Biostratigraphic Implications Research Articles

A New Calcareous Nannofossil Record from the Lower Jurassic of Kermanshah, Western Iran: Implications for Biostratigraphy and Evolutionary Reconstructions

Calcareous nannofossils are used here for the first time in order to establish a precise biostratigraphic framework for the Kermanshah Radiolarite Formation, an outcropping in Western Iran. The new data presented here challenge the previous tentative age interpretations (Pliensbachian to early Toarcian) based upon radiolarians. Calcareous nannofossil assemblages and events unequivocally indicated that the pelagic limestones and marls are late Sinemurian in age (NJT 3b nannofossil subzone), and that these are thrusted over shales and cherts dated as uppermost Sinemurian (NJT 3b-c nannofossil subzone) and lowermost Pliensbachian (NJT 4 nannofossil zone). This result leads not only to reconsideration of the age of the radiolarite formations, which are widespread in the Zagros orogenic system, but also a better understanding of the stratigraphic relationships between the various lithological units known in the area. Besides these new stratigraphic inferences, the calcareous nannofossil assemblages of the uppermost Sinemurian–lowermost Pliensbachian successions revealed the common presence of new morphologies of the Mitrolithus genus, never described before. These findings allow for the description of three new species, M. montgolfieri, M. pseudonannoconus, and M. tethysiensis, and reveal the existence of homeomorphy between the spine structure of conical Lower Jurassic coccoliths and the widespread Cretaceous nannoconids.

Eocene Teleostean Otoliths, Including a New Taxon, from the Clinchfield Formation (Bartonian) in Georgia, USA, with Biostratigraphic, Biogeographic, and Paleoecologic Implications

Eocene Teleostean Otoliths, Including a New Taxon, from the Clinchfield Formation (Bartonian) in Georgia, USA, with Biostratigraphic, Biogeographic, and Paleoecologic Implications

Middle–Late Ordovician chitinozoans from Songliang of Qiaojia, western South China, and their biostratigraphic implications

Ordovician chitinozoans are as yet inadequately documented from the western Yangtze Platform, South China. Here we present a systematic study on chitinozoans from a Middle–Upper Ordovician succession at Songliang of Qiaojia, northestern Yunnan, southwestern China. Altogether 34 species of 12 genera are identified from the upper Hungshihyen and the Huadan formations. The top of the Hungshihyen Formation yields typical Early and Middle Ordovician forms, for instance, Lagenochitina obeligis and Belonechitina chenjiawuensis, with the latter only known from the lower Darriwilian in South China, thus suggesting an early Darriwilian age for this interval. The chitinozoans recovered from the Huadan Formation include Lagenochitina prussica and Spinachitina fossensis, both are mainly confined in Katian and sometimes ranging into younger strata. This indicates an age younger than the middle to late Darriwilian previously determined for the Huadan Formation. However, conflicts exist in age assignment of the Huadan Formation based on chitinozoan and other evidence, and further work is required.

The evolution of Eocene (Ypresian/Lutetian) sphenoliths: biostratigraphic implications and paleoceanographic significance from North Atlantic Site IODP U1410

Sphenoliths are a diverse and evolutionarily dynamic group of Cenozoic nannofossils which are widely used in biostratigraphic and paleoecological studies. We document the early-middle Eocene evolut ...

Megaspores from the Late Triassic‒Early Jurassic of southern Scandinavia: taxonomic and biostratigraphic implications

ABSTRACT Here we investigate megaspores from 10 Triassic‒Jurassic localities of southern Sweden and Bornholm, Denmark, based on collections housed in the Swedish Museum of Natural History. We identify and describe 19 megaspore taxa belonging to three stratigraphically constrained assemblages, representing the Rhaetian, Hettangian and Pliensbachian, respectively. Megaspores are abundant and diverse (12 taxa) in the Rhaetian assemblage. Diversity markedly decreases across the Triassic–Jurassic boundary (TJB), with species richness reducing from 12 to two taxa. The Hettangian assemblage is well-preserved but depauperate, and is overwhelmingly dominated by Nathorstisporites hopliticus. A subsequent recovery of lycopsid diversity followed, recorded by an increase in richness to six taxa in the Pliensbachian assemblage. The disappearance of the hygrophilous and diverse heterosporous lycophyte communities across the TJB, suggests a shift to drier conditions in the earliest Jurassic. This is supported by lithological changes from coal-forming environments in the Rhaetian to sandstone-dominated fluvial-estuarine facies in the Hettangian. Throughout this study, we analysed the megaspores using fluorescence microscopy, which revealed detailed morphological features on specimens that were otherwise opaque under visible light. This non-destructive technique is particularly useful for examining opaque megaspores embedded in permanent mounting media, such as epoxy resin, and may provide new insights into historical megaspore collections elsewhere.

