Palaeoenvironmental changes across the Permian/Triassic boundary at Shangsi (N. Sichuan,China)

The section at Shangsi in Sichuan contains one of the most detailed and best records of events during the Permian/Triassic (P/T) mass extinction. Continuous deep water deposition is only punctuated by a minor shallowing in the late Changxingian. The micritic mudstones and wackestones of the Changxingian Dalong Formation contain abundant ammonoids and radiolaria and diverse and common benthic taxa (mostly bivalves and brachiopods) in a thoroughly bioturbated sediment. The presence of a well developed tiered burrow profile is just one line of evidence for a fully oxygenated water column in the late Permian. The faunal crisis occurs in the top few decimetres of the Dalong Formation and severely affected all groups (benthos, nekton and plankton). The extinction coincides precisely with the development of anaerobic and dysaerobic facies. The basal Triassic sediments of the Feixanguan Formation are thinnly‐bedded or laminated silicic marls and contain pyrite and several levels of elevated organic carbon concentrations. The fauna is restricted to rare ammonoids and a few bedding planes covered in Claraia. The presence of abundant coccoid cyanobacteria in these sediments may indicate an unusually simple trophic web in the early Triassic seas as these picoautotrophs are normally grazed by zooplankton, they are rarely directly incorporated into seafloor sediment. The recent discovery of black shales in P/T pelagic sediments of Japan indicates that the anoxic event also affected deep ocean waters and further strengthens the link between extinction and anoxia.     

A diverse Upper Jurassic dinosaur ichnofauna from central‐west Portugal

Mateus, O. & Milàn, J. 2009: A diverse Upper Jurassic dinosaur ichnofauna from central‐west Portugal. Lethaia, Vol. 43, pp. 245–257. A newly discovered dinosaur track‐assemblage from the Upper Jurassic Lourinhã Formation (Lusitanian Basin, central‐west Portugal), comprises medium‐ to large‐sized sauropod tracks with well‐preserved impressions of soft tissue anatomy, stegosaur tracks and tracks from medium‐ to large‐sized theropods. The 400‐m‐thick Lourinhã Formation consists of mostly aluvial sediments, deposited during the early rifting of the Atlantic Ocean in the Kimmeridgian and Tithonian. The stratigraphic succession shows several shifts between flood‐plain mud and fluvial sands that favour preservation and fossilization of tracks. The studied track‐assemblage is found preserved as natural casts on the underside of a thin bivalve‐rich carbonate bed near the Tithonian–Kimmeridgian boundary. The diversity of the tracks from the new track assemblage is compared with similar faunas from the Upper Jurassic of Asturias, Spain and the Middle Jurassic Yorkshire Coast of England. The Portuguese record of Upper Jurassic dinosaur body fossils show close similarity to the track fauna from the Lourinhã Formation. □Dinosaur tracks, Lusitanian Basin, Portugal, skin impressions, Upper Jurassic.     

Vertical displacement and taphonomic filtering of nannofossils by bioturbation in the Cretaceous–Palaeogene boundary section at Caravaca,SE Spain

K?dzierski, M., Rodríguez‐Tovar, F.J. & Uchman, A. 2011: Vertical displacement and taphonomic filtering of nannofossils by bioturbation in the Cretaceous–Palaeogene boundary section at Caravaca, SE Spain. Lethaia, Vol. 44, pp. 321–328. At the Caravaca section, SE Spain, the position of the Cretaceous–Palaeogene (K–Pg) boundary is well‐defined, with multidisciplinary datasets from a thin rusty layer at the base of the 10 cm dark boundary layer. Nannoplankton assemblages containing the Danian taxon Neochiastozygus sp. and enriched in Thoracosphaera spp. are displaced below the K–Pg boundary into the trace fossils Zoophycos, Thalassinoides and Chondrites. These trace fossils are filled with dark‐coloured sediments of the dark boundary layer. The nannofossil assemblage from the 1‐cm thick interval below the boundary, enriched in Thoracosphaera spp. and Braarudosphaera spp., may have been displaced by Chondrites tracemakers, the traces of which are abundant in this interval. The downward transport of the Danian nannofossils into the Maastrichtian by the tracemakers seems to be one of the common mechanisms responsible for their apparent appearance below the K–Pg boundary. The dark boundary layer contains very rare Danian specimens and abundant Maastrichtian nannofossils. The Maastrichtian taxa were most likely conveyed up on to the seafloor by tracemakers during the Danian. The redistribution of nannoplankton down and up across the rusty layer (K–Pg), challenges the usefulness of nannofossils for high‐resolution stratigraphy of the K–Pg boundary. □Nannoplankton, Cretaceous–Palaeogene boundary event, biogenic mixing, trace fossils.     

