380 research outputs found

    Reassessment of the evidence for postcranial skeletal pneumaticity in Triassic archosaurs, and the early evolution of the avian respiratory system.

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    Uniquely among extant vertebrates, birds possess complex respiratory systems characterised by the combination of small, rigid lungs, extensive pulmonary air sacs that possess diverticula that invade (pneumatise) the postcranial skeleton, unidirectional ventilation of the lungs, and efficient crosscurrent gas exchange. Crocodilians, the only other living archosaurs, also possess unidirectional lung ventilation, but lack true air sacs and postcranial skeletal pneumaticity (PSP). PSP can be used to infer the presence of avian-like pulmonary air sacs in several extinct archosaur clades (non-avian theropod dinosaurs, sauropod dinosaurs and pterosaurs). However, the evolution of respiratory systems in other archosaurs, especially in the lineage leading to crocodilians, is poorly documented. Here, we use ÂľCT-scanning to investigate the vertebral anatomy of Triassic archosaur taxa, from both the avian and crocodilian lineages as well as non-archosaurian diapsid outgroups. Our results confirm previous suggestions that unambiguous evidence of PSP (presence of internal pneumatic cavities linked to the exterior by foramina) is found only in bird-line (ornithodiran) archosaurs. We propose that pulmonary air sacs were present in the common ancestor of Ornithodira and may have been subsequently lost or reduced in some members of the clade (notably in ornithischian dinosaurs). The development of these avian-like respiratory features might have been linked to inferred increases in activity levels among ornithodirans. By contrast, no crocodile-line archosaur (pseudosuchian) exhibits evidence for unambiguous PSP, but many of these taxa possess the complex array of vertebral laminae and fossae that always accompany the presence of air sacs in ornithodirans. These laminae and fossae are likely homologous with those in ornithodirans, which suggests the need for further investigation of the hypothesis that a reduced, or non-invasive, system of pulmonary air sacs may be have been present in these taxa (and secondarily lost in extant crocodilians) and was potentially primitive for Archosauria as a whole

    Inferring the Characteristics of Ancient Populations using Bioinformatic Analysis of Genome-wide DNA Sequencing Data

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    In this thesis, I apply, evaluate, and develop methods for learning about past populations from genome-wide sequencing data. Specifically, I: • apply methods based on random genetic drift between populations, to determine that pre-Holocene gene flow occurred between the ancestors of domestic cattle (Bos primigenius) and European bison (Bison priscus), and that the contribution of Bos genealogy to the bison lineage was less than 10 %; • use simulations to assess the impact of short genomic scaffolds when inferring past populations sizes with the pairwise sequentially Markov coalescent, and show that population size inferences can be robust for scaffold lengths as short as 100 kb; • perform genetic sex determination of ancient DNA specimens to show that bison (Bison spp.) and brown bear (Ursus arctos) specimens are approximately 75% male, and that male-biased observations likely stem from the ecological and social structures of the populations; • and develop a suite of software tools for processing hairpin bisulfite sequencing data, which can be used to investigate genome-wide DNA methylation levels in ancient DNA.Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 201

    The last erythrosuchid-a revision of Chalishevia cothurnata from the late Middle Triassic of European Russia

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    Erythrosuchidae is a clade of early archosauriform reptiles that were large-bodied, hypercarnivorous, possibly apex predators in late Early and Middle Triassic ecosystems following the Permo-Triassic mass extinction. Chalishevia cothurnata from the late Middle Triassic (Ladinian) of Russia, is the stratigraphically youngest known erythrosuchid species, but the holotype and referred material of this taxon has received little study. Here, we provide the first detailed anatomical description of C. cothurnata, including comparisons to other erythrosuchids. Although known from relatively fragmentary material, the anatomy of C. cothurnata is distinctive, including an autapomorphic strongly slanted ventral border of the antorbital fossa. The presence of a large accessory opening (the “accessory antorbital fenestra”) in the skull between the premaxilla, nasal and maxilla, together with the inferred presence of a narrow postnarial process of the premaxilla that articulated with a slot on the nasal, provides strong evidence for a sister taxon relationship between C. cothurnata and the erythrosuchid Shansisuchus shansisuchus from the early Middle Triassic (Anisian) of China. The inferred basal skull length of C. cothurnata was approximately 80 cm, making it one of the largest erythrosuchids known.Fil: Butler, Richard. University of Birmingham; Reino UnidoFil: Sennikov, Andrey. Kazan Federal University. Institute of Geology and Petroleum Technologies; RusiaFil: Ezcurra, Martin Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Gower, David. Natural History Museum; Reino Unid

    The taxonomy and anatomy of rauisuchian archosaurs from the Late Triassic of Germany and Poland

