滇西巍山地区上三叠统诺利阶三合洞组牙形石年代及沉积相分析*

滇西兰坪-思茅地块晚三叠世诺利期(Norian)发育一套海相碳酸盐岩沉积(三合洞组)。对巍山三合洞剖面进行了实测与采样, 分离了三合洞组碳酸盐岩中的牙形石, 经鉴定其种属为Epigondolella vialovi, Epigondolella uniformis和Epigondolella aff. triangularis, 时代为早诺利期(Lacian亚期)。通过野外剖面及室内显微薄片观察, 采用微相分析的方法对剖面三合洞组碳酸盐岩的微相类型和沉积环境进行研究, 将巍山三合洞剖面三合洞组沉积归纳为9种微相, 并根据微相特征结合野外宏观特征, 将三合洞剖面划分为3种沉积相类型, 即局限台地相、开阔台地相和台地边缘礁相。在剖面不同层位的碳酸盐岩中发现的热液矿物石榴子石及发黑的牙形石化石(CAI指数约为5), 表明该区曾遭受热液作用的影响, 可能与三合洞组沉积后大陆边缘裂谷下陷或板块拼合引起的热卤水上涌有关。     

Bored Bivalves in Upper Triassic (Norian) Event Beds,Northeastern British Columbia,Canada

Skeletobionts are important components of most shallow marine ecosystems. Prior to the fossils reported herein, evidence of skeletobionts was absent from Upper Triassic successions on the northwestern margin of Pangaea. The boring Talpina ramosa is reported from bivalve body fossils from the Upper Triassic (Lower Norian) lower Pardonet Formation at Pink Mountain in northeastern British Columbia. This Ichnotaxon penetrates through both the outer and inner surface of articulated and disarticulated bivalve shells preserved within sharp-based event beds. The occurrence of these trace fossils underscores the paucity of borings, bioerosional structures, and encrusting taxa from Triassic successions in the western Pangaean realm. Due to erosional removal of shallow water strata by a post-Triassic unconformity, these event beds provide the only available information regarding the ecological health of Late Triassic depositional systems in the study area.     

Upper Triassic (Norian) hypercalcified sponges from the Musandam Peninsula (United Arab Emirates and Oman)

Supercalcified sponges, including sphinctozoans, inozoans, chaetetids, spongiomorphids, occurring in Upper Triassic (Norian-Rhaetian) shallow-marine limestones of Musandam Mountains in United Arab Emirates (UAE), are described. The following taxa were determined: sphinctozoans: Hajarispongia osmani Senowbari-Daryan and Yancey, Nevadathalamia arabica n. sp., Nevadathalamia conica n. sp., Fanthalamia milahaensis n. sp., Iranothalamia incrustans (Boiko), Cinnabaria regularis n. sp.; inozoans: Cavsonella triassica n. sp., Molengraaffia regularis Vinassa de Regny, Peronidella? sp., Circopora cf. caucasica Moiseev, Circopora? sp.; spongiomorphids: Spongiomorpha sp.; chaetetids: Lovcenipora chaetetiformis Vinassa de Regny, Lovcenipora musandamensis n. sp., Lovcenipora sp., chaetetid sponge gen. et sp. indet. The most abundant sponge in the studied material is Nevadathalamia arabica n. sp. The described sponge association of the Arabian shelf (Musandam Mountains) shows close affinity to the sponge association known from age-equivalent terranes in the Panthalassa Ocean (Sonora Mountains in Mexico; Pilot Mountains in Nevada, USA), but is remarkably different from sponge associations in carbonates bordering the Tethys. This difference goes along with the biogeography of wallowaconchid bivalves and is most likely attributed to climatic, palaeogeographic or oceanographic factors.     

Late Triassic (Late Norian) gastropods from the Wallowa Terrane (Idaho,USA)

