Early Ordovician reefs in South China (Chenjiahe section, Hubei Province): deciphering the early evolution of skeletal-dominated reefs

The Lower Ordovician (late Tremadocian–early Floian) Fenhsiang and the overlying Hunghuayuan Formations at the Chenjiahe section in the Three Gorges area of Hubei Province, South China, include four types of reef: microbe-dominated (lithistid sponge–stromatolite and lithistid sponge–calcimicrobial) reefs, and skeletal-dominated (lithistid sponge–bryozoan and bryozoan–pelmatozoan) reefs. The microbe-dominated reefs are characterized by the dominance of microbial sediments that encrusted and bound the surfaces of sponges to reinforce the reef frameworks. In contrast, the skeletal-dominated reefs are distinguished by bryozoans that encrusted frame-building sponges and pelmatozoans, and that grew downward to fill the open spaces available within the frameworks. A series of these reefs shows a temporal succession in reef type, with a decline in the lithistid sponge–stromatolite reefs and an increase in the lithistid sponges and receptaculitids within the lithistid sponge–calcimicrobial reefs in the Hunghuayuan Formation; the lithistid sponge–bryozoan reefs are common in both the Fenhsiang and Hunghuayuan Formations. These features of the Chenjiahe reefs are in marked contrast to other coeval reefs on the Yangtze Platform and elsewhere. Skeletal-dominated reefs first developed in the Three Gorges and adjacent areas, located on the central part of the platform. Likewise, lithistid sponges and receptaculitids first developed in the Three Gorges area and then expanded their range. In contrast, stromatolites declined over time, but remained abundant on a marginal part of the platform. The spatial–temporal distributions of these reefs on the Yangtze Platform reflect the initiation of the Great Ordovician Biodiversification Event and its consequences, although influenced by local environmental conditions. The Three Gorges area was a center for the development of skeletal-dominated reefs, which were established earlier here than elsewhere in the world. These reef types and their spatial–temporal successions provide invaluable clues to the earliest evolution of skeletal-dominated reefs and their ensuing development during the Middle–Late Ordovician.     

Aggregated Clumps of Lithistid Sponges: A Singular,Reef-Like Bathyal Habitat with Relevant Paleontological Connections

The advent of deep-sea exploration using video cameras has uncovered extensive sponge aggregations in virtually all oceans. Yet, a distinct type is herein reported from the Mediterranean: a monospecific reef-like formation built by the lithistid demosponge Leiodermatium pfeifferae. Erect, plate-like individuals (up to 80 cm) form bulky clumps, making up to 1.8 m high mounds (1.14 m on average) on the bottom, at a 760 m-deep seamount named SSS. The siliceous skeletal frameworks of the lithistids persist after sponge death, serving as a complex 3D substratum where new lithistids recruit, along with a varied fauna of other sessile and vagile organisms. The intricate aggregation of lithistid mounds functions as a “reef” formation, architecturally different from the archetypal "demosponge gardens" with disaggregating siliceous skeletons. Leiodermatium pfeifferae also occurred at two additional, close seamounts (EBJ and EBS), but, unlike at SSS, the isolated individuals never formed accretive clumps. The general oceanographic variables (temperature, salinity, dissolved nutrients, chlorophyll, and oxygen) revealed only minimal between-seamount differences, which cannot explain why sponge abundance at SSS is about two orders of magnitude higher than at EBJ or EBS. Large areas of the dense SSS aggregation were damaged, with detached and broken sponges and a few tangled fishing lines. Satellite vessel monitoring revealed low fishing activity around these seamounts. In contrast, international plans for gas and oil extraction at those locations raise serious concerns over the need for protecting urgently this unique, vulnerable habitat to avoid further alteration. Modern lithistids are a relict fauna from Jurassic and Cretaceous reefs and the roots of the very genus Leiodermatium can be traced back to those fossil formations. Therefore, understanding the causes behind the discovered lithistid aggregation is critical not only to its preservation, but also to elucidate how the extraordinary Mesozoic lithistid formations developed and functioned.     

