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Ultrastructural analysis of the brachiopod shells of the Saiwan Fm. (Lower Permian, Oman) for isotope studies and paleoclimatic interpretation.
No full textGUADALUPIAN BRACHIOPODS FROM TUNISIA AND TURKEY: SYSTEMATICS AND PALAEOBIOGEOGRAPHIC IMPLICATIONS
No full textIn the present PhD Thesis two Guadalupian brachiopod faunas are described respectively
from succession cropping out at Djebel Tebaga de Medenine, S Tunisia, and from the
Guadalupian lower-middle part of the Pamuçak Formation at Çürük Dağ, Antalya (Turkey). The
study is based on collection already available in Dipartimento di Scienze della Terra “A. Desio”,
Milano and on material newly collected by the writer. The taxonomic study and description of
the brachiopod collections, based on the observations of the macro- and micro- external and
internal morphological features, with critical comparison with the available literature, has
allowed the determinations of 1260 specimens at generic and specific level into 68 species
(including the undetermined ones) and 42 genera; they belong to orders Productida, Orthotetida,
Orthida, Rhynchonellida, Athyridida, Spiriferida and Terebratulida for the Tunisian fauna; to the
orders Productida, Orthotetida, Orthida, Rhynchonellida, Athyridida, Spiriferida, Spiriferinida
and Terebratulida for the Turkish fauna.
Five new species and two new genera are identified and established and are in press in two
publications (Verna et al. in press a, b). Several brachiopod taxa are revised and their diagnostic
characters better identified in order to make their determination, up to now problematic, easier
(i.e. Squamularia Gemmellaro, 1899 and Permophricodothyris Pavlova). In the course of this
research, the Gemmellaro collection of brachiopods from Sosio, Sicily has been also revised in
part.
The stratigraphic range of the Tunisian brachiopods is consistent with the Wordian- early
Capitanian age suggested by the associated fusulinids and conodonts which are the tools on
which the Permian Time Scale is based, allowing the correlation of the International (Global)
with the Tethyan regional scale, particularly for the Guadalupian part.
The age of the Turkish brachiopods coming from the lower middle part of the Pamuçak
Formation is mid-Roadian to Capitanian, based on conodonts, fusulinids and already published
data (Angiolini et al. 2007). The brachiopod record at Çürük Dağ section (Turkey) has
implications to understand the pattern of the end-Guadalupian biotic crisis which is here
represented by highly diversified pre-crisis assemblages terminating rather abruptly and being
followed by Lopingian brachiopod taxa which show a significantly lower biodiversity.
The last part of this study consists of a palaeobiogeographic analysis based on the
comparison of the brachiopod faunas from Tunisia and Turkey originally collected and studied by the writer, with coeval ones described in several publications in the recent and distant past
coming from the successions of Sosio (Sicily), Oman, N Iran, Central Afghanistan, Karakorum,
Salt Range, SE Thailand. This palaeobiogeographic analysis aims to test the palaeogeographic
reconstructions, independently derived from palaeomagnetic data and to derive the possible
dispersal pattern of the brachiopod genera during the Guadalupian. The methods used for this
analysis are cluster analysis and principal coordinate analysis (PCO), based on the similarity
indices of Jaccard and Simpson applied to a presence/absence data matrix (taxa per geographic
areas) of the brachiopod genera coming from Tunisia, Turkey and the other faunal stations
quoted above, using the software PAST (Hammer et al. 2001). The palaeobiogegraphic affinities
of the analyzed faunal stations are in agreement with the Guadalupian palaeogeographic
reconstruction based on palaeomagnetic data of Muttoni et al. (2009) and indicates a consistent
degree of isolation of Tunisia and Sosio from the other regions and strong faunal links between
Turkey and the Gondwanan margins, represented by Oman, Salt Range and S Thailand
Guadalupian brachiopod faunas from Tunisia, Turkey and North Iran and their implications for correlations across the Neo-Tethys
No full textVoorkomen en standplaats van Veronica praecox All. en V. verna L. in Nederland
No full textA few years ago, Veronica praecox en V. verna were supposed to be extinct in the Netherlands, being recorded for the last time in 1935 and 1947, respectively. In 1974 both were refound, however.
Formerly, V. praecox occurred on arable land in the Yssel valley in the surroundings of Deventer and at some localities south of Maastricht. The latter connect with localities in Belgium; the former constitute a kind of ‘outpost area’ northwest of the border of the species’ serried area. Possibly V. praecox, together with a few other species, can be looked upon as a ‘xerothermic relic’ there. Its habitat on the only recent locality near Gorssel (south of Deventer), where in the vicinity of V. praecox amongst others Vicia lathyroides, Saxifraga tridactylites and Holosteum umbellatum occur, is in accordance with that in Central Europe.