Early Crioceratites (heteromorphic ammonites) from the lower Hauterivian of south-eastern France: systematics, intraspecific variation and biostratigraphic implications

Two acmes of the genus Crioceratites were recorded in the current Crioceratites loryi Zone (lower Hauterivian) in the Lower Cretaceous series of south-eastern France (Vocontian Basin), both in the classic section of the Cheiron ravine (Castellane area) and in the Hauterivian GSSP area at La Charce. The revision of an abundant material allows us to define Crioceratites claveli sp. nov. The first acme and the first part of the second acme correspond to the range of C. claveli sp. nov. and not to C. loryi as previously admitted. The remaining of the second acme is related to this latter species solely. The great abundance of C. claveli sp. nov. in the lower interval Horizon allowed a detailed analysis of its variation around 3 factors: (1) dimorphism; (2) multipolar variation of order two here characterized by an absence of correlation between the ornamental and morphological shell parameters (non-covariant factors); and (3) ontogenic heterochronies, which depend on the robustness of the ornamentation only. On the other hand, the northern edge of the Provençal platform delivered C. jurensis (revised here) from the top part of the Acanthodiscus radiatus Zone, which reduces the gap with the older Crioceratites known in the uppermost Valanginian. Finally, the study of the stratigraphic distribution of C. claveli sp. nov. and C. loryi leads to propose the new C. claveli (Sub)Zone instead of the C. loryi (Sub)Zone. This proposal for the south-eastern France may have extension potential for the Mediterranean Province of the Mediterranean Caucasian Subrealm (Tethyan Realm).

Psammichnites gigas from the lower Cambrian of the Mackenzie Mountains, northwest Canada, and their biostratigraphic implications

New occurrences of Psammichnites gigas are reported from the Mackenzie Mountains, northwest Canada. A locality in the hanging wall of the Plateau Fault, just below the top of the upper member of the Backbone Ranges Formation, demonstrates that the uppermost part of the unit is Tommotian (latter part of Cambrian Age 2) or possibly earliest Atabanian (earliest Cambrian Age 3) in its previously undated proximal manifestation. Localities in the trilobite-bearing Sekwi Formation confirm that Psammichnites gigas can be at least as young as Atdabanian (early to middle parts of Cambrian Age 3) in Laurentia. A review of reported occurrences suggests Psammichnites gigas, and the related ichnotaxa Plagiogmus arcuatus and Taphrelminthopsis circularis, may be valuable for correlations in western Laurentia if their ichnotaxonomic relationships are clarified.

Planktic foraminiferal response to an early Paleocene transient warming event and biostratigraphic implications

The Latest Danian Event (LDE, ~ 62.2 Ma) is characterized by global changes in the carbon cycle as indicated by two negative δ13C excursions of up to ~ 1‰. These δ13C shifts are accompanied by a 2–3 °C warming of both surface and deep waters based on benthic and planktic foraminiferal δ18O measurements, and the LDE has, thus, been considered as a so-called hyperthermal event. The event lasted for 200 kyr and has been identified in various ocean basins and shallow marine settings. Here, we present a compilation of data from three deep-sea cores covering the Pacific, North and South Atlantic oceans as well as a southern Tethyan shelf section to document the response of planktic foraminifera assemblages to ocean warming. In all studied successions, we observe the disappearance of the planktic foraminifer genus Praemurica on a global scale that took place close to the onset of the LDE. Moreover, on the long run, praemuricids were contemporaneously replaced by morozovellids. Both the decline of Praemurica and a temperature increase started between 200 and 260 kyr before the LDE onset and were punctuated by the LDE itself. In this paper, we propose two mechanisms that have controlled the environmental changes associated with this event, (1) increased activity of the North Atlantic Igneous Province acting on long time-scales, and (2) changes of orbital parameters resulting in insolation changes on shorter time-scales.In contrast to a proposed muted benthic foraminiferal response, the planktic community has been substantially impacted by the LDE as indicated by changes in planktic foraminifera faunas and calcareous nannofossils. Finally, our quantitative and conventional approaches identifying stratigraphically important planktic foraminifera datum levels justify a revision of the upper Danian to lower Selandian planktic foraminifera biozonation.

