Permian reefs re-examined: extrinsic control mechanisms of gradual and abrupt changes during 40 my of reef evolution

The evolution of Permian reefs is characterized by the following sequence of events: (1) Late Carboniferous–Cisuralian radiation, (2) early Late Cisuralian (Artinskian–Kungurian) turnover, (3) Guadalupian radiation, (4) end-Guadalupian crisis, (5) Lopingian radiation, (6) end-Lopingian crisis at the PTB (Permian–Triassic boundary), and (7) the at least 7 my (million years) metazoan reef gap during the Early Triassic. The early Late Cisuralian turnover and the end-Guadalupian reef crisis are gradual changes, while the end-Lopingian reef crisis represents an abrupt event. Lopingian reefs occur in a zone from 40 °N to 15 °S, Guadalupian reefs in an extended equatorial zone from 35 °N to 35 °S, and Lopingian reefs in a narrow equatorial zone of 20 °N and 20 °S. This pattern resulted from a network of global and regional control mechanisms including the assemblage of Pangea, the northward drift of continents, the opening of Neo-Tethys, and second-order sea level changes. The mechanism of the extinction has been intensely debated and a combination of the above mentioned long-term changes and abrupt ocean anoxia or hypercapnia (CO₂-poisoning) for the end-Guadalupian reef crisis is considered.     

Evolution of Permian conodont provincialism and its significance in global correlation and paleoclimate implication

The main components of Asselian through Artinskian conodont faunas found around the world are basically the same, and the provincialism is indicated only by less common endemic elements such as Gondolelloides and New Genus A Henderson in North Pangea, Sweetognathus bucaramangus around the equator and Vjalovognathus in eastern Gondwana. Provincialism is marked by differences at the species level of Mesogondolella, Neostreptognathodus and Sweetognathus during the Kungurian, and becomes very distinct with differences at the genus level during the Guadalupian and Lopingian. Three provinces of Permian conodonts, referred to as the North Cool Water Province (NCWP), the Equatorial Warm Water Province (EWWP) and the peri-Gondwana Cool Water Province (GCWP), are recognized. The NCWP is marked by Gondolelloides in the early Cisuralian, dominance of Neostreptognathodus and no or rare Sweetognathus in the late Cisuralian, dominance of Merrillina and Mesogondolella and absence of Sweetognathus in the Guadalupian, and dominance of Merrillina and Mesogondolella and absence of Iranognathus in the Lopingian. The EWWP is characterized by the absence of Gondolelloides and Vjalovognathus in the Cisuralian, abundance of Sweetognathus and Pseudosweetognathus in the Kungurian (late Cisuralian), Jinogondolella and Sweetognathus in the Guadalupian, and Clarkina and Iranognathus in the Lopingian. The GCWP is marked by Vjalovognathus, Merrillina in the Cisuralian, Vjalovognathus, Merrillina and Mesogondolella in the Guadalupian, and Vjalovognathus and Merrillina in the Lopingian. Mixed faunas are recognized in regions bordering between the EWWP and GCWP including Western Timor during the Artinskian, Pamirs during the Kungurian and the Salt Range during the Guadalupian and Lopingian.

Three different conodont zonations are proposed, one for each of the three conodont provinces. Four potential horizons for inter-provincial correlation of Permian conodonts are recognized. They are in ascending order: (1) the first appearance of Sweetognathus whitei, which is closely related to the last occurrence of Carboniferous-type conodonts such as Streptognathodus and Adetognathus; (2) the first appearance of Neostreptognathodus pequopensis; (3) the base of the Jinogondolella nankingensis Zone; and (4) the base of the Clarkina postbitteri–Iranognathus erwini Zone.