A diverse Late Triassic (Late Norian) gastropod fauna is described from the Mission Creek Limestone of the Wallowa terrane (Idaho, USA). Sample standardization by rarefaction analysis indicates that the fauna is even more diverse than the Late Triassic gastropod fauna from the Pucara Formation (Peru) which represents the most diverse gastropod fauna from South America. The gastropod fauna consists of 66 species; several genera are reported for the first time from North America. A high percentage of the species are highly ornamented and several have distinct siphonal canals. This suggests that the appearance of truly Mesozoic elements among the gastropods began before the Mesozoic Marine Revolution in other clades. The fauna is dominated by high-spired strongly ornamented procerithiids, a group more characteristic for the Jurassic. Comparison of the present fauna and the Iranian Nayband Formation gastropod fauna show that the procerithiids underwent a first global radiation in the Late Triassic. The high number of new species in this fauna suggests that sampling of Late Triassic gastropod faunas is still incomplete and hinders palaeobiogeographic considerations. Previous suggesions that gastropod faunas from the Wallowa and Wrangellia terranes resemble each other and are distinct from those of Alexander, Chulitna, and Farewell terranes are basically corroborated. The gastropod fauna of the Mission Creek Limestone differs considerably from that of the western and central Tethys but shares several taxa with the Late Triassic gastropod fauna of the Pucara Formation in Peru. Thus, the Hispanic corridor was probably not present in the Norian but opened only in the Early Jurassic. The subfamily Andangulariinae is introduced and placed in the Zygopleuridae. The generaSpiniomphalus, Nodoconus, Gudrunella, Blodgettella, Idahospira, andSiphonilda and the subgenusCryptaulax (Wallowax) are introduced. 27 species are erected. A lectotype is designated forCryptaulax rhabdocolpoides Haas, 1953.      

Filograna (colonial serpulid worm tubes) from Upper Triassic (Norian) reef boulders of Taurus Mts. (southern Turkey)

Two colonial serpulid worm tubes—Filograna taurica n. sp. and Filograna serialis n. sp.—from the Upper Triassic (Norian) reef boulders occurring in Taurus Mts. (south Turkey) are described. As bafflers, both species of Filograna build microbioherms reaching dimensions of up to 15 cm. Both species were not known either in Turkey or in any other Triassic localities of the Tethyan realm.     

Extremely distal fluvial sandstone within the playa system of Arnstadt Formation (Norian,Late Triassic), Central Germany

The Wachsenburg Sandstone of Thuringia (Central Germany) occurs within playa deposits of the Arnstadt Formation (Late Triassic, Norian) and furnishes an example of ephemeral river metamorphosis under dryland conditions. Characterized by high flow regime features, the sand-dominated lithofacies constitution exhibits sedimentation by channel processes under the influence of recurring flash floods. Bearing signatures of subaerial exposures, the fining-upward lithofacies cycles are bound by low-angle lateral accretion elements suggesting deposition in a meandering stream. Channel migration in response to point bar expansion and active bank erosion, led to the development of four laterally shifting point bar events. Unimodal palaeocurrent patterns with low variance and azimuthal dispersion support the point bar origin of the Wachsenburg Sandstone. With reduced water budget under largely semi-arid climate, the river progressively became smaller, highly sinuous and ultimately abandoned. The resulting point bar succession was finally covered with sheet flow deposits of over bank origin. The sandstone was deposited during a period of low base-level when the playa system temporarily fell dry.     

Fluorescence intensity studies of Triassic acritarchs from the Yanchang Formation in Ordos basin,northwestern China

Fluorescence properties of Early Cambrian acritarchs were investigated using Leica das Mikroskop (DM)microscopy with a mercury lamp.Well-preserved autoflurescence properties show a correlation between acritarchs morphology and the intensity of emitted fluorescence.In accordance with the fluorescence intensity of organic cell walls,two groups ofmicrofossils were distinguished.Results of observation in this study,which are consistent with those of the previous foreign studies,are in good agreement with regular difference in autofluorescence intensity among palynomorphs reported by McPhilemy (1998).Spores and algae,including Botryococcus,have very bright fluorescence while acritarchs often show less intense fluorescence.Dark brown microfossils have been reworked,and have little or no fluorescence.     

Fluorescence intensity studies of Triassic acritarchs from the Yanchang Formation in Ordos basin, northwestern China

Fluorescence properties of Early Cambrian acritarchs were investigated using Leica das Mikroskop (DM) microscopy with a mercury lamp. Well-preserved autoflurescence properties show a correlation between acritarchs morphology and the intensity of emitted fluorescence. In accordance with the fluorescence intensity of organic cell walls, two groups of microfossils were distinguished. Results of observation in this study, which are consistent with those of the previous foreign studies, are in good agreement with regular difference in autofluorescence intensity among palynomorphs reported by McPhilemy (1998). Spores and algae, including Botryococcus, have very bright fluorescence while acritarchs often show less intense fluorescence. Dark brown microfossils have been reworked, and have little or no fluorescence. __________ Translated from Acta Micropalaeontologica Sinica, 2006, 23(3): 309–312 [译自: 微体古生物学报]     

Calcareous algae from the Triassic (Anisian reef boulders and Norian reef limestones) of Karaburun, western Turkey

Invertebrate Anisian and Norian reef boulders were found in the Gerence and Güvercinlik Formations, respectively, exposed in northeastern part of the Karaburun Peninsula, western Turkey. Halimedacean green algae and solenoporacean red algae, usually associated with other reef building organisms are described in this paper. The following taxa were determinated: halimedaceans: Egericodium hungaricum Flügel, Velledits, Senowbari-Daryan and Riedel, Aternasus irregularis n. gen., n. sp.; solenoporaceans: Solenopora cf. alcicornis Ott, Solenopora triasina Vinassa de Regny, Solenopora vachardi n. sp., Solenopora concentrica n. sp., Solenopora paraconcentrica n. sp., Tauristorea parallela Senowbari-Daryan and Link, Tauristorea discursa n. sp., and Parachaetetes cassianus (Flügel). The monospecific genus Aternasus n. gen. is the most abundant alga within the Anisian reef boulders. The solenoporaceans are represented by several taxa but the individual species are less abundant. E. hungaricum, T. parallela Senowbari-Daryan and Link, and S. triasina Vinassa de Regny are described from the Norian reef limestones embedded in Güvercinlik Formation, all other taxa from the Anisian reef boulders embedded in the Gerence Formation.     

The Lower Cretaceous Patuxent Formation Ichnofauna of Virginia

The vertebrate fauna from the Lower Cretaceous Patuxent Formation of Virginia is composed of a single partial fish impression from the James River at Dutch Gap and a diverse tetrapod ichnofauna from near Fredericksburg that includes trace fossils made by frogs, turtles, theropods, sauropods, ankylosaurs, and ornithopods. The footprints occur on overbank deposits preserved locally within a fluvial braided-stream sequence that formed near the western border of the Early Cretaceous Atlantic Coastal Plain.     

The Ichnofossils of the Triassic Hope Bay Formation,Trinity Peninsula Group,Antarctic Peninsula

The Triassic Hope Bay Formation (Trinity Peninsula Group) includes a diverse ichnocoenosis in the Puerto Moro succession (Hope Bay, Antarctic Peninsula). The Hope Bay Formation is a thick turbidite succession with a minimum vertical exposure of 533 meters along the Hope Bay coast. The rocks are locally affected by contact metamorphism related to later arc magmatism. The ichnofossils are found mainly in thick- and thin-bedded sandstone-mudstone facies composed of a monotonous repetition of sandstone-mudstone cycles. The sandstones are usually medium grained, massive or parallel laminated; the mudstones are massive and rarely laminated. In the fine-grained rocks, mainly the mudstones, there are distinct densities of bioturbation, and at least six patterns were observed. The following ichnogenera were recognized: Arenicolites Salter 1857, Lophoctenium Richter 1850, Taenidium Heer 1877, Palaeophycus Hall 1847, Phycosiphon von Fischer-Ooster 1858 and Rhizocorallium Zenker 1836. All appear to be feeding-traces. The trace fossil assemblages occur mainly in black mudstones rich in organic material that suggest a low oxygen environment. The stratigraphic interval in which they occur is interpreted as progradational supra-fan lobes with channel fill and levee deposits. The thin-bedded turbidite and mudstone lithofacies, where the ichnofossils are abundant, is interpreted as a distal fan turbidite or levee deposit related to a long-term channel fill. This study is the first significant report of trace fossils in the Hope Bay Formation.     

Basal dinosauriform and theropod dinosaurs from the mid–late Norian (Late Triassic) of Poland: implications for Triassic dinosaur evolution and distribution

The rise of dinosaurs during the Triassic is a widely studied evolutionary radiation, but there are still many unanswered questions about early dinosaur evolution and biogeography that are hampered by an unevenly sampled Late Triassic fossil record. Although very common in western North America and parts of South America, dinosaur (and more basal dinosauriform) remains are relatively rare in the Upper Triassic deposits of Europe, making any new discoveries critically important. One of the most diverse dinosauriform assemblages from Europe comes from the Por?ba site in Poland, a recently described locality with exposures of the Zb?szynek Beds, which have a palynomorph assemblage characteristic for the mid–late Norian in the biostratigraphic schemes of the Germanic Basin. Using a synapomorphy‐based approach, we evaluate several isolated dinosauriform specimens from Por?ba. This assemblage includes a silesaurid, a herrerasaurid and remains of another type of theropod (potentially a neotheropod). The Por?ba herrerasaurid is the first record of this rare group of primitive dinosaurs from Europe and one of the youngest records worldwide, whereas the silesaurid is the youngest record of a silesaurid from Europe. These findings indicate that silesaurids persisted alongside true dinosaurs into the mid–late Norian of Europe and that silesaurid–herrerasaurid–neotheropod assemblages (which are also known from the Norian of North America, at low latitudes) were more widespread geographically and latitudinally than previously thought. Silesaurid–herrerasaurid–neotheropod assemblages may have been a common ecological structuring of dinosaurs during their early evolution, and their widespread distribution may indicate weak palaeolatitudinal controls on early dinosaur biogeography during the latest Triassic.     

