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Abstract The Ancun gold deposit is located in the Dehua–Youxi–Yongtai ore region of Fujian Province, southeast China. The orebodies are mainly hosted in early Paleozoic quartz diorite and structurally controlled alteration zones along NW- and NE-trending faults. Based on the characteristics of mineralization, alteration mineral assemblages, fluid inclusions, and H–O–S isotope data, the Ancun gold deposit can be classified as an intermediate-sulfidation epithermal deposit. The primary metallic minerals are gold, electrum, pyrite, sphalerite, chalcopyrite, and galena, and the principal gangue minerals are quartz, calcite, sericite, and illite. The main types of wall rock alteration include sericitization, argillization, silicification, beresitization, and carbonation. Fluid inclusion studies were carried out on quartz and sphalerite from Au-bearing silicified massive ores and auriferous polymetallic-sulfide-bearing quartz veins from the main ore stage. Microthermometric measurements of fluid inclusions yielded homogenization temperatures (T h) of 152–255 °C and salinities of 0.9–5.3 wt% NaCl equivalent in quartz, and T h of 175–236 °C and salinities of 1.6–5.0 wt% NaCl equivalent in sphalerite. The low to moderate temperatures and salinities imply that the ore-forming fluids formed in epithermal environments. Gold deposition at Ancun is inferred to have been caused mainly by mixing of magmatic and diluted meteoric waters. The H and O isotopic compositions (δD H2O = −76.4‰ to −61.2‰; δ18O H2O = −6.1‰ to 4.0‰) of inclusion water in quartz imply that ore-forming fluids were derived mainly from magmatic sources. Sulfur isotopic values of sulfide minerals vary over a narrow range from −3.9‰ to −0.6‰, suggesting that S was derived from a homogeneous magmatic source. Based on the close temporal and spatial relationship between intermediate-sulfidation epithermal deposits and porphyry deposits, along with the alteration and mineralization characteristics of the Ancun gold deposit, potential exists in this region to drill into deeper-seated porphyry deposits. Highlights • The Ancun gold deposit is an intermediate-sulfidation epithermal gold deposit. • Reliable microthermometry data were obtained for gangue and ore minerals. • Mineralization was formed from low–medium temperature and salinity fluids. • Stable isotope data indicate that ore-forming fluids were mainly of magmatic origin. • Gold deposition was caused by mixing of magmatic and meteoric water. [ABSTRACT FROM AUTHOR]

This article provides stratigraphic and geochronological data from a central part of Gondwana's northern margin - the Moroccan Meseta Domain. This region, located to the north of the Anti-Atlas area with extensive outcrops of Precambrian and lower Paleozoic rocks, has hitherto not received much attention with regard to its Precambrian geology. Detrital and volcanic zircon ages have been used to constrain sedimentary depositional ages and crustal affinities of sedimentary source rocks in stratigraphic key sections. Based on this, a four-step paleotectonic evolution of the Meseta Domain from the Ediacaran until the Early Ordovician is proposed. This evolution documents the transition from a terrestrial volcanic setting during the Ediacaran to a short-lived carbonate platform setting during the early Cambrian. The latter then evolved into a rifted margin with deposition of thick siliciclastic successions in graben structures during the middle to late Cambrian. The detritus in these basins was of local origin, and a contribution from a broader source area (encompassing parts of the West African Craton) can only be demonstrated for postrifting, i.e., laterally extensive sandstone bodies that seal the former graben. In a broader paleotectonic context, it is suggested that this Cambrian rifting is linked to the opening of the Rheic Ocean, and that several peri-Gondwanan terranes (Meguma and Cadomia-Iberia) may have been close to the Meseta Domain before drifting, albeit some of them seem to have been constituted by a distinctly different basement. [ABSTRACT FROM AUTHOR]

The Hongseong area in the southwestern Gyeonggi Massif in South Korea is considered to represent the eastward extension of the Qinling–Dabie–Sulu collision belt in China. We have carried out zircon U–Pb SHRIMP dating and P–T estimations of the gneisses and amphibolites in the eastern Wolhyeonri complex within the Hongseong area in order to constrain their metamorphic and tectonic evolutions. The protoliths of the migmatitic biotite gneisses formed during the Neoproterozoic and underwent granulite-facies metamorphism (750–880 °C, 12–15 kbar) at 442–413 Ma. These rocks subsequently experienced amphibolite-facies retrograde metamorphism at 585–660 °C and 7.5–10.3 kbar. Mylonitic biotite gneiss, hornblende gneiss, and folded amphibolite in the study area yield metamorphic ages that range from 429 to 420 Ma. The protoliths of some garnet amphibolites that formed at 470–456 Ma are arc magmatic rocks; they experienced metamorphism at the boundary between amphibolite- and eclogite-facies (ca. 625–700 °C and 13–15.5 kbar) before 418 Ma and underwent retrograde amphibolite-facies metamorphism (ca. 625–700 °C and 8–9 kbar) at 418–405 Ma. These data suggest that a regional intermediate-P/T metamorphic event occurred during the Middle Paleozoic. In contrast, Paleoproterozoic augen gneiss blocks enclosed in the Deokjeongri gneiss complex preserve evidence of high-pressure (HP) metamorphism (840–960 °C, 17–21.8 kbar) at 234–230 Ma, which are similar to the previously reported results from eclogite blocks in this area. The occurrence of Middle Paleozoic regional metamorphism before the Permo-Triassic HP metamorphism in the Hongseong area may be correlated with the Middle Paleozoic metamorphism in the Qinling belt in China; such regional metamorphic events were caused by the collision of microcontinents with the North or South China Cratons prior to the collision between the North and South China Cratons in the Permo-Triassic. [ABSTRACT FROM AUTHOR]

