156 research outputs found

    Réponse à Didier Fassin

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    L’argumentation de mon collègue Didier Fassin s’attache dans le détail à dire que Le déni des cultures est un travail « scientifiquement infondé », elle ne propose pas une ligne d’interprétation alternative. Je vais aborder les remarques sur la cohérence puis j’essaierai de montrer que, au-delà des points de méthode et d’analyse statistique, c’est l’ensemble de ma démarche qui a peut-être été mal comprise par l’auteur. Ce que suggèrent aussi quelques citations tronquées. [Premier paragraphe

    Fourth Amendment Accommodations: (UN)Compelling Public Needs, Balancing Acts, and the Fiction of Consent

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    The problems of public housing-including crime, drugs, and gun violence- have received an enormous amount of national attention. Much attention has also focused on warrantless searches and consent searches as solutions to these problems. This Note addresses the constitutionality of these proposals and asserts that if the Supreme Court\u27s current Fourth Amendment jurisprudence is taken to its logical extremes, warrantless searches in public housing can be found constitutional. The author argues, however, that such an interpretation fails to strike the proper balance between public need and privacy in the public housing context. The Note concludes by proposing alternative consent-based regimes that would pass constitutional muster

    Comprendre les brachiopodes linguloides : Obulus et Ungula comme exemples

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    EMIG (2002) a revu la taxonomie du genre Obolus EICHWALD du Cambrien moyen - Ordovician basal des régions baltes orientales dans le cadre d'un projet de révision de l'ensemble des critères de la systématique des linguloides. Il a suggéré que les études taxonomiques antérieures sur Obolus et les formes apparentées sont fondées à tort sur des caractères dépourvus de toute valeur taxonomique. La révision proposées par EMIG s'appuie principalement sur les faibles variations morphologiques observées entre taxons fossiles et récents au sein d'une seule famille de linguloide, les Lingulidae. Notre article s'attache à démontrer la validité taxonomique des critères diagnostiques utilisés dans la classification au sein des familles, pour la plupart éteintes, de la Superfamille des Linguloidea, car ils présentent une bien plus grande diversité morphologique. Cette étude montre aussi que EMIG n'a pas proposé une base satisfaisante pour étayer les changements et révisions radicaux qu'il souhaite apporter à la taxonomie, en vigueur et largement acceptée, des Obolidae des séries du Cambrien à l'Ordovician basal des régions baltes orientales. Obolus EICHWALD et Ungula PANDER sont considérés comme des genres distincts comprenant les espèces Obolus apollinis EICHWALD, O. ruchini KHAZANOVITCH et POPOV, O. transversus (PANDER), Ungula ingrica (EICHWALD), U. inornata (MICKWITZ) et U. convexa PANDER.EMIG (2002) re-examined the taxonomy of the genus Obolus EICHWALD from the Middle Cambrian - earliest Ordovician of the East Baltic region as part of a proposal for a wholesale revision of the principles of linguloid systematics. He contended that previous taxonomic studies on Obolus and related forms were carried out erroneously using characters that have no taxonomic value. EMIG´s proposed revision is based mainly on the limited morphological diversity between fossil and Recent taxa within a single linguloid Family, the Lingulidae. However, the present study demonstrates the taxonomic validity of the diagnostic characters used for classification within the mostly extinct families of the Superfamily Linguloidea, for they exhibit far more variation in morphology. This study also shows that EMIG has provided no satisfactory basis for his radical changes and revisions to the existing widely accepted taxonomy of the Cambrian to earliest Ordovician Obolidae of the East Baltic. Obolus EICHWALD and Ungula PANDER are shown to constitute distinctive and discrete genera comprising the species Obolus apollinis EICHWALD, O. ruchini KHAZANOVITCH et POPOV, O. transversus (PANDER), Ungula ingrica (EICHWALD), U. inornata (MICKWITZ), and U. convexa PANDER

    Reconstruction of the first consumer-driven marine ecosystem on Earth, perspectives from early Cambrian small skeletal fossils from China

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    Biological activity was the major triggering factor driving Earthâs organic and inorganic cycles across the biosphere, lithosphere, and atmosphere. A key question in the evolution of Earthâs ecosystem is when and how different animals emerged and flourished and how their appearance impacted the hydrosphere-atmosphere-lithosphere cycles. The Cambrian Explosion of metazoans in the EdiacaranâCambrian boundary interval resulted in sudden appearance of most of the readily fossilizable modern animal groups as macro-consumers in the Earthâs oceans. This explosive radiation event led for the first time to the emergence and diversification of animals on Earth, to the establishment of complex trophic webs with animals as consumers, and marks the onset of the Phanerozoic oceanic ecosystem. Our presentation aims to discuss the at least half-billion-year-old world of tubular and conical shelled organisms (sponges, conulariids, chancelloriids, hyoliths, mollusks, tommotiids, and other lophotrochozoans) that are unseen in the present-day oceans but were recovered by us from the siliciclastic and carbonate rocks in and outside of China. Additionally, to study the body fossils of exceptionally preserved biotas (Konversat-Lagerstätten) across China, efforts are underway to understand how the early animals, notably early bilaterians, created the over 500-million-year-old oceanic ecosystems without the influence of land plants, which appeared later