The spatial and temporal distribution pattern of Permian conodonts suggests that temperature is the primary controlling factor. Evolution of Permian conodont provincialism reveals a glaciation during the Asselian and Sakmarian, a global warming during the Artinskian, a climate cooling in North Pangea during the Kungurian, a continuation of Kungurian climate trends in the Guadalupian, a relatively minor warming during the Wuchiapingian, a returned cooling in the Changhsingian and Lower and Middle Griesbachian, and a global warming in the Late Griesbachian, which ended the Permian conodont lineage.     

Changhsingian (Late Permian) foraminifers from the topmost part of the Xiala Formation in the Tsochen area,central Lhasa Block,Tibet and their geological implications

A foraminiferal fauna consisting of 15 genera and 19 species is documented for the first time from the topmost part of the Xiala Formation in the Aduogabu area in Tsochen County, central Lhasa Block. This foraminiferal fauna is dominated by Colaniella, indicating a broadly Changhsingian age. The presence of Colaniella, Reichelina and absence of the typical tropical fusuline genus Palaeofusulina in the fauna indicate that the Lhasa Block has not merged into equatorial regions during the Changhsingian. More importantly, the widespread Lopingian (Late Permian) marine carbonates with warm-water faunas and the stable platform carbonate sequence through the Guadalupian and Lopingian in the Lhasa Block present an obvious contrast against the contemporaneous sequences in the South Qiangtang Block and Gondwana margin. It suggests that both the Bangong-Nujiang Ocean and the Neotethys Ocean would have opened by the Guadalupian and Lopingian.     

CALIBRATED DIVERSITY,TREE TOPOLOGY AND THE MOTHER OF MASS EXTINCTIONS: THE LESSON OF TEMNOSPONDYLS

Abstract: Three family‐level cladistic analyses of temnospondyl amphibians are used to evaluate the impact of taxonomic rank, tree topology, and sample size on diversity profiles, origination and extinction rates, and faunal turnover. Temnospondyls are used as a case study for investigating replacement of families across the Permo‐Triassic boundary and modality of recovery in the aftermath of the end‐Permian mass extinction. Both observed and inferred (i.e. tree topology‐dependent) values of family diversity have a negligible effect on the shape of the diversity curve. However, inferred values produce both a flattening of the curve throughout the Cisuralian and a less pronounced increase in family diversity from Tatarian through to Induan than do observed values. Diversity curves based upon counts of genera and species display a clearer distinction between peaks and troughs. We use rarefaction techniques (specifically, rarefaction of the number of genera and species within families) to evaluate the effect of sampling size on the curve of estimated family‐level diversity during five time bins (Carboniferous; Cisuralian; Guadalupian–Lopingian; Early Triassic; Middle Triassic–Cretaceous). After applying rarefaction, we note that Cisuralian and Early Triassic diversity values are closer to one another than they are when the observed number of families is used; both values are also slightly higher than the Carboniferous estimated diversity. The Guadalupian–Lopingian value is lower than raw data indicate, reflecting in part the depauperate land vertebrate diversity from the late Cisuralian to the middle Guadalupian (Olson’s gap). The time‐calibrated origination and extinction rate trajectories plot out close to one another and show a peak in the Induan, regardless of the tree used to construct them. Origination and extinction trajectories are disjunct in at least some Palaeozoic intervals, and background extinctions exert a significant role in shaping temnospondyl diversity in the lowermost Triassic. Finally, species‐, genus‐, and family trajectories consistently reveal a rapid increase in temnospondyl diversity from latest Permian to earliest Triassic as well as a decline near the end of the Cisuralian. However, during the rest of the Cisuralian family diversity increases slightly and there is no evidence for a steady decline, contrary to previous reports.     

