Irish Research Council Government of Ireland Postdoctoral Fellowship (GOIPD/2018/768) awarded to A.C. and an ERC Starting Grant H2020-2014-StG-637691-ANICOLEVO and an ERC Consolidator Grant H2020-2020-CoG-101003293-PALAEOCHEM awarded to M.N. We thank M. Benton for providing the original data and code used in the phylogenetic reconstruction2, Z. Yang for providing raw melanosome measurements used to compare melanosome geometry in pterosaurs and J. Cillis for assistance with SEM. MCT.R.1884 was photographed by T. Hubin (RBINS).
- Published
- 2021
113. Helicobacter pylori resistance to antibiotics in Europe in 2018 and its relationship to antibiotic consumption in the community
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Megraud, Francis, Bruyndonckx, Robin, Coenen, Samuel, Wittkop, Linda, Huang, Te-Din, Hoebeke, Martin, Benejat, Lucie, Lehours, Philippe, Goossens, Herman, Glupczynski, youri, European Helicobacter Pylori Antimicrobial Susceptibility Testing Working, Group, Bordeaux population health (BPH), Université de Bordeaux (UB)-Institut de Santé Publique, d'Épidémiologie et de Développement (ISPED)-Institut National de la Santé et de la Recherche Médicale (INSERM), European Helicobacter Pylori, DARMIGNY, SANDRINE, Bordeaux Research In Translational Oncology [Bordeaux] (BaRITOn), Université de Bordeaux (UB)-CHU Bordeaux [Bordeaux]-Institut National de la Santé et de la Recherche Médicale (INSERM), Hôpital Pellegrin, CHU Bordeaux [Bordeaux]-Groupe hospitalier Pellegrin, Vaccine & Infectious Disease Institute [Antwerp, Belgium] (VAXINFECTIO), University of Antwerp (UA), Hasselt University (UHasselt), Institut de Santé Publique, d'Epidémiologie et de Développement (ISPED), Université Bordeaux Segalen - Bordeaux 2, Université de Bordeaux (UB), CHU UCL Namur, European Helicobacter pylori Antimicrobial Susceptibility Testing Working Group: Athanasios Makristathis, Lyudmila Boyanova, Ante Tonkic, Marija Tonkic, Leif Andersen, Benjamin Blumel, Erick Glocker, Ina Tammer, Alexander Link, Sebastian Suerbaum, Karl Dichtl, Andreas Mentis, Beatriz Marintez-Gonzales, Sinead Smith, Deirdre McNamara, Maria Pina Dore, Rosa Monno, Antonio Lippolis, Dace Rudzite, Marcis Leja, Juozas Kupcinskas, Kjetil K Melby, Grazyna Gosciniak, Tomasz M Karpinski, Monica Oleastro, Samo Jeverica, Xavier Calvet, Maria José Ramirez-Lázaro, Milagrosa Montes Ros, Ana Morilla, Sjoukje Boonstra, Peter M Schneeberger, UCL - SSS/IREC/MONT - Pôle Mont Godinne, and UCL - (MGD) Laboratoire de biologie clinique
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0301 basic medicine ,medicine.medical_specialty ,medicine.drug_class ,[SDV]Life Sciences [q-bio] ,Gastric diseases ,030106 microbiology ,Antibiotics ,Drug resistance ,antibiotics ,WATER ,SURVEILLANCE ,ERADICATION ,MULTICENTER ,PREVALENCE ,Helicobacter pylori infection ,03 medical and health sciences ,0302 clinical medicine ,Antibiotic resistance ,Levofloxacin ,Clarithromycin ,Internal medicine ,medicine ,drug resistance ,biology ,business.industry ,Gastroenterology ,gastric diseases ,Helicobacter pylori ,biology.organism_classification ,Quinolone ,bacterial infections and mycoses ,3. Good health ,[SDV] Life Sciences [q-bio] ,Metronidazole ,030211 gastroenterology & hepatology ,[SDV.SPEE]Life Sciences [q-bio]/Santé publique et épidémiologie ,Human medicine ,business ,medicine.drug - Abstract
ObjectiveOur aim was to prospectively assess the antibiotic resistance rates in Helicobacter pylori strains in Europe in 2018 and to study the link between antibiotic consumption in the community and H. pylori resistance levels in the different countries.DesignThe proportion of primary antibiotic resistance cases of H. pylori and their corresponding risk factors were investigated in 24 centres from 18 European countries according to a standardised protocol. Data on antibiotic consumption in the community were collected for the period 2008–2017. The link between antibiotic consumption and resistance data was assessed using generalised linear mixed models. The model with the best fit was selected by means of the Akaike Information Criterion.ResultsH. pylori resistance rates for the 1211 adult patients included were 21.4% for clarithromycin, 15.8% for levofloxacin and 38.9% for metronidazole and were significantly higher in Central/Western and Southern than in the Northern European countries.The best model fit was obtained for the Poisson distribution using 2013 consumption data. A significant association was found between H. pylori clarithromycin resistance and consumption in the community of macrolides (p=0.0003) and intermediate-acting macrolides (p=0.005), and between levofloxacin resistance and consumption of quinolones (p=0.0002) and second-generation quinolones (p=0.0003).ConclusionThis study confirms the positive correlation between macrolide and quinolone consumption in the community and corresponding H. pylori resistance in European countries. Hence, H. pylori treatment with clarithromycin and levofloxacin should not be started without susceptibility testing in most European countries.
