Middle and Late Triassic radiolarians from northern Tibet: Implications for the Bayan Har Basin evolution

During the Triassic, the Bayan Har Basin is a huge triangular basin surrounded by the North China Platform, South China Platform and Qingtang Terrane. It is filled by a Triassic turbidite sequence, the Bayan Har Group. For a long time, the series of Bayan Har Group in the eastern part of the basin were considered to be a Lower to Upper Triassic sequence, and in the western part, was attributed to the Upper Triassic. A well-preserved diversified radiolarian fauna was recovered from radiolarian chert and tuffite interbeds of the Bayan Har Group turbidites and adjacent stratigraphic units in the Hoh Xil area, northern Tibet. Sixty-seven species are identified and subdivided into two assemblages: late Anisian and early Carnian. Combined with the discovery of the Late Permian and Early Triassic turbidite in the Bayan Har Group in this area by Huang et al., it proves that all the Triassic is also present in the Bayan Har Group sequence in the western part. The evolution of the Bayan Har Basin may be traced back to the Late Permian. The massive sequence of the Bayan Har Group and its provenance indicate that the Kunlun and Qinling orogenic belts rapidly rise during the Middle-Late Triassic. The basin extended to the end of the Triassic, possibly locally to the Jurassic.     

Smithian (Early Triassic) ammonoids from Tulong, South Tibet

Intensive sampling of the Tulong Formation in South Tibet has facilitated the construction of a highly-resolved middle and late Smithian ammonoid succession. The new biostratigraphical sequence comprises the middle Smithian Brayardites compressus beds, Nammalites pilatoides beds, and the Nyalamites angustecostatus beds followed by the late Smithian Wasatchites distractus beds and Glyptophiceras sinuatum beds. This faunal succession correlates very well with that of other Tethyan sequences such as the Salt Range (Pakistan), Spiti (India), Oman and South China. The Smithian faunal sequence from Tulong contains several taxa with broad geographic distribution (e.g., Owenites, Paranannites spathi, Shigetaceras, Wasatchites), thus enabling correlation with faunal successions from areas outside the Tethys (e.g., USA, British Columbia, Arctic Canada, South Primorye, Siberia). Early Smithian ammonoid faunas are almost absent in Tulong because of a preservation bias (absence of carbonate rocks). Five new ammonoid genera (Brayardites, Nammalites, Nyalamites, Shigetaceras, Tulongites) and six new species (Brayardites crassus, Brayardites compressus, Prionites involutus, ?Subflemingites compressus, Tulongites xiaoqiaoi, Urdyceras tulongensis) are described.     

First report of dinosaurian claws from the Late Triassic of India

The Late Triassic Tiki Formation has yielded five isolated nearly complete claws or ungual phalanges from a fossil locality, which are described in detail and compared with other Late Triassic tetrapods. Of these, four ungual phalanges are slender, asymmetric, ventrally recurved, transversely compressed, and contain deep collateral grooves on either side, a low median keel on the proximal articular surface and a prominent proximoventral flexor tubercle showing their high similarity to the theropod dinosaurs. The remaining claw is unlike that of any theropods in terms of high robusticity and near symmetry. However, as in dinosaurs it is ventrally recurved and contains deep lateral grooves, a small flexor tubercle, lateromedially extended proximal articular surface with a distinct median keel and is considered as belonging to an indeterminate dinosaur. Although it is not possible to ascertain whether the unguals belong to a single taxon or multiple taxa, this new find points towards the presence of small dinosaurs in the Late Triassic Tiki fauna.     

A theropod tooth from the Late Triassic of southern Africa

An isolated, large recurved and finely serrated tooth found associated with the prosauropodEuskelosaurus from the Late Triassic part of the Elliot Formation is described here. It is compared to the Triassic thecodonts and carnivorous dinosaurs and its possible affinity is discussed. The tooth possibly belongs to a basal theropod and shows some features similar to the allosauroids. This tooth is of significance, as dinosaur remains except for some footprints and trackways, are poorly known in the Late Triassic horizons of southern Africa.     

