The evolution of modern corals and their early history

Scleractinians are a group of calcified anthozoan corals, many of which populate shallow-water tropical to subtropical reefs. Most of these corals calcify rapidly and their success on reefs is related to a symbiotic association with zooxanthellae. These one-celled algal symbionts live in the endodermal tissues of their coral host and are thought responsible for promoting rapid calcification. The evolutionary significance of this symbiosis and the implications it holds for explaining the success of corals is of paramount importance. Scleractinia stands out as one of the few orders of calcified metazoans that arose in Triassic time, long after a greater proliferation of calcified metazoan orders in the Paleozoic. The origin of this coral group, so important in reefs of today, has remained an unsolved problem in paleontology. The idea that Scleractinia evolved from older Paleozoic rugose corals that somehow survived the Permian mass extinction persists among some schools of thought. Paleozoic scleractiniamorphs also have been presented as possible ancestors. The paleontological record shows the first appearance of fossils currently classified within the order Scleractinia to be in the Middle Triassic. These earliest Scleractinia provide a picture of unexpectedly robust taxonomic diversity and high colony integration. Results from molecular biology support a polyphyletic evolution for living Scleractinia and the molecular clock, calibrated against the fossil record, suggests that two major groups of ancestors could extend back to late Paleozoic time. The idea that Scleractinia were derived from soft-bodied, “anemone-like” ancestors that survived the Permian mass extinction, has become a widely considered hypothesis. The 14-million year Mesozoic coral gap stands as a fundamental obstacle to verification of many of these ideas. However, this obstacle is not a barrier for derivation of scleractinians from anemone-like, soft-bodied ancestors. The hypothesis of the ephemeral, “naked coral”, presents the greatest potential for solution of the enigma of the origin of scleractinians. It states that different groups of soft-bodied, unrelated “anemone-like” anthozoans gave rise to various calcified scleractinian-like corals through aragonitic biomineralization. Although there is evidence for this phenomenon being more universal in the mid-Triassic interval, following a lengthy Early Triassic post-extinction perturbation, it appears to have occurred at least three other times prior to this interval. This idea suggests that, because of ephemeral characteristics, the skeleton does not represent a clade of zoantharian evolution but instead represents a grade of organization. In the fossil record, skeletons may have appeared and disappeared at different times as some clades reverted to soft-bodied existence and these phenomena could account for notable gaps in the taxonomic and fossil record. A fuller understanding and possible solution to the problem of the origin of modern corals may be forthcoming. However, it will require synthesis of diverse kinds of data and an integration of findings from paleobiology, stratigraphy, molecular biology, carbonate geochemistry, biochemistry and invertebrate physiology.     

Fossils explained 79

Rugose corals are an extinct group of marine animals that are frequently found in Palaeozoic shallow marine sediments. Just like their counterparts the stony corals (the Scleractinia) do today, during the Palaeozoic the rugose corals were important constructors of reefs. Although at first glance rugose corals look very similar to the Scleractinia, they differ in important details. The rugose corals are a very special group whose relationships have been disputed for a long time. They were restricted to the Palaeozoic Era and experienced an exciting evolutionary history of victories and defeats; there were times when they built up huge reefs (and were valuable in stratigraphy), and other times when they suffered through extinction events.     