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- 2021
114. Taphonomy of pigmentary colours in fossil insects
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Álvarez Armada, Nidia, McNamara, Maria, Jarvis, David (Ed), and Gill, Fiona
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Pigments ,Trace elements ,fungi ,XRF ,Transport ,Organic chemistry ,Fossil preservation ,Colour patterning ,Insects ,Insect cuticle ,stomatognathic system ,LCMS ,Decay experiments ,GCMS ,Fossil chemistry ,Fossil colour ,Inorganic chemistry - Abstract
Extant insects are renowned for the striking colouration displayed in their cuticles. Although fossil insects are abundant and the patternings in their cuticles highly resemble those found in extant insects, these are commonly monotonal, especially in those insects preserved across deep geological time. Colouration mechanisms in extant insects are majorly a combination of colour producing molecules called pigments and occasionally colour producing structures, which can be present in combination, but colouration mechanisms are largely unknown in their counterpart fossil taxa. Here, an experimental approach is utilized to elucidate the taphonomy of pigmentary colours in fossil insects. Decay and tumbling experiments are combined to explore environmental, biological and compositional biases constraining the potential for fossilisation of cuticles in various extant taxa. In addition, the trace elemental signatures embedded in patterned cuticles of extant taxa are characterized and compared with trace elemental signatures in fossil taxa. These analyses indicate that the fossilisation potential for insect cuticle is greatly diminished for those regions of the cuticle where the sclerotisation molecule, melanin, is not present. Environmental conditions also play an important role in the potential for fossilisation, where the increase of alkalinity in the media accelerates the process of internal decay and aids in the proliferation of decomposing bacteria, especially on those regions of the cuticle where melanin is absent. Physical decay of cuticles appears to be affected by the distribution of the pigment components throughout the cuticle; the rate of physical decay differs in cuticles with variables degrees of patterning, and those cuticles without heterogeneous distribution of pigments resist decay related to transport for longer periods of time. Trace elemental chemistry is taxonomically constrained in extant taxa at order and family levels. At genera level, these broad taxonomical trends are overprinted by a strong pigment-specific signal. The trace element chemistry in fossil insects is controlled by both taxonomy and depositional context, indicating some diagenetic overprinting. Regions of the fossilized cuticles displaying different tones contain distinct suites of elements, which suggests that there is a preservation of a pigmentary component in the chemical signal of fossil insects. Revealing biases in the fossil record of insects assist to the interpretation of fossil insect assemblages, the conditions of the environment of deposition and any biological constraints in the preservation potential of fossil insects. Trace elemental chemistry of fossil insects aids in the interpretation of original colours of fossil insects, and consequently informs on the models of evolution of colour and its ecological functions in insects through deep time.