A new species of the “condylarth” Hyopsodus from the middle Eocene of the Erlian Basin, Inner Mongolia, China, and its biostratigraphic implications

A new species of the “condylarth” Hyopsodus from the middle Eocene of the Erlian Basin, Inner Mongolia, China, and its biostratigraphic implications

Taxonomic revision of the genus Carinolithus (Early - Middle Jurassic) based on morphometric analyses and diagenesis observations: Implications for biostratigraphy and evolutionary trends

We applied morphometric analyses performed with a polarizing light microscope on a total of 100 specimens of Carinolithus superbus and C. magharensis to clarify the taxonomy based on measurements of total height (TH), stem height (SH), stem width (SW), proximal shield width (PS), distal shield width (DS) and thickness of the distal shield (TDS). Statistical analyses showed that three of these parameters, namely the DS, TDS and SW, are diagnostic for taxa discrimination. New taxa include C. superbus subsp. crassus subsp. nov. and C. magharensis subsp. minor subsp. nov. Specimens of C. cantaluppii were qualitatively investigated to assess the potential role of secondary modifications and our results revealed that, indeed, C. cantaluppii is a diagenetic artefact due to different degrees of overgrowth on specimens of C. poulnabronei, C. superbus subsp. crassus, C. superbus subsp. superbus, C. magharensis subsp. minor and C. magharensis subsp. magharensis. This implies that C. cantaluppii is not a true taxon, and the overgrowth phase of Carinolithus specimens is an effective proxy to assess the diagenetic degree. The morphometry-based revised taxonomy of the genus Carinolithus was applied to improve the biostratigraphic resolution of the Toarcian-Aalenian interval, with further implications for the reconstruction of evolutionary trends.

Quaternary megafauna from the Dnieper alluvium near Kaniv (central Ukraine): Implications for biostratigraphy

Subfossil remains of the Quaternary megafauna from two Ukrainian natural history collections stored at Kaniv Nature Reserve and the National Museum of Natural History NAS of Ukraine were examined. Most of the bones were collected in 1965–1966, in the building pit and the gateway of the Kaniv hydroelectric power plant. The fauna is represented at least by ten taxa (Gulo gulo, Mammuthus trogonterii chosaricus, Mammuthus intermedius, Coelodonta antiquitatis, Megaloceros giganteus, Alces alces, Bison priscus, Cervus elaphus, Capra cf. ibex, and Equus ferus). Skeletal parts are represented mainly by skulls, long bones, horns, and tusks. Based on the species composition of proboscideans, at least part of the faunal assemblage is dated by the end of the Middle Pleistocene (Dnieper Stage = Saale, Warta, MIS 6), but majority of bones could be older or younger (Late Pleistocene and Holocene age) due to the alluvial origin of accumulation.

Unraveling late Pennsylvanian brachiopod assemblages from the San Rafael Basin (Argentina): Biostratigraphic implications to southwestern Gondwana

New and previous fossil remains and resulting biostratigraphy of the El Imperial Formation at Arroyo del Imperial, Quebrada de La Horqueta, and Cañón del Atuel key sections are analyzed, while the faunal relationships among them are clarified. Two diachronnous faunas, the pTS and TSAIII associations, relatives to the Tivertonia-Streptorhynchus assemblage are recognized and constrained to early late Bashkirian and Moscovian ages, respectively. These age assignments are supported by statistical analyses and available palynological and radiometric dating. Previous mentions of brachiopods from Arroyo del Imperial and Quebrada de La Horqueta are elucidated with the identification of Buxtonia cf. riojanae (Leanza), Streptorhynchus inaequiornatus Leanza, Spiriferellina? sp., Septosyringothyris (Precosyringothyris) aff. jaguelensis Lech, Septosyringothyris (Precosyringothyris) cf. feruglioi (Amos), Saltospirifer guevarai Cisterna and Archbold and Pericospira sp. A new marine fauna from the upper part of the Cañón del Atuel section (Cabecera del Cañón Member) is reported. It includes the brachiopods Argentiella cf. A. stappenbecki Archbold, Cisterna and Sterren, Oehlertella annae (Feruglio), Orbiculoidea saltensis Reed, Calytrixia piersoni Taboada, Coolkilella aredesi Taboada, Costatumulus sp. and Septosyringothyris? sp. A bio-chronostratigraphic correlation scheme, including key lithostratigraphic units and biozones of central-western Argentina is updated.

