Brachiopods from the family Ambocoeliidae George (Order Spiriferida) from the Emsian (Lower Devonian) of northeastern Russia

Brachiopods from the family Ambocoeliidae George from the Emsian (Lower Devonian) of northeastern Russia are described: Bisinocoelia despecta sp. nov.; Yakutospirifer gen. nov. with the type species Y. krivensis sp. nov.; Micospirifer gen. nov. with the type species M. simplex sp. nov.; Kolymospirifer gen. nov. with the type species K. optatus sp. nov. (subfamily Ambocoeliinae); Datnospirifer gen. nov. with the type species D. alius sp. nov.; Khalimospirifer gen. nov. with the type species Kh. microscopicus sp. nov.; Gerospirifer gen. nov. with the type species G. normalis sp. nov., and G. gerensis sp. nov.; Dogdospirifer gen. nov. with the type species D. yolkini sp. nov. (subfamily Rhynchospiriferinae).     

Orthid brachiopods from the Lower and Middle Devonian of northeastern Russia

Brachiopods of the order Orthida from the Lower and Middle Devonian of northeastern Russia: Skenidium diversus Baranov (family Skenidiidae); Datnia gen. nov., with the type species D. asiatica sp. nov. (subfamily Prokopiinae); Janzhinshinia gen. nov., with the type species J. datnensis sp. nov. (subfamily Isorthinae); Cortezorthis chobotchalensis (Alekseeva) (subfamily Cortezorthinae); Elenia gen. nov., with the type species E. gerensis sp. nov. (family Dicoelosiidae); Seimtchania communis (family Seimtchaniidae); Simakovia gen. nov., with the type species S. rara sp. nov. (family Draboviidae); Schizophoria distenta sp. nov., S. grande Baranov, S. striatula (Schlotheim) (family Schizophoriinae); and Hypsomionia sinsera Baranov (family Hypsomioniidae) are described.     

New Lower Devonian brachiopods of the family Reticulariidae Waagen (order Spiriferida) of northeastern Russia

New Lower Devonian brachiopod taxa of the family Reticulariidae (order Spiriferida) are described from northeastern Russia: Havlicekospirifer gen. nov. with the type species H. mirabilis sp. nov. (subfamily Reticulariinae) and Pavlovispirifer gen. nov. with the type species P. pelagicus sp. nov. (subfamily Rhenothyridinae).     

A late Devonian (Frasnian) coral-bafflestone reef at Houshan in Guilin, South China

Summary Givetian to early Carboniferous sediments of South China are characterized by carbonates. Middle and Late Devonian strata are best developed in the Guilin area. Reefs and organic shoals are recorded by various lithofacies types indicating the existence of an extended carbonate platform and a change of the composition of reef communities in time. Starting in the late Devonian, stromatoporoids and corals were replaced by algae that subsequently played an important role together with stromatoporoids, receptaculitids and fasciculate rugose corals in reef communities. In Houshan, 5 km west of Guilin, a coral-bafflestone reef occurs in the Frasnian strata, situated near an offshore algal-stromatoporoid reef. The coral reef was formed in a back-reef area adjacent to the inner platform margin. The coral-bafflestone reef is unique among the late Devonian reefs of South China with regard to the biotic composition. The reef is composed of fasciculate colonies ofSmithiphyllum guilinense n. sp. embedded within in packstones and wackestones. The height of colonies reaches 1 m. The community is low-diverse. The species ofSmithiphyllum occurring in the Frasnian reef complexes of Guilin exhibit a distinct facies control:Smithiphyllum guilinense occurs in or near to margin facies and formed bafflestone, constituting a coral reef whereasSmithiphyllum occidentale Sorauf, 1972 andSmithiphyllum sp.—characterized by small colonies with thin corallites—are restricted to the back-reef and marginal slope facies. The bush-like coral colonies baffled sediments. Algae and stromatoporoids (mainlyStachyodes) are other reef biota. Reef-dwelling organisms are dominated by brachiopods. The reefs are composed from base to top of five lithofacies types: 1) cryptalgal micrite, 2) peloidal packstone, 3) stromatactis limestone, 4) coral-bafflestone, and 5) pseudopeloidal packstone. The reef complex can be subdivided into back-reef subfacies, reef flat and marginal subfacies, and marginal fore-slope subfacies. The Houshan coral-bafflestone reef is not a barrier reef but a coral patch reef located near the inner margin of a carbonate platform.     