- Published
- 2020
115. A new non-destructive method to decipher the origin of organic matter in fossils using Raman spectroscopy.
- Author
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Rossi V, Unitt R, and McNamara M
- Abstract
Ancient biomolecules provide a unique perspective on the past but are underutilized in paleontology because of challenges in interpreting the chemistry of fossils. Most organically preserved soft tissues in fossils have been altered by thermal maturation during the fossilization process, obscuring original chemistry. Here, we use a comprehensive program of thermal maturation experiments on soft tissues from diverse extant organisms to systematically test whether thermally altered biosignatures can be discriminated using Raman spectroscopy. All experimentally matured samples show chemical signatures that are superficially similar. Comparative analysis of Raman spectra following peak deconvolution, however, reveals strong tissue-specific signals. Application of this approach to fossils from the Bolca (49 Ma) and Libros (10 Ma) Konservat-Lagerstätten successfully discriminates fossil vertebrate soft tissue from that of fossil plants. Critically, our data confirm that a robust interrogation of Raman spectra coupled with multivariate analysis is a powerful tool to shed light on the taxonomic origins of thermally matured fossil soft tissues., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)
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- 2024
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116. Reply to: Transformation of β-sheets into disordered structures during the fossilization of feathers.
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Slater TS, Edwards NP, Webb SM, Zhang F, and McNamara ME
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- Animals, Fossils, Protein Structure, Secondary, Feathers chemistry
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- 2024
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117. Cellular structure of dinosaur scales reveals retention of reptile-type skin during the evolutionary transition to feathers.
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Yang Z, Jiang B, Xu J, and McNamara ME
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- Animals, Animal Scales anatomy & histology, Epidermis anatomy & histology, Epidermis metabolism, Epidermis ultrastructure, beta-Keratins metabolism, Feathers anatomy & histology, Dinosaurs anatomy & histology, Fossils, Biological Evolution, Skin anatomy & histology, Skin metabolism, Reptiles anatomy & histology, Melanosomes metabolism, Melanosomes ultrastructure
- Abstract
Fossil feathers have transformed our understanding of integumentary evolution in vertebrates. The evolution of feathers is associated with novel skin ultrastructures, but the fossil record of these changes is poor and thus the critical transition from scaled to feathered skin is poorly understood. Here we shed light on this issue using preserved skin in the non-avian feathered dinosaur Psittacosaurus. Skin in the non-feathered, scaled torso is three-dimensionally replicated in silica and preserves epidermal layers, corneocytes and melanosomes. The morphology of the preserved stratum corneum is consistent with an original composition rich in corneous beta proteins, rather than (alpha-) keratins as in the feathered skin of birds. The stratum corneum is relatively thin in the ventral torso compared to extant quadrupedal reptiles, reflecting a reduced demand for mechanical protection in an elevated bipedal stance. The distribution of the melanosomes in the fossil skin is consistent with melanin-based colouration in extant crocodilians. Collectively, the fossil evidence supports partitioning of skin development in Psittacosaurus: a reptile-type condition in non-feathered regions and an avian-like condition in feathered regions. Retention of reptile-type skin in non-feathered regions would have ensured essential skin functions during the early, experimental stages of feather evolution., (© 2024. The Author(s).)
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- 2024
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118. Fossilized anuran soft tissues reveal a new taphonomic model for the Eocene Geiseltal Konservat-Lagerstätte, Germany.
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Falk D, Wings O, Unitt R, Wade J, and McNamara ME
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- Animals, Germany, Melanosomes metabolism, Fossils, Anura anatomy & histology
- Abstract
The Eocene Geiseltal Konservat-Lagerstätte (Germany) is famous for reports of three dimensionally preserved soft tissues with sub-cellular detail. The proposed mode of preservation, direct replication in silica, is not known in other fossils and has not been verified using modern approaches. Here, we investigated the taphonomy of the Geiseltal anurans using diverse microbeam imaging and chemical analytical techniques. Our analyses confirm the preservation of soft tissues in all body regions but fail to yield evidence for silicified soft tissues. Instead, the anuran soft tissues are preserved as two layers that differ in microstructure and composition. Layer 1 comprises sulfur-rich carbonaceous microbodies interpreted as melanosomes. Layer 2 comprises the mid-dermal Eberth-Katschenko layer, preserved in calcium phosphate. In addition, patches of original aragonite crystals define the former position of the endolymphatic sac. The primary modes of soft tissue preservation are therefore sulfurization of melanosomes and phosphatization of more labile soft tissues, i.e., skin. This is consistent with the taphonomy of vertebrates in many other Konservat-Lagerstätten. These findings emphasize an emerging model for pervasive preservation of vertebrate soft tissues via melanosome films, particularly in stagnation-type deposits, with phosphatization of more labile tissues where tissue biochemistry is favorable., (© 2024. The Author(s).)