Precocious sexual dimorphism and the Lilliput effect in Neo‐Tethyan Ostracoda (Crustacea) through the Permian–Triassic boundary

The Elikah River section spanning the Lopingian (Late Permian) to the Griesbachian (Early Triassic) time interval in the Central Alborz Mountains (north Iran) was sampled for ostracod analysis. We report 79 species distributed among 38 genera. Four new species are described: Acratia? pervagata Forel sp. nov., Microcheilinella alborzella Forel sp. nov., Basslerella superarella Crasquin sp. nov. and Cavellina nesenensis Crasquin sp. nov. The ontogeny of 13 species is described and sexual dimorphism in the genus Microcheilinella is here undoubtedly recognized for the first time. Six species show precocious sexual dimorphism of their carapace as early as A‐5 juvenile. The Lilliput effect is for the first time recorded and quantified for two species. Rare long‐time span Palaeocopida species, known throughout the entire Permian, document relatively long‐term evolution, including the size and growth rate modifications associated with the earlier appearance of carapace sexual dimorphism through time. These patterns might be related to the Guadalupian–Lopingian events and/or to climatic modifications occurring during the Permian interval.     

Latest Guadalupian brachiopods from the Guadalupian/Lopingian boundary GSSP section at Penglaitan in Laibin, Guangxi, South China and implications for the timing of the pre-Lopingian crisis

A brachiopod fauna comprising nine species in eight genera from three closely spaced stratigraphic horizons of the same stratigraphic section is described for the first time from the Laibin Limestone in the uppermost part of the Maokou Formation in the Guadalupian/Lopingian (G/L) GSSP section at Penglaitan, Guangxi Autonomous Region, South China. The brachiopod assemblages are bracketed between two conodont zones: Jinogondolella xuanhanensis Zone below and Jinogondolella granti Zone above and, therefore, they can be safely assigned to the latest Capitanian in age. However, all but one of the nine brachiopod species from the Laibin Limestone carry strong early Lopingian (Wuchiapingian) aspect. Thus, the discovery of this brachiopod fauna not only suggests that some Lopingian brachiopod species had already appeared in the late Guadalupian (Capitanian); more importantly, it has also highlighted the fact that both the previously noted pre-Lopingian life crisis (or end-Guadalupian or Middle Permian mass extinction) and Lopingian recovery/radiation actually occurred in late Capitanian times, sometime before the G/L chronostratigraphic boundary. So far, the Penglaitan GSSP section provides the highest-resolution disappearance patterns of different fossil groups around the G/L boundary.     

Middle Permian smaller foraminifers from the Maokou Formation at the Tieqiao section,Guangxi, South China

This paper documents smaller foraminifers from the Maokou Formation (Guadalupian) at the Tieqiao section in Laibin area, South China. The assemblage of smaller foraminifers reported herein consists of 69 species of 42 genera. Although the Maokou Formation of this section was deposited in a relatively deep-water environment, smaller foraminifers are diverse and abundant, especially in debris flow deposits and thin turbidite beds. This fauna bears most similarity with coeval foraminiferal assemblages from the other Palaeotethyan regions. There is a sharp decrease in the diversity and abundance of smaller foraminifers at the lithological boundary between the Maokou and Heshan formations. An overwhelming majority of genera of smaller foraminifers that occur in the Maokou Formation at this section can be found in the Lopingian strata of South China. The study of smaller foraminiferal fauna of the Guadalupian at the Tieqiao section indicates a much less pronounced effect of the pre-Lopingian crisis on smaller foraminifers.     

Middle–Late Permian tetrapods from the Rio do Rasto Formation,Southern Brazil: a biostratigraphic reassessment