Cambrian stratigraphy (Series 2 to Miaolingian) of the El Sahuaral area in central Sonora, Mexico: Biostratigraphic implications

The lower and middle Cambrian strata exposed in the state of Sonora, Mexico, consists of sequences of quartzarenite, limestone, shale and dolomite exposed in several localities, mainly in the northwestern and central regions of Sonora. Approximately 800 m interval of Cambrian marine sedimentary rocks are exposed in the El Sahuaral area, a new Cambrian locality in central Sonora. The sedimentary succession of these marine facies is divided into five lithostratigraphic units previously documented in Mexico: Proveedora, Buelna, Cerro Prieto, El Gavilán and El Tren formations. The Proveedora Formation is the oldest sequence of Cambrian strata in the region and consists of a 168 m thick sequence of bioturbated, fine-grained quartzarenite. The Buelna Formation conformably overlies the Proveedora Formation in the El Sahuaral and adjacent areas and consists of 70 m of interbedded limestone and shale, with abundant fragments of olenellid trilobites from either the Bristolia mohavensis or Bristolia insolens zones (Series 2, Stage 4). The overlying Cerro Prieto Formation is composed of a 70 m thick sequence of recrystallized oolitic limestone with possible fragments of Amecephalus arrojosensis, suggesting the Amecephalus arrojosensis Zone (uppermost Series 2, Stage 4). The El Gavilán Formation conformably overlies the Cerro Prieto Formation with a thickness of 225 m; it is composed of interbedded limestone and shale deposited in a marine open shelf environment, with abundant fauna of the upper Ehmaniella Zone (Altiocculus Subzone), Ptychagnostus praecurrens - Ptychagnostus gibbus Zone (Miaolingian Series, Wuliuan Stage). The El Tren Formation, reported by the first time in central Sonora, conformably overlies the El Gavilán Formation and consists of 250 m thick sequence of dolomitic limestone with unidentified trilobite fragments. The Cambrian deposits of central Sonora present marine facies that vary from the littoral zone to open marine shelf, accumulated in the western part of the North American craton and contains an abundant and diverse biota comprised by cyanobacteria, poriferans, brachiopods, trilobites, and echinoderms.

First record of organic-walled microfossils from the Tonian Shiwangzhuang Formation of the Tumen Group in western Shandong, North China

Organic-walled microfossils offer important information on the biospheric evolution in pre-Cryogenian and provide biostratigraphic implications for many Proterozoic fossiliferous sequences that are poorly age constrained for the lack of reliable radiometric date. Recently, macroscopic carbonaceous compression fossils have been reported for the first time from the Tonian Shiwangzhuang Formation of the Tumen Group in western Shandong, North China. However, organic-walled microfossils have never been discovered from this formation up till now. To improve our knowledge about Proterozoic biodiversity in North China, we conducted a micropaleontological survey on the argillaceous limestone samples of the Shiwangzhuang Formation, which also contain macroscopic carbonaceous compression fossils, from the Baishicun section in Anqiu, western Shandong, North China. Our investigation shows that the Shiwangzhuang microfossil assemblage is dominated by smooth-walled sphaeromorphic acritarchs and cyanobacterium-like filaments and relatively low abundance of other acritarchs, including 16 taxa, such as Polysphaeroides filliformis, Ostiana microcystis, Simia annulare, ?Jacutianema sp., Arctacellularia tetragonala, Pellicularia tenera, Polythrichoides lineatus, and Navifusa actinomorpha. The Shiwangzhuang organic-walled microfossil assemblage, although consisting of long-ranging and not age diagnostic taxa, is consistent with a Tonian age suggested by macroscopic carbonaceous compression fossils, including the Chuaria-Tawuia and Sinosabellidites-Protoarenicola-Pararenicola assemblages, revealed from the same fossiliferous horizon of the Shiwangzhuang Formation and by organic-walled microfossil assemblage, including the late Mesoproterozoic to Tonian index fossil Trachyhystrichosphaera aimika, from the underlying Tongjiazhuang Formation. However, it is also worth noting that a Cryogenian or Ediacaran age cannot be completely excluded based just on the Shiwangzhuang microfossils because of their limited biostratigraphic utility.

