Search

International audience; Au cours de ces dernières années, les coupes les plus représentatives de la limite Permien-Trias en milieu marin ont été échantillonnées pour l'étude des ostracodes (Crustacea). Nous avons travaillé, entre autres, le GSSP de Meishan en Chine du Sud, la coupe de Bulla dans les Dolomies italiennes, la coupe du Cürük dağ dans le Taurus en Turquie, une coupe dans les Montagnes du Bükk en Hongrie et une coupe dans l'Elbourz en Iran, dans le but d'évaluer les taux d'extinction et de récupération chez ce groupe. Les taux d'extinctions spécifiques sont de 98 à 100% dans la majorité des coupes sauf en Hongrie. Les taux d'extinction génériques sont faibles de 30 à 39%. Après l'événement d'extinction en masse qui se produit toujours avant la limite Permien-Trias, la biodiversité des ostracodes est strictement contrôlée par l'environnement. Nous avons pu distinguer différentes phases pour la récupération post-crise des ostracodes :  Une phase de survivance (Griesbachien) avec des faunes mixtes paléozoïques et méso-cénozoïques  Un maximum de pauvreté (Dienérien-Smithien), avec une diversité et une abondance très faibles  Une phase de récupération-dispersion (Spathien) qui marque le début de la récupération  Une phase de radiation à l'Anisien Le niveau de biodiversité des ostracodes du Permien moyen ne sera pas atteint avant le Ladinien.

International audience

International audience

International audience; During the Permian, areas on the western rim of Indochina terrane were parts of the Paleotethys; therefore, the Permian rocks exposed in central and northeastern Thailand are composed mainly of limestones with less siliciclastic rocks. Diversified fossils such as fusulinaceans, corals, brachiopods, conodonts recovered from these limestones and shales have been recorded for more than 50 years. Recently ostracods are recovered from limestones of Saraburi Group. Seventeen sections of Lower to Middle Permian located in Loei, Phetchabun, Nakhon Sawan, and Lopburi provinces were investigated. More than 200 species are identified, most are endemic. The ostracod assemblages including Bairdiidae, Acratiidae, Sigilloidae, Geroiidae, Cytherideidae, Cavellinidae, Polycopidae, Aparchitidae, Kloedenelidae, Knoxitidae, Paraparchitidae, Kirkbyidae, Amphissitidae, Youngiellidae, Hollinellidae, Coelonellidae are typical shallow marine species inhabiting on marginal marine to exterior platform environments. Thirty-one species are known from other sites within Paleotethys region and are also benthic inhabitants. Provincialism index suggests that the Early Permian ostracods from Thailand have close relationships with those reported from Eastern China, and the Middle Permian ones have relationships with Tunisia, South China, and Eastern China species.

P. 269-314 In order to precisely establish the bio- and chronostratigraphic position of several levels of the Silurian–Devonian succession of Bolivia, with respect to the International Time Scale, additional Silurian and Devonian localities belonging to the Eastern Cordillera and the Interandean Zone areas have been recently revised and sampled, both for macrofossils and palynomorphs. Specifically, the localities are Ñuñumayani, and Muruhuta from the late Silurian–early Devonian time interval. Correlations with other fossiliferous localities are discussed, namely Huacallani and Rumicorral. SI

