Weihong He

Anoxia/high temperature double whammy during the Permian-Triassic marine crisis and its aftermath

The Permian-Triassic mass extinction was the most severe biotic crisis in the past 500 million years. Many hypotheses have been proposed to explain the crisis, but few account for the spectrum of extinction selectivity and subsequent recovery. Here we show that selective losses are best accounted for by a combination of lethally warm, shallow waters and anoxic deep waters that acted to severely restrict the habitable area to a narrow mid-water refuge zone. The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery. Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters. In contrast, hypoxia tolerant but temperature intolerant small foraminifers were driven from shallow-waters but thrived on dysoxic slopes margins. Only those mollusc groups, which are tolerant of both hypoxia and high temperatures, were able to thrive in the immediate aftermath of the extinction. Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

A late Changhsingian (Late Permian) deepwater brachiopod fauna from the Talung Formation at the Dongpan Section, southern Guangxi, South China

Abstract This paper describes a unique deepwater brachiopod fauna from the upper part of the Talung Formation at the Dongpan Section, southern Guangxi, South China. This brachiopod fauna includes 10 species belonging to 10 genera. New taxa are Anidanthus mucronata n. sp., Dongpanoproductus elegans n. gen. and sp., Costatumulus dongpanensis n. sp., and Spinomarginifera semicircridge n. sp. This fauna is characterized by small, thin-shelled species with high abundance and low diversity, and therefore is different in generic and species composition from the coeval faunas of the Late Permian limestone facies in South China. The brachiopod fauna can be safely assigned to the latest Changhsingian as indicated by the presence of abundant Paracrurithyris pigmaea, the immediately underlying radiolarian Neoalbaillella optima Zone of late Changhsingian age, and the overlying ammonoid Ophiceras sp. cf. O. tingi Tien of the lowest Triassic. This fauna is most likely to have lived in a deepwater environment as indicated by coexistence with the radiolarian Latentifistularia, small thin-shelled brachiopods, and the dominance of silica-bearing mudstone.

CHANGXINGIAN (UPPER PERMIAN) RADIOLARIAN FAUNA FROM MEISHAN D SECTION, CHANGXING, ZHEJIANG, CHINA, AND ITS POSSIBLE PALEOECOLOGICAL SIGNIFICANCE

Abstract A well-preserved radiolarian fauna reported from the Changxing Formation in the Meishan D Section, Changxing, Zhejiang, China, mainly includes abundant Entactinia itsukaichiensis, Grandetortura nipponica, Copicyntra robustodentata, Lepingosphaera stauracanthus, and a few Entactinia meishanensis n. sp., Entactinia? sp., Entactinosphaera cimelia, Triaenosphaera sp., Tetragregnon sp., Paracopicyntra ziyunensis, Copicyntroides sp. cf. C. asteriformis, Copicyntroides sp., and Ishigum trifustis, with the conodont Neogondolella subcarinata Zone. One new species, Entactinia meishanensis, is described in this paper. This radiolarian fauna is characterized by low abundance and low diversity, and apparently occurred in a water depth of 150–200 m.

Controls on body size during the Late Permian mass extinction event

This study examines the morphological responses of Late Permian brachiopods to environmental changes. Quantitative analysis of body size data from Permian-Triassic brachiopods has demonstrated significant, directional changes in body size before, during and after the Late Permian mass extinction event. Brachiopod size significantly reduced before and during the extinction interval, increased for a short time in more extinction-resistant taxa in the latter stages of extinction and then dramatically reduced again across the Permian/Triassic boundary. Relative abundances of trace elements and acritarchs demonstrate that the body size reductions which happened before, during and after extinction were driven by primary productivity collapse, whereas declining oxygen levels had less effect. An episode of size increase in two of the more extinction-resistant brachiopod species is unrelated to environmental change and possibly was the result of reduced interspecific competition for resources following the extinction of competitors. Based on the results of this study, predictions can be made for the possible responses of modern benthos to present-day environmental changes.

TAXONOMY OF ORDER LATENTIFISTULARIA (RADIOLARIA) FROM THE LATEST PERMIAN IN SOUTHERN GUANGXI, CHINA

Abstract Caridroit, De Wever, and Dumitrica (1999) promoted stauraxon (Radiolaria) to an order, order Latentifistularia, and De Wever et al. (2001) proposed a classification using family and genus levels. However, the taxonomy of this order in genus level is still problematic because some genera were named according to broken specimens. A radiolarian fauna with a high diversity was collected from the late Changxingian in southern Guanxi, China. These specimens are very well preserved so that they are rare material for roundly describing the characters of some genera. They are identified as 42 species belonging to 16 genera and 5 families. Fifteen new species and one new genus are described, some genera are discussed, and some species are revised.