A biometric analysis of the Eiffellithus eximius species complex and its biostratigraphic implications

Abstract The evolution of the calcareous nannofossil Eiffellithus turriseiffelii – E. eximius lineage in the Turonian from the western tropical Atlantic and Indian Ocean indicates identical eiffellithid forms with morphological change in the rotation of the crossbar, relative to the longitudinal axis, from an “x” (E. turriseiffelii) to a “+” (E. eximius). Within these indistinguishable eiffellithid assemblages, neither the size nor shape show significant change during the morphological transition of the crossbar orientation. The rotation of the crossbar toward an axial alignment results in two shifts in the mean angle values. Prior to the first shift, the mean angles of the eiffellithid assemblage have values between 35o and 45o with no forms with crossbar angles of

El registro más austral de la Fauna Aseptella-Tuberculatella / Rhipidomella-Micraphelia (Serpukhoviano tardío-Bashkiriano) en la cuenca Calingasta-Uspallata, Argentina

The Agua del Jagüel Formation crops out in the southernmost part of the Calingasta-Uspallata basin, in central western Argentina. The lower part of the unit is characterized by a glacigenic sequence with diamictites and mudstones with dropstones. In the latter, elements of the Aseptella-Tuberculatella/Rhipidomella-Micraphelia Fauna (AT/RM Fauna), such as the brachiopods Rhipidomella discreta Cisterna, Micraphelia indianae Simanauskas and Cisterna and Orbiculoidea? sp., the gastropods Murchisonia? sp., and Glabrocingulum (Stenozone)? sp., the bivalve Nuculanidae indet., rugose corals, and indeterminate fragments of nautiloids and hyolithids, have been identified. The importance of this fauna mainly resides in its paleoenvironmental and biostratigraphic implications. AT/RM Fauna is characteristic of restricted environments with relatively low concentrations of oxygen and nutrients in the seafloor, which is consistent with the glaciomarine sequences in fjord-type coasts suggested for the Agua del Jagüel Formation. The relatively low diversity of the fauna in this unit compared to that defined in the El Paso Formation, located further north in the basin, might suggest more restricted sectors for benthic colonization, related to the paleovalle’s isolation from oceanic waters. The postglacial mudstones with marine invertebrate faunas of late Serpukhovian-Bashkirian age would have been deposited in relatively restricted (palaeofjord) part of the Uspallata-Calingasta basin as well as in open shelf environments. The marine flooding over drastically different coast configurations and the availability of nutrient and oxygen in the water column would have propitiated the development of faunas with important differences in the taxonomic composition and the paleoecological structure (AT/RM and Levipustula Faunas) occurring at the same time interval. Radiometric data in Agua del Jagüel Formation and paleontological records in the glacial-postglacial sedimentary succession in the basin (marine invertebrate faunas, palynomorphs and plants) are the most important tools to adjust the timing of the postglacial transgression. This information herein presented complements the scheme proposed for the Carboniferous sequences throughout the central western of Gondwana but is not sufficient to assign a more precise age of the fauna studied within the late Serpukhovian-Bashkirian interval.

A new early Pliocene murine rodent from the Iberian Peninsula and its biostratigraphic implications

Fil: Pinero Garcia, Pedro. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Division Zoologia de Vertebrados. Seccion de Mastozoologia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata; Argentina

Distribution of Alveolina assemblages in the Ypresian (Ilerdian-Cuisian) successions from Iran and Turkey (central and western Tethys): biostratigraphic implications for regional correlation

Benthic foraminiferal assemblages dominated by Alveolina species from the Ypresian (Ilerdian-Cuisian) are studied herein from numerous localities of Iran and Turkey. From these successions, highly diversified assemblage of 58 alveolinid species are identified along with their detailed biostratigraphical application, which resulted in the recognition of eight shallow benthic zones (SBZ5-SBZ12). Our findings are based upon the distribution ranges of Alveolina from the Ilerdian-Cuisian sediments in Iran (Central Tethys) that are considered to have a strong affinity with their coeval fauna in Turkey (Western Tethys). In this study, the wide expansion ranges of Alveolina permit us to achieve a high-resolution biostratigraphy and apply the shallow benthic zones of the peri-Mediterranean region (Western Tethys) to the Ilerdian-Cuisian successions in Iran (Central Tethys). Nevertheless, the distribution of some Alveolina species, even the zonalmarkers consisting of Glomalveolina lepidula, Alveolina ellipsoidalis, A. pisiformis, A. laxa, A. subpyrenaica, A. varians, A. fornasinii and A. canavarii are found occurring at younger stratigraphic levels in Iran and/or Turkey than in the western European shallow marine deposits.

