Facies and biota of Anisian to Carnian carbonate platforms in the Northern Calcareous Alps (Tyrol and Bavaria)

Summary During the Middle and early Late Triassic carbonate ramps and rimmed platforms developed at the northwestern margin of the Tethys ocean. In the Northern Calcareous Alps, Anisian stacked homoclinal ramps evolved through a transitional stage with distally steepened ramps to huge rimmed platforms of Late Ladinian to Early Carnian age. Middle Triassic to early Late Triassic facies and biota of basin, slope and platform depositional systems are described. Special emphasis is given to foraminifers, sponges, microproblematic organisms and algae. The Ladinian to early Carnian reef associations are characterized by the abundance of segmented sponges, microproblematica, biogenic crusts and synsedimentary cements. Among the foraminifers, recifal forms likeHydrania dulloi andCucurbita infundibuliformis (Carnian in age) are reported from the Northern Calcareous Alps for the first time. Some sphinctozoid sponges likeParavesicocaulis concentricus were known until now only from the Hungarian and Russian Triassic.     

What really happened in the late Triassic?

Major extinctions occurred both in the sea and on land during the Late Triassic in two major phases, in the middle to late Carnian and, 12–17 Myr later, at the Triassic‐Jurassic boundary. Many recent reports have discounted the role of the earlier event, suggesting that it is (1) an artefact of a subsequent gap in the record, (2) a complex turnover phenomenon, or (3) local to Europe. These three views are disputed, with evidence from both the marine and terrestrial realms. New data on terrestrial tetrapods suggests that the late Carnian event was more important than the end‐Triassic event. For tetrapods, the end‐Triassic extinction was a whimper that was followed by the radiation of five families of dinosaurs and mammal‐like reptiles, while the late Carnian event saw the disappearance of nine diverse families, and subsequent radiation of 13 families of turtles, crocodilomorphs, pterosaurs, dinosaurs, lepidosaurs and mammals. Also, for many groups of marine animals, the Carnian event marked a more significant turning point in diversification than did the end‐Triassic event.     

Taxonomical and palaeoecological investigations of the chondrichthyan and osteichthyan fish remains from the Middle-Late Triassic deposits of the Villány Hills (Southern Hungary)

Two sites in the Villány Hills, Hungary, have yielded rich fish assemblages from Middle to Late Triassic shallow marine deposits. The collected material comes from the Ladinian Templomhegy Dolomite Member and from the Carnian Mészhegy Sandstone Formation. The ichthyofauna is composed of both chondrichthyans (Hybodontidae indet., Palaeobates angustissimus, ‘Polyacrodus’ sp., ?Lissodus sp.) and osteichthyans (Gyrolepis sp., Birgeria sp., and further indeterminate actinopterygians). Despite the large sample size, no remains of neoselachians have been found. The Ladinian Templomhegy Dolomite is dominated by durophagous hybodontiforms (Palaeobates angustissimus, ?Lissodus sp.), but the piscivorous hybodontid and the generalist ‘Polyacrodus’ sp. are missing, while in the fish fauna collected from the Carnian Mészhegy Formation indeterminate piscivorous hybodontids are the most common elements and durophagous forms are much less abundant. The dominance of piscivorous hybodontids in the Carnian Mészhegy Sandstone could be related to the global decrease of diversity of marine fish-eating reptiles (e.g., nothosaurs) or to a change of paleoenvironmental conditions. The present study improves our knowledge on the poorly known Triassic vertebrate faunas of the Tisza Mega-unit, which formed a segment of the passive Neotethys margin of the European Plate and shows an important example of a potential vertebrate faunal shift during the Middle to Late Triassic.     

