School of Geography and Tourism, Huanggang Normal University, Huanggang, Hubei, P. R. China.
State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan, Hubei, China.
PeerJ. 2023 Jan 17;11:e14517. doi: 10.7717/peerj.14517. eCollection 2023.
The Sevatian of the late Norian is one of the key intervals in biotic turnover and in changes of paleoclimate and paleoenvironments. Conodont faunas recovered from two sections of upper Norian strata of the Dashuitang and Nanshuba formations near Baoshan City in western Yunnan province provide new insights into the diversity and biostratigraphy of the Sevatian conodonts within China as well as globally. A lower (.) Zone and an upper (.) Zone are identified in this area according to the first occurrences of and of . Rich conodont fauna of is detailed and presents various intraspecific forms. A total of 19 forms of P elements are presented, which, when combined with the reported conodonts in the Zone, suggest that there was a peak in conodont diversity within the Zone. A biotic crisis in the uppermost Zone is recognized from the contrast between the diverse conodont fauna in the Zone and the rare conodonts in the Zone. The conodont turnover during the middle Sevatian highlights the fact that the prolonged phases of the end-Triassic mass extinction probably began in the transition interval from Zone to Zone.
晚诺利阶的 Sevatian 是生物大转变和古气候、古环境变化的关键时期之一。在中国西部云南省保山市附近的大沙塘组和南山坝组上诺利阶地层的两个剖面上采集的牙形石动物群为 Sevatian 牙形石的多样性和生物地层学提供了新的认识，不仅在国内，在全球范围内也是如此。根据 和 的首次出现，在该地区确定了一个下部 （.） 带和一个上部 （.） 带。详细描述了丰富的 带牙形石动物群，并呈现出各种种内形态。共提出了 19 种 P 元素，与 带中报告的牙形石相结合，表明 带内牙形石多样性达到了高峰。在上部 带中，由于 带中多样的牙形石动物群与 带中稀少的牙形石之间的对比，识别出了一个生物危机。在中 Sevatian 的牙形石更替突出表明，三叠纪末大灭绝的漫长阶段可能始于从 带到 带的过渡区间。