Palynology of Triassic–Jurassic boundary sections in northern Switzerland

A first palynostratigraphic scheme of Upper Triassic deposits in northern Switzerland was established based on spore-pollen associations and dinoflagellate cyst records from the upper part of the Upper Triassic Klettgau Formation and the lower part of the Lower Jurassic Staffelegg Formation. Drill cores from the Adlerberg region (Basel Tabular Jura) and from Weiach (northern part of Canton Zurich) as well as from an outcrop at the Chilchzimmersattel (Basel Folded Jura) were studied and five informal palynological associations are distinguished. These palynological associations correlate with palynological association of the Central European Epicontinental Basin and the Tethyan realm and provide a stratigraphic framework for the uppermost Triassic sediments in northern Switzerland. Throughout the uppermost Triassic to Jurassic palynological succession a remarkable prominence of Classopollis spp. is observed. Besides Classopollis spp. the three Rhaetian palynological associations A to C from the Upper Triassic Belchen Member include typical Rhaetian spore-pollen and dinoflagellate taxa (e.g., Rhaetipollis germanicus, Geopollis zwolinskae, Rhaetogonyaulax rhaetica, and Dapcodinium priscum). Association B differs from association A in a higher relative abundance of the sporomorph taxa Perinopollenites spp. and the consistent occurrence of Granuloperculatipollis rudis and Ricciisporites tuberculatus. Spore diversity is highest in the late Rhaetian palynological association C and includes Polypodiisporites polymicroforatus. A Rhaetian age for the Belchen Member is confirmed by palynological associations A–C, but there is no record of the latest Rhaetian and the earliest Jurassic. In contrast to the Rhaetian palynological associations the Early Jurassic associations W and D include Pinuspollenites spp., Trachysporites fuscus (in association W), and Ischyosporites variegatus. In the view of the end-Triassic mass extinction and contemporaneous environmental changes the described palynofloral succession represents the pre-extinction phase (associations A and B) including a distinct transgression, the extinction phase (association C) associated with a regression, and the post-extinction phase (association W).     

西藏海相三叠系—侏罗系界线及晚三叠世生物绝灭事件研究

1998—2004年间在西藏聂拉木、林周、墨竹工卡和洛扎等地进行的三叠系/侏罗系界线地层研究表明,西藏隆子县和洛扎县尚未发现具有连续菊石层序的三叠系/侏罗系界线地层剖面。拉萨以北地区广泛分布的火山岩时代确定为晚三叠世—早侏罗世早期,这有助于解释晚三叠世末期生物绝灭与晚三叠世岩浆侵入和大规模的火山活动有关,但T/J界线尚待精确限定。聂拉木县格米格剖面是特提斯地区唯一未曾“压缩”的三叠系/侏罗系界线地层剖面,具有瑞替阶MARSHI菊石带、赫塘阶Tibeticum、Callyphyllum和Pleuro-notum菊石带。格米格剖面三叠系/侏罗系界线碳稳定同位素曲线记录了晚三叠世瑞替阶末期(Marshi菊石带)突然的负偏移,它很有可能和晚三叠世末期的由超级温室效应所产生的生物绝灭事件相对应。     

Petrological and geochemical interpretation of Triassic–Jurassic boundary sections from northern Iraq

Triassic–Jurassic sedimentary successions (Baluti and Sarki formations) in northern Iraq record a variety of environmental changes that may be related to global Triassic–Jurassic (Tr/J) boundary events. The diversity of some benthic fauna decreases through the transitional boundary beds. The coastal marine environment of the lower part of the Baluti Formation is followed by shallower tidal flat and supratidal marginal marine environments at the transitional boundary with the Jurassic‐age Sarki Formation. The alternating calcareous mudrocks and dolomitic limestones of the transitional succession are overlain by a succession of calcareous mudrocks and dolomicrites that form a dolocrete bed in the latest Triassic. The early Jurassic carbonates (lower part of Sarki Formation) were deposited in a shallow‐marine to lagoonal environment. Geochemical evidence supports this interpretation. TOC% increases towards the Tr/J boundary and the lower part of the Sarki Formation. This increase can be interpreted as resulting from the primary precipitation of dolocrete as palaeosol horizons. The variations in the oxygen isotope ratios mainly reflect the facies and diagenetic effects. Th/K ratio is generally constant and shows an increase in the calcareous mudrock beds of the upper part of the Baluti Formation, possibly related to the degradation of K‐bearing clay minerals. Low Th/U ratios are due to the depletion in thorium, typical of many marine carbonates rather than to an increase in authigenic uranium. This explanation is also corroborated by the presence of abundant fossils in some of the studied carbonates. Copyright © 2013 John Wiley & Sons, Ltd.     

