3 resultados para Attenuatella


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Attenuatella mengi sp. nov. and ?Attenuatella sp. from the Talung Formation, southern Guangxi Zhuang Autonomous Region, South China, are described herein. This discovery represents the first report of Attenuatella from the late Changhsingian (latest Permian) in South China and provides evidence that Attenuatella expanded its range from high-latitude cold-water regions to palaeoequatorial warm water areas in the Late Permian. Attenuatella
species appear to have been pseudoplanktonic, judging from their hair-like spinose ornamentation, which could have contributed to the global palaeogeographical distribution of Attenuatella.

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A new brachiopod fauna is described from the Early and Middle Permian of Zadoi and Zhidoi counties, southern Qinghai (Changdu block), northwest China. This fauna includes 13 species in nine genera with Spinomarginifera concentrica n. sp. and Transennatia waterhousei n. sp. The Early to Middle Permian brachiopod fauna from southern Qinghai is very similar to the contemporary Cathaysian faunas of South China with which the new fauna shares 70 per cent of its species. On the other hand, the Qinghai brachiopods also demonstrate a significant link with the Permian brachiopod fauna of the Sino-Mongolian-Japanese Province in northeast China, as suggested by Marginifera septentrionalis and Attenuatella. In particular, the occurrence of the bipolar brachiopod genus Attenuatella suggests that southern Qinghai may have played an important role as a biogeographic stepping stone in the marine faunal interchanges between the northern and southern hemispheres during the Early and Middle Permian.

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Four Ambocoeliidae brachiopod species including one new species (Crurithyris tazawai sp. nov., Crurithyris sp., Paracrurithyris pygmaea and Attenuatella mengi) are described from the Changhsingian (Late Permian) deep-water facies of South China. Analysis of the morphology, palaeoecology and palaeogeographical and temporal distributions of these species revealed that the presence of a delthyrium and/or the micro-ornaments among three of the four species (Crurithyris tazawai sp. nov., Paracrurithyris pygmaea and Attenuatella mengi) favoured an epifaunal (epiphytic) lifestyle. Morphological differences suggest that Paracrurithyris pygmaea may have been more effective metabolically in forming the shell compared with Attenuatella mengi and Crurithyris tazawai. The temporal and palaeogeographical distribution of Attenuatella suggests that A. mengi inhabited cool or cold deep waters. Both Crurithyris tazawai and Attenuatella mengi disappeared earlier in the stratigraphic record than Paracrurithyis pygmaea during the Permian–Triassic mass extinction. These differences in timing of extinction, morphology and palaeogeographical distributions suggest that oxygen deficiency and trophic resource limitation (a consequence of the changing composition of marine phytoplankton in the seas) may have contributed to the end-Permian mass extinction.