Upper Norian conodonts from the Baoshan block, western Yunnan, southwestern China, and implications for conodont turnover

Weiping Zeng; Haishui Jiang; Yan Chen; James Ogg; Muhui Zhang; Hanxinshuo Dong

doi:10.7717/peerj.14517

Upper Norian conodonts from the Baoshan block, western Yunnan, southwestern China, and implications for conodont turnover

PeerJ. 2023 Jan 17:11:e14517. doi: 10.7717/peerj.14517. eCollection 2023.

Authors

Weiping Zeng^{1

2}, Haishui Jiang², Yan Chen², James Ogg^{2

3}, Muhui Zhang², Hanxinshuo Dong²

Affiliations

¹ School of Geography and Tourism, Huanggang Normal University, Huanggang, Hubei, P. R. China.
² State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan, Hubei, China.
³ Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, United States.

Abstract

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 Mockina (M.) bidentata Zone and an upper Parvigondolella (P.) andrusovi Zone are identified in this area according to the first occurrences of M. bidentata and of P. andrusovi. Rich conodont fauna of M. zapfei is detailed and presents various intraspecific forms. A total of 19 forms of P₁ elements are presented, which, when combined with the reported conodonts in the M. bidentata Zone, suggest that there was a peak in conodont diversity within the M. bidentata Zone. A biotic crisis in the uppermost M. bidentata Zone is recognized from the contrast between the diverse conodont fauna in the M. bidentata Zone and the rare conodonts in the P. andrusovi 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 M. bidentata Zone to P. andrusovi Zone.

Keywords: Conodont; Diversity; Norian; South China; Triassic; Yunnan; biostratigraphy.

MeSH terms

China
Extinction, Biological*
Fossils*

Grants and funding

This work was supported by the National Natural Science Foundation of China (Grant numbers 41830320, 41972033). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.