161 research outputs found
Dorsal views of giant and tiny pterosaur humeri.
No full text<p>A, <i>Quetzalcoatlus northropi</i> (10–11 m wingspan); B, <i>Pteranodon</i> (7 m wingspan); C, <i>Pterodactylus</i> (45 cm wingspan). Note that each bears a large deltopectoral crest (dp) and robust extremities. Scale bars represent 100 mm (A and B) and 10 mm (C). A and C, from Witton <i>et al. </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013982#pone.0013982-Witton4" target="_blank">[121]</a>; B, modified from Bennett <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013982#pone.0013982-Bennett2" target="_blank">[12]</a>.</p
A small azhdarchoid pterosaur from the latest Cretaceous, the age of flying giants
No full textPterosaur fossils from the Campanian–Maastrichtian of North America have been reported from the continental interior, but few have been described from the west coast. The first pterosaur from the Campanian Northumberland Formation (Nanaimo Group) of Hornby Island, British Columbia, is represented here by a humerus, dorsal vertebrae (including three fused notarial vertebrae), and other fragments. The elements have features typical of Azhdarchoidea, an identification consistent with dominance of this group in the latest Cretaceous. The new material is significant for its size and ontogenetic stage: the humerus and vertebrae indicate a wingspan of ca 1.5?m, but histological sections and bone fusions indicate the individual was approaching maturity at time of death. Pterosaurs of this size are exceedingly rare in Upper Cretaceous strata, a phenomenon commonly attributed to smaller pterosaurs becoming extinct in the Late Cretaceous as part of a reduction in pterosaur diversity and disparity. The absence of small juveniles of large species—which must have existed—in the fossil record is evidence of a preservational bias against small pterosaurs in the Late Cretaceous, and caution should be applied to any interpretation of latest Cretaceous pterosaur diversity and success
New insights into the skull of Istiodactylus latidens (Ornithocheiroidea, Pterodactyloidea)
No full textThe skull of the Cretaceous pterosaur Istiodactylus latidens, a historically important species best known for its broad muzzle of interlocking, lancet-shaped teeth, is almost completely known from the broken remains of several individuals, but the length of its jaws remains elusive. Estimates of I. latidens jaw length have been exclusively based on the incomplete skull of NHMUK R3877 and, perhaps erroneously, reconstructed by assuming continuation of its broken skull pieces as preserved in situ. Here, an overlooked jaw fragment of NHMUK R3877 is redescribed and used to revise the skull reconstruction of I. latidens. The new reconstruction suggests a much shorter skull than previously supposed, along with a relatively tall orbital region and proportionally slender maxilla, a feature documented in the early 20(th) century but ignored by all skull reconstructions of this species. These features indicate that the skull of I. latidens is particularly distinctive amongst istiodactylids and suggests greater disparity between I. latidens and I. sinensis than previously appreciated. A cladistic analysis of istiodactylid pterosaurs incorporating new predicted I. latidens skull metrics suggests Istiodactylidae is constrained to five species (Liaoxipterus brachyognathus, Lonchengpterus zhoai, Nurhachius ignaciobritoi, Istiodactylus latidens and Istiodactylus sinensis) defined by their distinctive dentition, but excludes the putative istiodactylids Haopterus gracilis and Hongshanopterus lacustris. Istiodactylus latidens, I. sinensis and Li. brachyognathus form an unresolved clade of derived istiodactylids, and the similarity of comparable remains of I. sinensis and Li. brachyognathus suggest further work into their taxonomy and classification is required. The new skull model of I. latidens agrees with the scavenging habits proposed for these pterosaurs, with much of their cranial anatomy converging on that of habitually scavenging birds
Topotype specimens probably attributable to the giant azhdarchid pterosaur Arambourgiania philadelphiae (Arambourg 1959)
No full textA new pterosaur specimen from the Upper Tunbridge Wells Sand Formation (Cretaceous, Valanginian) of southern England and a review of <i>Lonchodectes sagittirostris</i> (Owen 1874)
No full textTh e new giant pterosaurs: novel anatomies and habits in the largest fl ying animals
No full textAbstract Azhdarchid pterosaurs, a derived group of Cretaceous pterodactyloids, are among the most famous of all fl ying reptiles. Instrumental to this fame is the attainment of giant proportions by several azhdarchid species, such as Quetzalcoatlus northropi and Hatzegopteryx thambema, which are the largest fl ying animals known with estimated wingspans of 10 m
The probable azhdarchid trace fossil <i>Haenamichnus uhangriensis</i>.