Dias‐da‐Silva, S. 2011: Middle–Late Permian tetrapods from the Rio do Rasto Formation, Southern Brazil: a biostratigraphic reassessment. Lethaia, Vol. 45, pp. 109–120. The Rio do Rasto Formation (Permian of Southern Brazil) was previously regarded as Guadalupian–early Lopingian age. Three tetrapod‐based localities are known: the Serra do Cadeado area, Aceguá and Posto Queimado. The latest tetrapod‐based biostratigraphic contribution considers that the Posto Queimado and Aceguá faunas are coeval and Wordian (middle Guadalupian) in age, correlated to the Isheevo faunas from Eastern Europe and to the Tapinocephalus Assemblage Zone of South Africa; whereas the Serra do Cadeado fauna is Capitanian (late Guadalupian), correlated to the Kotelnich fauna of Eastern Europe and, from bottom to top, to upper Pristerognathus, Tropidostoma and lower Cistecephalus assemblage zones of South Africa. A re‐evaluation of the tetrapods from the Rio do Rasto Formation and new fossil discoveries in the localities of Posto Queimado and Serra do Cadeado area (melosaurine and platyoposaurine temnospondyls, a basal anomodont, a dinocephalian and a basal dicynodont) supports a new tetrapod‐based biostratigraphic scheme for the Rio do Rasto Formation. Accordingly, the age of the fauna at Aceguá is late Roadian‐early Wordian, whereas the locality of Posto Queimado is late Wordian‐Capitanian. The Serra do Cadeado Area is correlated with both southernmost ones (Guadalupian) but also Wuchiapinghian (early Lopingian). □Paraná Basin, Passa Dois Group, tetrapod biostratigraphy, Western Gondwana.     

New materials of Cisuralian (early Permian) radiolarians from western Cambodia: Paleobiogeographic implications in the Paleotethys

Radiolarians, including the new species Entactinia pailinensis Ito n. sp., were obtained from the Pailin area, western Cambodia. The radiolarians indicated an age around the Asselian–Sakmarian of the Cisuralian (early Permian). The new species is characterized by an evenly-sized-porous exosphere composed of a polygonal outer porous plate and circular inner porous plate with some radial outer spines. A previous study concluded that Entactinia Foreman rapidly expanded in the early–middle Cisuralian. Our discovery of this new species adds further occurrence data of Entactinia in the early–middle Cisuralian. In addition, another previous study highlighted the uneven distribution of Pseudotormentus De Wever and Caridroit compared with the wider distribution of Quadriremis Nazarov and Ormiston through the Permian, in particular the Guadalupian (middle Permian). Our results combined with those of previous studies indicate that the uneven distribution might extend back to the Sakmarian of the Cisuralian at least.     

Late Paleozoic–early Mesozoic continental biostratigraphy — Links to the Standard Global Chronostratigraphic Scale

Nonmarine biostratigraphic/biochronologic schemes have been created for all or parts of the late Carboniferous–Middle Triassic using palynomorphs, megafossil plants, conchostracans, blattoid insects, tetrapod footprints and tetrapod body fossils, and these provide varied temporal resolution. Cross correlation of the nonmarine biochronologies to the Standard Global Chronostratigraphic Scale has been achieved in some parts of the late Carboniferous–Middle Triassic in locations where nonmarine and marine strata are intercalated, the nonmarine strata produce biochronologically significant fossils and the marine strata yield fusulinids, conodonts and/or ammonoids. Other cross correlations have been aided by magnetostratigraphy, chemostratigraphy and a growing database of radioisotopic ages. A synthetic nonmarine biochronology for the late Carboniferous–Middle Triassic based on all available nonmarine index fossils, integrated with the Standard Global Chronostratigraphic Scale, is presented here. The focus is on the nonmarine biostratigraphy/biochronology of blattoid insects, conchostracans, branchiosaurid amphibians, tetrapod footprints and tetrapod body fossils within the biochronological framework of land-vertebrate faunachrons. Correlation to the Standard Global Chronostratigraphic Scale presented here is divided into seven time intervals: Pennsylvanian, Carboniferous–Permian boundary, Cisuralian, Guadalupian, Lopingian, Permian–Triassic boundary and Early to Middle Triassic. The insects, conchostracans and branchiosaurs provide robust nonmarine correlations in the Pennsylvanian–Cisuralian, and the footprints and tetrapod body fossils provide robust correlations of varied precision within the entire Pennsylvanian–Middle Triassic. Radioisotopic ages are currently the strongest basis for cross correlation of the nonmarine biostratigraphy/biochronology to the Standard Global Chronostratigraphic Scale, particularly for the Pennsylvanian–Cisuralian. Chemostratigraphy and magnetostratigraphy thus far provide only limited links of nomarine and marine chronologies. Improvements in the nonmarine-marine correlations of late Paleozoic–Triassic Pangea require better alpha taxonomy and stratigraphic precision for the nonmarine fossil record integrated with more reliable radioisotopic ages and more extensive chemostratigraphic and magnetostratigraphic datasets.     