广西兴安早石炭世晚期三叶虫新资料

记述了产于广西兴安早石炭世晚期大塘阶双切尾虫亚科的１新亚属－Ｐａｌａｄｉｎｓｕｂｇｅｎ．ｎｏｖ．及其３新种：Ｐ．（Ｓ．）ｇｕｉｂｅｉｅｎｓｉｓｓｐ．ｎｏｗ．．Ｐ．（Ｓ．）ｘｉｎｇａｎｅｎｓｉｓｓｐ．ｎｏｖ。     

An integrative ichnological and taphonomic approach in a transgressive–regressive cycle: a case study from Devonian of Paraná Basin,Brazil

The palaeoenvironmental context of a section of the Devonian Ponta Grossa Formation (Paraná Basin) was examined using an integrated ichnological and taphonomic approach. Three taphofacies (T‐A, T‐B and T‐C) and six ichnofabrics are recognized. T‐A is mainly composed of disarticulated organisms and is associated with Chondrites, Planolites‐Palaeophycus, Asterosoma‐Zoophycos and Asterosoma‐Chondrites ichnofabrics, representing the Cruziana ichnofacies. The upward increase in diversity and abundance of body fossils for Taphofacies A can be explained by changes in sedimentation rates during aggradational to progradational phases. T‐B beds, represented by articulated brachiopods, occur in distal tempestites associated with the Skolithos ichnofabric (Skolithos ichnofacies) and represent higher hydrodynamic energy and oxygenation than in T‐A. Taphofacies C, characterized by a mix of articulated and disarticulated organisms, generally lacks bioturbation except for Chondrites ichnofabrics occurring only at the bed tops, suggesting low substrate oxygenation and low‐energy conditions. T‐C indicates the maximum transgression in the T‐R cycle, characterizing it as a good indicator of maximum flooding surfaces. The composite Asterosoma‐Teichichnus ichnofabric (bioturbation degree 5) occurs in layers without body fossils and represents suites of the Cruziana ichnofacies. This likely reflects intense intrastratal activity at all substrate levels, which facilitated the oxygenation of the substrate disallowing the preservation of organism remains. This observation indicates that the bioturbation is an important factor controlling the loss of taphonomic information within the TAZ, mainly when associated with detritus‐feeding trace fossils.     

Composite Trace Fossil Assemblage in a Distal Carbonate Setting from the Tethys (Middle Jurassic,Betic Cordillera,Southern Spain)

Ichnological analysis of a Middle Jurassic carbonate surface from the Betic Cordillera (southern Spain) reveals a complex trace fossil assemblage, including softground Ophiomorpha, firmground Arenicolites, Thalassinoides and Gastrochaenolites, and hardground Trypanites as well as possible Gastrochaenolites. The ecological replacement in the macrobenthic community is interpreted according to successive suites that are controlled mainly by substrate consistency. Variations in composition and abundance of trace fossils between suites can be ecologically and/or taphonomically determined.     

The Upper Carboniferous Hamilton Fossil-Lagerstätte in Kansas: a valley-fill, tidally influenced deposit