A Primitive Late Triassic 'ictidosaur' from Rio Grande Do Sul, Brazil

A primitive 'ictidosaur' from lower Norian beds of southern Brazil, Riograndia guaibensis gen. et sp. nov., represented by a fragmentary skull and a lower jaw bearing a complete dentition, shows a more generalized morphology than Chaliminia from the Upper Triassic of Argentina and Pachygenelus Diarthrognathus from the Lower Jurassic of South Africa, Canada and Greenland. The frontal bone borders the orbit, and ventrally contacts the dorsal process of the palatine. The secondary bony palate extends back to the last postcanine. I1 and i2 are reduced, whereas I2-3 and i1 are hypertrophied. Both PC 1–7 and pc 1–7 have blade-like crowns without cingula and with 5–9 small sharp cuspules. The upper postcanine crowns are semicircular in labial view with the cuspules around their margins. The lower postcanine crowns are asymmetrical with most of the cuspules dorsodistally distributed. The possible origin of this peculiar dentition is interpreted as the retention of the juvenile dentition of ancestors. The hypothesis that Riograndia guaibensis and the so-called 'ictidosaurs' might have been derived from gomphodont cynodonts is presented.     

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.     

Late paleozoic and Late Triassic limestones from north Palawan Block (Philippines): Microfacies and paleogeographical implications

Summary Selected Late Paleozoic and Triassic limestone exposures were studied on northern Palawan Island, Philippines, with regard to microfacies, stratigraphy and facies interpretation. Although some of the outcrops were already reported in literature, we present the first detailed microfacies study. Late Paleozoic carbonates in the El Nido area are represented by widley distributed Permian and locally very restricted Carbonifenous limestones. Of particular interest is the first report of Carboniferous limestones in the Philippines dated by fossils. Fusulinids indicate a ‘Middle’ Carboniferous (Moscovian-Kasimovian) age of the Paglugaban Formation only known from Paglugaban Island. The Permian Minilog Formation consists mostly of fusulinid wackestones and dasycladacean wacke-/packstones. Fusulinid datings (neoschwagerinids and verbeekinids) provide a Guadalupian (Wordian-Capitanian) age. The depositional setting of the Middle Permian carbonates corresponds to a distally steepened ramp with biostromes built by alatoconchid bivalves locally associated with richthofeniid brachiopods. Late Triassic limestones occur in isolated exposures on and around Busuanga Island (Calamian Islands). The age of the investigated carbonates is Rhaetian based on the occurrence ofTriasina hantkent Maizon. Microfacies data indicate the existence of reefs (Malajon Island) and carbonate platforms (Kalampisanan Islands, Busuanga Island, Coron Island). Reef boundstones are characterized by abundant solenoporacean red algae, coralline sponges and corals. Platform carbonates yield a broad spectrum of microfacies types, predominantly wacke- and packstones with abundant involutinid foraminifera and some calcareous algae. These facies types correspond to platform carbonates known from other parts of Southeast Asia (Eastern Sulawesi and Banda Basin; Malay Peninsula and Malay Basin). The Philippine platform carbonates were deposited on and around seamounts surrounded by deeper water radiolarian cherts. The new data on facies and age of the Philippine Permian and Triassic carbonates contradict a close paleogeographical connection between the North Palawan Block and South China and arise problems for the currently proposed origin of the North Palawan Block at the paleomargin of South China. We hypothesize that North Palawan was part of the Indochina Block during the Carboniferous and Permian, separated from the Indochina Block during the Middle Permian and collided with the South China Block in the Late Cretaceous.     