Cambrian Series 3 lithistid sponge–microbial reefs in Shandong Province,North China: reef development after the disappearance of archaeocyaths

The Cambrian Series 3 Zhangxia Formation in Shandong Province, North China, includes small‐scale lithistid sponge–microbial reefs. The lithistid sponges grew on oolitic and bioclastic sediments, which were stabilized by microbial activities. The relative abundances of microbial components (e.g. calcimicrobe Epiphyton and stromatolites) vary among the reefs. However, the microbial components commonly encrusted or bound the lithistid sponges, formed remarkable encrustations on the surfaces of the sponges. Epiphyton especially grew upward and downward. The lithistid sponges thus provided substrates for the attachment and development of microbes, and the microbes played essential roles as consolidators, by encrusting reef‐building sponges. Additionally, the lithistid sponges were prone to degradation via microbial activities and diagenetic processes, and were thus preserved as micritic bodies, showing faint spicular networks or abundant spicules. Such low preservation potential within the reef environment obscured the presence of the sponges and their widespread contribution as reef‐building organisms during the Cambrian. During the prolonged interval after the demise of archaeocyaths, purely microbial reefs, such as stromatolites and thrombolites have been considered to be the principal reef builders, in association with rare lithistid sponge–microbial associations. However, recent findings, including those from Shandong Province and Korea, suggest that the lithistid sponge‐bearing reefs were more extensive during the Epoch 3 to the Furongian than previously thought. These lithistid sponge–microbial reefs were precursors of the sponge–microbial reefs that dominated worldwide in the Early Ordovician.     

A high‐stress shelly fauna associated with sponge mud‐mounds in the Coniacian Arnager Limestone of Bornholm,Denmark

The benthic macrofaunas of the Upper Cretaceous chalk of NW Europe show characteristically high species‐richnesses and commonly high densities. They are predominated by bivalves, brachiopods, polychaetes, echinoids, crinoids, asteroids, sponges and towards the end of the Cretaceous also by bryozoans. The mound‐bedded chalk of the Coniacian Arnager Limestone on the island of Bornholm in the Baltic Sea, Denmark, differs from this general picture. It was deposited on a small fault block adjacent to the main Bornholm block, which was emerged during much of the Mesozoic and thus occupied a much more proximal position than most other Upper Cretaceous chalks in NW Europe. The Arnager Limestone contains a unique, exceptionally rich and well‐preserved fauna of mainly hexactinellid, lyssacinosan sponges. The low mud‐mounds are interpreted as formed by baffling and trapping of fine sediment particles by the dense sponge thickets. In contrast, the associated shelly fauna is unusually sparse, of very low richness and extremely low density, except for inoceramid bivalves. It represents a strongly depauparated version of the shelly faunas of contemporaneous chalks in NW Europe. The rare specimens of non‐inoceramid shelly species are interpreted to represent occasional successful spatfalls of benthic species from the deeper‐water chalk farther offshore in the Baltic area. The sponge mud‐mounds of the Arnager Limestone show remarkable resemblances with modern sponge mounds recently discovered on the continental shelf of western Canada. They form an important link between the well‐known older Mesozoic sponge mud‐mounds or ‘reefs’ and the modern mounds and are among the youngest examples of Mesozoic sponge mounds.     