Late Permian marine ecosystem collapse began in deeper waters: evidence from brachiopod diversity and body size changes

Analysis of Permian-Triassic brachiopod diversity and body size changes from different water depths spanning the continental shelf to basinal facies in South China provides insights into the process of environmental deterioration. Comparison of the temporal changes of brachiopod diversity between deepwater and shallow-water facies demonstrates that deepwater brachiopods disappeared earlier than shallow-water brachiopods. This indicates that high environmental stress commenced first in deepwater settings and later extended to shallow waters. This environmental stress is attributed to major volcanic eruptions, which first led to formation of a stratified ocean and a chemocline in the outer shelf and deeper water environments, causing the disappearance of deep marine benthos including brachiopods. The chemocline then rapidly migrated upward and extended to shallow waters, causing widespread mass extinction of shallow marine benthos. We predict that the spatial and temporal patterns of earlier onset of disappearance/extinction and ecological crisis in deeper water ecosystems will be recorded during other episodes of rapid global warming.

A LATE PERMIAN TO EARLY TRIASSIC BIVALVE FAUNA FROM THE DONGPAN SECTION, SOUTHERN GUANGXI, SOUTH CHINA

Abstract A bivalve fauna from the Permian—Triassic interval of the Dongpan section, Guangxi, South China is described herein. This bivalve fauna includes 16 species belonging to 10 genera. New taxa are Euchondria fusuiensis, Palaeoneilo qinzhouensis, and Claraia liuqiaoensis. Bed 12 of the interval (Talung Formation) contains the typical late Late Permian ammonoids: Huananoceras sp., Laibinoceras cf. L. compressum Yang, and Qiangjiangoceras sp. Bed 13 (Luolou Formation) contains typical Early Triassic bivalves Claraia dieneri Nakazawa, C. cf. C. wangi (Patte), and C. griesbachi (Bittner), which coexist with the earliest Triassic ammonoid Ophiceras sp. The bivalve and ammonoid distributions at the Dongpan section indicate that bed 12 should be assigned to the Late Permian, and bed 13 should be assigned to the Early Triassic. From the early Changhsingian to the Induan, the byssal notches of Claraia species tend to become progressively narrower, and change from being ventrally extended to being horizontally extended. The species level diversity of Claraia also increases through this interval.

Changhsingian (latest Permian) deep-water brachiopod fauna from South China

This paper describes 45 brachiopod species (including 15 undetermined species) in 23 genera belonging to seven orders (Productida, Spiriferida, Athyridida, Orthida, Orthotetida, Rhynchonellida and Lingulida) from the Talung Formation (Changhsingian, latest Permian) of the marine deep-water facies of South China. Two new genera are proposed: Chaohochonetes and Parapygmochonetes; along with nine new species: Tethyochonetes rectangularis, Tethyochonetes? sinuata, Chaohochonetes triangusinuata, Neochonetes (Zhongyingia?) liaoi, Neochonetes (Huangichonetes?) wufengensis, Paryphella majiashanensis, Paryphella minuta, Parapygmochonetes parvulus and Meekella sparsiplicata. The taxonomic composition, significant morphological features and palaeoecological implications of this deep-water brachiopod fauna are summarized, and the fauna is compared with the Permian–Triassic boundary (PTB) mixed brachiopod fauna of South China. The Changhsingian (latest Permian) deep-water brachiopod fauna of South China shares some common features with the PTB mixed brachiopod fauna, especially in terms of taxonomic composition and certain apparent morphological adaptations. This commonality is interpreted to indicate a time and a broad marine environment of widespread low oxygen supply and/or reduced trophic resources during the end-Permian life crisis in South China. http://zoobank.org/urn:lsid:zoobank.org:pub:744771BB-7377-4239-8A29-89183ECEBE09

Latest Permian Entactinaria (Radiolaria) from southern Guangxi, China

A highly diverse and well-preserved latest Permian radiolarian fauna was obtained from muddy siliceous rocks and siliceous mudstones of the Dalong Formation, southern Guangxi, China. Specimens of the Order Entactinaria were selected for taxonomic study. Thirty-four species, among which were nine new species and twelve unidentified species, are included in this investigation. The nine new species are Entactinia wangi, Entactinia minuta, Entactinia sashidai, Trilonche textiles, Triaenosphaera variabilis, Triaenosphaera megacantha, Provisocyntra densa, Provisocyntra ormistoni and Wuyia dongpanica. Permian species of the Family Spongentactiniidae Nazarov are reported first and the extinction pattern of the Order Entactinaria is discussed.

ALBAILLELLIDAE (RADIOLARIA) FROM THE LATEST PERMIAN IN SOUTHERN GUANGXI, CHINA

Abstract A delicate and well-preserved latest Permian radiolarian fauna was obtained from muddy siliceous rocks and siliceous mudstones in the Dongpan Section, southwest Guangxi, China. The specimens of family Albaillellidae in the fauna have been selected for taxonomic study in this paper. Two genera and 14 species belonging to this family are recognized and described, including three new species and one new subspecies, namely Neoalbaillella minuta, Albaillella flabellata, Albaillella fida, and Albaillella yaoi longa, respectively. This assemblage is correlated to the Neoalbaillella optima Assemblage Zone. Its biostratigraphic significance and the final extinction of Albaillellidae at the end of Late Permian are observed and discussed herein.