The Guadalupian–Lopingian boundary (Permian) in a pelagic sequence from Panthalassa recognized by integrated conodont and radiolarian biostratigraphy

Guadalupian–Lopingian sedimentary rocks are widely distributed in accretionary complexes in Japan, but the Guadalupian–Lopingian boundary (G–LB) is not well documented from these pelagic sediments. To identify the G–LB and to better correlate an extinction event that occurred around the Guadalupian–Lopingian boundary, we examined the conodont biostratigraphy from a Permian pelagic chert sequence in the Gujo-hachiman section, Gifu, southwest Japan. Age-diagnostic conodonts, including Clarkina postbitteri postbitteri, were found in this section. The biostratigraphic occurrences of these age-diagnostic conodonts can pinpoint the “G–L transitional zone” in the Gujo-hachiman section by comparison with well-studied sections from south China, including the GSSP section. The transitional zone was recognized by the first occurrence horizons of both Clarkina postbitteri hongshuiensis and C. p. postbitteri. The G–LB has been placed at or above the first occurrence horizon of the radiolarians Albaillella yamakitai or Albaillella cavitata in previous studies from China and Japan. We detected the first occurrence horizon of A. yamakitai below the base of the “G–L transitional zone,” in the Upper Capitanian. The conodont biostratigraphy is consistent with the radiolarian biostratigraphy in this section, which can be correlated to relevant sections in China.     

First record of Cisuralian–Guadalupian plant fossils from the Shan Plateau,eastern Myanmar

Permian plant fossils have never been reported from the Shan Plateau in eastern Myanmar. Recently, a black to gray carbonaceous mudstone unit containing abundant plant fossils was discovered just below the lowest part of Thitspin Limestone Formation from the Linwe Area, eastern Myanmar. Although only five taxa were identified, the plant assemblage provides the first evidence of the occurrence of Cathaysian elements in eastern Myanmar and potentially indicates the presence of a highly diverse Permian flora. Among the five species, Cordaites principalis and Annularia mucronata were cosmopolitan species; while Callipteridum cf. koraiense, Taeniopteris crassinervis Mo and Rhipidopsis lobata were mostly recorded in the Cathaysia Flora. Therefore, the present assemblage generally indicates a palaeobiogeographical affinity to the Cathaysian Province. Stratigraphically, Callipteridum cf. koraiense was mainly reported from Cisuralian to Wordian; whereas Taeniopteris crasssnervis Mo and Rhipidopsis lobata were recorded from Capitanian to Changhsingian, which suggests a general Permian age based on the plant assemblage itself only. However, the carbonaceous mudstone at the outcrop is overlain by the Thitspin Limestone Formation containing middle Guadalupian fusulinids. Based on previous faunal analyses, the Sibumasu terrane contains typical Gondwanan cold-water faunas during the early Cisuralian, warm-water faunas occurred after Sakmarian. Thus, age of the fossil-plant-containing carbonaceous mudstone is very likely between late Cisuralian and early Guadalupian as constrained by its overlying fusulinids and its warm Cathaysian palaeobiogeographical affinity.     