This is the first record of a Permian seep deposit and an associated, morphologically bizarre, bivalve-dominated fauna from the Passa Dois Group, Paraná Basin, Brazil. Shales of the outer-shelf facies of the Serra Alta Formation preserve a low-diversity but high-abundant, large-sized bivalve fauna with unusual morphologies inside discoidal carbonate concretions. The bivalves are about ten times larger than tiny bivalves found scattered in laterally equivalent mudstones of the same unit. Intercalated between two concretion-bearing horizons, a cm-thick, sheet-like, disrupted, “brecciated”, partially silicified carbonate layer with microbially-induced lamination is recorded. In some areas, the carbonate layer shows vertical structures formed by injections of mud mixed with white limestone clasts and microbial linings. Immediately above this, silicified mudstones preserve small domal structures (= mounds) with a slightly depressed center. Monospecific concentrations of closed articulated shells of Tambaquyra camargoi occur at the base of these domes. Carbon-isotope (δ 13 C) values from the shells, “brecciated” carbonates, and fossil-rich concretions are all depleted (negative values ∼ −6.1 to −7.6‰). Combined taphonomic, sedimentological, petrographic, geochemical and paleontological data suggest that the disrupted, “brecciated” carbonate and associated fauna and domes may have formed by an exudation system. Indeed, this interval of the Serra Alta Formation is ∼8.7 m above the contact with the underlying, oil-rich Irati Formation. This unit has very high total organic carbon (up to 23%) values and high sulphur contents, supporting the interpretation of the lithological and paleontological features as result of seepage of organic compounds at the seafloor. Where the gases and hydrocarbons escaped, the seabed was colonized by, at least facultatively, chemosymbiotic bivalves. The species above belong to a highly endemic group of pachydomids that were shallow infaunal bivalves (SIB). Hence, they are not related to “classical” bivalves with extant representatives, which are chemosymbionts. This may reflect an extreme adaptive radiation and repopulation of anoxic-dysoxic bottoms of the Paraná Basin by SIB species. [ABSTRACT FROM AUTHOR]

The Bohemo-Iberian regional scale for South Gondwana, involving the 'Mediterranean Province', comprises five regional stages (Arenigian, Oretanian, Dobrotivian, Berounian and Kralodvorian) plus the global Tremadocian and Hirnantian. The predominance of shallow-water taxa in those high-latitude faunas imposes serious difficulties for correlating the regional succession with the formal global chronostratigraphy because of the almost total absence of the key graptolites and conodonts defining the base of the standard series, stages and stage slices. Instead, the abundant benthic faunas (trilobites, brachiopods, molluscs, echinoderms) of South Gondwanan origin largely dominated in the area from the middle Darriwilian to the late Katian. The poleward faunal migration of originally Avalonian, Baltic, Laurentian and even Asiatic taxa during the Boda Event of global warming progressively ends with the endemicity in the region, where the ensuing benthic assemblages were severely affected by the Hirnantian glaciation. The regional scale significantly improves the precision of correlations between Ordovician strata from SW and central Europe, North Africa and a large part of the Middle East. An updated record of palaeontological data from areas where Mediterranean faunas remain practically unknown, or are still poorly investigated, is also included. Palaeobiogeographical relationships based on the distribution of faunas across South Gondwana are suggested as an improvement for positioning many territories in modern palaeogeographical reconstructions and offer a constructive approach to problems related to the pre-Variscan and pre-Alpine orogenic puzzles. [ABSTRACT FROM AUTHOR]

The Upper Cenomanian cover of the Palaeozoic Mouthoumet Massif (southern Corbières, Aude, France), on the southern flank of the Bézu anticline, shows accumulations of large platy corals. However, while being already presented in stratigraphic, palaeoecological and sedimentological contexts, these organisms have not been the subject of a palaeontological study. The coral fauna encompasses 16 species of the families Leptophylliidae, Microsolenidae, and Siderastraeidae and is here presented in detail. [ABSTRACT FROM AUTHOR]

Plastically deformed and silicified worm tubes from the Late Emsian (Early Devonian) of the Parana Basin are described herein as a new species and genus of annelid worms Annulitubus mutveii gen. et sp. nov. The tubes are straight and ornamented by smooth rings. Their microstructure is homogenous, which most likely is a diagenetic alteration. The characteristic early diagenetic compression of the tubes may point out to their original elastic organic tube wall. We cannot state it with full confidence but the most likely tube producers were tube-dwelling polychaete annelids, which were otherwise uncommon in the Paleozoic times. [ABSTRACT FROM AUTHOR]

Stromatoporoids hosted a diverse fauna of symbiotic endobionts during the Silurian and Devonian. Assemblages of symbiotic endobionts from the Ordovician, Silurian and Devonian differ significantly. The only symbiotic association in the Ordovician is cornulitid-stromatoporoid. The diversity of Silurian and Devonian symbiotic associations is similar, but the taxonomic compositions of the Silurian (i.e. rugosans, syringoporids, cornulitids, lingulids, Chaetosalpinx and Helicosalpinx ) and Devonian (i.e. syringoporids, Torquaysalpinx , Chaetosalpinx , Streptindytes , and rugosans) associations are different. Symbiotic corals dominated both Silurian and Devonian associations, rugosans dominated the Silurian associations, and syringoporids dominated the Devonian associations. [ABSTRACT FROM AUTHOR]