    Siphonotretoid brachiopods – a thorny problem

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    Siphonotretoids are presently placed within the subphylum Linguliformea and the class Lingulata, where they constitute a small, relatively short-lived superfamily and order, appearing near the end of the mid-Cambrian, with most forms becoming extinct near the end of the Late Ordovician, but with some rare forms ranging through the Silurian and even into the early Devonian. It has been noted previously that siphonotretides are very different from all other lingulates in shell structure, ontogeny and ornamentation, and may have diverged from other lingulates already during the early Cambrian. Findings of exceptionally preserved âsoft-shelledâ possible early stem-group setigerous representatives such as Acanthotretella in the Burgess Shale and the Chengjiang fauna have strengthened this view. Exceptionally preserved siphonotretides from Iran clearly show that they are provided with organic setal structures associated with spines, and similar setal structures are known from stem brachiopods, such as Micrina and Mickwitzia, as well as from some later true rhynchonelliforms. Evidence for preserved setal structures is now also recorded from the CambrianâOrdovician boundary beds in Wyoming. In the Ordovician, the spinous structures include complex branching forms, such as the widely distributed Alichovia, and Siphonotreta itself has clear evidence of branching spines. The branching spines probably also contained setal structures, and similar forked setae are known from living annelids

    Soft-Part Preservation in a Linguliform Brachiopod from the Lower Cambrian Wulongqing Formation (Guanshan Fauna) of Yunnan, South China

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    Late Ordovician gastropods from the Zhaolaoyu Formation in the southwestern margin of the North China Platform

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    The Ordos Basin is located in the western part of the North China Platform and is the second largest sedimentary basin in China; the basin has a huge thickness of the Early Palaeozoic marine deposits, especially the Ordovician ones. The Zhaolaoyu Formation is distributed in the Fuping area of the southern Ordos Basin, where brachiopods, gastropods, graptolites, sponge spicules and ichnofossils are abundant. Ordovician gastropods are abundant, widespread and well known from different palaeocontinents across the world and are important for the study of biogeography and palaeoenvironments of the Ordovician. However, gastropods from the Ordovician in the Ordos Basin of North China have been rarely documented. The Early to Middle Ordovician of gastropod fauna from the Zhouzishan area, Inner Mongolia, western Ordos Basin, is dominated by the discoidal gastropods with a three to four whorls. Twelve genera of gastropods from the Ordovician of the western and southern Ordos Basin were documented, all with larger spire angle and up to four whorls. Since then, no other Ordovician gastropod fossils have been reported from the Ordos Basin. Herein, we reported and illustrated a gastropod fauna from the Late Ordovician in the Ordos Basin of North China. All gastropod specimens were preserved as internal moulds, which were manually picked from the residues after the samples were chemically dissolved in buffered acetic acid (5â10%). The fauna was recovered from the Zhaolaoyu Formation at the Zhaolaoyu section, Fuping County and consists of several species: Hormotoma sp., Lophonema sp., Lophospira sp. and Lophospira cf. sinensis. This fauna is dominated by high-spired gastropods with more than five whorls and provides an important supplement to the palaeontological information of the studied area

    When lingulid brachiopods became infaunal(?) – perspectives from the morphological and anatomical information

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    Morphology usually serves as an effective proxy for functional ecology, and the evaluation of morphological, anatomical, and ecological changes allows for a deeper understanding of the nature of diversification and macroevolution. Lingulid (Order Lingulida) brachiopods were diverse and abundant during the early Palaeozoic, but decreased in diversity over time, with only a few genera of linguloids and discinoids present in modern marine ecosystems, frequently referred to as âliving fossilsâ. The dynamics that drove this decline remain unclear and it has not been determined if there is an associated decline in morphological and ecological diversity. We applied geometric morphometrics to reconstruct global morphospace occupied by lingulid brachiopods through the Phanerozoic, with results showing that maximum morphospace occupation was reached in the Early Ordovician. At this time of peak diversity, linguloids with sub-rectangular shells already possessed several evolutionary features common to all modern infaunal forms such as the rearrangement of mantle canals and reduction of the pseudointerarea. The end-Ordovician mass extinction had a differential effect on linguloids, disproportionally wiping out those with rounded shells whilst forms with sub-rectangular shells survived both the end-Ordovician and the PermianâTriassic mass extinctions, with post-extinction faunas predominantly composed of infaunal forms. For discinoids, both morphospace occupation and epi-benthic life strategies remain consistent through the Phanerozoic. Analysis of the morphospace occupation of lingulids over time, taking into account their body size, anatomical features and ecological changes, suggests that the reduced morphological and ecological diversity observed in modern lingulid brachiopods reflects evolutionary contingency rather than deterministic processes

    Stratigraphy 12 (2) Biostratigraphy of the Cambrian-Ordovician boundary beds at Kopet-Dagh, Iran

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    ABSTRACT: A continuous succession comprising upper Cambrian (Furongian) to Lower Ordovician (Tremadocian) conodont biozones is reported for the first time from the Kopet-Dagh Region of northeastern Iran. Seven biostratigraphical units are recognized, including the Proconodontus tenuiserratus and Proconodontus posterocostatus zones; these two lowermost biostratigraphical units are defined by euconodont species which have not been previously reported from Iran and temperate latitude peri-Gondwana. The conodont diversity and abundance decreased significantly above the Eoconodontus notchpeakensis Zone; the conodont faunas of the succeeding Cordylodus proavus, Cordylodus lindstromi (sensu lato) and Cordylodus angulatus zones are characterised by oligotaxic to monotaxic associations dominated by species of Cordylodus. In the absence of diagnostic conodont species, the position of the lower boundary of the Ordovician System in the Kalat Valley Section can be placed somewhat below the first occurrence of the early planktonic graptolite Rhabdinopora flabelliformis, which approximately coincides with the onset of black shale deposition
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