Recovery dynamics of benthic marine communities from the Lower Triassic Werfen Formation,northern Italy

The Lower Triassic Werfen Formation of northern Italy represents an important archive for Early Triassic ecosystems. Based on quantitative community analysis using species level identifications, we reconstruct the recovery of benthic ecosystems after the end‐Permian mass extinction throughout this unit. The analysis of benthic macrofossil communities shows that incipient recovery has taken place during the Griesbachian and the Griesbachian–Dienerian transition. A probable deterioration in environmental conditions is observed towards the end of the Dienerian. The Smithian part of the Werfen Formation is characterized by high siliciclastic input, which ceases around the Smithian‐Spathian boundary. The Spathian marks the definitive phase of recovery in the Werfen Formation. The comparison of this pattern with other palaoegeographical regions suggests that both the Griesbachian recovery and the Dienerian decline were of inter‐regional if not global extent, whereas the Smithian diversity low in the Werfen Formation is a local signal. In contrast to the recovery dynamics of ammonoids and conodonts, the Smithian–Spathian boundary interval was no caesura for benthic ecosystems. The Spathian recovery pulse is possibly also an inter‐regional event, at least in the palaeotropics. These results are in contrast with the previously proposed scenario of persistent hostile conditions during the Griesbachian time interval and highlight an initial recovery phase restricted to Griesbachian times. Instead, the apparently sluggish recovery of benthic ecosystems was at least partly shaped by set‐backs due to short‐term environmental perturbations during the Dienerian.     

Reassessment of cf. Halticosaurus orbitoangulatus from the Upper Triassic (Norian) of Germany – a pseudosuchian,not a dinosaur

The holotype of cf. Halticosaurus orbitoangulatus Huene, 1932, comprises an incomplete and macerated but associated skull of an archosaurian reptile from the middle (second) Stubensandstein (middle Löwenstein Formation; Upper Triassic: Norian) of Baden‐Württemberg, Germany. It was originally interpreted as a theropod dinosaur but more recently it has been suggested that this taxon has crocodylomorph affinities. Detailed preparation of the holotype of cf. H. orbitoangulatus has revealed much new anatomical information and permitted reassessment of its affinities. The maxilla lacks both a distinct antorbital fossa and a medial bony lamina bordering the antorbital fenestra. The lateral surface of the dentary bears a pronounced horizontal ridge. The squamosal differs from that of basal crocodylomorphs in being L‐shaped rather than arcuate in dorsal view, lacking a dorsolateral overhang, and lacking an interlocking contact with the paroccipital process as, for example, in the basal crocodylomorph Saltoposuchus connectens from the same horizon and locality. Phylogenetic analysis placed cf. H. orbitoangulatus amongst loricatan pseudosuchians (but not amongst Crocodylomorpha) rather than amongst theropod dinosaurs. The holotype of cf. H. orbitoangulatus represents a previously unrecognized taxon of loricatan pseudosuchian, which is here named Apatosuchus orbitoangulatus and set apart from other known Norian‐age non‐crocodylomorph loricatans by its apparently much smaller size. © 2013 The Linnean Society of London     

Triassic temnospondyl biostratigraphy, biochronology and correlation of the German Buntsandstein and North American Moenkopi Formation

Based on temnospondyl distributions, we propose a correlation of the non-marine Lower and Middle Triassic strata of Germany and the western United States. This correlation relies principally on the presence of two genera, Nonesian (late Early Triassic) Parotosuchus and Perovkan (early Middle Triassic) Eocyclotosaurus . The distribution of Parotosuchus helgolandicus indicates that the Torrey Member of the Moenkopi Formation in Utah, USA is equivalent to the Volpriehausen Formation of the German Buntsandstein of Nonesian age. Magnetostratigraphy and the distribution of Eocyclotosaurus indicate that the Perovkan Holbrook Member of the Moenkopi Formation in Arizona corresponds to a short interval of Anisian time, as does the German Upper Buntsandstein. The Buntsandstein and Moenkopi biostratigraphic schemes agree with a recently proposed biochronology of Triassic terrestrial tetrapods.     