A model is presented for what may be the first recognized ancient analogue of migration of a Mendocino-style triple junction, exposed at mid-crustal levels in the eastern New England Appalachians (northeastern United States). In the model, the mid-Paleozoic subvertical crustal-scale dextral transpressive Norumbega fault system formed as a result of subduction of an oceanic ridge and associated transform fault, similar to the evolution of the modern San Andreas fault system in western North America. Ridge subduction in eastern New England started in the latest Silurian at the latitude of the Coastal Volcanic belt in eastern Maine, causing bimodal plutonism and volcanism in the area. Subduction of an associated transform fault, and the transition from convergence between the northern Rheic Ocean plate and Laurentia to dextral transpression between the southern Rheic Ocean plate and Laurentia, resulted in development of the Norumbega fault system starting in the Middle to Late Devonian. The Norumbega triple junction gradually moved ~200 km southwestward throughout the Devonian, similar to northward migration of the Mendocino triple junction at the northern end of the San Andreas fault system over the past ~30 m.y. The ridge subduction model explains why convergent tectonics was ongoing until the latest Devonian or earliest Carboniferous in eastern Massachusetts, analogous to motion along the modern Cascadia subduction zone (western North America), while to the north, a progressive southwestward transition from predominantly convergent tectonics to predominantly strike-slip movement along an active Norumbega fault system occurred, reflecting migration of a triple junction similar to the Mendocino triple junction. [ABSTRACT FROM AUTHOR]

The fossil record of Paleozoic ophiuroids includes a number of forms which share striking similarities with modern relatives in terms of skeletal morphology. These so called modern-type Paleozoic ophiuroids yield an enormous potential for a better understanding of ophiuroid evolution, yet the scarcity of accurate and sufficiently detailed morphological descriptions available to date precludes any further-reaching assessments. Here, we describe an articulated ophiuroid specimen from the Late Tournaisian (early Carboniferous) of Czatkowice quarry, southern Poland, as a new species Aganaster jagiellonicus sp. nov. The good preservation of the specimen allowed for a morphological analysis at a level comparable to recent ophiuroid descriptions. It shows remarkable morphological similarities with extant former ophiolepidids Ophiomusium and Ophiosphalma. The new find thus contributes to a solid basis for future investigations on the position of the modern-type Paleozoic ophiuroid in the phylogeny of the class. [ABSTRACT FROM AUTHOR]

The Angosto de Lampazar, a classic locality for the study of lower Paleozoic successions in the Cordillera Oriental, NW Argentina, has yielded a late Cambrian relatively diverse, lingulate brachiopod fauna. Sandy lenses with calcareous cement from the uppermost levels of the Lampazar Formation have yielded abundant remains of articulate and phosphatic brachiopods. Among the latter, the new species Eurytreta harringtoni Mergl and Herrera, Lingulella? melonica Mergl and Herrera, Libecoviella lenticularis Mergl and Herrera, and Schizambon cardonalis Mergl and Herrera, as well as the new genus and species Saltaia lampazarensis Mergl and Herrera are formally introduced. Trilobites and conodonts from the same horizons characterize the Cordylodus proavus Zone, allowing a correlation with Stage 10 of the Furongian Series. Although the information on lingulate brachiopods from the C. proavus Zone is scarce across the world, the composition of the studied association displays a relationship with coeval and slightly younger faunas of Utah and Kazakhstan. The Argentine brachiopods, the first described from the late Cambrian Proto-Andean margin of Gondwana, are more closely related to temperate Laurentian faunas than to those from the high latitude North African margin of Gondwana. [ABSTRACT FROM AUTHOR]

The relationship between brachiopods and bivalves has been widely discussed in previous studies. Based on analyses at different temporal and spatial scales, several authors have argued either for the indifference or the interaction between the two clades. In this contribution we evaluate brachiopod and bivalve coexistence at two different spatial scales in a siliciclastic shelf developed during the Late Paleozoic in Western Argentina. At regional scale, bivalves were more diverse than brachiopods, although both had a similar total number and comparable distribution of occurrences. At local scale, however, multivariate analyses indicate that brachiopods and bivalves were segregated. Null models reinforce this pattern confirming the non-random co-occurrence pattern, and that the coexistence of brachiopods and bivalves was significantly low. In addition, multivariate analyses indicate that the biotic gradient neither followed the bathymetrical, nor a geographical or temporal gradient. The possibility that such segregation would have been caused by taphonomic (storm) reworking, was also disregarded considering multivariate analyses together with taphonomic evidence. The lack of environmental segregation between brachiopods and bivalves, coupled to analyses taking into account ecological guilds, indicates that possible factors controlling the segregation, such as turbidity, substrate or productivity were not relevant. As a whole, these results suggest a possible competitive interaction between brachiopods and bivalves at local scales. Interestingly, brachiopod–bivalve coexistence at regional scale did not foster local coexistence, indicating that the processes acting at these two scales are, at least partially, decoupled. Finally, the regional coexistence pattern suggests that the major transition between brachiopod and bivalve dominated communities was most probably related to processes acting at regional to biogeographic scales rather than to competition. [ABSTRACT FROM AUTHOR]

Three chondrichthyan radiations are registered in the Famennian of the Ardenne Massif (Belgium). These radiations are already observed in Morocco and in the Carnic Alps, their acme being related with the early expansa transgression. Comparisons of univariate statistical descriptors like Margalef richness and Shannon–Wiener diversity index show variations between both margins of the Paleotethys, variations interpreted in terms of trophic relationships. The Ardenne area, a northern shallow carbonate platform is characterized during the Famennian by endemic shark taxa with durophagous dentition. The southern open deep-sea area, the Variscan Sea, contains large placoderms probably disclosing a negative feedback on “cladodont” chondrichthyans. This supports the hypothesis that the Armorica platelet behaved like a barrier between the central southern Laurussia and northern Gondwana. [ABSTRACT FROM AUTHOR]