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- 2024
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119. Taphonomic experiments reveal authentic molecular signals for fossil melanins and verify preservation of phaeomelanin in fossils.
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Slater TS, Ito S, Wakamatsu K, Zhang F, Sjövall P, Jarenmark M, Lindgren J, and McNamara ME
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- Animals, Pigmentation, Vertebrates, Feathers, Melanins chemistry, Fossils
- Abstract
Melanin pigments play a critical role in physiological processes and shaping animal behaviour. Fossil melanin is a unique resource for understanding the functional evolution of melanin but the impact of fossilisation on molecular signatures for eumelanin and, especially, phaeomelanin is not fully understood. Here we present a model for the chemical taphonomy of fossil eumelanin and phaeomelanin based on thermal maturation experiments using feathers from extant birds. Our results reveal which molecular signatures are authentic signals for thermally matured eumelanin and phaeomelanin, which signatures are artefacts derived from the maturation of non-melanin molecules, and how these chemical data are impacted by sample preparation. Our model correctly predicts the molecular composition of eumelanins in diverse vertebrate fossils from the Miocene and Cretaceous and, critically, identifies direct molecular evidence for phaeomelanin in these fossils. This taphonomic framework adds to the geochemical toolbox that underpins reconstructions of melanin evolution and of melanin-based coloration in fossil vertebrates., (© 2023. Springer Nature Limited.)
- Published
- 2023
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120. Preservation of corneous β-proteins in Mesozoic feathers.
- Author
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Slater TS, Edwards NP, Webb SM, Zhang F, and McNamara ME
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- Animals, Keratins analysis, Keratins genetics, Keratins metabolism, Biological Evolution, Skin, Feathers, beta-Keratins analysis, beta-Keratins genetics, beta-Keratins metabolism
- Abstract
Fossil proteins are valuable tools in evolutionary biology. Recent technological advances and better integration of experimental methods have confirmed the feasibility of biomolecular preservation in deep time, yielding new insights into the timing of key evolutionary transitions. Keratins (formerly α-keratins) and corneous β-proteins (CBPs, formerly β-keratins) are of particular interest as they define tissue structures that underpin fundamental physiological and ecological strategies and have the potential to inform on the molecular evolution of the vertebrate integument. Reports of CBPs in Mesozoic fossils, however, appear to conflict with experimental evidence for CBP degradation during fossilization. Further, the recent model for molecular modification of feather chemistry during the dinosaur-bird transition does not consider the relative preservation potential of different feather proteins. Here we use controlled taphonomic experiments coupled with infrared and sulfur X-ray spectroscopy to show that the dominant β-sheet structure of CBPs is progressively altered to α-helices with increasing temperature, suggesting that (α-)keratins and α-helices in fossil feathers are most likely artefacts of fossilization. Our analyses of fossil feathers shows that this process is independent of geological age, as even Cenozoic feathers can comprise primarily α-helices and disordered structures. Critically, our experiments show that feather CBPs can survive moderate thermal maturation. As predicted by our experiments, analyses of Mesozoic feathers confirm that evidence of feather CBPs can persist through deep time., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)
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- 2023
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121. The origins of colour patterns in fossil insects revealed by maturation experiments.
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Wang S, McNamara ME, Wang B, Hui H, and Jiang B
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- Animals, Color, Melanins, Insecta, Fossils, Coleoptera
- Abstract
Many fossil insects show monochromatic colour patterns that may provide valuable insights into ancient insect behaviour and ecology. Whether these patterns reflect original pigmentary coloration is, however, unknown, and their formation mechanism has not been investigated. Here, we performed thermal maturation experiments on extant beetles with melanin-based colour patterns. Scanning electron microscopy reveals that melanin-rich cuticle is more resistant to degradation than melanin-poor cuticle: with progressive maturation, melanin-poor cuticle regions experience preferential thinning and loss, yet melanin-rich cuticle remains. Comparative analysis of fossil insects with monotonal colour patterns confirms that the variations in tone correspond to variations in preserved cuticle thickness. These preserved colour patterns can thus be plausibly explained as melanin-based patterning. Recognition of melanin-based colour patterns in fossil insects opens new avenues for interpreting the evolution of insect coloration and behaviour through deep time.
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- 2023
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122. Allometric wing growth links parental care to pterosaur giantism.