Refinements in the Upper Permian to Lower Jurassic stratigraphy of Karakorum, Pakistan

New sampling on critical intervals of the uppermost Permian and Triassic successions of the Northern Karakorum Terrain in the Karakorum Range (Pakistan) has refined the stratigraphy. Two types of successions may be distinguished in the Karakorum Range: a carbonate platform succession, spanning the whole interval from Upper Permian to Upper Triassic, possibly with several gaps; and a basinal succession, deposited from the Middle Permian to Early Carnian (Late Triassic), when the carbonate platform prograded into the basin. With the approaching and later docking of the Karakorum Block against the Asian margin closing the Paleo-Tethys, a portion of Karakorum emerged while another part subsided as a fore-deep, receiving clastics from the emerging Cimmerian Range. Molassic sediments filled the basin, whilst shallow-water carbonates transgressed over the emerged carbonate platform sometime between the latest Triassic and the Pliensbachian (Early Jurassic), with Cimmerian deformation occurring to the north. The age control is provided by conodonts, with assemblages of late Wuchiapingian, Changhsingian, Induan (Griesbachian and Dienerian), late Olenekian, early Anisian, late Ladinian, and early Carnian ages, respectively. Some information on the section around the P/T boundary is provided by palynology and isotopic C¹³ values. The dating of the Norian/Rhaetian platform is provided by foraminifers.     

Phytoclasts in palynofacies definition: the example of Rhaetian sedimentary organic matter in SE France

The aim of this paper is to calibrate palynofacies with eight classes of phytoclasts using statistical methods in order to construct a reference. Seven categories of palynomorphs are compared to the phytoclast reference. Principal components analysis (PCA) were performed, firstly using separated phytoclast and palynomorph parameters and, secondly, the two grouped describers on samples from two Rhaetian sections that outcrop in SE France. Factor plots of phytoclast data show an arrangement that we assume to be relevant to a crescent buoyant phytoclast order previously described by literature. This arrangement is associated with palynomorph describers (abundance of spores and acritarchs Micrhystridium and pollen Ovalipollis). Some lithological observations are antinomic with an interpretation of these groupings in terms of depositional energy but are presumably coherent with the water depth. Testing all the parameters simultaneously, we define six types of palynofacies ordered on a hypothesized water depth gradient, sustained by an inferred “buoyant factorial plan”. A low water depth palynofacies is associated with lagoons, beaches and marine-shelves. The phytoclasts present are the most buoyant particles on the palynomaceral arrangement. Bays, lagoons, foreshores, beaches, restricted-marine and marine-shelves produce the highest water depth palynofacies. The phytoclasts present are the poorest buoyant particles on the palynomaceral arrangement. Although the exact nature of the relations between energy, water depth and phytoclasts are unknown, the definition of palynofacies by PCA is an objective method for investigating and correlating sedimentary sections.     

New Late Triassic gastropods from the wallowa Terrane (Idaho) and their biogeographic significance

Summary Two characteristic new species and one new genus are described from the Late Triassic of Idaho (Wallowa Terrane):Brochidiella idahoensis n. gen., n. sp. andPtychostoma ornata n. sp.Brochidiella is only known from western North America.Ptychostoma is present in the Carnian of the European Alps (Tethys) and is widespread in the western part of the North American continent (Panthalassa). Late Triassic gastropod faunas from the accreted terranes of North America are poorly known but hold a great potential for future palaeobiogeographic reconstructions.     

<Emphasis Type="Italic">Noriphyllia</Emphasis>, a new Tethyan Late Triassic coral genus (Scleractinia)

Noriphyllia gen. n. is a distinctive coral representing the Coryphylliidae, a group of Late Triassic scleractinian corals. Coral faunas of this age are poorly known. The new coral is distinguished from related corals belonging to the reimaniphylliids by key features of septal microstructure as discerned in thin sections. This microstructure consists of a straight/wavy midseptal zone and lateral septal stereome organized into thin fascicles of fibres, producing a fine and sharp micromorphology of the septal sides. The solitary genus Noriphyllia gen. n. contains two Early Norian species: N. anatoliensis sp. n. chosen as the type species and N. dachsteinae sp. n., and a Carnian species referred to as N. monotutoensis sp. n. The new genus is widely distributed in the Late Triassic, Early Norian reef facies of the Tethys region (Northern Calcareous Alps, Austria; Taurus Mountains, Turkey) and it also occurs in the Carnian of Timor. Noriphyllia gen. n. is unique and details of its microstructural features add new understanding to the composition of both Late Carnian and Early Norian corals.     