The shift from the Paleozoic to the Modern (post-Paleozoic) Fauna involved a major influx of benthic molluscs (gastropods and bivalves) into offshore marine environments, resulting in mixed brachiopod–benthic mollusc paleocommunities as early as the late Paleozoic Era; this change might be expected to have affected contemporaneous predators. Gastropods and productidine brachiopods from five upper Pennsylvanian shales in Texas (United States) show greater repair frequencies than do other taxa, suggesting that crushing predators readily consumed gastropods early in the faunal transition but that some brachiopod taxa still composed an important component of predator diets. In contrast, drilling predators continued to prefer brachiopods almost exclusively over benthic molluscs; Paleozoic drillers may have been incapable of taking mobile prey. Contrary to previous hypotheses, brachiopods were probably not “mistaken” prey, at least during the Paleozoic. The addition of gastropods to the diet of crushing predators suggests a major change in ecological processes in response to the new fauna. [ABSTRACT FROM AUTHOR]

Abstract: Phanerozoic diversity curves illustrate that the transition from taxonomic dominance of the Paleozoic Fauna to taxonomic dominance of the Modern Fauna is coincident with the Permo–Triassic boundary. Although a corresponding transition in ecological dominance must have occurred, its timing is unclear. One way to assess ecological dominance during the Early-Middle Triassic recovery interval is through the study of bioclastic accumulations. Bioclastic accumulations from the Early Triassic are largely dominated by constituents of the Modern Fauna. In this study, we examined bioclastic accumulations from the Middle Triassic, the interval after the environmental stress associated with the end-Permian extinction abated. Bioclastic accumulations from Panthalassan deposits (Ladinian portion of the Liard Formation at Williston Lake, Canada) and Tethyan deposits (Anisian–Ladinian Muschelkalk Group, Germany) were examined. Although the most common shell bed-producer differed between the two sites (bivalves, constituents of the Modern Fauna, in Germany and brachiopods, constituents of the Paleozoic Fauna, in Canada), both sites, though geographically disparate, contained significant crinoidal bioclastic accumulations (encrinites). Crinoids, like many constituents of the Paleozoic Fauna, suffered drastic diversity losses at the end-Permian mass extinction and maintained relatively low diversity through the Middle Triassic. Despite reduced diversity, bioclastic accumulations show that crinoids regained some measure of ecologic dominance in the Middle Triassic. In addition, brachiopods, another constituent of the Paleozoic Fauna that suffered severe diversity losses at the end-Permian extinction, regained at minimum local ecological dominance in the Middle Triassic of Panthalassa. These data demonstrate that the transition to Modern faunal taxonomic dominance was decoupled from the transition to Modern faunal ecological dominance. [Copyright &y& Elsevier]

Early Paleozoic paleomagnetic data from NW Argentina and Northern Chile have shown large systematic rotations within two domains: one composed of the Western Puna that yields very large (up to 80°) counter-clockwise rotations, and the other formed by the Famatina Ranges and the Eastern Puna that shows (~40°) clockwise rotations around vertical axes. In several locations, lack of significant rotations in younger rocks constrains this kinematic pattern to have occurred during the Paleozoic. Previous tectonic models have explained these rotations as indicative of rigid-body rotations of large para-autochthonous crustal blocks or terranes. A different but simple tectonic model that accounts for this pattern is presented in which rotations are associated to crustal shortening and tectonic escape due to the collision of the allochthonous terrane of Precordillera in the Late Ordovician. This collision should have generated dextral shear zones in the back arc region of the convergent SW Gondwana margin, where systematic domino-like clockwise rotations of small crustal blocks accommodate crustal shortening. The Western Puna block, bordering the Precordillera terrane to the north, might have rotated counterclockwise as an independent microplate due to tectonic escape processes, in a fashion similar to the present-day relationship between the Anatolia block and the Arabian microplate. [ABSTRACT FROM AUTHOR]

Abstract: The Tucumán foreland basin is bounded by: 1) basement cored ranges with elevations over 6000 m in the west; 2) inverted extensional grabens to the north; 3) basement thrust blocks in the south and 4) basement cored small ranges in the east. This foreland basin is located between two geological provinces: the Sierras Pampeanas and the Santa Bárbara system. Cretaceous Salta rifting extended southwards covering the entire eastern part of the province of Tucumán in NW Argentina. Syn-rift and post-rift deposits can be recognized in accordance with their architectural geometries. Foreland basin sediments progressively covered the rift deposits as the Andean orogen propagated towards the east. Despite some early studies, the Tucumán basin is poorly documented. For the present study, 44 sections of 2D seismic surveys amounting to more than 730 km were used to describe the structure and the depositional evolution of the basin. The present structure is the result of a long sequence of events that includes a compressional deformation during the Paleozoic, a rifting stage during the Cretaceous and a foreland stage during the late Cenozoic. Although tectonic inversion, which has played a role during the foreland stage since the Miocene, can be observed in many sectors of the basin, it is more prominent along the margins. Reactivation of old basement discontinuities and inversion of Cretaceous normal faults produced the compartmentalization of the foreland, giving rise to the present shape of the Tucumán basin. This evolution is recorded in the Neogene deposits. [Copyright &y& Elsevier]