Protopteraspis Gosseleti (Vertebrata: Pteraspidomorphi: Heterostraci) from the Lower Devonian of Shropshire, England

New Protopteraspis material from Shropshire is sufficiently similar to Protopteraspis leathensis from the Welsh Borderland, and the type-species Protopteraspis gosseleti from France, to justify transfering P. leathensis to P. gosseleti . The Anglo-Welsh, biostratigraphic leathensis Zone is changed to the Protopteraspis Zone ( sensu Blieck and Janvier 1989). Possible lifestyles are discussed for Protopteraspis gosseleti .     

Assessing early recruitment dynamics and its demographic consequences among tropical reef fishes: Accommodating variation in recruitment seasonally and longevity

Abstract When settlement of pelagic juveniles of reef fishes is highly and predictably seasonal, annual, end-of-season surveys of surviving recruits (which are commonly used on the Great Barrier Reef) are useful for assessing recruitment dynamics and their demographic effects. However, when settlement is continuous or weakly seasonal, with patterns that vary both between species and within species among years, regular, sometimes year-round, recruitment surveys at intervals linked to short-term settlement dynamics are needed to quantify fluctuations in recruitment strength. Monthly recruitment surveys may be appropriate in the tropical northwest Atlantic, where settlement is often both lunar periodic, and broadly and variably seasonal. Use of a variety of recruit-census methods impedes comparisons of recruitment patterns and their demographic effects, because recruit densities and recruit:adult ratios cannot be directly compared when recruits (because they have widely varying post-settlement ages) have experienced very different levels of early post-settlement mortality. Examining the relationship between changes in adult populations and annual, end-of-season recruitment may be satisfactory for long-lived species with strong settlement seasonality and maturation times of approximately 1 year. However, it is inappropriate for short-lived, rapidly maturing species, particularly those that have broad and variable settlement seasons and whose populations fluctuate substantially throughout the year in response to short-term fluctuations in recruitment. Comparisons of demographic effects of recruitment among species with different longevity require the use of non-arbitrary time scales, such as the time to maturity and the adult half-life.     

云南早泥盆世一流线型盔甲鱼及其分类学与古生态学意义(英文)

记述了云南昭通早泥盆世布拉格期坡松冲组华南鱼目一新属、新种——剑裂甲鱼(Rhegmaspis xiphoidea gen.et sp.nov.)。新属的主要特征是:具有鱼雷形头甲,细长吻突,眶孔位于头甲腹侧位,鳃穴向头甲腹面弯曲,角、内角和腹环丢失。鉴于以上特征,新属被归到了包括鸭吻鱼和乌蒙山鱼在内的鸭吻鱼科。根据新材料提供的信息,修订了鸭吻鱼科,包括鸭吻鱼和乌蒙山鱼的鳃穴、腹环、角、内角等特征。裂甲鱼属是该地区发现的第一个具有流线形体型的盔甲鱼类,指示了该地区一些盔甲鱼类可能开始了一种营上底栖的生活方式,具有更加主动的取食行为。新属的发现不仅丰富了该地区华南鱼目的多样性,而且提供了盔甲鱼类在早泥盆世布拉格期通过占据新的生态位而发生的最后一次辐射演化的证据。     

A new scolenaspidid (Osteostraci, Vertebrata) from the Lower Devonian of Podolia, Ukraine

Anew osteostracan genus and species,Victoraspis longicornualis n. gen., n. sp., is described based on material from Rakovets’, present day Ukraine. This new taxon shares characters with the two generaStensiopelta Denison, 1951 andZychaspis Janvier, 1985. A phylogenetic analysis supports the position ofVictoraspis as the sister group to a monophyleticStensiopelta, while the interrelationships of the various species ofZychaspis are poorly resolved. A morphometric analysis is carried out in an attempt to further resolve the taxonomic affinity. This analysis groups all examinedZychaspis species closely together, and further supports the establishment ofVictoraspis as separate genus.      