滇东南泸西县上三叠统卡尼阶小凹组菊石*

本文对云南省东南部的泸西县白水镇小兴安村上三叠统卡尼阶小凹组菊石类进行了详细研究,共发现菊石9属13种,其中Anasirenites属为华南首次发现。依据各物种组合特征及其地层分布情况,自下而上识别出菊石Trachyceras multituberculatum带和Austrotrachyceras triadicum带,时代对应于晚三叠世早卡尼期的Julian 1和Julian 2。该菊石组合不仅记录了卡尼期Julian期Trachyceratidae的辐射事件,同时该菊石组合与卡尼期特提斯域和泛大洋域的菊石组合均有良好的对比性,并且为华南古地理研究提供了新的补充材料。另外,通过对剖面的岩性特征与菊石生物地层特征分析,认为在滇东南地区由于卡尼期湿润幕事件(CPE)所导致的碳酸盐岩台地消亡起始时间应为Julian 1末期略早于陆源碎屑输入的Julian 2亚期。     

云南中三叠世豆齿龙类(爬行纲：楯齿龙目)—新属(英文)

中国已知的楯齿龙目(Placodontia)化石仅见于贵州省西南部地区,其中豆齿龙亚目(Cya- modontoidea)产自关岭地区的法郎组瓦窑段,时代为晚三叠世卡尼期;楯齿龙亚目(Placodon- toidea)产自盘县的关岭组Ⅱ段,时代为中三叠世安尼期。本文记述的豆齿龙类新属种——康氏雕甲龟龙(Clyphoderma kangi gen.et sp.nov.)产于云南富源的法郎组竹杆坡段,属中三叠世拉丁期。正型标本保存于浙江自然博物馆(编号:M 8729),其头骨高度愈合,代表一个完全成年之个体,根据以下特征明显区别于我国的Psephochelys和欧洲的Psephoderma:1)头骨枕部具3枚大型的锥状鳞;2)背甲甲片结构更为复杂,具明显的放射状沟/脊结构。到目前为止,康氏雕甲龟龙是龟龙科(Placochelyidae)中惟一的中三叠世属种,该科的其他成员全部发现于上三叠统。     

云南中三叠世豆齿龙类（爬行纲：楯齿龙目）一新属

中国已知的檐齿龙目(Placodontia)化石仅见于贵州省西南部地区,其中豆齿龙亚目(Cya-modontoidea)产自关岭地区的法郎组瓦窑段,时代为晚三叠世卡尼期;楯齿龙亚目(Placodon-toidea)产自盘县的关岭组Ⅱ段,时代为中三叠世安尼期.本文记述的豆齿龙类新属种--康氏雕甲龟龙(Glyphoderma kangi gen.et sp.nov.)产于云南富源的法郎组竹杆坡段,属中三叠世拉丁期.正型标本保存于浙江自然博物馆(编号:M 8729),其头骨高度愈合,代表一个完全成年之个体,根据以下特征明显区别于我国的Psephochelys和欧洲的Psephoderma:1)头骨枕部具3枚大型的锥状鳞;2)背甲甲片结构更为复杂,具明显的放射状沟/脊结构.到目前为止,康氏雕甲龟龙是龟龙科(Placochelyidae)中惟一的中三叠世属种,该科的其他成员全部发现于上三叠统.     

Evolutionary rates of the Triassic marine macrofauna and sea-level changes: Evidences from the Northwestern Caucasus,Northern Neotethys (Russia)

A diverse Triassic marine macrofauna from the Northwestern Caucasus sheds new light on the biotic evolution after the end-Permian mass extinction. In the early Mesozoic, the study area was located on the northern margin of the Neotethys Ocean. Data on stratigraphic ranges of 130 genera of brachiopods, bivalves, ammonoids, corals, and sponges have been used to calculate the changes in two evolutionary rates, namely faunal transformation rate (FTR) and rate of transformation of the taxonomic diversity structure (TTDSR). The FTR demonstrates the changes in the generic composition of assemblages through geologic time, whereas the TTDSR indicates changes in the generic control of the species diversity. The Triassic marine macrofauna of the Northwestern Caucasus was characterized by very high FTR and TTDSR during the Early Triassic through early Late Triassic. The FTR slowed in the Middle Triassic, and accelerated again in the Carnian–Norian. In contrast, the FTR was abnormally slow in the Norian–Rhaetian. A remarkable turnover among macrofauna occurred at the Carnian–Norian transition. Regional sea-level changes were similar to the global eustatic fluctuations. It is difficult to establish their direct connections with changes in the evolutionary rates, although the turnover at the Carnian–Norian boundary coincided with a prominent regressive episode. In general, high evolutionary rates reported for the Triassic marine macrofauna of the Northwestern Caucasus may be explained as a consequence of the devastating end-Permian mass extinction.     