Abstract: The Tedeleaceae are late Paleozoic Filicalean ferns with two known genera, Ankyropteris and Senftenbergia, which partially overlap morphologically and have the same known stratigraphic ranges—Namurian A to Lower Permian in Euramerica. Ankyropteris is anatomically known and Senftenbergia is almost exclusively based on compression specimens. Both genera exhibit abaxially, laminar-borne sori and/or solitary sporangia with some schizaeoid attributes. The sporangia are pyriform to tear-drop shaped, erect to slightly curved with a two to multiseriate apical annulus and mature spores usually of the Raistrickia type. Detailed morphological comparisons of Ankyropteris with Senftenbergia emphasize generic overlaps as well as lack of congruence. Ankyropteris brongniartii, a classic vine in anatomy, defines the stratigraphic range of the genus and provides recurrent ecological observations of habit and associated plants in ecotonal swamp reaches as well as in volcanic environments and on other clastic substrates. Ankyropteris may have originated from the clepsydroid zygopterid clade outside of the swamps. Ankyropteris brongniartii occurred as an epiphytic vine on Psaronius tree ferns as they expanded into coal swamps and often co-occurred with Paralycopodites even earlier in Middle Pennsylvanian. Vine stem anatomy and functional morphology of aphlebiae are emphasized in A. brongniartii with comparisons to Austroclepsis, an early “vining” false tree fern. Anatomical comparisons of Ankyropteris species based on shoots emphasize divergent habits with similar robust sizes; all exhibited aphlebiae. Known only from coal balls, Ankyropteris corrugata (Westphalian A–B) had a rampant habit on exposed peat with a succulent, dichotomous rhizome and erect fronds. The Lower Pennsylvanian specimen of Ankyropteris hendricksii is a compact tree fern with crowded frond bases and intercalated roots. Tyloses commonly occur in A. corrugata and A. brongniartii indicating water-stressed conditions. Apical meristems of shoot and fronds are reported for the first time, suggesting response growth to disturbance and rapid burial. [Copyright &y& Elsevier]

Terra Nova, 22, 330–340, 2010 The youngest Ordovician conodont fauna in SW Europe has been found in the Malaguide Complex of the Betic Cordillera, SE Spain. It is also the first Ordovician conodont fauna in the Western Mediterranean Alpine Orogen. The conodont association, attributed to the Hirnantian (upper part of the Amorphognathus ordovicicus Biozone), is characterized by the predominance of Walliserodus amplissimus and Scabbardella altipes and by the absence of Sagittodontina and Istorinus, typical of the Mediterranean Province. This fauna differs markedly from those of the same biozone recorded in the Spanish Variscan Orogen of the Iberian Massif, which are attributed to the Katian. The Malaguide fauna shows, however, striking similarity to faunas of the Carnic Alps and some resemblance to those of the Pyrenees, Northern England and North Wales. These features suggest that Palaeozoic terranes of the Betic Cordillera were located far to the east of their present location and displaced westward during the Alpine Orogeny. [ABSTRACT FROM AUTHOR]

Abstract: The latest works on iniopterygians question their monophyly when considering only the neurocranium of the two families (Sibyrhynchidae and Iniopterygidae), which have different conditions of preservation. Some of the synapomorphies of the Iniopterygia concern the pectoral girdle and fins. However, the anatomy of these different elements is still poorly known in this taxon. Here we describe in details three dimensionally preserved cartilages of the pectoral girdle and fins of the sibyrhynchid Iniopera sp. These structures have been extracted virtually from phosphatised nodules thanks to conventional and synchrotron microtomography, using absorption and phase contrast based techniques in the later case. The pectoral girdle of Iniopera sp. consists of three elements, which are, from dorsal to ventral, a paired suprascapular cartilage, a pair of robust scapulocoracoids and an unpaired intercoracoid cartilage. The scapular part of the scapulocoracoids is extremely reduced and the suprascapular cartilages link the scapulcoracoids to the rear of the neurocranium. These characters may be iniopterygian synapomorphies. Iniopterygians, stem and crown-holocephalans share a basipterygium that articulates with the pectoral girdle and bears an enlarged first pectoral fin radial. Posteriorly, the basipterygium articulates with either a well-defined metapterygium (in crown-holocephalans) or a metapterygial axis (in stem-holocephalans). [ABSTRACT FROM AUTHOR]

Abstract: Tetrapod footprints from the Permian Ikakern Formation of the Argana Basin have long been known but never studied in detail. Here we present the first comprehensive description of recently discovered tracks and trackways that come from near the uppermost layers of an up to 1800m thick red-bed sequence. Assigned to Hyloidichnus and Pachypes, these ichnofossils suggest a Middle to Late Permian age of the track-bearing strata. Potential trackmakers are medium to large-sized moradisaurine captorhinids and pareiasaurs. This strongly parallels the bodyfossil record inasmuch as the only known skeletal remains of terrestrial tetrapods from the study area belong to both of these groups. Based on this twofold evidence, captorhinids and Pareiasauria have to be considered as abundant faunal elements of the ancient floodplain environment that is represented by the upper part of the Ikakern Formation. As one of only a few places in the world with closely associated body and ichnofossils of Late Palaeozoic age, the Argana Basin has a high potential for allowing the reconstruction of terrestrial ecosystems during the early stages of the break-up of central Pangaea and just before Mesozoic diapsid reptiles gained ascendancy. Further research on this stimulating topic will significantly contribute to the understanding of still poorly known Middle and Late Permian tetrapod ichnofaunas. [Copyright &y& Elsevier]

The article offers information on trigonotarbids, a species of the class arachnida of the phylum arthropods. As stated, trigonotarbids were amongst the earliest and most important predators in the nascent terrestrial communities of the Silurian period. Their body is split into two halves in which the anterior half is covered by the carapace. Fossil evidence has proved that trigonotarbids were present in some of the earliest terrestrial ecosystems and lived on land.