Facies of Liassic sponge mounds, central High Atlas, Morocco

Summary Liassic sponge mounds of the central High Atlas (Rich area, northern Morocco) have a stratigraphic range from the Lower/Upper Sinemurian boundary interval up to the lower parts of the Lower Pliensbachian (Carixian). The base of Liassic sponge mounds consists of a transgressive discontinuity, i.e., a condensed section of microbioclastic wackestones with firm- and hardgrounds, ferruginous stromatolites, sponge spicules and ammonites. The top of Liassic sponge mounds is an irregular palaeorelief covered by cherty marl-limestone rhythmites, namely hemipelagic spicular wackestones with radiolaria. In the Rich area, section Foum Tillicht, the sponge mound succession has a total thickness of about 250 meters. Within this succession we distinguished between three mound intervals. The lower mound interval shows only small, meter-scale sponge mounds consisting of boundstones with lyssakine sponges, commensalicTerebella and the problematicumRadiomura. This interval forms a shallowing-upward sequence culminating in a bedded facies withTubiphytes, calcareous algae (Palaeodasycladus), sponge lithoclasts, coated grains, and thin rims of marine cement. The middle mound interval is aggradational with decametric mounds and distinct thrombolitic textures and reefal cavities. The mound assemblage here consists of hexactinellid sponges, lithistid demosponges, non-rigid demosponges,Radiomura, Serpula (Dorsoserpula), Terebella, encrusting bryozoa, and minor contributions by calcareous sponges, and excavating sponges (typeAka). Thrombolites are dendrolitic and may reach sizes of several tens of centimeters, similar to the maximum size of siliceous sponges. The upper mound interval appears retrogradational and geometries change upsection from mound shapes to flat lenses and level-bottom, biostromal sponge banks. The biotic assemblage is similar to that of the middle mound interval and there is no difference between mound and bank communities. The demise of sponge mounds is successive from regional spread in the Sinemurian to more localised spots in the Lower Pliensbachian. This reduction correlates with an increasing influence of pelagic conditions. At Foum Tillicht, sponge mounds lack any photic contribution and there is virtually no differentiation into subcommunities between mound surface and cavity dwelling organisms. There is some evidence that the heterotrophic food web of mound communities was sourced by oxygen minimum zone edge effects, namely microbial recycling of essential elements such as N and P. Basin geometry suggests a waterdepth of several 100's of meters, well below the photic zone and possibly only controlled by the depth range of the oxygen minimum zone. Palaeoceanographic conditions of well-stratified deeper water masses diminished gradually during widespread transgression across the Sinemurian to Pliensbachian boundary culminating in the Lower Pliensbachianibex ammonite zone.     

The oldest bryozoan reefs: a unique Early Ordovician skeletal framework construction

Adachi, N., Ezaki, Y. & Liu, J. 2011: The oldest bryozoan reefs: a unique Early Ordovician skeletal framework construction. Lethaia, Vol. 45, pp. 14–23. The oldest bryozoan reefs occur in the Lower Ordovician (late Tremadocian) Fenhsiang Formation of the Three Gorges area, South China. These reefs show a unique type of bryozoan (Nekhorosheviella) framework, and were constructed as follows: the first stage involved colonization by lithistid sponges, which acted as a baffler to trap sediments, providing bryozoans with a stable substrate for attachment. The bryozoans then grew as an encruser on the surfaces of sponges, showing a preferential downwards and lateral growth within the sponge scaffolding to avoid biological and physical disturbance. Finally, these biotic combinations among skeletal organisms formed a rigid, three‐dimensional skeletal framework. This mode of bryozoan growth in association with lithistid sponges is remarkable and unique in its growth direction, and the appearance of such reefs, just prior to the widespread development of skeletal‐dominated reefs as part of the Great Ordovician Biodiversification Event, provides an excellent example of the earliest attempts by skeletal organisms to form frameworks by themselves. This find significantly enhances our understanding of the initial stages of skeletal‐dominated reef evolution and the ensuing development of reefs during the Middle–Late Ordovician. □Bryozoa, Early Ordovician, lithistid sponge, Ordovician radiation, reef.     

A Paleocene coral—algal—sponge reef from southwestern Alabama and the ecology of Early Tertiary reefs

The Late Paleocene Salt Mountain Limestone from southwestern Alabama is a coral-algal-sponge buildup which further characterizes the faunal makeup of early post-Cretaceous reefs. Thin sectioning has disclosed a variety of lithologies, including large foram-algal packstone, algal bindstone, and sponge bafflestone. A low-diversity fauna of massive scleractinian corals caps the sequence, but may be developed intermittently throughout the section as well. The constructional importance of coralline algae and the low diversity of scleractinian corals are characteristic of Paleocene reefs in general. Sponges, however, are virtually unknown in earliest Tertiary sediments. Their abundance in the Salt Mountain demonstrates not only their local contribution to Early Tertiary reefs, but may also reflect an opportunistic response of sponges as reef constructors following the extinction of oligotrophic, rudist-coral reef communities of the Late Cretaceous. □ Paleocene, reef, paleoecology, sponges, extinction.     