Foraminiferal biostratigraphy and sequence stratigraphy of peritidal carbonates at the Triassic–Jurassic boundary (Karaburun Peninsula,Western Turkey)

Continuous shallow marine carbonates spanning the Triassic–Jurassic boundary are exposed in the Karaburun Peninsula, Western Turkey. The studied section (Tahtaiskele section) consists of Upper Triassic cyclic shallow marine carbonates intercalated with clastics overlain by Lower Liassic carbonates. Based on the microfacies stacking patterns, three main types of shallowing-upward cycles have been recognized. Cycles are mostly composed of subtidal facies at the bottom, intertidal/supratidal facies and/or subaerial exposure structures at the top. The duration of the cycles suggests that cycles were driven by the precessional Milankovitch rhytmicity. In the sequence stratigraphic frame of the Tahtaiskele section 4 sequence boundaries were detected and globally correlated. The first sequence boundary is located at the Alaunian–Sevatian boundary nearly coinciding with the first appearance of Triasina hantkeni. The second falls in the Rhaetian corresponding to a major sea level fall which led to the invasion of forced regressive siliciclastic deposits over the peritidal carbonates. The third occurs close to the T/J boundary and the fourth lies slightly above the base of the Jurassic. In the studied section, extinction, survival and recovery intervals have been recognized based on the stratigraphic occurrence patterns of benthic foraminifera and algae. Foraminifers became nearly totally extinct in the inner carbonate shelves at the Triassic–Jurassic boundary and an interval of approximately 0.5 my passed before the begining of the recovery of Jurassic foraminifera.     

The Triassic of Timor: Lithostratigraphy, chronostratigraphy and palaeogeography

The palaeontologically rich and lithologically diverse Triassic successions of Timor provide a key stratigraphic and palaeontological link between northwestern Australia and other terranes of former eastern Gondwana (present-day Southeast Asia). Timor is now located in the zone of collision between the northern margin of the Australian continent and island arc terranes bordering the Eurasian plate, with the Triassic successions exposed in a fold-and-thrust belt and an extensive mélange complex. Three formal lithostratigraphic units have been defined previously within the main Triassic succession in Timor (Niof, Aitutu and Babulu formations), with a fourth, the Wai Luli Formation, primarily Jurassic in age but extending down into the Triassic. The Niof Formation (Anisian to Ladinian, possibly also Early Triassic) is a fine-grained deepwater succession, succeeded conformably by the Aitutu and Babulu formations (Ladinian to Norian/Rhaetian), which were deposited contemporaneously, with the Aitutu Formation continuing locally into the Lower Jurassic. The Aitutu Formation consists of deep shelf limestones interbedded with shales and marls, while the Babulu Formation is a deltaic to turbiditic siliciclastic succession. The Late Triassic to Jurassic Wai Luli Formation is characterised by marine shales and marls.Informal stratigraphic units include the Cephalopod Limestone Facies, a Rosso Ammonitico-type deposit, which contains an extremely rich fossil fauna (particularly ammonoids) and ranges through the entire Triassic; and the Fatu Limestone and Pualaca Facies which consists of shallow to marginal marine carbonates (mud mounds, oolitic limestones and reefs) restricted to the Late Triassic. Facies diversity was low during the Early Triassic and Anisian, but became more pronounced from the Ladinian and continuing through the Late Triassic, probably as a consequence of renewed tectonic extension. Triassic extension was not associated with major volcanism, unlike a previous phase of extension in the Early Permian.The Cablac Limestone Formation, originally defined as a Miocene stratigraphic element, is now recognised to be at least partly Late Triassic–Early Jurassic in age, with lithologies comparable to parts of the Fatu Limestone. The stratigraphy of these shallow marine carbonate sequences is clearly in need of rigorous revision, but it is not yet possible to suggest appropriate redefined formations.     

Was Phanerozoic reef history controlled by the distribution of non-enzymatically secreted reef carbonates (microbial carbonate and biologically induced cement)?