Recent studies of crinoids reveal that their connective tissue, known to be mutable, is also contractile, and that certain stalked taxa are capable of crawling and subject to predation by cidaroid sea urchin. Aspects of crinoid functional morphology, ecology, and paleobiology are reviewed in the context of these findings. Mutability and contractility of ligament are important to autotomy, posture maintenance, and motility, and those, in turn, are shown to play a role in how crinoids acquire nutrients, select habitats and respond to predation pressure. A review of predation on crinoids supports the view that it is ecologically significant. Motility, a trait critical for handling predation pressure by stalkless crinoids, is shown to play an analogous role in stalked crinoids. The distribution of traits required for motility among extant and fossil crinoids reveals that their frequency increased dramatically following the Permo-Triassic extinction, with low values characterizing the Paleozoic and high values characterizing the post-Paleozoic. [ABSTRACT FROM AUTHOR]

Abstract: Dorsal valves of the cementing strophomenide brachiopods Leptaenoidea silurica Hedström and Liljevallia gotlandica Hedström are described for the first time, and it is shown that both these species could also live ambitopically. The lower Wenlock Scamnomena rugata (Lindström) represents young individuals of the ambitopic variant of Leptaenoidea silurica, and is placed in synonymy, resulting in the valid name for the taxon being Leptaenoidea rugata. The range of this species now spans the whole Wenlock, from the upper Visby Formation to the Klinteberg Formation, and possibly even into the Ludlow. Ambitopic gerontic specimens of L. rugata develop very thick shells, in which the ventral valves have strong curvature, and become deeper not by geniculation but by successive mantle retractions and subsequent re-growth, in a way similar to that of atrypides. This shape was probably an adaptation to “floating” on softer substrates. The thickened gerontic dorsal valves have well-developed lophophoral support, showing the shape of the lophophore, which comprises two branches that curve inwards and then backwards; the lophophore was probably ptycholophous and similar to that in living members of the Thecideidina. Ambitopic specimens of Liljevallia could grow to a much larger size than cementing forms, where the dorsal valves have very large, posterior-facing cardinal process lobes and deeply impressed muscle fields and anterior scars. The presence of a ventral process and long, posteroventrally elongated cardinal process lobes, and the absence of dental plates reveals that Liljevallia was probably an early member of the Douvillinidae and is thus removed from the Leptaenoideidae. [Copyright &y& Elsevier]

Abstract: For the first time, dipnoan remains are described from the Devonian of Spitsbergen. According to the stratigraphy and the associated vertebrate fauna, they are considered as Late Emsian–Early Eifelian in age. Unfortunately remains are too sketchy and non-diagnostic to be referred or compared to a known Devonian dipnoan. This new material, determined as Dipnoi gen. et sp. indet., is nevertheless important in biostratigraphical and palaeobiogeographical points of view, since it is amongst the earliest dipnoan occurrences, and the first one in the Devonian of Spitsbergen. To citer this article: G. Clément et al., C. R. Palevol 5 (2006) . [Copyright &y& Elsevier]

Abstract: The Devonian cemented brachiopod Schuchertellopsis durbutensis has proved difficult to classify and its possible taxonomic relationships are unknown. Morphologically Schuchertellopsis resembles more closely members of the Orthotetidina than the Davidsoniidina. Examination of the shell structure, a key diagnostic feature of the Orthotetidina, shows that Schuchertellopsis has the cross laminar secondary shell typical of all orthotetidines. However, the presence of both pseudopunctate and incipient an extropunctate fabric within the ventral valve is unique amongst orthotetidine brachiopods and is thought to represent a phase of shell fabric experimentation. Schuchertellopsis probably fits most comfortably within the Schuchertellidae, and is the earliest representative of that family. [Copyright &y& Elsevier]