Coral-rudist bioconstructions in the Upper Cretaceous Haidach section (Gosau Group; Northern Calcareous Alps, Austria)

Summary In the area of Haidach (Northern Calcareous Alps, Austria), coral-rudist mounds, rudist biostromes, and bioclastic limestones and marls constitute an Upper Cretaceous shelf succession approximately 100 meters thick. The succession is part of the mixed siliciclasticcarbonate Gosau Group that was deposited at the northern margin of the Austroalpine microplate. In its lower part, the carbonate succession at Haidach comprises two stratal packages that each consists, from bottom to top, of a coral-rudist mound capped by a rudist biostrome which, in turn, is overlain by bioclastic limestones and, locally, marls. The coral-rudist mounds consist mainly of floatstones. The coral assemblage is dominated by Fungiina, Astreoina, Heterocoeniina andAgathelia asperella (stylinina). From the rudists, elevators (Vaccinites spp., radiolitids) and recumbents (Plagioptychus) are present. Calcareous sponges, sclerosponges, and octocorals are subordinate. The elevator rudists commonly are small; they settled on branched corals, coral heads, on rudists, and on biolastic debris. The rudists, in turn, provided settlement sites for corals. Predominantly plocoid and thamnasteroid coral growth forms indicate soft substrata and high sedimentation rates. The mounds were episodically smothered by carbonate mud. Many corals and rudists are coated by thick and diverse encrustations that indicate high nutrient level and/or turbid waters. The coral-rudist mounds are capped byVaccinites biostromes up to 5 m thick. The establishment of these biostromes may result from unfavourable environmental conditions for corals, coupled with the potential of the elevator rudists for effective substrate colonization. TheVaccinites biostromes are locally topped by a thin radiolitid biostrome. The biostromes, in turn, are overlain by bioclastic limestones; these are arranged in stratal packages that were deposited from carbonate sand bodies. Approximately midsection, an interval of marls with abundantPhelopteria is present. These marls were deposited in a quiet lagoonal area where meadows of sea grass or algae, coupled with an elevated nutrient level, triggered the mass occurrence ofPhelopteria. The upper part of the Haidach section consists of stratal packages that each is composed of a rudist biostrome overlain by bioclastic wackestones to packstones with diverse smaller benthic foraminifera and calcareous green algae. The biostromes are either built by radiolitids,Vaccinites, andPleurocora, or consist exclusively of radiolitids (mainlyRadiolites). Both the biostromes and the bioclastic limestones were deposited in a low-energy lagoonal environment that was punctuated by high-energy events.In situ-rudist fabrics typically have a matrix of mudstone to rudistclastic wackestone; other biogens (incl. smaller benthic foraminifera) are absent or very rare. The matrix of rudist fabrics that indicate episodic destruction by high-energy events contain a fossil assemblage similar to the vertically associated bioclastic limestones. Substrata colonized by rudists thus were unfavourable at least for smaller benthic foraminifera. The described succession was deposited on a gently inclined shelf segment, where coral-rudist mounds and hippuritid biostromes were separated by a belt of bioclastic sand bodies from a lagoon with radiolitid biostromes. The mounds document that corals and Late Cretaceous elevator rudists may co-occur in close association. On the scale of the entire succession, however, mainly as a result of the wide ecologic range of the rudists relative to corals, the coral-dominated mounds and the rudist biostromes are vertically separated.     

Middle Jurassic Porifera from Kachchh, western India

From the Late Bathonian sponge biofacies at Jumara Dome, Kachchh (western India) 11 species of ‘lithistid’, hexactinellinid and calcarean sponges are described. New taxa are the order Sigmatospirida, the genusJumarella, and the speciesJumarella astrorhiza, Mastosia rhytidodes, Radicispongia kraspedophora, andHexactinella prisca. The diverse sponge assemblage is associated with a rich fauna of epibenthic bivalves and brachiopods and formed meadows on fine-grained carbonate substrates. The sponge meadows grew on a carbonate ramp at the lower end of the photic zone, in quiet waters below storm wave base. The rate of sedimentation exceeded that of sponge production. This prevented the development of reef-like bodies. In contrast to Mesozoic sponge reefs, growth of the sponge meadows appears to have been confined to the regressive phases of small transgressive-regressive cycles.     