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    The German Late Triassic archosaur Teratosaurus suevicus is a historically important taxon, being the first described rauisuchian. Unfortunately the holotype is a single element, a maxilla, which is poorly preserved and incomplete. We redescribe this maxilla and identify a single potential autapomorphy. The fragmentary type specimen complicates attempts to refer additional material to this taxon, and other unassociated archosaur and rauisuchian specimens from the Mittlerer Stubensandstein of Germany cannot be referred to T. suevicus with any degree of confidence. The stratigraphically older T. silesiacus, from the upper Carnian of Poland, is represented by a much more complete and better preserved specimen. Comparison of the maxillae of T. suevicus and T. silesiacus reveals that the two are distinct taxa, contra recent suggestions, but also that they do not share any synapomorphies or a unique combination of characters relative to Postosuchus kirkpatricki and other rauisuchians. Thus, the Polish material must be transferred to a new genus, Polonosuchus gen. nov. Both Polonosuchus and Teratosaurus are very similar to Postosuchus kirkpatricki, and the three taxa are likely closely related

    Primary physical education, coaches and continuing professional development

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    This is an Author's Accepted Manuscript of an article published in Sport, Education and Society, 16(4), 485 - 505, 2011, copyright @ Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/13573322.2011.589645.Physical education (PE) in primary schools has traditionally been taught by qualified primary teachers. More recently, some teaching of PE in primary schools has been undertaken by coaches (mostly football coaches). These coaches hold national governing body awards but do not hold teaching qualifications. Thus, coaches may not be adequately prepared to teach PE in curriculum time. The purpose of this study was to evaluate the perceptions of a group of community-based football coaches working in primary schools for the impact of a Continuing Professional Development (CPD) programme on their ability to undertake ‘specified work’ to cover PE in primary schools. The programme focused on four areas identified as important to enable coaches to cover specified work: short- and medium-term planning, pedagogy, knowledge of the curriculum and reflection. Results showed that for the majority of coaches the CPD programme had made them more aware of the importance of these four areas and had helped to develop their knowledge and ability to put this into practice in covering planning, preparation and assessment time. However, further input is still required to develop coaches’ knowledge and understanding in all four areas, but especially their curriculum knowledge, as well as their ability to put these into practice consistently. These findings are discussed in relation to the implications of employing coaches to cover the teaching of PE in primary schools and, if employed, what CPD coaches need to develop the necessary knowledge, skill and understanding for covering specified work in schools

    The New Generation Atlas of Quasar Spectral Energy Distributions from Radio to X-rays

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    We have produced the next generation of quasar spectral energy distributions (SEDs), essentially updating the work of Elvis et al. (1994) by using high-quality data obtained with several space and ground-based telescopes, including NASA's Great Observatories. We present an atlas of SEDs of 85 optically bright, non-blazar quasars over the electromagnetic spectrum from radio to X-rays. The heterogeneous sample includes 27 radio-quiet and 58 radio-loud quasars. Most objects have quasi-simultaneous ultraviolet-optical spectroscopic data, supplemented with some far-ultraviolet spectra, and more than half also have Spitzer mid-infrared IRS spectra. The X-ray spectral parameters are collected from the literature where available. The radio, far-infrared, and near-infrared photometric data are also obtained from either the literature or new observations. We construct composite spectral energy distributions for radio-loud and radio-quiet objects and compare these to those of Elvis et al., finding that ours have similar overall shapes, but our improved spectral resolution reveals more detailed features, especially in the mid and near-infrared.Comment: 46 pages, 10 figures, 10 tables, Accepted by ApJS. Composite SED data files for radio-loud and radio-quiet quasars (rlmsedMR.txt, rqmsedMR.txt) are included in the source (Other formats -> Source). Supplemental figures are not include

    Dietary carbohydrate restriction as the first approach in diabetes management:Critical review and evidence base

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    AbstractThe inability of current recommendations to control the epidemic of diabetes, the specific failure of the prevailing low-fat diets to improve obesity, cardiovascular risk, or general health and the persistent reports of some serious side effects of commonly prescribed diabetic medications, in combination with the continued success of low-carbohydrate diets in the treatment of diabetes and metabolic syndrome without significant side effects, point to the need for a reappraisal of dietary guidelines. The benefits of carbohydrate restriction in diabetes are immediate and well documented. Concerns about the efficacy and safety are long term and conjectural rather than data driven. Dietary carbohydrate restriction reliably reduces high blood glucose, does not require weight loss (although is still best for weight loss), and leads to the reduction or elimination of medication. It has never shown side effects comparable with those seen in many drugs. Here we present 12 points of evidence supporting the use of low-carbohydrate diets as the first approach to treating type 2 diabetes and as the most effective adjunct to pharmacology in type 1. They represent the best-documented, least controversial results. The insistence on long-term randomized controlled trials as the only kind of data that will be accepted is without precedent in science. The seriousness of diabetes requires that we evaluate all of the evidence that is available. The 12 points are sufficiently compelling that we feel that the burden of proof rests with those who are opposed
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