Six modifications to the hinge occur in strophomenoid brachiopods from Anticosti Island: (1) overhanging socket ridges; (2) posterolateral socket ridges along the interarea articulate with grooves on the posterior of teeth; (3) anteromedian dental notches articulate with the crests of socket ridges; (4) dental crenulations on the surfaces of teeth mesh with socket ridges; (5) denticles extend laterally to the cardinal extremities; and (6) the margin of the ventral interarea fits into a long socket along the dorsal interarea forming a lateral tooth. Denticulate hinges and dental notches that typify Silurian and Devonian strophomenids begin in the fauna of the Ellis Bay Formation. Thus the most important interval of strophomenid faunal turnover was at the base of the Gamachian (the base of the Hirnantian) and not at the Ordovician–Silurian boundary. Muscle attachment pads in the delthyrial cavity do not correspond to the positions of either the adductor or diductor muscle scars. Pedicle adjustor muscles in modern brachiopods occupy this position. The round gap between the median fold of the pseudodeltidium and groove on chilidium is proposed as the point of emergence of the pedicle muscle. The tiny foramen, commonly sealed early in growth, is suggested to be part of a neanic water-intake system, active before the growth of the cardinal process in ephebic shells. Once the cardinal process appeared, the foramen was blocked. Recurring types of strophomenid ornamentation, such as posteriorly steepened rugae and checkerboard ornamentation, may have served as a plow to redistribute sediment as the shell was pulled backwards along the pedicle.Six modifications de la charnière sont présentes dans les Brachiopodes strophoménoïdés de l'Île d'Anticosti: (1) la présence de crêtes fossulaires surplombantes, (2) les crêtes fossulaires postéro-latérales le long de l'interaréa sont articulées avec des rainures sur la partie postérieure des dents, (3) des échancrures antéro-médianes s'articulent avec les crêtes fossulaires, (4) des crénulations sur la surface des dents s'engrènent avec les crêtes fossulaires, (5) des denticules sont présentes latéralement jusqu'aux extrémités cardinales et (6) la marge de l'interaréa ventral s'insère dans une longue fossette le long de l'interaréa dorsal, formant une dent latérale. Les charnières denticulées et les échancrures dentales typiques des strophoménidés du Silurien et du Dévonien débutent dans la faune de la Formation d'Ellis Bay. Ainsi, le changement faunique le plus important des strophoménidés se situe à la base du Gamachien (base de l'Hirnantien) et non pas à la limite Ordovicien–Silurien. Les cicatrices des muscles dans la cavité delthyriale ne correspondent pas aux positions des muscles adducteurs ou diducteurs. Les muscles ajusteurs pédonculaires occupent cet endroit dans les Brachiopodes modernes. Le trou rond entre le pli médian du pseudodeltidium et le sillon sur le chillidium est proposé comme point d'émergence du muscle pédonculaire. Le petit foramen, généralement calfaté pendant la croissance précoce, est suggéré comme faisant partie du système néanique d'inspiration d'eau, fonctionnel avant la croissance du processus cardinal dans les coquilles éphébiques. Une fois le processus cardinal apparu, le foramen était bouché. Certains types périodiques d'ornementation de strophoménidés, tels les rugae postérieurement plus abruptes et l'ornementation en damier, auraient pu servir de charrue pour redistribuer les sédiments quand la coquille était tirée vers l'arrière le long du pédoncule.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The earliest rhynchonellid brachiopods were small-shelled and preferred cool-water conditions in both siliciclastic and carbonate environments. Relatively large shells of Rhynchotrema evolved in mid-Caradoc time and rapidly became widespread in Laurentia. Hiscobeccus probably evolved from Rhynchotrema during the late Caradoc by developing a large, globular, strongly lamellose shell. The earliest form of Hiscobeccus shows transitional characteristics between Rhynchotrema and typical Hiscobeccus, most notably in its nonglobular shell that is wrinkled by growth lamellae only on the anterior two thirds of the shell. By early Ashgill time, Hiscobeccus became widespread in North American inland basins, although it remained common in marginal carbonate platforms and basins. During the Ashgill, Hiscobeccus, Lepidocyclus, and Hypsiptycha represented a distinct North American fauna, characterized by large, globular, and completely wrinkled shells. These morphological features were adaptations to the shallow, well-circulated, epicontinental, tropical seas with a soft muddy substrate. The gigantism exhibited by the Hiscobeccus Fauna is also shown by orthid and strophomenid brachiopods, gastropods, nautiloids, and trilobites. Extinction of the Hiscobeccus Fauna was probably related to its narrow range of environmental tolerance, especially during the Gondwana continental glaciation, which brought a major global sea-level drawdown and lowered ocean temperature. The cool-water Rostricellula and Rhynchotrema were uncommon in inland seas during the Ashgill and were represented by several opportunistic species in the Anticosti Basin during the Hirnantian and Llandovery, and most of these preferred siliciclastic-rich or deep-water shelf carbonate environments.Les plus précoces brachiopodes de la sous-famille des Rhynchonellidae avaient de petites coquilles et préféraient des conditions d'eau fraîche dans des environnements silicoclastiques ou carbonatés. Les coquillages relativement larges des Rhynchotrema ont évolué au milieu du Caradocien et se sont rapidement répandus à travers la Laurentie. Hiscobeccus a probablement évolué de Rhynchotrema durant le Caradocien tardif en développant une grande coquille globulaire fortement lamellée. La forme du Hiscobeccus la plus précoce montre des caractéristiques de transition entre Rhynchotrema et le Hiscobeccus typique, surtout par sa coquille non globulaire qui est plissée par les lamelles de croissance seulement sur les deux tiers antérieurs de la coquille. À l'Ashgillien précoce, Hiscobeccus était répandu dans les bassins intérieurs de l'Amérique du Nord, bien qu'il soit resté fréquent dans les plates-formes et bassins marginaux carbonatés. Au cours de l'Ashgillien, Hiscobeccus, Lepidocyclus et Hypsiptycha représentaient une faune nord-américaine distincte, caractérisée par des larges coquilles globulaires et complètement plissées. Ces caractéristiques morphologiques étaient des adaptations aux mers tropicales peu profondes à bonne circulation et épicontinentales dont le fond était composé de boues non consolidées. Le gigantisme démonté par la faune Hiscobeccus est aussi démontré par les Brachiopodes Orthida et Strophomenida, des Gastéropodes, des Nautiloidae, et des Trilobites. L'extinction de la faune Hiscobeccus était probablement liée à sa faible plage de tolérance environnementale, surtout au cours de la glaciation continentale du Gondwana où il y eut un grand abaissement global du niveau de la mer et de la température de l'océan. Les brachiopodes d'eau fraîche Rostricellula et Rhynchotrema étaient peu communs dans les mers intérieures au cours de l'Ashgillien et ils étaient représentés par plusieurs espèces opportunistes dans le bassin de l'Anticosti au cours de l'Hirnantien et du Llandovérien ainsi que dans la plupart de ces environnements de choix riches en silicoclastiques ou de plate-forme carbonatée d'eau profonde.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The development of a prominent Middle Devonian Eifelian and an Upper Devonian Frasnian ostracode faunal sequence of western Canada is used to trace their evolutionary pathways, to illustrate evolutionary dynamics, and to evaluate the most probable causes and implications of the major and minor changes, which are clearly expressed in two sets of charts. A connection between sedimentary transgressive–regressive and evolutionary cycles is evident and documented in sample-for-sample accounts. Major changes in sea level were the primary cause for the most obvious breaks and trends in the faunal sequences and were responsible for the cyclic development of both the sedimentary and ostracode records. In contrast, numerous subordinate faunal breaks impart a distinctly punctuated pattern to both extinction and speciation pathways. Their regular spacing point to rhythmic influences that are interpreted to reflect primarily temperature fluctuations to which ostracodes are known to react in direct and indirect ways. In turn, the periodicity of the changes falls within the time frame of the Milankovitch Effect or to any one, or a combination, of its three variables. By combining the overall cyclic development with the punctuated progression of both extinction and speciation events in an "event-stratigraphic chart," a blueprint of the evolutionary dynamics emerges, which can be directly applied in sequence-stratigraphic reconstructions.On se sert du développement d'une séquence proéminente de faune ostracode dans l'ouest canadien, Eifélien au Dévonien moyen et Frasnien au Dévonien supérieur, pour en tracer les voies évolutives, illustrer la dynamique évolutive et pour évaluer les causes et les implications les plus probables des changements majeurs et mineurs qui sont clairement démontrés dans deux séries de diagrammes. Un lien entre les cycles sédimentaires de transgression–régression et d'évolution est évident et documenté dans des décomptes échantillon par échantillon. Des changements majeurs du niveau de la mer ont été la cause primaire des plus évidentes coupures et tendances des séquences fauniques et ils sont responsables du développement cyclique des sédiments et des ostracodes. Par contre, de nombreuses coupures dans la faune subordonnée donnent un patron nettement intermittent à la fois aux voies d'extinction et de spéciation. L'espacement régulier indique des influences rythmiques qui sont interprétées surtout comme le reflet des fluctuations de température auxquelles on sait que les ostracodes réagissent de façon directe et indirecte. Toutefois, la périodicité des changements tombe à l'intérieur de la période de temps de l'effet Milankovitch ou à l'une de ses trois variables ou une combinaison de celles-ci. En combinant le développement cyclique global et la progression intermittente des événements d'extinction et de spéciation dans un diagramme « événement-stratigraphie », il en ressort un plan directeur de la dynamique évolutive qui peut être directement appliqué aux reconstructions de séquences stratigraphiques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The early evolution of ecosystems in Palaeozoic soils remains poorly understood because the fossil record is sparse, despite the preservation of soil microarthropods already from the Early Devonian (~410 Mya). The soil food web plays a key role in the functioning of ecosystems and its organisms currently express traits that have evolved over 400 my. Here, we conducted a phylogenetic trait analysis of a major soil animal group (Oribatida) to reveal the deep time story of the soil food web. We conclude that this group, central to the trophic structure of the soil food web, diversified in the early Paleozoic and resulted in functionally complex food webs by the late Devonian. The evolution of body size, form, and an astonishing trophic diversity demonstrates that the soil food web was as structured as current food webs already in the Devonian, facilitating the establishment of higher plants in the late Paleozoic. Ina Schaefer and Tancredi Caruso report a phylogenetic trait analysis of the major soil animal group Oribatida. They show that the diversification of oribatid mites resulted in complex soil food webs in the late Devonian, which facilitated the establishment of higher plants. [ABSTRACT FROM AUTHOR]

