Ostracod fauna across the Permian-Triassic boundary at Chongyang, Hubei Province, and its implication for the process of the mass extinction

Abstract

Thirty species of 10 ostracod genera were identified from 440 fossil specimens isolated through the hot acetolysis of the rock samples collected across the Permian-Triassic boundary at Chongyang section. Twenty species of 6 genera are found to occur in the limestone of Changxing Formation, and 11 species of 7 genera above the main faunal mass extinction horizon. The ostracod assemblages identified at the Chongyang section are obviously different from those previously reported in the contemporaneous microbialites in Guangxi and Chongqing regions, not only in the ostracod components but also in the abundance of filter-feeding ostracods relative to the deposit-feeding ostracods, an indicator of the oxygen level of the seawater. This spatial difference in ostracod assemblages might reflect the diversity of oceanic environmental conditions after the end-Permian mass extinction. Ostracods disappear at 200 cm below and near the main mass extinction horizon, and on the top of the microbialites, respectively, showing an episodic and gradual collapse process at the Chongyang section. The carbon isotope composition is found to appear at 200 cm below the main mass extinction horizon, indicating the initial deterioration of oceanic environment. Fluctuation of the carbon isotope composition is obviously related with the episodic evolution of ostracod species, but not with the abundance of ostracods. ostracod, microbialite, Permian-Triassic, mass extinction, Chongyang Citation:Liu H, Wang Y B, Yuan A H, et al. Ostracod fauna across the Permian-Triassic boundary at Chongyang, Hubei Province, and its implication for the process of the mass extinction.

Early Triassic microbialites from the Changxing Region of Zhejiang Province, South China

“…That crisis wiped out many of those benthic organisms that adapted to normal, shallow marine environments, whilst some anoxia-or high-temperature-tolerant organisms survived and even flourished in the harsh conditions, spreading into newly available ecological niches. Like other reported Early Triassic microbialites Liu et al 2010;Yang et al 2011;Crasquin and Forel 2014;Wu et al 2016), the metazoan fossils in this unit at Panjiazhuang section are dominated by ostracods, small gastropods and microconchid tubes ( Fig. 6).…”

Diverse earliest Triassic ostracod fauna of the non-microbialite-bearing shallow marine carbonates of the Yangou section, South China

“…Similar high diversity and abundance of ostracods within PTBMs have also been reported in the Chongyang and Laolongdong sections on the Yangtze Platform, the Lung Cam section in Vietnam and the Cürük Dag section in Turkey (Crasquin & Kershaw ; Liu et al . ; Crasquin et al . ).…”

The ‘Last Hurrah of the Reigning Darwinulocopines’? Ostracoda (Arthropoda, Crustacea) from the Lower Jurassic Moenave Formation, Arizona and Utah, USA

“…The Permian-Triassic (P-Tr) extinction event greatly reduced darwinulocopine diversity in nonmarine environments in ways similar to those observed in marine ones (Jin et al, 2000;Liu et al, 2010;Forel, 2013). It is still poorly known how these nonmarine faunas rebounded from such event during the Triassic, as they would soon be hit by another major extinction event, the ETE, which was probably caused by a disruption in the global carbon cycle due to emplacement of the Central Atlantic Magmatic Province (CAMP) (Beerling and Berner, 2002).…”