A diverse assemblage of unusually well-preserved marine, euryhaline, freshwater, and terrestrial fossils (invertebrates, vertebrates, and plants) occurs within an Upper Carboniferous (Stephanian) Konservat Fossil-Lagerstätte near Hamilton, Kansas, USA. The Lagerstätte occurs within a paleovalley that was incised into the surrounding Carboniferous cyclothemic sequence during a time of low sea level, and was then filled-in during a subsequent transgression. The stratigraphically lowest and most voluminous facies within the valley is a cross-bedded, polymictic limestone conglomerate that contains caliche clasts and charcoal fragments as well as some normal-marine fossils apparently in situ. The origin of the conglomerate is enigmatic, but it was probably deposited by a migrating tidal channel. Overlying and interbedded with the conglomerate is an ostracode wackestone that contains plants (primarily seed ferns and ferns), eurypterids, shrimp, brachiopods, bivalves, and rare fish. The ostracode wackestone was deposited in a low-energy, marginal-marine environment. A thin sequence (<1 m thick) of interbedded laminated limestone and mudstone overlies the conglomerate in a small area. This facies contains a well-preserved mixed assemblage of terrestrial (conifers, insects, myriapods, reptile), freshwater (ostracodes), aquatic (amphibians, reptile), brackish or euryhaline (ostracodes, eurypterids, spirorbids, fish), and marine (brachiopods, echinoderms) fossils. Many of the vertebrates are articulated and show no evidence of preburial decay, scavenging, or predation. A few vertebrates exhibit signs of flotation. Most articulated vertebrate specimens exhibit soft-tissue preservation in the form of dark-brown to black early-diagenetic microbialite body outlines (‘skin preservation’) containing fossil bacteria. Rhythmic patterns of lamination thickness variation in the limestones and mudstones indicate that this facies was deposited in a tidal environment. High sedimentation rate and variable salinity (and therefore exclusion of bioturbators and invertebrate scavengers) are interpreted as key elements that led to the excellent preservation of the fossils in this ancient estuarine environment. □Lagerstätte, taphonomy, estuarine, tidal bedding, paleovalley, Carboniferous, Kansas.     

The discovery of Eifelian ammonoids in the Central Kyzylkum Desert (Aristantau Mountains,Uzbekistan)

Eifelian ammonoids are described for the first time from the Central Kyzylkum Desert (Uzbekistan, Navoiy Region, Aristantau Mountains). The ammonoid assemblage includes the typical Eifelian genera Fidelites, Subanarcestes (a new species S. aristanensis Nikolaeva sp. nov. is described), and Cabrieroceras, found in association with brachiopods, conodonts, and dacryoconarids. The ammonoid assemblage is similar to that from the Chote? beds of Barrandien and their equivalents in the Urals, Salair, Germany, and Morocco (Subanarcestes macrocephalus Zone), suggesting a connection between the Eifelian Kyzylkum Basin, which was part of the Turkestan Paleoocean, and European, North African, Siberian, and Uralian basins. The ammonoids studied are not associated with black shale and apparently existed in normal marine environments.     

Small carbonaceous fossils (SCFs) from the Terreneuvian (lower Cambrian) of Baltica

We describe a new assemblage of small carbonaceous fossils (SCFs) from diagenetically minimally altered clays and siltstones of Terreneuvian age from the Lontova and Voosi formations of Estonia, Lithuania and Russia. This is the first detailed account of an SCF assemblage from the Terreneuvian and includes a number of previously undocumented Cambrian organisms. Recognizably bilaterian‐derived SCFs include abundant protoconodonts (total‐group Chaetognatha), and distinctive cuticular spines of scalidophoran worms. Alongside these metazoan remains are a range of protistan‐grade fossils, including Retiranus balticus gen. et sp. nov., a distinctive funnel‐shaped or sheet‐like problematicum characterized by terminal or marginal vesicles, and Lontohystrichosphaera grandis gen. et sp. nov., a large (100–550 μm) ornamented vesicular microfossil. Together these data offer a fundamentally enriched view of Terreneuvian life in the epicratonic seas of Baltica, from an episode where records of non‐biomineralized life are currently sparse. Even so, the recovered assemblages contain a lower diversity of metazoans than SCF biotas from younger (Stage 4) Baltic successions that represent broadly equivalent environments, echoing the diversification signal recorded in the coeval shelly and trace‐fossil records. Close comparison to the biostratigraphical signal from Fortunian small shelly fossils supports a late Fortunian age for most of the Lontova/Voosi succession, rather than a younger (wholly Stage 2) range.     

New paleobiogeographical and paleoenvironmental insight through the Tortonian brachiopod and ichnofauna assemblages from the Mediterranean-Atlantic seaway (Guadix Basin,SE Spain)