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Yang Z, Jiang B, Benton MJ, Xu X, McNamara ME, and Hone DWE
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- Animals, Wings, Animal, Locomotion, Body Size, Flight, Animal, Biological Evolution, Fossils
- Abstract
Pterosaurs evolved a broad range of body sizes, from small-bodied early forms with wingspans of mostly 1-2 m to the last-surviving giants with sizes of small airplanes. Since all pterosaurs began life as small hatchlings, giant forms must have attained large adult sizes through new growth strategies, which remain largely unknown. Here we assess wing ontogeny and performance in the giant Pteranodon and the smaller-bodied anurognathids Rhamphorhynchus , Pterodactylus and Sinopterus . We show that most smaller-bodied pterosaurs shared negative allometry or isometry in the proximal elements of the fore- and hindlimbs, which were critical elements for powering both flight and terrestrial locomotion, whereas these show positive allometry in Pteranodon . Such divergent growth allometry typically signals different strategies in the precocial-altricial spectrum, suggesting more altricial development in Pteranodon . Using a biophysical model of powered and gliding flight, we test and reject the hypothesis that an aerodynamically superior wing planform could have enabled Pteranodon to attain its larger body size. We therefore propose that a shift from a plesiomorphic precocial state towards a derived state of enhanced parental care may have relaxed the constraints of small body sizes and allowed the evolution of derived flight anatomies critical for the flying giants.
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- 2023
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123. Pterosaur melanosomes support signalling functions for early feathers.
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Cincotta A, Nicolaï M, Campos HBN, McNamara M, D'Alba L, Shawkey MD, Kischlat EE, Yans J, Carleer R, Escuillié F, and Godefroit P
- Subjects
- Animals, Pigmentation, Biological Evolution, Dinosaurs anatomy & histology, Feathers, Fossils, Melanosomes
- Abstract
Remarkably well-preserved soft tissues in Mesozoic fossils have yielded substantial insights into the evolution of feathers
1 . New evidence of branched feathers in pterosaurs suggests that feathers originated in the avemetatarsalian ancestor of pterosaurs and dinosaurs in the Early Triassic2 , but the homology of these pterosaur structures with feathers is controversial3,4 . Reports of pterosaur feathers with homogeneous ovoid melanosome geometries2,5 suggest that they exhibited limited variation in colour, supporting hypotheses that early feathers functioned primarily in thermoregulation6 . Here we report the presence of diverse melanosome geometries in the skin and simple and branched feathers of a tapejarid pterosaur from the Early Cretaceous found in Brazil. The melanosomes form distinct populations in different feather types and the skin, a feature previously known only in theropod dinosaurs, including birds. These tissue-specific melanosome geometries in pterosaurs indicate that manipulation of feather colour-and thus functions of feathers in visual communication-has deep evolutionary origins. These features show that genetic regulation of melanosome chemistry and shape7-9 was active early in feather evolution., (© 2022. The Author(s).)- Published
- 2022
- Full Text
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124. Synchrotron X-ray absorption spectroscopy of melanosomes in vertebrates and cephalopods: implications for the affinity of Tullimonstrum .
- Author
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Rogers CS, Astrop TI, Webb SM, Ito S, Wakamatsu K, and McNamara ME
- Subjects
- Animals, Fossils, Melanins, Phylogeny, Pigmentation, Synchrotrons, X-Ray Absorption Spectroscopy, Biological Evolution, Cephalopoda, Melanosomes, Vertebrates
- Abstract
Screening pigments are essential for vision in animals. Vertebrates use melanins bound in melanosomes as screening pigments, whereas cephalopods are assumed to use ommochromes. Preserved eye melanosomes in the controversial fossil Tullimonstrum (Mazon Creek, IL, USA) are partitioned by size and/or shape into distinct layers. These layers resemble tissue-specific melanosome populations considered unique to the vertebrate eye. Here, we show that extant cephalopod eyes also show tissue-specific size- and/or shape-specific partitioning of melanosomes; these differ from vertebrate melanosomes in the relative abundance of trace metals and in the binding environment of copper. Chemical signatures of melanosomes in the eyes of Tullimonstrum more closely resemble those of modern cephalopods than those of vertebrates, suggesting that an invertebrate affinity for Tullimonstrum is plausible. Melanosome chemistry may thus provide insights into the phylogenetic affinities of enigmatic fossils where melanosome size and/or shape are equivocal.
- Published
- 2019
- Full Text
- View/download PDF
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