巴基斯坦盐岭地区二叠纪生物地层研究的新进展

近30年来,巴基斯坦盐岭地区的Wargal组和Chhidru组以及在喜马拉雅地区相当地层的地质时代被许多学者视为中二叠世(瓜达鲁普世)。根据华南与盐岭地区瓜达鲁普统和乐平统的牙形类化石带对比,可以确定Amb组和Wargal组底部的时代为瓜达鲁普世晚期,瓜达鲁普统与乐平统的界线位于Wargal组下部,吴家坪阶与长兴阶的界线位于Chhidru组的下部,而二叠与三叠系的界线位于Mianwali组下部的Kathwai段之内。我国西藏南部色龙群及相当地层含有与巴基斯坦盐岭地区Kalabagh段和Chhidru组可对比的乐平世腕足动物群以及二叠系—三叠系界线附近连续的牙形类化石带,由此可以推定色龙群的时代应为乐平世。     

Lopingian (Late Permian) brachiopods around the Wuchiapingian-Changhsingian boundary at the Meishan Sections C and D, Changxing, South China

The strata below the defined Wuchiapingian-Changhsingian boundary GSSP are mostly covered and obscured by faulting at the Meishan Section D. Therefore, it is very difficult to collect fossils there. After an intensive excavation at Meishan Section C, a diverse fauna based on high-resolution biostratigraphy comprising brachiopods, ammonoids, conodonts, fusulinids and small foraminifers were found. Among these fossils, brachiopods are the most dominant. Eleven species of 10 genera based on more than 1300 specimens are identified. This brachiopod fauna is of late Wuchiapingian-Changhsingian of Lopingian (Late Permian) in age as well constrained by the associated ammonoid Pseudogastrioceras sp., Jinjiangoceras and Konglingites sp., the fusulinid Palaeofusulina and the conodont lineage from C. longicuspidata to C. wangi. In terms of the changes of brachiopod fauna composition around Wuchiapingian-Changhsingian boundary, it clearly indicates a continuous transgression from the upper part of the Lungtan Formation to the lower part of the Changhsing Formation. A new species, Neochonetes (Huangichonetes) meishanensis, is described and some other species are discussed based on the new collection from Meishan Sections C and D.     

广西来宾瓜达鲁普统—乐平统界线地层的牙形类化石——一个独立验证报告

王成源（Wang,2000）和金玉Gan（Jin,2000）提出了关于乐平统底界定义的不同论点。为了对此进行独立的验证,卡尔加里大学微体古生物实验室对采自华南广西来宾地区瓜达鲁普统－乐平统界线地层的牙形类化石大块样品进行了处理。结果如下：1.Jinogondolella和Clarkina在样品中没有共生;2.由Jinogondolella granti演化为Clarkina postbitteri的变化发生在层115－6i;3.C.postbitteri的首次出现层位（FAD）在蓬莱滩剖面位于层115－6i上部;4.这个变化标志着一个才的生物信号和一个重要的点断演化事件。Jinogondolella granti演化为Clarkina postbitteri的事件很可能是受瓜达鲁普统与乐平统之交的海平面降至最低水位所触发和控制。层115－6i下部为较浅水相颗粒灰岩,代表瓜达鲁普统末期层序高位域之顶或上覆层序低位域之底部。作为Clarkina属的第一个代表,Clarkina postbitteri是界线地层中最易识别的种之一,而Clarkina postbitterigkp带的识别较容易和稳定一致。Clarkina postbitteri和Clarkina dukouensis可以通过基于锯齿型式,居群和个体发育的分类体系来加以稳定地区分。Clarkina postbitteri和Clarkina dukouensis之间的过渡是渐变的,其间的分界点只能人为地确定,如果采用这样一个人为确定的点来定义全球界线层型（GSSP）,将难以稳定一致地对其加以识别。来自层114.6-6k的被Wang(2000)鉴定为Clarkina dukouensis的标本应当是C. postbitteri,或精确地可能是C. postbitteri的一个新亚种,没有争议的Clarkina dukouensis在蓬莱滩剖面最早出现于层114－7e。从生物演化和层序地层的角度看,C. postbitteri的首次出现层位（FAD）是瓜达鱼普统和乐平统界线在最清楚的侯选位置。     