Microfloristic provincialism in the Upper Triassic Circum-Mediterranean area and palaeogeographic implication

This study represents a contribution to the developing knowledge about the microfloristic provincialism affecting Upper Triassic palynoflora. The compositional differences existing between the Onslow and the Ipswich microfloras are mainly based on the presence, in the Onslow microflora, of a diverse and more varied group of gymnosperm pollen grains, including typical European elements. In this study, the palynological assemblages recovered from Carnian successions of the western Tethyan margin (Sicily, Tunisia, Albany, Libya and Israel) are compared with those of West Timor microfloral assemblages, which have been referred to the Onslow microflora of southern hemisphere. They contain several common taxa, mainly consisting of conifer miospores widely recorded in Carnian European successions and less frequently recovered in the Carnian of western and eastern Australia. The number of Circum-Mediterranean sporomorphs in the Onslow microflora assemblages is wider than previously thought, providing new evidences to extend the distribution of the Onslow microflora to include Carnian associations formerly assigned to the Circum-Mediterranean assemblages. These broad microfloral affinities seem to indicate the existence of a homogeneous microflora that maintains, with minor variations, its composition from western Tethys coasts to the northern Australian margin (West Timor). The parent plant community grew in a coastal environment, along the continental margins; the establishment of an equable climatic regime influenced by warm equatorial currents and suitable humid conditions probably conditioned its diffusion. It has long been recognised that the strong floral provinciality which characterised the Late Triassic world gave way to a more homogeneous flora in the Early Jurassic. The decrease in macrofloral diversity is associated with a less pronounced microfloristic provincialism, which in turn coincides with the rise, to strong dominance, of cheirolepidiaceous conifers (Circumpolles producers). This important microfloristic event occurs in the southern hemisphere during the Early Jurassic, however this study reveals their incipient diffusion during the Norian.     

A new species of Golunda (Rodentia, Muridae) from the Late Pleistocene of Indian Himalaya

The youngest fossil Golunda (Rodentia, Muridae) is described from the Late Pleistocene fluvio-lacustrine deposits, exposed at Dulam (Bageshwar), Kumaun Lesser Himalaya, India. The age of fossiliferrous horizon is estimated as 31,000 yr BP. A new species, Golunda dulamensis nov. sp. has highly derived characters, e.g., antero-posteriorly stretched molars, upper molars with more length and less width, stephanodonty, cusps in M₃ strongly inclined backward giving the molars a very stretched aspect, and metaconid and entoconid in M₃ forming almost straight lingual row of the cusps. G. dulamensis nov. sp. is most similar to present day G. ellioti but differs from the later slightly by larger size, a thin connection between t₄ and t₅ in M¹, and comparatively larger entoconid and very weakly developed antero-labial cusp in M₃. We suggest that highly specialized molars of G. dulamensis nov. sp. and present day G. ellioti are derivable through G. kelleri. We also propose that Golunda migrated from Asia to Africa, not from Africa to Asia as was thought by earlier workers.     

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.      

Some Late Triassic gastropods from the Nayband formation in Central Iran

Summary Six gastropod species from the Late Triassic Nayband Formation are reported. The following taxa are introduced as new:Trochonodus iranicus n. gen., n. sp. andCryptaulax convexa n. sp. The following species are transferred toTrochonodus n. gen.:Riselloidea aliabadensis Nützel and Senowbari-Daryan 1999 (type species ofTrochonodus),Riselloidea biarmata (Münster),Riselloidea bitorquata (Hébert and Eudes-Deslongchamps),Scalaria limatula Ammon, andAmberleya trimonilis (Orbigny). The holotype ofChulitnacula jenningsi (Douglas) is newly illustrated and described. According to the current state of knowledge, the gastropod faunas of the Nayband Formation near Esfahan and near Tabas differ considerably from each other. They share onlyAnulifera binodosa. TheAnulifera species-cluster has representatives in the Norian/Rhaetian from the North Alps, Iran, Burma, and South China. Contribution to the Triassic Paleontology of Iran No. 10. For No. 9 see previous text in this volume.     