V. verna, one of the scarce irano-turanic elements in the West and Central European flora and very rare in most of western Europe, was recorded from some scattered outposts in the Dutch coastal area; recently it is only known from Aerdenhout near Haarlem. It is found there on slightly eroded spots on a sunny western slope in the old inner dunes poor in lime. Its habitat is obviously influenced by men and animals. The community in which V. verna occurs is a slightly ruderalized Tortulo-Phleetum without lichens ( table 1)
Guadalupian Palaeobiogeography across the Neotethys Ocean.
No full textThe Guadalupian was a period of climate change and plate tectonic reconfiguration. Climate changed from glacial conditions at the dawn of the Permian to warm global conditions in the Guadalupian. The Cimmerian terranes migrated from southern Gondwanan paleolatitudes in the Early Permian to subequatorial paleolatitudes by the Middle-Late Permian as the result of the opening of the Neo-Tethys Ocean. This opening was asymmetrical, with higher seafloor spreading rates for the central Cimmerian terranes (central Afghanistan, Karakoram) than for the western terranes (Iran), and it took place contemporaneously with the transformation of Pangea from an Irvingian B to a Wegenerian A-type configuration. During this Early to Middle Permian tectono-climatic transition, bioprovincial patterns evolved rapidly across the southern and northern margins of the opening Neo-Tethys Ocean, making brachiopod palaeobiogeography a useful tool to test its complex opening. Guadalupian (Wordian) brachiopod faunas from Sicily, Tunisia, Turkey, Oman, N Iran, Central Afghanistan, Karakorum, Salt Range and S Thailand have been compared by multivariate analysis to test their similarity and pattern of distribution.
The results of cluster analysis and principal coordinate analysis have been placed on an independently derived palaeogeographic reconstruction, allowing to draw the following conclusions: (i) Central Afghanistan and Karakorum faced the Palaeotethys open ocean and were bathed by a palaeoequatorial current that dispersed larvae towards the Tethyan Gulf and the Gondwanan margin. (ii) Tunisia and Sicily (Sosio) were located in the westernmost Tehyan Gulf were thus more prone to isolation with respect to Tethyan open ocean faunas. (iii) N Iran shows affinitities to the Perigondwanan regions of Turkey, Oman, and Salt Range being only slightly detatched from the Gondwanan margin due to the incipient opening of the Neotethys; a current gyre bathed both the Gondwanan margin and the Iranian block. (iv) S Thailand and the Salt Range shows affinitities to the northern Gondwanan margin
Paleobiogeography of the Permian Neo-Thetys shores
No full textThe Permian was a period of marked climate change and plate-tectonic reconfiguration. Climate changed from glacial conditions at the dawn of the period to warm conditions in the Middle Permian. The Cimmerian terranes migrated from southern Gondwanan paleolatitudes in the Early Permian to subequatorial paleolatitudes by the Middle – Late Permian as the result of the opening of the Neo-Tethys Ocean. This opening was asymmetrical, with higher seafloor spreading rates for the central Cimmerian terranes (central Afghanistan, Pakistan and Karakoram) than for the western terranes (Iran), and it took place contemporaneously with the transformation of Pangea from an Irvingian B- to a Wegenerian A-type configuration. During this Early to Middle Permian tectono-climatic transition, bioprovincial patterns evolved rapidly across the southern and northern margins of the opening Neo-Tethys Ocean, as testified by the rich fossil record. Here we place climate-sensitive biotic associations on paleomagnetically based paleogeographic reconstructions of the Gondwanan margin and the Cimmerian blocks for the Early and Middle Permian and use them to reconstruct the evolution of oceanic circulation patterns, latitudinal thermal gradients, and biogeography in this time interval. We show that, in the Early Permian, the tropical Gondwanan margin and the western Cimmerian terranes benefited from a warm subtropical surface current gyre, which was confined to low latitudes. At the same time at higher southern latitudes, the central Cimmerian terranes were affected by cold surface currents promoted by the Gondwanan ice caps that distributed cold biota toward the tropics. These results suggest that low-latitude, sea-surface temperature did not undergo significant cooling during the Gondwanan glaciation, and that there was a steep thermal gradient between the compressed tropical belt and the expanded cold high-latitude belt. This situation changed abruptly in the Middle Permian with the creation of current gyres in the newly opened Neo-Tethys Ocean that arranged biotic associations in distinct bioprovinces. Wordian brachiopods from the western Cimmerian terranes contain a significant proportion of Gondwanan taxa some of which are restricted to the Gondwanan margin (Tunisia, Turkey and Oman). Coeval brachiopods from central Cimmerian terranes are different and pertain to a separate, low-latitude bioprovince supporting the paleomagnetically derived differential drift of Cimmerian terranes
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
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