Zoophycos composite ichnofabrics and tiers from the Permian neritic facies in South China and south‐eastern Australia

Gong, Y.‐M., Shi, G.R., Zhang, L.‐J. & Weldon, E.A. 2009: Zoophycos composite ichnofabrics and tiers from the Permian neritic facies in South China and south‐eastern Australia. Lethaia, Vol. 43, pp. 182–196. Zoophycos composite ichnofabrics (ZCI) comprising two or more suites of the same form of Zoophycos are widespread and densely distributed in Early and Middle Permian (Cisuralian–Guadalupian) neritic limestones (Qixia and Maokou Formations) of palaeotropical origin in the Laibin area, Guangxi, South China. Similar ZCI also occur in neritic greywackes of glaciomarine origin from the Middle Permian (Guadalupian) Westley Park Sandstone Member (Broughton Formation) in the southern Sydney Basin, south‐eastern Australia. Zoophycos from both regions consists of planar spreite with major and minor lamellae and a cylindrical tunnel interpreted as a marginal tube and/or axial shaft. The cylindrical tunnel is herein considered to be an essential component of Zoophycos, and thus can be used to define and characterize the morphological variability of Zoophycos. It is suggested that the variation of spreite and major and minor lamellae originated from the different morphologies and migration manners of the cylindrical tunnel. The shallowest, shallow, middle and deepest Zoophycos tiers have been distinguished in ZCI on the basis of cross‐cutting relationships, the soft‐sediment deformation and the contrast in colour between Zoophycos and its host rock. The multiple tiers may represent the substrate consistency spectrum from a softground through a stiffground to a firmground. The different Zoophycos tiers may have been constructed by tracemakers of either different or the same taxonomic affinities in response to the gradual accretion and lithification of sediment layers on the seafloor. The tracemakers appeared to be very sensitive to neither climate nor lithology. The width of the planar spreiten of Zoophycos decreases slightly with the depth of tiering in ZCI. □Composite ichnofabric, Permian, South China, south‐eastern Australia, tier, Zoophycos.     

An unusually diverse mollusc fauna from the earliest Triassic of South China and its implications for benthic recovery after the end-Permian biotic crisis

A single carbonate coquinoid lens from the Griesbachian (Early Triassic) of Shanggan, South China, yielded 11 bivalve species described in this study in addition to four gastropod and one ammonoid species reported elsewhere. This makes the Shanggan fauna one of the richest mollusc faunas from the early post-extinction interval after the end-Permian mass extinction event. Four of the present genera are long-term survivors, five are holdovers that went extinct at the end of the Griesbachian or later in the Early Triassic, and seven first appear in the Griesbachian. Three new bivalve species are described: Myalinella newelli nov. sp., Scythentolium scutigerulus nov. sp., and Eumorphotis shajingengi nov. sp. The genus Astartella, previously assumed to have vanished at the end of the Permian, is reported for the first time from the Early Triassic, which also removes Astartidae from Early Triassic Lazarus taxa. The small growth size of the Astartella specimens supports an earlier hypothesis that many of the Early Triassic Lazarus taxa did not survive in unknown refuges but were simply overlooked due to the scarcity of easily observable large-sized specimens. Ecologically, a comparatively high proportion of infaunal bivalve species (4/11) is remarkable for the early post-extinction interval, supporting the impression of a relatively advanced recovery state. Moreover, abundance-data of the bivalve-gastropod community reveal a remarkably low dominance index (D = 0.17) that is suggestive for advanced recovery and stable environmental conditions. It is proposed that the Shanggan fauna represents a late Griesbachian benthic recovery event that coincided with the appearance of similarly diverse benthic faunas in Oman and Primorye. A high proportion of genera that have previously not been reported from the Early Triassic indicate that the prevalence of poor preservation conditions is a major obstacle in identifying early phases of recovery from the greatest crisis in the history of metazoan life. The early recovery of benthic faunas reported in this study questions previous claims of a prolonged lag phase as a consequence of the extraordinary extinction magnitude or the persistence of adverse environmental conditions.     