A primitive ornithischian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia

Although the group played an important role in the evolution of Late Mesozoic terrestrial ecosystems, the early evolutionary history of the ornithischian dinosaurs remains poorly understood. Here, we report on a new primitive ornithischian, Eocursor parvus gen. et sp. nov., from the Late Triassic (?Norian) Lower Elliot Formation of South Africa. Eocursor is known from a single specimen comprising substantial cranial and postcranial material and represents the most complete Triassic member of Ornithischia, providing the earliest evidence for the acquisition of many key ornithischian postcranial characters, including an opisthopubic pelvis. A new phylogenetic analysis positions this taxon near the base of Ornithischia, as the sister taxon to the important and diverse clade Genasauria. The problematic clade Heterodontosauridae is also positioned basal to Genasauria, suggesting that an enlarged grasping manus may represent a plesiomorphic ornithischian condition. This analysis provides additional phylogenetic support for limited ornithischian diversity during the Late Triassic, and suggests that several major ornithischian clades may have originated later than generally believed. There are few morphological differences between Late Triassic and Early Jurassic ornithischians, supporting previous suggestions that the Early Jurassic ornithischian radiation may simply represent the filling of vacant ecological space following Late Triassic terrestrial extinctions.     

The role of the forelimb in prey capture in the Late Triassic reptile Megalancosaurus (Diapsida,Drepanosauromorpha)

The pectoral girdle and forelimb of the Late Triassic drepanosauromorph reptile Megalancosaurus are redescribed and their function reinterpreted. The whole skeleton of this diapsid is highly specialised for arboreal life, and also the peculiarities of the shoulder girdle and forelimb were interpreted as adaptations for a limb-based locomotion using gap-bridging to move from one support to another, as in chameleons. Re-examination of the pectoral girdle and forelimb revealed the presence of clavicles fused into a furcula-like structure, a saddle-shaped glenoid and a tight connection between the radius and ulna that strengthened the forearm but hindered pronation and supination movements at that joint. The new information plus a reconstruction of the pectoral and forelimb musculature suggests that the forelimb was also specialised for grasping and raking in addition to climbing and thus prey capture may have been an important function for the forelimb. The new functional interpretation fits well with the overall body architecture of Megalancosaurus’ skeleton, suggesting that this reptile was an ambush predator that may have assumed a stable tripodal position, secured by the hooked tail and hind limbs, freeing its forelimbs to catch prey by sudden extension of the arm and firm grasping with the pincer-like digits.     

Larger foraminifera as a substratum for encrusting bryozoans (Late Oligocene,Tethyan Seaway,Iran)

Considering the diversity and abundance of larger foraminifera examined from a wide range of Late Oligocene to Early Miocene palaeoenvironments in the Tethyan Seaway, encrusting bryozoans make extremely little use of their tests as substratum. Significant encrustations by bryozoans were exclusively found on large (ø c. 6 cm), undulating tests of Lepidocyclina spp., on which, however, a remarkable 34 taxa of encrusting bryozoans were recorded. This shallow-water fauna of Chattian age was analyzed in respect of the bryozoan taxa present, colony growth type, and mode of budding, colony size, as well as onset of reproduction. Taxic and morphological similarities between the fossil assemblage and modern faunas encrusting mobile substrata indicate a long history of bryozoans as part of the interstitial habitat, while the tests of certain larger foraminifera may have played a significant role in the evolution of shallow-water bryozoans by providing substrata for encrusting species in otherwise unfavorable environments.     

Late Triassic palynofloras in the Sichuan Basin,South China: Synthesis and perspective

Mesozoic strata are well developed and exposed continuously across the Sichuan Basin, South China. In particular, the Upper Triassic strata yield diverse and abundant spore-pollen fossils, providing a significant reference for the study of palaeoenvironmental variations across the Triassic–Jurassic transition where mass extinctions were occurring. In this paper, we summarize the major progress on Late Triassic palynological studies in this basin. To date, 151 genera (454 species) of sporomorph fossils have been reported from the Late Triassic strata in the Sichuan Basin. Three palynological assemblages are distinguished for the Late Triassic in the Sichuan Basin. Late Triassic vegetation in the Sichuan Basin shows a remarkable predominance of ferns, followed by conifers and cycads/ginkgophytes, and conifers show a distinct increase in abundance in the latest Triassic. In general, the Late Triassic palaeoclimate in the Sichuan Basin was tropical-subtropical, humid and warm. A synthesis of the data shows that the Late Triassic did not have a constant palaeoclimate in the Sichuan Basin, several climatic events are recognized: two warm and humid climate events in Norian-Rhaetian time, coupled with a cooler and drier condition in the latest Late Triassic. Further investigations in higher resolution at more continuous sections in the Sichuan Basin are needed to better understand the Late Triassic vegetation response, climate changes, as well as palaeoecosystem variations across the Triassic–Jurassic boundary.     