International audience

International audience; Here we describe 41 brachiopod species belonging to the orders Productida, Orthotetida, Orthida, Rhynchonellida, Athy-ridida, Spiriferida, Spiriferinida, and Terebratulida coming from the Guadalupian lower-middle part of the Pamuçak Formation at Çürük Dag, Antalya (Western Taurus, Turkey). Associated conodonts are also reported and illustrated. The brachiopod taxa are either pedicle attached genera, with one genus also stabilized by penetration of its elongate umbo, or free living concavo-convex semi-infaunal genera; this indicates that the energy of the environment was never very high, as in settings just below the fair weather wave-base or in a back-reef, more protected inner platform. The brachiopods from the Pamuçak Formation are very similar to the Wordian fauna of southeastern Oman, and they are similar to the Guadalupian assemblages of Chios, North Iran, South Thailand, and Salt Range. In comparison they share only a few taxa with the Guadalupian faunas of Central Afghanistan and Karakorum. Therefore the biotic affinity of the Guadalupian brachiopods of the Pamuçak Formation is clearly peri-Gondwanan. The brachiopod record at Çürük Dag has implications for understanding the pattern of the end-Guadalupian (pre-Lopingian) bi-otic crisis. The pre-Lopingian crisis assemblages are quite diverse and nearly totally consist of Guadalupian genera and species except for a single Lopingian incomer. Their stratigraphic range terminates rather abruptly and the following 120 metres of shallow water limestones are barren of brachiopods, after which there is the first occurrence of Lopingian brachiopod taxa, which show a much lower biodiversity. This pattern is different from that observed in South China and it shows that the end-Guadalupian crisis is not only characterized by taxonomic selectivity, but also by a strong local control on the extinc-tion/recovery pattern of some groups. Riassunto. Nel presente lavoro vengono descritte 41 specie di brachiopodi appartenenti agli ordini Productida, Orthotetida, Orthi-da, Rhynchonellida, Athyridida, Spiriferida, Spiriferinida e Terebratu-lida, provenienti dalla parte medio-bassa della piattaforma carbonatica della Formazione Pamuçak affiorante lungo i versanti del Çürük Dag, Antalya (Turchia), di età Guadalupiana. Vengono inoltre riportati e illustrati i conodonti associati alle faune a brachiopodi. I taxa descritti comprendono sia forme attaccate al substra-to tramite peduncolo che generi concavo-convessi, liberi e semi-in-faunali. Questa distribuzione di stili di vita suggerisce che l'energia idrodinamica dell'ambiente non fosse mai elevata, ma caratteristica di ambienti posti al di sotto del livello di base dell'onda normale o di retroscogliera e piattaforma interna protetta. I brachiopodi della Formazione Pamuçak risultano estremamente simili alle faune di età Wordiana dell'Oman sudorientale; sono inoltre simili alle associazioni Guadalupiane di Chios, dell'Iran settentrionale, della Tailandia meri-dionale e del Salt Range, mentre hanno solo pochi taxa in comune con le faune coeve dell'Afghanistan centrale e del Karakorum. Questo per-mette di affermare che l'affinità biotica delle associazioni a brachio-podi della Formazione di Pamuçak è chiaramente peri-Gondwaniana. La distribuzione dei brachiopodi nelle sezioni di Çürük Dag ri-veste un importante ruolo nell'interpretazione della crisi biotica di fine Guadalupiano. Le associazioni di età Wordiano-Capitaniano, ovvero quelle che precedono la crisi, sono caratterizzate da un'alta biodiversi-tà e comprendono quasi totalmente generi e specie del Guadalupiano, oltre ad una specie che è nota sinora solo nel Lopingiano. La loro di-stribuzione stratigrafica viene bruscamente troncata a ca. 500 m dalla base della formazione; i 120 m di serie successivi comprendono calcari di acque basse privi di macrofaune, al di sopra dei quali compaiono taxa Lopingiani che formano associazioni a bassa e molto bassa biodiversità. Queste modalità di estinzione e della successiva ripresa sono diverse da quanto si osserva in altre località, in particolare in Cina meridionale, e mettono in evidenza che la crisi di fine Guadalupiano non è caratte-rizzata solo da selettività tassonomica, ma anche da un forte controllo locale sulle modalità di estinzione e ripresa di alcuni gruppi fossili.

International audience; 46 samples were processed for a taxonomic ostracod study from the Lower-Middle Triassic (Smithian to Anisian) of South Tibet. Forty four species belonging to 15 genera are recognized. One genus and seven species are described as new: Bairdia jeancharlesi Forel n. sp., Bairdia letangae Forel n. sp., Bairdiacypris combeae Forel n. sp., Petasobairdia collini Forel n. sp., Hungarella tulongensis Crasquin n. sp., Triassicindivisia tibetinella Crasquin n. gen., n. sp., Liuzhinia larmae Forel n. sp. The goal of this paper is to describe the new taxa as a preliminary step to palaeoenvironmental reconstruction.; Quarante-six échantillons ont été analysés pour l’étude des ostracodes du Trias inférieur et moyen (Smithien à Anisien) du sud Tibet. Quarante-quatreespèces appartenant à 15 genres ont été identifi ées. Un genre et sept espèces sont nouveaux : Bairdia jeancharlesi Forel n. sp., Bairdia letangae Forel n. sp., Bairdiacypris combeae Forel n. sp., Petasobairdia collini Forel n. sp., Hungarella tulongensis Crasquin n. sp., Triassicindivisia tibetinella n. gen. n. sp., Liuzhinia larmae Forel n. sp. Le sujet de cet article est la description des nouveaux taxons en prélude à une reconstruction paléoenvironnementale.

International audience

International audience

International audience

International audience

International audience

International audience

International audience

International audience

International audience

International audience

The 1st International Symposium on Ostracoda (ISO) was held in Naples (1963). The philosophy behind this symposium and the logical outcome of what is now known as the International Research Group on Ostracoda (IRGO) are here reviewed, namely ostracodology over the last 50 years is sociologically analysed. Three different and important historic moments for the scientific achievements of this domain are recognised. The first one, between about 1963 and 1983, is related to applied research for the oil industry as well as to the great interest in the better description of the marine environment by both zoologists and palaeontologists. Another important aspect during this period was the work by researchers dealing with Palaeozoic ostracods, who had their own discussion group, IRGPO. Gradually, the merger of this latter group with those dealing with post-Palaeozoic ostracods at various meetings improved the communication between the two groups of specialists. A second period was approximately delineated between 1983 and 2003. During this time-slice, more emphasis was addressed to environmental research with topics such as the study of global events and long-term climate change. Ostracodologists profited also from the research “politics” within national and international programmes. Large international research teams emerged using new research methods. During the third period (2003–2013), communication and collaborative research reached a global dimension. Amongst the topics of research we cite the reconstruction of palaeoclimate using transfer functions, the building of large datasets of ostracod distributions for regional and intercontinental studies, and the implementation of actions that should lead to taxonomic harmonisation. Projects within which molecular biological techniques are routinely used, combined with sophisticated morphological information, expanded now in their importance. The documentation of the ostracod description improved through new techniques to visualise morphological details, which stimulated also communication between ostracodologists. Efforts of making available ostracod information through newsletters and electronic media are evoked.