Response of Carnian Pluvial Episode evidenced by organic carbon isotopic excursions from western Hubei,South China

We here report a high-resolution organic C-isotope record from terrestrial–marine transitional sediments of the Badong Formation in the Luojiagou section, Zigui Basin of Hubei Province, South China. Our organic carbon isotope (δ¹³C_org) profile, ranging from -21.2‰ to -26.2‰, shows four negative carbon-isotope shifts. We suggest that the sharpest negative carbon isotope excursion in the upper portion of the Badong Formation marks the main phase of the Carnian Pluvial Episode (CPE) in the basin, likely correlated with those in other depositional records of this time. The occurrence of the CPE in the Badong Formation would imply that the stratigraphic coverage of the Badong Formation might be prolonged to incorporate (at least part of) the Late Triassic Carnian stage. This result provides a potential case for understanding the CPE in continental–marine environments in the eastern Tethys realm, and is significant for exploring the palaeoclimate variation across the Late Triassic.     

Onset and demise of the Wetterstein Carbonate Platform in the mélange areas of the Zlatibor Mountain (Sirogojno,SW Serbia)

A kilometer-sized block in the Sirogojno carbonate-clastic mélange provides a complete succession of the Wetterstein Carbonate Platform evolution. The platform starts its progradation in Early Carnian times over hemipelagic Late Ladinian cherty limestones with fine-grained allodapic limestone intercalations. Shallow-water reef-slope, reefal to back-reef/lagoonal limestones evolved in the Early Carnian. The top of the platform is recrystallized and partly slightly dolomitized, and in parts karstification is visible. After a period of omission caused by uplift, new subsidence started in the early Late Carnian. This is documented by a flooding respectively drowning sequence of the same age, starting with reefal carbonates and rapidly followed by hemipelagic-influenced limestones. The evolution of the onset and the drowning of the Wetterstein Carbonate Platform prove a paleogeographic derivation of this block from the outer shelf-area facing the Neotethys Ocean, but still in a shallow-water carbonate platform position transitional to the Hallstatt facies zone. This paleogeographic position is especially confirmed by the new pulse of subsidence in the Late Carnian after a long lasting phase of omission. The evolution of the Wetterstein Carbonate Platform in the Inner Dinarides corresponds to successions known from the Northern Calcareous Alps or the southern Western Carpathians. In the Late Triassic both regions belong to the same northeast–southwest striking shelf area facing the Neotethys Ocean to the east and southeast, respectively.     

Exploring the major depletions of conodont diversity during the Triassic

In this paper, we show that the Triassic fossil record reflects just two great depletions of conodont diversity before the Rhaetian, which occurred in the Smithian (Olenekian, Early Triassic) and in the Julian (Carnian, Late Triassic). By exploring this context, our results highlighted that they respond to different origination–extinction dynamics. Thus, while the Smithian diversity depletion can be interpreted as a consequence of elevated extinction, the Julian diversity depletion was triggered by fluctuations in origination regime. This evidence suggests that, despite the role of extinction on diversity losses, conodonts suffered crucial changes on the origination regimes during the Late Triassic which triggered these events. Notwithstanding, our results indicate that the end-Triassic diversity depletion of conodonts was produced by background extinction levels in a context of lower origination. This suggests that several biological factors, rather than a unique, environmental and/or cyclic cause, could have influenced the evolutionary history of conodonts during the Triassic.     