Late Paleozoic faunal, climatic, and geographic changes in the Baoshan block as a Gondwana-derived continental fragment in southwest China

The Carboniferous and Permian of the Baoshan block consist of three major depositional sequences: a Lower Carboniferous carbonate sequence, a Lower Permian siliciclastic sequence, and a Middle Permian carbonate sequence. These three sequences were interrupted by two major regressive events: first, the Namurian Uplift ranging in age from Serpukovian to Gzhelian, and second, the Post-Sakmarian Regression occurring probably at Artinskian time in the Baoshan block, although the precise time interval of the latter event is still unclear. The Baoshan block is characterized by warm-water, highly diverse and abundant faunas during the Early Carboniferous, by cold-water and low diversity faunas during the Early Permian, and by possibly warm-water but low diversity faunas during the Middle Permian. The Sweetognathus bucaramangus conodont fauna constrains the upper boundary of the diamictite-bearing siliciclastic deposits (Dingjiazhai Formation) to the Sakmarian to early Artinskian, as well as the eruption of the rifting basalts (Woniusi Formation) to, at least, the post-early Artinskian. Paleozoogeographically, affiliation of the faunas in the Baoshan block changed from Eurasian in the Early Carboniferous, to Peri-Gondwanan in the Early Permian, and to Marginal Cathaysian/Cimmerian in the Middle Permian. Cimmerian blocks have more or less comparable geohistory to one another in the Carboniferous and Permian. During the Middle Permian, the eastern Cimmerian blocks such as Sibumasu (s.s), Baoshan, and Tengchong are not far from the palaeoequator, but apparently more distant than the western Cimmerian blocks based on the presence or absence of some index taxa such as the fusulinaceans Eopolydiexodina and Neoschwagerina, and the corals Thomasiphyllum and Wentzellophyllum persicum.     

Late Paleozoic reef mounds of the Carnic Alps (Austria/Italy)

The Late Paleozoic (early Kasimovian-late Artinskian) sedimentary sequence of the Carnic Alps (Austria/Italy) is composed of cyclic, shallow-marine, mixed siliciclastic-carbonate sedimentary rocks. It contains different types of skeletal mounds in different stratigraphic levels. The oldest mounds occur at the base of the Auernig Group, within a transgressive sequence of the basal Meledis Formation. These mounds are small and built by auloporid corals. Algal mounds are developed in the Auernig Formation of the Auernig Group, forming biostromes, and Lower Pseudoschwagerina Limestone of the Rattendorf Group forming biostromes and bioherms. The dominant mound-forming organism of these mounds is the dasycladacean alga Anthracoporella spectabilis. In mounds of the Auernig Formation subordinately the ancestral corallinacean alga Archaeolithophyllum missouriense is present, whereas in mounds of the Lower Pseudoschwagerina Limestone a few calcisponges and phylloid algae occur locally at the base and on top of some Anthracoporella mounds. Mounds of the Auernig Formation formed during relative sea level highstands whereas mounds of the Lower Pseudoschwagerina Limestone formed during transgression. The depositional environment was in the shallow marine, low-turbulence photic zone, just below the active wave base and lacking siliciclastic influx. The algal mounds of the Carnic Alps differ significantly from all other algal mounds in composition, structure, zonation and diagenesis; the formation of the mounds cannot be explained by the model proposed by Wilson (1975). The largest mounds occur in the Trogkofel Limestone, they are composed of Tubiphytes/Archaeolithoporella boundstone, which shows some similarities to the “Tubiphytes thickets” of stage 2 of the massive Capitan reef complex of the Guadalupe Mountains of New Mexico/West Texas.