Psammosteiforms (Agnatha,Heterostraci) from the Lower Frasnian of the Mikhailovskii Mine,Kursk Region,Russia

Psammosteiforms, including Tartuosteus (?) zheleznogorskensis, sp. nov. and Psammosteus cf. P. praecursor Obruchev, from the Lower Frasnian (Upper Devonian) of the Mikhailovskii Mine (Kursk Region) are described. Agnathans, placoderms, crossopterygians, and acanthodians from this locality are determined. The similarity of the Mikhailovskii Fish Assemblage to the assemblage of southern Timan suggests it be assigned to the Upper Timan Regional Stage.     

Coralline algae indicate Pleistocene evolution from deep,open platform to outer barrier reef environments in the northern Great Barrier Reef margin

Coralline algae from a drill core in Ribbon Reef 5 have been used to interpret changes in the depositional palaeoenvironments in the northern Australian Great Barrier Reef over the last 790 ka. Three main coralline algal assemblages, each dominated by members of a particular subfamily, have been distinguished by quantitative analysis: (1) mastophoroid assemblages, usually occurring as crusts on corals, are typical of the shallowest reef settings; (2) lithophylloid assemblages within algal nodules may represent shallow-water, cooler environments or deeper reef subenvironments; and (3) melobesioid assemblages are characteristic of deeper-water platform areas. The algal assemblages between 96 and 210 m b.s.f. (metre below sea floor) record a fluctuating but progressive shallowing-upwards from deep, outer-platform to shallower, non-reefal depositional environments. Two intervening episodes dominated by mastophoroids represent two phases of reef growth. The section above 96 m b.s.f. comprises several stacked reefs in which mastophoroid crusts similar to the present-day shallow-water assemblages predominate.Electronic Supplementary Material Supplementary material is available for this article at .Communicated by: Geological Editor P.K. Swart     

A new microphyllous plant from the Lower Devonian of Yunnan Province, China

Sterile and fertile shoots of a microphyllous vascular plant are described from the Lower Devonian Posongchong Formation (? upper Siegenian), Yunnan Province, southern China and placed in the new taxon Halleophyton zhichangense gen. et sp. nov. The sterile axes are characterized by conspicuous, contiguous swollen rhomboidal to hexagonal leaf bases and relatively broad spatulate laminae. The relief of the leaf bases is not so pronounced in the fertile areas, which bear numerous cauline sporangia with two equal valves. In vegetative characters the new fossils, although smaller and more fragmentary, resemble Drepanophycus gaspianus but in the absence of information on the fertile parts of the latter and because of the controversy surrounding the concept of the genus Drepanophycus, we decided to erect a new genus. Its relationship to the lycophytes sensu stricto is equivocal as exact details of the relationship of sporangium with leaf and sporangium vascularization remain unknown.     

Brachiopods of the suborder Delthyridina Ivanova (order Spiriferida) from the Lower and Middle Devonian of northeastern Russia

New brachiopods of the suborder Delthyridina Ivanova (order Spiriferida) from the Lower and Middle Devonian of northeastern Russia, Ivanothyris costatus sp. nov. (subfamily Delthyridinae), Eoreticularia lata sp. nov., Yania gen. nov. with the type species Y. tumida sp. nov. (subfamily Eoreticulariinae), Reticulariopsis equitans Modzalevskaya, and R. (?) borealis sp. nov. (subfamily Reticulariopsinae) are described.     