Eocene siliceous sponges from the Ebro Basin (Catalonia, Spain)

The Eocene (Bartonian) marls of the La Guixa Member and Gurb Member, Vic Marls Formation (Ebro Basin, Catalonia, Spain), contain a very rich and diversified siliceous sponge fauna. The fauna is dominated by hexactinellids; lithistids and other demosponges are rare. It consists of 16 species representing 16 genera. Eleven new species and two new genera are proposed for these sponges: Reguantella cavernosa nov. gen. nov. sp., Regadrella concinna nov. sp. (both Hexactinellida, Lyssacinosa), Eurete clava nov. sp., Pleuroguettardia iberica nov. sp., Aphrocallistes almeriae nov. sp., Hexactinella informis nov. sp. (all Hexactinellida, Hexactinosa), Brachiolites munterensis nov. sp., Centrosia viquensis nov. sp., Callicylix eocenicus nov. sp., Rhizocheton robustus nov. sp. (all Hexactinellida, Lychniscosa), Propetrosia pristina nov. gen. nov. sp. (Demospongia, Haplosclerida). Some genera of sponges in this fauna are still extant, but, in general, the predominant ones are very close in morphology, and, without doubt, closely related to the Late Cretaceous sponges. This fauna also differs considerably, in terms of composition, from most other described faunas of Tertiary sponges from the Mediterranean region, which are dominated by lithistid sponges. Lithistid sponges are rare in this investigated assemblage, which seems most similar to an as yet undescribed Eocene fauna from Italy. There is ecological differentiation in the proportions of particular sponges in various outcrops and/or stratigraphical levels that is clearly associated with water-depth-related controlling factor(s): Munter, Tona and Sta. Cecilia represent the deepest facies, Gurb is intermediate, and St. Roc and Vespella are the most shallow. The exact bathymetric position of the sponge fauna is difficult to estimate, but it seems that 100 m (but probably 200 m and more in the case of the deepest parts) of water depth may be inferred for this facies.     

Ramp morphology controlling the facies differentiation of a Late Ordovician reef complex at Bachu,Tarim Block,NW China

A carbonate ramp in the shallow‐marine northwestern part of the Central Tarim Uplift, Bachu, NW China, exhibits an extraordinary Late Ordovician reef complex along the Lianglitag Mountains, exposed for a distance of about 25 km. Seven localities within the ‘Middle Red Limestone’ of the Upper Member of the Lianglitag Formation (Katian, Late Ordovician) illustrated the changes in biofacies and lithofacies: northern, seaward‐directed patch reefs are replaced towards the south by coeval grain banks. The patch reef units are dominated by microbial and calcareous algal components. The reefs at the northernmost locality are knoll‐shaped, kalyptra‐shaped or irregularly shaped with sizes of individual reefs increasing from about 2 m in height and diameter. Stratigraphically upward, reefs notably expand to larger structures by several mounds coalescing; they are generally about 10 m thick and tens of metres in lateral extent. The maximum thickness of the main patch reef is more than 30 m, and its diameter is around 100 m. The reefal units turn into biostromes with gentler relief southward and still further south grade into banks composed of peloids and coated grains. The southernmost locality is still a shallow‐water bank, and the coastline is not documented in the study area. The present evidence indicates that the Late Ordovician palaeo‐oceanography provided a number of environments for the optimal growth of carbonate build‐ups; microbial‐calcareous algal communities could thrive in areas where the innovative metazoan reef frameworks consisting of corals and stromatoporoids did not play a significant role. The ramp morphology, especially changes in water depth, controlled the configuration of the reef complex.     

Early ordovician reefs from Argentina: Stromatoporoid vs stromatolite origin

Summary Late Arenigian biohermal reef mounds and biostromes within the shallow-marine platform facies of the upper San Juan Formation of the Precordillera (Western Argentina) represent a new Early Ordovician reef type. The meter-sized reefs are dominated byZondarella communis n.g. n. sp. The new taxon is characterized by domical, bulbous and laminar morphotypes exhibiting growth layers and thin horizontal and vertical as well as intermingled skeletal elements included within different sets. The fossil maybe compared with stromatolites and stromatoporoids but an interpretation as primitive stromatoporoids is favoured.     