The paleogeography of the Late Neogene Atlantic-Mediterranean seaway via the Betic-Rifean Domain is quite complex due to the presence of several marine corridors. The study of transitional basins in these seaways is crucial to understand the configuration and evolution of the Mediterranean-Atlantic inter-connection. A mixed skeletal-siliciclastic sandstone succession located in one of these transitional areas (Guadix Basin, Southern Spain) was studied from a comprehensive paleontological standpoint focused on the main benthic assemblages (foraminifera, brachiopods, and trace fossils), integrating the data with the study of planktic foraminifera for an accurate biostratigraphic framework. Brachiopods are mostly represented by the Aphelesia-Gryphus assemblage. Two trace fossil assemblages were observed, dominated by Ophiomorpha with Bichordites (1) and Macaronichnus (2), respectively. The benthic foraminiferal assemblage is mostly represented by Planulina and Cibicides. The data gathered from the benthic communities reveal habitats with high-energy and turbulent conditions in an outer neritic-upper bathyal bathymetric range. Brachiopods from the Alicún section show a Mediterranean paleobiogeographic affinity. They were constrained in the Late Tortonian to the restricted basins of the Betic-Rifean Seaway and after the Messinian Salinity Crisis proliferated in both Mediterranean- and Atlantic-type basins of the Betic-Rifean Domain. The Guadix Basin contributed to the Mediterranean-Atlantic faunal inter-connection through the Betic-Rifean Seaway during the Late Tortonian and facilitated the earliest Pliocene expansion of brachiopods in the Mediterranean.     

贵州南部独山地区泥盆纪弗拉期的石燕贝类腕足动物

弗拉期是了解泥盆纪弗拉-法门灭绝事件之前古代生物多样性的一个关键阶段.贵州南部的独山地区因其所具有的完整层序及丰富的底栖牛物化石成为我国主要泥盆系参考剖面之一.独山剖面弗拉期的石燕贝类腕足动物至少包括5种类型,其中4种在本文中为首次描述和图示.Conispirifer之前只发现于欧洲及北美的弗拉期地层中,目前也首次在华南独山剖面的同期地层中发现.大多先前从贵州南部其他地区弗拉期地层中描述的多种Cyrtospirifer可归于Cyrtospirifer subextensoides新种内.鉴于前人对Emanuella的模式种E.takwanensis 的内部构造描述的矛盾状况,本文暂把研究区具有抬离壳面的纤细铰窝、固着于壳面的主突起以及其前方下面为外铰板支撑的标本归于E.takwanensis.在华南弗拉期可初步识别出三个腕足动物群组合带:Yocrarhynchus-Phlogoiderhynchus动物群以小嘴贝类-无洞贝类-双腔贝类腕足动物为特征,其时代大致从弗拉阶底部至Pa.punctata带;之后为Cyrtospirifer动物群,以Cyrtospirifer的存在为特征,又可分为早晚两部分,前者(未命名)以conispiriferid类的Conispirifer和Pyramidaspirifer、弓石燕类、无洞贝类等为特征,其时代大致为Pa."hassi"带至下Pa.rhenana带;后者为Hunanotoechia动物群,以丰富的小嘴贝类-无洞贝类.弓石燕类腕足动物为特征,其时代大致为上Pa.rhenana带至Pa.1inguiformis带.     

Ammonite succession at the Bajocian/Bathonian boundary in the Cabo Mondego region (Portugal)

The Cabo Mondego outcrops exposed along the cliffs, on the western margin of the Iberian Plate, show an expanded stratigraphic section of Lower Bathonian deposits containing abundant ammonoids. Upper Bajocian deposits correspond to similar facies, of muddy limestones alternating with marlstones, although ammonoids are scarce. A detailed succession of ammonites across the Bajocian/Bathonian boundary has been recognized at Cabo Mondego, which can form a useful bio‐ and chronostratigraphic standard for the Lusitanian Basin. The revision of previous collections from the classical section and new field samplings of two other separate sections allow the recognition through up to twenty metres of thickness, the highest zone of Bajocian (Parkinsoni Zone) and the lowest zone of Bathonian (Zigzag Zone). The Parkinsoni and the Zigzag zones established for NW European areas and belonging to the Northwest European Province, can be identified in the Lusitanian Basin, although the ammonite fossil assemblages are composed of Submediterranean taxa. However, a subdivision of the Parkinsoni Zone is not possible, due to the scarcity of well preserved ammonoids. The Zigzag Zone can be recognized and characterized as composed of two subunits (Parvum and Macrescens subzones) as represented in diverse European basins of the Submediterranean Province. Ammonite fossil assemblages of the Parvum Subzone may be grouped into two successive horizons, which are biochronostratigraphically equivalent to the subdivisions of the Convergens Subzone distinguished in the Digne‐Barrême area (SE France). New biochronostratigraphic data on the Bigotitinae, youngest members of Leptosphinctinae and oldest members of Zigzagiceratinae are relevant in understanding the evolution and faunal turnover of the West Tethyan Perisphinctidae during earliest Bathonian. The ammonite succession at the Bajocian/Bathonian boundary in the Cabo Mondego region (Portugal) represents one of the most complete biostratigraphic records so far recognized on the Iberian Plate.     