The temnospondyl amphibian Cyclotosaurus from the Upper Triassic of Poland

Abstract:  A gap in the Late Triassic fossil record of the capitosaur amphibian Cyclotosaurus is filled by new material from lacustrine deposits at Krasiejów, Poland, corresponding in age to the Lehrberg Beds (late Carnian) of Germany. The skull of the Polish cyclotosaur is intermediate in several respects between that of Cyclotosaurus robustus from the middle Carnian Schilfsandstein of Germany and the younger C. mordax from the early Norian Stubensandstein. It shows a decrease in the width of the skull and in the degree of concavity of the posterior margin of the skull roof. The differences are significant enough to warrant erection of a novel species, the name Cyclotosaurus intermedius sp. nov. being proposed. The pectoral girdle, identified for the first time in Cyclotosaurus , suggests the genus was more fully adapted to an aquatic mode of life than was Paracyclotosaurus .     

New information on Bobosaurus forojuliensis (Reptilia: Sauropterygia): implications for plesiosaurian evolution

Preparation of the holotype specimen of Bobosaurus forojuliensis, a large sauropterygian from the lower Carnian of northeastern Italy, revealed new morphological data relevant in establishing its phylogenetic affinities among pistosauroid taxa and its relationships with plesiosaurians. Inclusion of B. forojuliensis in two phylogenetic analyses focusing, respectively, on sauropterygians and pistosauroids agreed in placing the Italian taxon as closer to plesiosaurians than to other pistosauroids. The phylogenetic interpretation of Bobosaurus was not biased by assumptions on character weighting, is consistent with its relatively younger age compared to most pistosauroids, extends the fossil record of the plesiosaurian basal lineage back to the Carnian and supports the earliest diversification of the clade during the Late Triassic in agreement with the record of several distinct lineages of rhomaleosaurids, plesiosauroids and pliosauroids in the lowermost Jurassic. Bobosaurus shows that the evolution of the plesiosaurian body plan from the ancestral pistosauroid grade was a step-wise process, and that some of the vertebral and appendicular specialisations of Jurassic and Cretaceous plesiosaurians had already developed in the earliest Late Triassic.     

西藏丁青蛇绿岩带中一个晚三叠世放射虫动物群

西藏丁青地区晚三叠世Carnian期放射虫动物群共描述19属35种（7个未定种）,归于16科（亚科）中,以Capnuchosphaera,Palaeosaturnalis,Perispongidium,Spongostylus,Annulotriassocampe,Poulpus,Xenorum,Veghicyclia,Tetraporobrachia,Canoptum,Xiphotheca等属为主的这个动物群被命名为Capnuchosphaera triassica组合带,由于Capnuchosphaera属在全世界广泛分布,无论在特提斯生物大区还是环太平洋生物大区,以这个属为主的放射虫动物群已成为国际间Carnian期至Norian早中期放射虫地层学对比的重要依据。     

A Basal Sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic,Carnian) and the Early Evolution of Sauropodomorpha

Background

The earliest dinosaurs are from the early Late Triassic (Carnian) of South America. By the Carnian the main clades Saurischia and Ornithischia were already established, and the presence of the most primitive known sauropodomorph Saturnalia suggests also that Saurischia had already diverged into Theropoda and Sauropodomorpha. Knowledge of Carnian sauropodomorphs has been restricted to this single species.

Methodology/Principal Findings

We describe a new small sauropodomorph dinosaur from the Ischigualsto Formation (Carnian) in northwest Argentina, Panphagia protos gen. et sp. nov., on the basis of a partial skeleton. The genus and species are characterized by an anteroposteriorly elongated fossa on the base of the anteroventral process of the nasal; wide lateral flange on the quadrate with a large foramen; deep groove on the lateral surface of the lower jaw surrounded by prominent dorsal and ventral ridges; bifurcated posteroventral process of the dentary; long retroarticular process transversally wider than the articular area for the quadrate; oval scars on the lateral surface of the posterior border of the centra of cervical vertebrae; distinct prominences on the neural arc of the anterior cervical vertebra; distal end of the scapular blade nearly three times wider than the neck; scapular blade with an expanded posterodistal corner; and medial lamina of brevis fossa twice as wide as the iliac spine.

Conclusions/Significance

We regard Panphagia as the most basal sauropodomorph, which shares the following apomorphies with Saturnalia and more derived sauropodomorphs: basally constricted crowns; lanceolate crowns; teeth of the anterior quarter of the dentary higher than the others; and short posterolateral flange of distal tibia. The presence of Panphagia at the base of the early Carnian Ischigualasto Formation suggests an earlier origin of Sauropodomorpha during the Middle Triassic.