Throughout most of the Phanerozoic, reef rigidity resulted as much, or more, from early lithification by microbial carbonates and biologically induced cements (non-enzymatic carbonates) than from biological encrustation of, or by, large, enzymatically secreted metazoan skeletons. Reef framework is divided into four categories: (1) skeletal metazoan; (2) non-skeletal microbialite (stromatolite and thrombolite); (3) calcimicrobe; and (4) biocementstone, in which small or delicate organisms serve as scaffolds for rigid cement crusts. The last three categories are dominated by non-enzymatic carbonates. Skeletal framework and non-skeletal microbialite framework were the most abundant framework types through the Phanerozoic. The composition and abundance of skeletal framework was controlled largely by mass extinction events, but most reefs consisted of both microbialite and skeletal organisms in a mutually beneficial relationship. Microbialite framework was abundant throughout the Palaeozoic and early Mesozoic, but declined after the Jurassic. Calcimicrobe framework was important during the Cambrian-Early Ordovician and Devonian and biocementstone framework was important from the late Mississippian to the Late Triassic. The Phanerozoic history of reefs does not correlate well with the stratigraphic distribution of large, skeletal ‘reef builders’, or with a variety of physicochemical parameters, including sea-level history, Wilson Cycle or global climate cycles. Because non-enzymatic carbonates result from induction by non-obligate calcifiers, and not enzymatic precipitation by obligate calcifiers, the distribution of these carbonates was controlled to a larger extent by temporal changes in physicochemical parameters affecting the saturation state of sea water with respect to carbonate minerals. Changes in pCO₂, Ca/Mg ratios, cation concentrations and temperature may have affected the abundance of non-enzymatic carbonates and, hence, reefs, independently from the effects of these same parameters and mass extinction events on skeletal reef biota. The decline in abundance of reefal microbialite and absence of calcimicrobe and biocementstone reef framework after the Jurassic may be a result of relatively low saturation states of sea water owing to increased removal and sequestration of finite marine carbonate resources by calcareous plankton since the Jurassic. Reef history is difficult to correlate with temporal changes in specific global parameters because these parameters affect skeletal biota and biologically induced carbonate precipitation independently. Hence, reef history was regulated not just by skeletal reef biota, but by parameters governing non-enzymatic carbonates.     

Floral biodiversity and geology of the Talcher Basin,Orissa, India during the Permian–Triassic interval

The review paper provides an updated account of the previous and recently published records concerning the palaeobiology and the geology of the Talcher Basin of Orissa State, India. We conclude that fossil floral species in this basin originated in the earliest Permian Talchir Formation and evolved and diversified through the Karharbari Fm., Barakar Fm., Barren Measures Fm. and the uppermost Kamthi Fm. (Late Permian–Triassic). The megaflora and the palynology of the different formations of the basin are also discussed briefly. The geological setting of the basin along with the status of different formations (especially the Kamthi Formation) has been redefined. The post‐Barakar Fm. rocks, earlier retained in the Raniganj/Kamthi, Panchet and Mahadeva formations in this basin, have been critically assessed and redefined as the Lower and Upper Kamthi formations of Late Permian and Triassic ages, respectively. Accordingly, the geological map of the basin has been modified. Permian deposits (particularly the Barakar and the lower Kamthi formations) not only have the best preserved flora but also possess the highest diversity, whereas the upper Kamthi Triassic sediments have a meagre number of taxa. The plant diversity of the basin has been discussed in detail to interpret the development of the flora, evolutionary trends and palaeoenvironments of the basin. The patchy Gangamopteris vegetation of the Talchir glacial phase has ultimately evolved and diversified through time (Karharbari Fm. to Lower Kamthi Fm.) and gave rise to the thick dense swampy forests consisting of large Glossopteris trees and other shade‐loving under‐storied pteridophytes. Several groups of plants including spores and pollen have disappeared in a ladder pattern during the Permian–Triassic interval (Lower Kamthi–Upper Kamthi Fm.) and, similarly, in steps, many new fore‐runners appeared in the Upper Kamthi Formation. Records of marine acritarchs and ichnofossils in this basin at various Permian–Triassic levels demonstrate that there were marine influences. These features suggest a paralic (coastal marine to deltaic) mode of origin of the coal beds and associated sediments in the basin. The present study also advocates the continued survival of plants, rather than a mass extinction near the vicinity of the Permian–Triassic (P–T) boundary in this basin. Copyright © 2012 John Wiley & Sons, Ltd.     

二叠纪-三叠纪之交双壳类的灭绝与复苏过程

为了建立早-中三叠世双壳类的残存-复苏模式及深入探讨双壳类迟缓复苏的原因,对全球范围内该时期双壳类属的 时限分布进行了统计.总体来看,3个亚纲(Pteriomorphia、Palaeotaxodont和Heteroconchia亚纲)和5种生活方式(外栖活动 类、外栖固着类、半内栖类、内栖浅掘穴类和内栖深掘穴类)的双壳类均展示出了一致的规律,属级分异度直到中三叠世Anisian 期才恢复到晚二叠世末生物大灭绝之前的水平.二叠纪残存类型在早-中三叠世双壳类中所占的比例逐步降低,从占过 渡层的77.3%降低到了中三叠世Anisian期的33.7%,指示双壳类的缓慢复苏过程.而在整个早三叠世的漫长复苏期中,双壳 类仅遭受背景灭绝,表明双壳类的迟缓复苏受限于长时期的高压环境,随着海洋环境的逐步好转,才逐渐出现新的类型.      

Stratigraphy of the Triassic?Jurassic Boundary Successions of the Southern Margin of the Junggar Basin, Northwestern China

The Triassic?Jurassic (Tr?J) boundary marks a major extinction event, which (~200 Ma) resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in determining the exact location of the terrestrial Tr?J boundary, because of endemism of taxa and the scarcity of fossils in terrestrial settings leading to difficulties in linking marine and terrestrial sedimentary successions. Investigation based on palynology and bivalves has been carried out over a 1113 m thick section, which is subdivided into 132 beds, along the Haojiagou valley on the southern margin of the Junggar Basin of the northern Xinjiang, northwestern China. The terrestrial Lower Jurassic is conformably resting on the Upper Triassic strata. The Upper Triassic covers the Huangshanjie Formation overlaid by the Haojiagou Formation, while the Lower Jurassic comprises the Badaowan Formation followed by the Sangonghe Formation. Fifty six pollen and spore taxa and one algal taxon were identified from the sediments. Based on the key-species and abundance of spores and pollen, three zones were erected: the Late Triassic (Rhaetian) Aratrisporites?Alisporites Assemblage, the Early Jurassic (Hettangian) Perinopollenites?Pinuspollenites Assemblage, and the Sinemurian Perinopollenites?Cycadopites Assemblage. The Tr?J boundary is placed between bed 44 and 45 coincident with the boundary between the Haojiagou and Badaowan formations. Beds with Ferganoconcha (?), Unio?Ferganoconcha and Waagenoperna?Yananoconcha bivalve assemblages are recognized. The Ferganoconcha (?) bed is limited to the upper Haojiagou Formation, Unio?Ferganoconcha and Waagenoperna?Yananoconcha assemblages are present in the middle and upper members of the Badaowan Formation. The sedimentary succession is interpreted as terrestrial with two mainly lake deposit intervals within Haojiagou and Badaowan formations, yielding fresh water algae and bivalves. However, the presence of brackish water algae Tasmanites and the marine?littoral facies bivalve Waagenoperna from the Badaowan Formation indicate that the Junggar Basin was influenced by sea water caused by transgressions from the northern Tethys, during the Sinemurian.     

Mesozoic Holcoptera (Coleoptera: Coptoclavidae) from England and the United States

The impact of mass extinctions on insect evolution is debated, so investigating taxa that span a crisis is important for understanding such large-scale environmental perturbations. The beetle genus Holcoptera has been found in deposits from the Late Triassic: Norian to the Early Jurassic: Sinemurian of England and the United States, and possibly Italy. Historical collections of Rev. P.B. Brodie and J.F. Jackson were re-examined and the ages of British localities reviewed, US collections were re-interpreted, and new material from the Dorset Coast was considered. Holcoptera schlotheimi and Holcoptera confluens are synonymised based on morphological similarities; Holcoptera giebeli remains distinct and a new complete specimen confirms the placement of this genus in the family Coptoclavidae. Three new species are described: Holcoptera pigmentatus sp. nov. from the Penarth Group of Warwickshire, Holcoptera alisonae sp. nov. (based on the rejected neotype of H. schlotheimi) from the Lower Lias of Dorset and Holcoptera solitensis sp. nov. from the Newark Supergroup of Virginia. H. schlotheimi and H. giebeli are known from the Late Triassic Penarth Group and Early Jurassic Lias Group and so survived the end-Triassic extinction, whereas H. alisonae and H. pigmentatus are only known from the Lias Group. H. solentensis is the oldest described species in this genus and is not known from any other locality.     

Impacts,volcanism and mass extinction: random coincidence or cause and effect?

Large impacts are credited with the most devastating mass extinctions in Earth's history and the Cretaceous?–?Tertiary (K/T) boundary impact is the strongest and sole direct support for this view. A review of the five largest Phanerozoic mass extinctions provides no support that impacts with craters up to 180 km in diameter caused significant species extinctions. This includes the 170 km-diameter Chicxulub impact crater regarded as 0.3 million years older than the K/T mass extinction. A second, larger impact event may have been the ultimate cause of this mass extinction, as suggested by a global iridium anomaly at the K/T boundary, but no crater has been found to date. The current crater database suggests that multiple impacts, for example comet showers, were the norm, rather than the exception, during the Late Eocene, K/T transition, latest Triassic and the Devonian?–?Carboniferous transition, but did not cause significant species extinctions. Whether multiple impacts substantially contributed to greenhouse warming and associated environmental stresses is yet to be demonstrated. From the current database, it must be concluded that no known Phanerozoic impacts, including the Chicxulub impact (but excluding the K/T impact) caused mass extinctions or even significant species extinctions. The K/T mass extinction may have been caused by the coincidence of a very large impact (>?250 km) upon a highly stressed biotic environment as a result of volcanism. The consistent association of large magmatic provinces (large igneous provinces and continental flood-basalt provinces) with all but one (end-Ordovician) of the five major Phanerozoic mass extinctions suggests that volcanism played a major role. Faunal and geochemical evidence from the end-Permian, end-Devonian, end-Cretaceous and Triassic/Jurassic transition suggests that the biotic stress was due to a lethal combination of tectonically induced hydrothermal and volcanic processes, leading to eutrophication in the oceans, global warming, sea-level transgression and ocean anoxia. It must be concluded that major magmatic events and their long-term environmental consequences are major contributors, though not the sole causes of mass extinctions. Sudden mass extinctions, such as at the K/T boundary, may require the coincidence of major volcanism and a very large Impact.     

重大地史事件、节律及圈层耦合

文章讨论了岩石圈的联合古陆事件，生物圈的重要生物类别的出现、生物爆发事件和集群绝灭事件，水圈和大气圈的海平面变化事件和气候的变冷、变暖事件。联合古陆事件包括陆核型联合古陆（２５００Ｍａ）、初始原地台型联合古陆（１９００Ｍａ）、成熟原地台型联合古陆（１４５０Ｍａ）、地台型联合古陆（８５０Ｍａ）和大陆型联合古陆（２５０Ｍａ）事件；生物圈事件包括原核生物、真核生物、后生动物、带壳后生动物的出现事件，寒武纪生物大爆发事件，奥陶纪—志留纪之交（４３９Ｍａ）、晚泥盆世弗拉斯期—法门期之交（３６７Ｍａ）、二叠纪—三叠纪之交（２５０Ｍａ）、三叠纪—侏罗纪之交（２０８Ｍａ）、白垩纪—第三纪之交（６５Ｍａ）的生物集群绝灭事件，并从遗迹化石的角度，阐述了后生动物及其行为习性的起源和演化的新观点。水圈和大气圈事件包括晚震旦世、奥陶纪—志留纪之交、晚石炭世的自节律海平面变化事件，奥陶纪和白垩纪的他节律高海平面事件，震旦纪—寒武纪和二叠纪—三叠纪之交的耦合节律海平面变化事件，并以泥盆纪为例作了进一步阐述。这些事件是岩石圈、生物圈、水圈和大气圈发展、演化的重要里程碑。上述事件的重要特征是，在时间上的节律性和在成因上的圈层耦合效应。     

Triassic Scleractinian Corals in China: A Review of Present Knowledge

Scleractinian corals appeared during the Anisian period of the Triassic after the end-Permian mass extinction, which in Triassic were distinct from the Jurassic-Cretaceous scleractinian corals. The study on Triassic scleractinian coral fauna as a separate field is significant for exploring the development and evolution of modern corals and investigating environmental changes since the Mesozoic. The first Triassic coral in China was reported in 1925, and since then, nearly 25 articles dealing with taxonomy and 17 papers about fossil reports on Triassic scleractinian corals in China have been published, which refer to 60 genera and 312 species, 49 localities and 25 strata. In this paper, the history, taxonomy, localities, stratigraphic distribution, current research, and existing knowledge gaps of the Triassic scleractinian corals in China are reviewed. More specifically, the research findings of the Triassic scleractinain coral in China since 1925 are discussed; the species of the Triassic scleractian coral fossil reported in China, has been examined and its synonyms have been sorted out; the geographical distributions of the Middle and Late Triassic scleractinian corals in China are systematically treated; the Triassic coral biostratigraphy in China has been improved; and the stratigraphic ranges of existing genera and species are provided. The above conclusions are presented in the form of complete figures. At the same time, we analyzed shortcomings in current research and identified productive future research directions of the Triassic scleractinian corals in China.     