The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction

The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle–late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.     

Orthoconic cephalopods and associated fauna from the late Ordovician Soom Shale Lagersta¨tte, South Africa

ABSTRACT. Orthoconic cephalopods from the Soom Shale Member (Ashgill) are exceptionally preserved and are colonized by lingulate brachiopods and cornulitids. Other fossils commonly associated with orthocones include myodocopid ostracodes and chitinozoans. Size distribution analysis of the brachiopods on one orthocone indicates that it was colonized in vivo. Four orthocone radulae are preserved extending the record of these structures 50 My back to the late Ordovician. Orthocone radula configuration is more similar to that of ammonoids and coleoids than to that of nautiloids.     

Small shelly fossils and trace fossils near the Precambrian-Cambrian boundary in the Yukon Territory, Canada

In the past an ‘explosion’ in diversity and abundance of small shelly fossils and of trace fossils has served to mark the base of the Cambrian. However, no evidence has been presented to prove that the ‘explosions’ of the two groups were synchronous. We describe small shelly fossils and trace fossils from the same phosphatic limestone beds that indicate that the two events were separate in time. The small shelly fossils are Anabarites trisulcatus, Hyolithellus cf. H. isiticus, Microcornus? sp., Protohertzina anabarica, P. unguliformis, P. sp. A, Pseudorthotheca sp. A, Rushtonia? sp. A, four types of tuberculate plates and one type of reticulate plate. These fossils represent a restricted, ‘pre-explosion’ fauna and are assigned to the Anabarites-Circotheca-Protohertzina Assemblage Zone, an uppermost Precambrian zone in the Meishucun Stage, Yunnan Province, China. A point at the top of this zone has received strong international endorsement for future designation as the base of the Cambrian. Associated with the small shelly fossils are the trace fossils Cruziana sp. A, Cruziana? sp. B, Rusophycus sp. A, Palaeophycus rubdark and arthropod scratch marks. If found in isolation, this trace fossil assemblage would be considered as post-Precambrian because it includes large, highly organized arthropod traces that are traditionally accepted as occurring above the trace fossil ‘explosion’. We therefore conclude that the trace fossil ‘explosion’ predates the small shelly fossil ‘explosion’. If the proposed location of the base of the Cambrian in Yunnan is accepted, the small shelly fossil ‘explosion’ concept and its relationship to the boundary would not be greatly modified. The trace fossil ‘explosion’, however, would no longer indicate the base of the Cambrian and the ranges of some trace fossils would be extended into the Precambrian.     

新疆吐鲁番盆地桃树园晚二叠世非海相腹足类

提要新疆吐鲁番盆地桃树园地区晚二叠世地层称作下仓房沟群,自下而上分为泉子街组、梧桐沟组和锅底坑组,为河–湖相碎屑沉积,剖面连续,层序清楚,动、植物化石丰富。文中研究的腹足类标本产于桃东沟剖面梧桐沟组下部和中部的介壳灰岩层和灰岩透镜体中,见有2层,计有2科4属6种:Xinjiangospira rotundata Yu et Zhu,Xinjiangospira habita sp.nov.、Hydrobia turpanensis Wei、Hydrobia orientalis sp.nov.、Pseudamnicola taodonggouensis sp.nov.和Valvata complanusa sp.nov.;与腹足类共生的有双壳类、叶肢介、介形类,以及植物和脊椎动物化石等,其中双壳类主要是Palaeanodonta,Palaeomutela和Anthraconauta等属。该腹足动物群由Hydrobiidae和Valvatidae的属种组成,标本数量多,壳体小,保存完好,是迄今已知属种最丰富的古生代淡水腹足类动物群。当前梧桐沟组腹足动物群面貌与准噶尔盆地大龙口剖面小龙口组...     

Seafloor erosion and sea-level change: Early Jurassic Blue Lias Formation of central England

Minor bedforms within the mudstone-dominated Early Jurassic Hettangian Saltford Shale Member (Liasicus up to Angulata Chronozone) of the Blue Lias Formation in central England, indicate weak seafloor erosion in a mid to outer ramp setting. Distal storm flows below maximum storm wave base are proposed as the most likely generative mechanism for silty scour and gutter casts that enclose concentrations of well-preserved schlotheimiid ammonites and arthropod trace fossils. Within the upper part of the Saltford Shale (probably Angulata Chronozone), a discrete layer of reworked and bioencrusted limestone nodules signifies an episode of more persistent seafloor erosion. The immediately overlying strata, transitional to the Hettangian–Sinemurian Rugby Limestone Member, are relatively bioturbated and feature fossils of macrobenthos, as well as shell concentrations resembling relatively proximal storm beds. This suggests that the reworked nodule horizon marks sea-level fall, rather than stratigraphic condensation associated with sediment starvation. The biostratigraphic evidence raises the possibility that this erosional episode correlates with a mid-Angulata Chronozone hiatus documented from the Wessex Basin, southwest England. Equally however, it could be linked to contemporaneous movement on one or more nearby faults, affecting the southern part of the English East Midlands Shelf.     

Infaunal augurs of the Cambrian explosion: An Ediacaran trace fossil assemblage from Nevada,USA

Morphologically complex trace fossils, recording the infaunal activities of bilaterian animals, are common in Phanerozoic successions but rare in the Ediacaran fossil record. Here, we describe a trace fossil assemblage from the lower Dunfee Member of the Deep Spring Formation at Mount Dunfee (Nevada, USA), over 500 m below the Ediacaran–Cambrian boundary. Although millimetric in scale and largely not fabric‐disruptive, the Dunfee assemblage includes complex and sediment‐penetrative trace fossil morphologies that are characteristic of Cambrian deposits. The Dunfee assemblage records one of the oldest documented instances of sediment‐penetrative infaunalization, corroborating previous molecular, ichnologic, and paleoecological data suggesting that crown‐group bilaterians and bilaterian‐style ecologies were present in late Ediacaran shallow marine ecosystems. Moreover, Dunfee trace fossils co‐occur with classic upper Ediacaran tubular body fossils in multiple horizons, indicating that Ediacaran infauna and epifauna coexisted and likely formed stable ecosystems.     

Tommotiids from the early Cambrian (Series 2, Stage 3) of Morocco and the evolution of the tannuolinid scleritome and setigerous shell structures in stem group brachiopods

An assemblage of tannuolinid sclerites is described from the Amouslek Formation (Souss Basin) of the Anti‐Atlas Mountains in Morocco. The assemblage contains two species, Tannuolina maroccana n. sp., which is represented by a small number of mitral and sellate sclerites, and Micrina sp., represented by a single mitral sclerite. Tannuolina maroccana differs from other species of the genus in the presence of both bilaterally symmetrical and strongly asymmetrical sellate sclerites. This observation suggests that the scleritome of Tannuolina was more complex than previously thought and that this tommotiid may have held a more basal position in the brachiopod stem group than previously assumed. The shell structure of both T. maroccana and Micrina sp. is well preserved and exhibits two fundamentally different sets of tubular structures, only one of which was likely to contain shell‐penetrating setae. Based on these observations, the structure of the tannuolinid shell is discussed and its implications for the evolution of tubular microstructures in stem and crown group brachiopods are analysed.     

Giant Bathysiphon (Foraminiferida) from Cretaceous turbidites, northern California

Straight-sided, tubular fossils occur together with a diverse assemblage of deep-water trace fossils in linegrained Franciscan turbidites at Point Saint George. Pacific Coast of California. Based on comparison with living abyssal organisms and on skeletal microstructure, these tubes are interpreted as recrystallized siliceous tests of the large abyssohenthic foraminiferid, Bathysiphon. Tubes found preserved in-place show that life orientation of the Franciscan species was vertical with the broader, mature end protruding several millimetres above the muddy seafloor. Positioned in this way the organisms probably were suspension feeders or carnivores. Bathysiphon and trace fossils taken together reflect a diverse deep-water benthic community that was disrupted (or locally eliminated) repeatedly by turbidity currents reaching the outer margins of a submarine fan. ▭ Bathysiphon, deep-water benthos, outer fan/basin floor, trace fossils, Franciscan Complex, flysch, Cretaceous.