Kieselschwämme aus dem unterjurassischen Misonekalk der Trento-Plattform (Südalpen): Taxonomie und phylogenetische Relevanz

The Lower Jurassic Misone Limestone of the Trento Platform (Southern Alps, Italy) contains a siliceous sponge fauna which is here described. Besides the well-known Moroccan sponge carbonates, these Lower Jurassic spongioliths from the Trento Platform are presently the second mass occurrence of siliceous sponges, which is known from the southern margin of the Tethys. They differ from each other in regard of the composition of the sponge fauna and the absence of microbial crusts in the spongioliths of the Trento Platform. There, hexactinosans and lithistid demosponges occur in equal proportions. Sphinctozoans are another very characteristic element. Because of the richness in both sphinctozoans and siliceous sponges, the Trento occurrences may be considered as a transitional fauna between the late Palaeozoic-Triassic sponge fauna dominated by sphinctozoans and the post-Liassic sponge fauna dominated by more modern groups of siliceous sponges. Two new siliceous sponge genera with their species are established:Misonia baldensis n. gen. n. sp. (Hexactinosa) andBenacia princeps n. gen. n. sp. (lithistid Demospongiae). The rarity of siliceous sponge dominated spongioliths in the Early Jurassic is due to the restricted occurrence of low energy, deeper shelf areas.     

Additional dinosaur teeth from the Cenomanian (Late Cretaceous) of Charentes,southwestern France

Some isolated teeth of theropod and sauropod dinosaurs from the Cenomanian (Late Cretaceous) of Charentes are described. Two new teeth of Troodontidae confirm the presence of this theropod family, previously based on a single specimen. New dental morphotypes are recognized within Dromaeosauridae and Brachiosauridae in comparison with those already known from Charentes. Lastly, a very small tooth is tentatively assigned to an embryonic or neonatal sauropod. The palaeobiogeographical history of European hadrosauroids is briefly discussed. This history was probably more complex than it appears, involving exchanges with both North America and Asia as early as the mid-Cretaceous (Albian–Cenomanian).     

The Bacterial Community of the Lithistid Sponge Discodermia spp. as Determined by Cultivation and Culture-Independent Methods

The marine lithistid sponge Discodermia spp. (Family Theonellidae) contains many types of associated bacteria visible in the mesohyl while biofilms cover the pinacoderm. This study determined the identity of bacteria associated with members of the genus Discodermia using microbial culture, 16S rRNA gene clone libraries and fluorescence in situ hybridization. Four samples of Discodermia spp. were collected at depths between 24–161?m near Grand Bahama Island and Cay Sal Bank, Bahamas. A total of 80 unique isolates and 94 different clone sequences from at least eight bacterial classes were obtained. It appeared that Discodermia spp. may have a core community of bacteria that is common to all sponges of this genus. Species of at least six different classes of bacteria were regularly found in most of the sponge specimens collected, irrespective of collection depth or location. This indicates that a diverse spectrum of bacteria is associated with lithistid sponges irrespective of the transient seawater community that enters the sponge.     

Living on the edge: the sponge fauna of Australia’s southwestern and northwestern deep continental margin

This first assessment of sponges on Australia’s deep western continental margin (100–1,100 m) found that highly species-rich sponge assemblages dominate the megabenthic invertebrate biomass in both southwestern (86%) and northwestern (35%) areas. The demosponge orders Poecilosclerida, Dictyoceratida, Haplosclerida, and Astrophorida are dominant, while the presence of the order Agelasida, lithistid sponges, and the Verongida are noteworthy in providing contrasts to other studies from the deep temperate Australian margin. Most sponge species appeared to be rare as two-thirds were present in only one or two samples—a finding consistent with studies of the shallow Australian sponge fauna. The Demospongiae and Calcarea had similar distribution and abundance patterns being found in the greatest numbers in the south on the outer shelf and shelf edge in hard substrates. In contrast, the Hexactinellida were more abundant at deeper depths and in soft substrates, and were more common in the north. Although the environmental factors that influence sponge distributions on the western margin cannot be completely understood from the physical covariates analyzed in this study, the data suggest depth-related factors, substrate type, and current regimes are the most influential. Incompletely documented historic demersal trawling may partly account for the lower sponge biomass found in the north. The potentially high importance of sponges to benthic ecosystems, as well as the potential for high impacts on sponges by bottom trawling, indicates that maintaining healthy sponge assemblages should be an important consideration for marine conservation planners. Successful management will need to be under-pinned by additional research that better identifies the ecological roles of sponges, and their distributions over local and broad environmental scales.     