Composition and similarity of global anomodont-bearing tetrapod faunas

Anomodont synapsids represent the dominant herbivores of Permian and Triassic terrestrial vertebrate ecosystems. Their taxonomic diversity and morphological disparity in combination with their cosmopolitan distribution makes them an ideal study object for macroevolutionary patterns across the most devastating extinction event in earth history. This study provides a thorough review of anomodont-bearing tetrapod faunas to form the basis for a faunal similarity analysis and future studies of anomodont diversity. The stratigraphic correlation and composition of all known anomodont assemblages is revisited, including a discussion of the validity of the globally distributed anomodont species. The similarity analysis of anomodont faunas is performed on the basis of presence–absence data of anomodont taxa, using explorative methods such as cluster analysis (UPGMA) and non-metric multidimensional scaling (NMDS). The recovered faunal groupings indicate a common biostratigraphic age and furthermore reflect biogeographic patterns. Even though endemism and faunal provinciality was a constant element in anomodont faunas of the Permian and Triassic, the available evidence indicates that the end-Permian extinction resulted in a distinct uniformity that was unique to Early Triassic anomodont faunas. This is in particular characterized by the global distribution and overwhelming abundance of the disaster taxon Lystrosaurus. In contrast, cosmopolitan anomodonts also existed in the Late Permian (e.g., Diictodon) and Middle Triassic (e.g., Shansiodon), but those taxa coexisted with endemic faunal elements rather than dominated the fauna as Lystrosaurus did.     

对雅鲁藏布江结合带形成演化的再探讨

通过1∶5万区域地质调查和收集相关资料的综合研究,本文对雅鲁藏布江结合带的形成演化作了进一步的探讨。雅鲁藏布江特提斯洋具有弧后扩张洋盆的性质,在早三叠世至中三叠世中期洋盆初步形成,中三叠世晚期至晚三叠世洋盆全面形成,从早侏罗世至晚白垩世洋盆逐步萎缩,到古新世至始新世关闭。南带的蛇绿岩主要为洋中脊扩张型(MORB型),形成于中三叠世晚期至晚三叠世。北带的蛇绿岩主要为与洋内俯冲相关的俯冲带上盘型(SSZ型),形成于早中侏罗世。带内侏罗纪至白垩纪其他岩浆岩主要为前弧玄武岩类(FAB型)。显示雅鲁藏布江特提斯洋从早侏罗世开始发生了洋内俯冲,并同步向北向冈底斯带之下主动俯冲消减和向南向喜马拉雅地块之下被动俯冲消减,持续发展到晚白垩世,在古新世至始新世俯冲碰撞消亡转化为结合带。     

石珊瑚目的早期系统发育和系统分类研究

石珊瑚目是中新生代的重要造礁生物。直到中三叠世才大量出现多种石珊瑚化石，距二叠纪末生物大灭绝、古生代皱壁珊瑚和床板珊瑚灭亡14 Ma之久。石珊瑚的起源和早期系统发育，成为生物大灭绝及复苏的一个难题。文章目的是综述多学科研究石珊瑚早期系统发育的进展，以及多家系统分类，展望前景。研究方法有骨骼构造与微细构造及软体的对比，时空分布分析，寻找早期珊瑚化石及分子生物学等。研究结果主要有石珊瑚可能起源于只有软体的海葵类，发现早期石珊瑚化石，以及石珊瑚在300 Ma之前已演化为两支，但还有不少空白和争议。结论是为了查明石珊瑚的早期系统演化和分类，需要加强古生物与今生物学者多学科交叉的综合研究，努力寻找中间环节，填补研究空白。