Summary The symmetrical, flexible teleost fish ‘tail’ has been a prime example of recapitulation — evolutionary change (phylogeny) mirrored in development (ontogeny). Paleozoic ray-finned fishes (Actinopterygii), relatives of teleosts, exhibited ancestral scale-covered tails curved over their caudal fins. For over 150 years, this arrangement was thought to be retained in teleost larva and overgrown, mirroring an ancestral transformation series. New ontogenetic data for the 350-million-year-old teleost relative Aetheretmon overturns this long-held hypothesis. The ancestral state consists of two outgrowths with distinct organizers and growth trajectories; a lower median fin turned caudal fin, and an upper vertebrae-bearing tail, equivalent to that of tetrapods. These two tails appear at a shared developmental stage in Aetheretmon , teleosts and all living actinopterygians. Ontogeny does not recapitulate phylogeny; instead, differential outgrowth determines final morphology. In Aetheretmon and other Paleozoic fishes, the vertebrae-bearing tail continues to grow beyond the caudal fin. In teleosts, and some others, a stunted tail is eclipsed by the upward-expanding caudal fin, rendering a once ventral body margin as the terminus. The double tail likely reflects the ancestral state for bony fishes. Many tetrapods and non-teleost actinopterygians have undergone body elongation through tail outgrowth extension, by mechanisms likely shared with distal limbs. Teleosts have gone to the other extreme; losing tail outgrowth for functional reasons. Recognition of the tail as a limb-like outgrowth has important implications for the evolution of vertebrate form. [ABSTRACT FROM AUTHOR]

Abstract: The rise of vascular land plants in the Paleozoic is hypothesized to have driven lower atmospheric CO2 levels through enhanced weathering of Ca and Mg bearing silicate minerals and rocks. However, this view overlooks the co-evolution of roots and mycorrhizal fungi, with many of the weathering processes ascribed to plants potentially being driven by the combined activities of roots and fungi. Here mesocosm scale controlled laboratory experiments quantifying the effects of plant and fungal evolution on silicate rock weathering under ambient and elevated CO2 concentrations are described. A snapshot is presented of C allocation through roots and mycorrhizal fungi and biological activity associated with geochemical changes in weathered mineral substrates via transfer of elements from solid phases into solution. [Copyright &y& Elsevier]