Entobia exogyrarum (Frič, 1883) from the Upper Cretaceous of the Bohemian Cretaceous Basin

The validity of the little-known ichnospecies Entobia exogyrarum (Fri?) is verified. Shells of an oyster, Rhynchostreon suborbiculatum (Lam.), represent the substrate for the sponge borings. The borings occur in many Upper Cenomanian to Middle Turonian localities of the Bohemian Cretaceous Basin. This study revealed that the sponges attacked shells of living oysters. Entobia exogyrarum (Fri?) also represents one of the shallowest occurrences of Entobia borings in the Upper Cretaceous rocks.     

The oldest labechiid stromatoporoids from intraskeletal crypts in lithistid sponge–Calathium reefs

Early Ordovician (early Floian) reefs of South China include lithistid sponge–Calathium reefs with a three‐dimensional skeletal framework. These structures are among the first post‐Cambrian skeletal‐dominated reef structures and provides an opportunity to test how the novel metazoan builders changed the environments and increased topographic complexity within benthic communities. We document the oldest labechiid stromatoporoid (Cystostroma) in a lithistid sponge–Calathium reef of the Hunghuayuan Formation in southeastern Guizhou, South China. These earliest stromatoporoids may have originated in reefs, and we argue that the complex topography created by the hypercalcified sponge Calathium facilitated the emergence of stromatoporoids. Beyond Cystostroma, keratose sponges, Pulchrilamina (hypercalcified sponge) and bryozoans have also inhabited in the micro‐habitats (cavities and hard substrates) provided by Calathium. These findings suggest that ecosystem engineering by Calathium played an important role in the further diversification of reefs during the Ordovician.     

Phylogeny of Orbirhynchia Pettitt, 1954 (Brachiopoda: Rhynchonellida)

A computer-based parsimony analysis of the brachiopod genus Orbirhynchia (Late Albian–Middle Campanian) is described. The resulting cladogram indicates that the genus divided into two distinct lineages soon after its appearance in the Late Albian. One group is known only from marly and sandy facies of Cenomanian age, while the second, more diverse, group appeared later in the Cenomanian but persisted into the Campanian. These two groups exhibit distinct morphological trends which may be related to different ecological niches, perhaps with respect to local sedimentary environment. K ey words : brachiopod, Orbirhynchia , Cretaceous, phylogeny, palaeoecology.     

Bathyal sponges from the late Early Miocene of the Vienna Basin (central Paratethys,Slovakia)

Here we report, for the first time, a very rich and diversified sponge assemblage from late Early Miocene deposits of a central part of the Vienna Basin (Paratethys) in Slovakia. Bodily preserved sponges are described as a new genus and species Paracinachyrella fossilis (Tetiliidae, Demospongiae). Dissociated spicules reveal the presence of the “soft” demosponges that belong to families Tetillidae, Theneidae, Geodiidae, Samidae, Thrombidae, Thoosidae, Agelasidae, Myxillidae, Bubaridae, and Tedaniidae, the lithistid family Pleromidae, and an undetermined rhizoclone-bearing lithistid. Fragments of dictyonal skeleton indicate the presence of hexactinellid sponges that belong to the families Farreidae and Euretidae, and lychniscosan sponges. We estimate that at least 16–19 different species of siliceous sponges inhabited this region of the Central Paratethys during the latest Burdigalian. Most of these sponges are reported for the first time from the Miocene of the Paratethys. This sponge fauna has clear Tethyan affinities and indicates the existence of connection between Paratethys and Tethys during the latest Burdigalian, as well as the presence of open marine, deep-water, bathyal conditions in this part of the Vienna Basin.