GRIESBACHIAN AND DIENERIAN (EARLY TRIASSIC) AMMONOID FAUNAS FROM NORTHWESTERN GUANGXI AND SOUTHERN GUIZHOU (SOUTH CHINA)

Abstract: Intensive sampling of the Luolou (northwestern Guangxi) and the Daye (southern Guizhou) Formations in South China leads to the recognition of a regional Griesbachian and Dienerian ammonoid succession for this key palaeobiogeographical area. The new biostratigraphical sequence comprises the upper Griesbachian ‘Ophiceras beds’ and the lower Dienerian ‘Proptychites candidus beds’, which are separated from the uppermost Dienerian ‘Clypites beds’ by an unfossiliferous interval. These faunas contain some taxa with wide geographic distribution (e.g. Ambites, Pleurambites, Pleurogyronites, Proptychites candidus), thus facilitating correlation with faunal successions from other regions (i.e. British Columbia, Canadian Arctic, Himalayas and South Primorye). Two new genera (Jieshaniceras and Shangganites) and three new species (Anotoceras subtabulatus, Pleurambites radiatus and Shangganites shangganense) are described.     

An upper Kungurian/lower Guadalupian (Permian) brachiopod fauna from the South Qiangtang Block in Tibet and its palaeobiogeographical implications

A brachiopod fauna including 15 species belonging to 14 genera is described from a thin carbonate succession of the Lugu Formation at the Anmu section in the northern part of the South Qiangtang Block, which is about 15 km south to the Longmu Co-Shuanghu Suture. The brachiopod fauna is late Kungurian or early Guadalupian in age in terms of the presence of the brachiopod species Vediproductus punctatiformis, “Cryptospirifer” omeishanensis, and Paraplicatifera regularis. This is also generally consistent with the age indicated by the fusulines (e.g., Cancellina, Chusenella, Monodiexodina, Nankinella, Neofusulinella, Pseudofusulina, and Sphaerulina) from this formation at the nearby Mari and Duoma A (DMA) sections. Palaeobiogeographically, the brachiopod fauna exhibits a typical Cathaysian affinity and all the species are reported commonly from the equivalents in South China and Cimmerian blocks, which strongly suggest that the South Qiangtang Block had drifted to a position in the warm-water or temperate regime close to South China.     

When and how did the terrestrial mid-Permian mass extinction occur? Evidence from the tetrapod record of the Karoo Basin,South Africa

A mid-Permian (Guadalupian epoch) extinction event at approximately 260 Ma has been mooted for two decades. This is based primarily on invertebrate biostratigraphy of Guadalupian–Lopingian marine carbonate platforms in southern China, which are temporally constrained by correlation to the associated Emeishan Large Igneous Province (LIP). Despite attempts to identify a similar biodiversity crisis in the terrestrial realm, the low resolution of mid-Permian tetrapod biostratigraphy and a lack of robust geochronological constraints have until now hampered both the correlation and quantification of terrestrial extinctions. Here we present an extensive compilation of tetrapod-stratigraphic data analysed by the constrained optimization (CONOP) algorithm that reveals a significant extinction event among tetrapods within the lower Beaufort Group of the Karoo Basin, South Africa, in the latest Capitanian. Our fossil dataset reveals a 74–80% loss of generic richness between the upper Tapinocephalus Assemblage Zone (AZ) and the mid-Pristerognathus AZ that is temporally constrained by a U–Pb zircon date (CA-TIMS method) of 260.259 ± 0.081 Ma from a tuff near the top of the Tapinocephalus AZ. This strengthens the biochronology of the Permian Beaufort Group and supports the existence of a mid-Permian mass extinction event on land near the end of the Guadalupian. Our results permit a temporal association between the extinction of dinocephalian therapsids and the LIP volcanism at Emeishan, as well as the marine end-Guadalupian extinctions.