Dinoflagellate cysts of the La Meseta Formation (middle to late Eocene), Antarctic Peninsula: implications for biostratigraphy, palaeoceanography and palaeoenvironment

AbstractDinoflagellate cyst assemblages recovered from the La Meseta Formation cropping out in Seymour Island, Antarctic Peninsula, are studied herein and their distribution is compared with the biostratigraphic scheme available for the Palaeogene of the Southern Ocean and other high-latitude regions. In this way, the La Meseta Formation is dated as middle Lutetian to Priabonian (46.2–36 Ma), which differs from the age provided by other fossils, isotopes and also with the magnetostratigraphic scheme recently performed for the unit. The dinoflagellate cyst data support the proposal of ocean circulation patterns on the South American Shelf prior to the opening of Drake Passage. Assemblages from the La Meseta Formation contain Antarctic-endemic taxa which are also dominant in several circum-Antarctic sites, located south of 45° S. Their distribution reflects an ocean-circulation scheme with wide clockwise gyres surrounding Antarctica that were disrupted as a consequence of the deepening and definitive apertures of the Tasmanian Gateway and Drake Passage towards the Eocene/Oligocene transition. The palaeoenvironmental inference based on the S/D ratio (sporomorphs versus dinoflagellate cysts) and the P/G ratio (peridinioid versus gonyaulacoid dinoflagellate cysts) suggests an overall trend through the section from marine-dominated assemblages with poorly productive waters in the lower part of the section to more terrestrially dominated assemblages with increasing productivity in the upper part of the unit, reflecting a shallowing trend to the top.

Biostratigraphical and palaeogeographical implications of Early Cambrian hyoliths from the North China Platform

Pan, B., Skovsted, C.B., Sun, H.J. & Li, G.X., 18 June 2019. Biostratigraphical and palaeogeographical implications of Early Cambrian hyoliths from the North China Platform. Alcheringa 43, 351–380. ISSN 0311-5518.A succession of diverse hyolith assemblages comprising 10 genera and 14 species are reported from the lower Cambrian Shangwan and Sanjianfang sections of the Xinji Formation, and Xiaomeiyao section of the Houjiashan Formation, which crop out along the southern margin of the North China Platform. Most of the specimens are represented by both conchs and opercula. The identified orthothecids include Conotheca australiensis, Cupitheca holocyclata, C. costellata, Neogloborilus applanatus, N. spinatus, Tegminites hymenodes, Triplicatella disdoma, T. xinjia sp. nov. and Paratriplicatella shangwanensis gen. et sp. nov. The hyolithids comprise Protomicrocornus triplicensis gen. et sp. nov., Microcornus eximius, M. petilus, Parkula bounites and Parakorilithes mammillatus. Some anomalous taxa possess characteristics of both Hyolithida and Orthothecida, such as C. australiensis, Neogloborilus and P. triplicensis. Protomicrocornus may constitute a sister group of other hyolithids. The teeth of Parkula bounites and clavicles of Parakorilithes mammillatus are documented for the first time. The hyolith assemblages from North China are probably coeval, and can be correlated with the Cambrian upper Stage 3–lower Stage 4. Many taxa are also globally distributed and have significant potential for biostratigraphical correlations. In accordance, the hyoliths from North China reveal closest compositional similarities to faunas from eastern Gondwana, and especially South Australia. However, some taxa are shared with Laurentian assemblages suggesting cosmopolitanism, and possibly planktonic larval dispersal.Bing Pan* [bpan@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, PR China; Christian B. Skovsted [christian.skovsted@nrm.se], Department of Palaeobiology, Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden; Haijing Sun [hjsun1987@163.com], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, PR China; Guoxiang Li [gxli@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, PR China. *Also affiliated with: University of Science and Technology of China, Hefei 230026, PR China and Department of Palaeobiology, Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden.