1,720,991 research outputs found
The fossil record of birds from the James Ross Basin, West Antarctica
Get PDFThe fossil record of birds from Antarctica is concentrated in the James Ross Basin, located in north-east of the Antarctic Peninsula. Birds are here represented by an extensive Paleogene record of penguins (Sphenisciformes) and Cretaceous–Paleogene record of Anseriformes, followed by other groups with a minor representation (Procellariiformes, Falconiformes, and Pelagornithidae), and others previously assigned controversially to “Ratites”, Threskiornithidae, Charadriiformes, Gruiformes, Phoenicopteriformes, and Gaviiformes. We provide a complete update of these records, commenting on the importance of some of these remains for the evolution of the major clades.Fil: Acosta Hospitaleche, Carolina Ileana Alicia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Jadwiszczak, Piotr. University Of Bialystok; PoloniaFil: Clarke, Julia A.. University of Texas at Austin; Estados UnidosFil: Cenizo, Marcos. Museo de Historia Natural de La Pampa, División Paleontología; Argentina. Fundación de Historia Natural Félix de Azara; Argentin
No solo cauquenes: presencia de Anas georgica (pato maicero) en el sitio Laguna Las Vegas (cuenca media del río Coyle, Santa cruz, Argentina)
Get PDFEn el sitio Laguna Las Vegas, en la estepa de Patagonia continental austral, se evidenció la explotación antrópica de cauquenes (Chloephaga sp.). Se propuso que su obtención habría sucedido en cercanías del sitio y se habrían transportado hacia allí las partes esqueletarias de mayor rinde económico junto con las unidades anatómicas asociadas (Belardi y Stoessel, 2022). Los fechados radiocarbónicos indican la contemporaneidad aproximada en la depositación de los materiales arqueológicos (artefactos líticos y restos arqueofaunísticos entre los que predominan los de guanaco, Lama guanicoe) alrededor de 3200 años AP (Belardi y Stoessel, 2022, Stoessel et al., 2021). Con posterioridad a la publicación del trabajo se advirtió un error en la asignación de algunos restos a ejemplares juveniles de Chloephaga sp. Se informa su correcta determinación y se ponderan las implicaciones sobre la presencia de aves en el sitio.Fil: Cenizo, Marcos Martín. Fundación de Historia Natural Félix de Azara; ArgentinaFil: Belardi, Juan Bautista. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Santa Cruz. Universidad Tecnológica Nacional. Facultad Regional Santa Cruz. Centro de Investigaciones y Transferencia de Santa Cruz. Universidad Nacional de la Patagonia Austral. Centro de Investigaciones y Transferencia de Santa Cruz; ArgentinaFil: Stoessel, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano; Argentin
Ein der Stammgruppe Falconidae angehörender Vogel aus dem Untereozän der Antarktis und die frühe südliche Radiation der Falken
Get PDFAntarctoboenus carlinii nov. gen. nov. sp. is a large-sized falconiform bird from the La Meseta Formation (Lower Eocene) at Seymour (Marambio) Island, West Antarctica. The holotypical tarsometatarsus was originally assigned to Falconidae and its affinities to Polyborinae were pointed out. Detailed osteological and comparative analyses of the Antarctic specimen allowed recognition of the new taxon as a member of stem group Falconidae, i.e. it is supposed to belong to the early radiation of the falconiform lineage. Antarctoboenus carlinii is distinguished from members of crown group Falconidae by having a very shallow sulcus extensorius, a large foramen vasculare distale, an undistinguishable tendinal attachment for the m. adductor digiti II, and short trochlea metatarsi II, among its main diagnostic characters. Purported phylogenetic relationships between A. carlinii and Polyborinae are based on plesiomorphic characters retained in the tarsometatarsus of the latter clade. Our conclusions reinforce the hypothesis about the Neotropical or Austral origin of Falconidae supported by previous molecular phylogenies.Antarctoboenus carlinii nov. gen. nov. sp. ist ein großer falkenartiger Vogel aus der La Meseta Formation (Untereozän) auf der Seymour-Insel (Isla Marambio) in der Westantarktis. Der Holotyp-Tarsometatarsus wurde ursprünglich den Falconidae (Falkenartigen) zugeordnet, und seine Ähnlichkeiten mit den Polyborinae (Geierfalken) wurden hervorgehoben. Detaillierte osteologische und vergleichende Analysen des Antarktis-Exemplars ermöglichten es, das neue Taxon als ein Mitglied der Stammgruppe Falconidae anzuerkennen, d.h. es gehört vermutlich der frühen Radiation der Falconiformes-Abstammungslinie an. Antarctoboenus carlinii unterscheidet sich von den Mitgliedern der Kronengruppe Falconidae durch mehrere diagnostische Merkmale, u.a. einen sehr flachen sulcus extensorius, ein großes foramen vasculare distale, einen undeutlichen Sehnenansatz für den m. adductor digiti II und kurze trochlea metatarsi II. Angebliche phylogenetische Beziehungen zwischen A. carlinii und Polyborinae basieren auf plesiomorphen Merkmalen, die im Tarsometatarsus der Polyborinae erhalten sind. Unsere Schlussfolgerungen stärken die Hypothese eines Neotropen- oder Austral-Ursprungs der Falconidae, die auch von bisherigen molekularen Stammbäumen gestützt wird.Fil: Cenizo, Marcos. Fundación de Historia Natural Félix de Azara; Argentina. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; ArgentinaFil: Noriega, Jorge Ignacio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Reguero, Marcelo Alfredo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Late Miocene continental birds from the Cerro Azul Formation in the Pampean region (central-southern Argentina)
Get PDFThe oldest known birds from the Cerro Azul Formation are described, including the oldest records for the genera Eudromia and Nothura (Tinamidae), Milvago (Falconidae), Pterocnemia (Rheidae) and an undetermined Tyrannidae. The first remains of Phorusrhacidae for this formation are reported and a specimen previously referred to the giant teratorn Argentavis magnificens is reassigned to this family. We outline and update the current knowledge of the groups studied herein. The palaeornithological record from the Cerro Azul Formation is congruent with palaeoenvironmental inferences previously drawn from mammalian assemblages recovered from this unit, which point to the existence of open environments, possibly xerophyllous shrubby steppes, perhaps with some trees. These records are the first indications of a typically Pampean bird fauna at the end of the late Miocene in central-southern Argentina.Fil: Cenizo, Marcos Martín. Universidad Nacional de La Pampa; ArgentinaFil: Tambussi, Claudia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Montalvo, Claudia Inés. Universidad Nacional de La Pampa; Argentin
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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