No full text<p>A, the 7.3 m trackway CNUPH.P9; B, <i>H. uhangriensis</i> holotype (CNUPH.P2), manus (top) and pes (bottom) prints. Modified from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002271#pone.0002271-Hwang1" target="_blank">[46]</a>. Scale bars represent 1 m (A) and 100 mm (B).</p
A comparison between primary grasslands and abandoned quarries of the magnesian limestone, county Durham, with special reference to scrub invasion
No full textSeven grassland Sites of Special Scientific Interest on the Magnesian Limestone of County Durham were botanically surveyed using the methodology of the National Vegetation Classification. Both primary grasslands and grassland developed in abandoned quarries were included, but the sampling was limited to open calcicolous grassland and scrub-invaded grassland, with areas of impenetrable scrub and woodland being avoided. Characteristic of these grasslands is blue moor grass, Sesleria albicans, which reaches its southern lowland limit in County Durham. The results were analysed using multivariate techniques to reveal patterns in community composition and possible environmental factors causing this variation. Six main communities are described, comprising both grassland and scrub vegetation. A successional sequence linking these communities and their sub-communities is postulated. It is suggested that abandoned quarries are floristically different from primary grasslands, but may achieve similarity in time if there is a nearby seed source of S. albicans. Scrub invasion, mainly by hawthorn, Crataegus monogyna, is ubiquitous in both the primary and secondary grasslands and presents the major threat to the integrity of the limestone flora. The botanical survey reveals a significant change to the flora under scrub, with some of the low-growing calcicoles being partially replaced by tall nutrient-demanding grasses and herbaceous species. However, the invasion of willow (Salix spp.) at one of the abandoned quarries has had negligible impact on the ground flora. The two most common scrub species, hawthorn and dog rose (Rosa canina agg.) appear to have more influence on the ground flora than any other species. It is suggested that the age of these species is more important than density in altering the ground flora. The results of this investigation have been used to make tentative suggestions for management of the sites
El viaje y los objetos en la obra poética de Marina Tsvietáieva
No full textSpa: ste proyecto de investigación tiene como objetivo profundizar en la experiencia exílica de la poeta rusa Marina Tsvietáieva. Para ello, se plantea el desplazamiento en términos del viaje en tres etapas: pérdida, travesía y retorno. En cada uno de estos se localizan objetos que demuestran una transformación de sentido lírico y compositivo que crea la poeta. Para profundizar en los objetos como espacios de
creación, se consideraron los postulados de Gastón Bachelard en su obra La poética del espacio. De este modo, el primer capítulo corresponde a un estado de la cuestión, una revisión de investigaciones, artículos académicos y tesis alrededor del exilio en Tsvietáieva. El segundo capítulo está dedicado a los objetos inmersos en el valor de la pérdida y la construcción de una poética alrededor de la separación. El tercer
capítulo centra su análisis en la travesía, rastreando, sobre todo, un conjunto de objetos que dan cuenta de desplazamientos y caminos poéticos. Por último, el cuarto capítulo recolecta objetos que reflejan la experiencia vital del retorno.Eng: This thesis aims to delve into the exilic experience of the Russian poet Marina Tsvetaeva. To this end, displacement is posed in terms of the journey in three stages: loss, crossing and return. In each of these, objects demonstrate a transformation of lyrical and compositional meaning by the poet. To deepen in the objects as spaces of creation, the postulates of Gaston Bachelard in his work The Poetics of Space
were considered. Thus, the first chapter corresponds to a literature review concerning on Tsvetaeva‘s exile. The second chapter is dedicated to the objects immersed in the value of loss and the construction of poetics around separation. The third chapter focuses its analysis on the journey, mainly tracing a set of objects that account for displacements and poetic paths. Finally, the fourth chapter collects objects that
reflect the vital experience of return.Bibliografía y webgrafía: páginas 1230-124.MaestríaMagister en Literatur
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