Evidence of arthropod-plant interactions in the Upper Triassic of the southwestern United States

Leaves from the Upper Triassic Chinle Formation in the southwestern United States show evi dence of having provided nourishment and shelter for several different types of arthropods. This evidence consists of three or four morphotypes of feeding traces and a well-defined type of gall. The feeding traces occur on the pinnules of the filicalean fern Cynepteris lasiophora (Daugherty) Ash and the pinnae of the bennettitalean leaf Zamites sp. and Marcouia neuropter-oides Ash, a gymnosperm leaf of uncertain relationships. Typically, the feeding traces are only a few mm in length and have smooth, continuous margins which are often bordered by a nar-row dark band that represents reaction tissue formed in response to feeding. Presence of this tissue indicates that the leaves continued to function after the damage occurred and while they were still attached to the parent plant. The relatively small size and shape of the feeding traces shows that they were most likely produced by grazing insects. Gall-like swellings are found on the leaves of Dechellyia gormanii Ash, another gymnosperm fossil of uncertain relationships. The swellings are well defined, round to deltoid in outline, and bulbous. Typically, only one such swelling occurs on a leaf. Leaves that have these swellings are often distorted or terminate abruptly at the disturbance, particularly if the structure extends over the edge of the leaf. The swellings resemble galls induced on leaves of certain modern plants by eriophyid mites and apparently are either prosoplasmatic histioid pit galls or pouch galls.     

Early Triassic bivalves from the Feixianguan Formation in Xingyi,Guizhou and the Ximatang Formation in Qiubei,Yunnan (southern China)

Based on newly collected materials from the Lower Triassic Feixianguan Formation of Xiongwu section in Xingyi, Guizhou and the Ximatang Formation of Ximatang section in Qiubei, Yunnan, southern China, nine species belonging to seven genera are described. Two bivalve assemblages are recognized and regionally correlated in South China. The bivalve assemblage from the Feixianguan Formation of Xiongwu exhibits a higher diversity including seven species belonging to seven genera: Claraia griesbachi, Leptochondria virgalensis, Entolium (Entolium) microtis, Towapteria scythicum, Bakevillia exporrecta, Bositra sp., and Unionites? fassaensis. In contrast, the bivalve assemblage from the Ximatang Formation of Ximatang has a much lower diversity, consisting of only two species, i.e., Claraia griesbachi and Claraia radialis. Additionally, C. griesbachi and C. radialis, as the most common species of Claraia in the Early Triassic, are revised.     

Trace fossils in fluvial deposits of the uppermost Stockton Formation (Late Triassic), Newark Basin,New Jersey

Abstract

Fluvial deposits of the uppermost Stockton Formation (Late Triassic), Newark Basin, west-central New Jersey have yielded an assemblage of trace fossils. Dominated by burrows, specimens include Cochlichnus anguineus, Helminthoidichnites tenuis, Planolites beverleyensis, Scoyenia gracilis, Spongeliomorpha carlsbergi, Treptichnus bifurcus, Treptichnus pollardi, plant remains, and an undetermined vertebrate trace fossil. The assemblage belongs to the Scoyenia ichnofacies. On the basis of stratification and primary sedimentary structures, the beds are interpreted as deposits in a meandering stream environment. Larval insects, wormlike forms, and arthropods are probably responsible for most of the animal traces in wet or moist channel, floodplain, and point bar sediments subject to subaerial exposure.     

A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record

The Upper Triassic tetrapod fossil record of North America features a pronounced discrepancy between the assemblages of present-day Virginia and North Carolina relative to those of the American Southwest. While both are typified by large-bodied archosaurian reptiles like phytosaurs and aetosaurs, the latter notably lacks substantial representation of mammal relatives, including cynodonts. Recently collected non-mammalian eucynodontian jaws from the middle Norian Blue Mesa Member of the Chinle Formation in northeastern Arizona shed light on the Triassic cynodont record from western equatorial Pangaea. Importantly, they reveal new biogeographic connections to eastern equatorial Pangaea as well as southern portions of the supercontinent. This discovery indicates that the faunal dissimilarity previously recognized between the western and eastern portions of equatorial Pangaea is overstated and possibly reflects longstanding sampling biases, rather than a true biogeographic pattern.