Patch reef development in the florigemma-Bank Member (Oxfordian) from the Deister Mts (NW Germany): a type example for Late Jurassic coral thrombolite thickets

Small reefal bioconstructions that developed in lagoonal settings are widespread in a few horizons of the Late Jurassic (Oxfordian) succession of the Korallenoolith Formation, exposed southwest of Hannover, Northwest Germany. Especially the florigemma-Bank Member, “sandwiched” between oolite shoal deposits, exposes a high variety of build-ups, ranging from coral thrombolite patch reefs, to biostromes and to coral meadows. The reefs show a distribution with gradual facies variations along an outcrop belt that extends about 30 km from the Wesergebirge in the NW to the Osterwald Mts in the SE.The patch reefs from the Deister Mts locality at the “Speckhals” are developed as coral-chaetetid-solenoporid-microbialite reefs and represent a reef type that was hitherto unknown so far north of its Tethyan counterparts. They are mainly built up by coral thickets that are preserved in situ up to 1.5 m in height and a few metres in diameter. They contain up to 20 coral species of different morphotypes but are chiefly composed of phaceloid Stylosmilia corallina and Goniocora socialis subordinately. The tightly branched Stylosmilia colonies are stabilized by their anastomosing growth. The coral branches are coated with microbial crusts and micro-encrusters reinforcing the coral framework. Encrusters and other biota within the thicket show a typical community replacement sequence: Lithocodium aggregatum, Koskinobullina socialis and Iberopora bodeuri are pioneer organisms, whereas the occurrence of non-rigid sponges represents the terminal growth stage. The latter are preserved in situ and seem to be characteristic so far poorly known constituents of the Late Jurassic cryptobiont reef dweller community. The distance and overall arrangement of branches seems to be the crucial factor for the manifestation of a (cryptic) habitat promoting such community replacement sequences. Widely spaced branches often lack any encrusting and/or other reef dwelling organisms, whereas tightly branched corals, as is St. corallina, stimulate such biota. Hence, such reefs are well suited for research on coelobites and community sequences of encrusting and cavity dwelling organisms.     

A new pachyosteomorph arthrodire (Pisces: Placodermi) from the Upper Frasnian of the Central Devonian Field,Russia

A new genus and species of pachyosteomorph arthrodire, Omalosteus krutoensis gen. et sp. nov. from shallow-water marine deposits of the Evlanovo Regional Stage (Upper Frasnian, Upper Devonian) of the Central Devonian Field is described. It is tentatively referred to the family Trematosteidae Gross, 1932, which was earlier believed to be endemic to central Europe. The new genus is characterized by a rounded, dorsoventrally compressed cross section of the pectoral region and smooth head shield and postcranial membrane bones. The centrale is elongated, forming a narrow lateral lobe. The praeorbitale, postorbitale, and centrale come in contact in the center of the orbital region. The mediodorsale is wide, its carinal process projects considerably posteriorly. The anterior margin of the anterior ventrolaterale lacks articular facets for the interlaterale.     

Paleoecology of Upper Eifelian and Lower Givetian coral limestones in the northwestern Sauerland (Devonian; Rhenish Massif)

Summary The prevailing sandy/silty lower part of the Middle Devonian in the northwestern Sauerland includes two coral limestone horizons, which contain a rich fauna of corals, stromatoporoids, and calcareous algae. The Ihmert-Formation is subdvided into three parts. The older coral limestone horizon is the Grünewiese-Member of the Ihmert-Formation (uppermost Eifelian), the younger is in the Bredenbruch-Member of the Unterhonsel-Formation (lower Lower Givetian). Conclusions about the environmental constraints are drawn from the sedimentology and the fossil content of the coral limestones. Predominant biostromes are built between storm wave base and normal wave base. Only the few bioherms grew above the normal wave base. These coral limestones were deposited in a tropical or subtropical normal marine environment in the shallow euphotic zone. Among the reef-builders epoecism is very frequent, and until now this phenomenon has not been investigated in detail. Fragile rugose and tabulate corals lived as commensals with stromatoporoids. Some other aspects of paleoecology are concisely presented.     

New radiolarians from the Devonian of the southern Ural Mountains: 2. Middle-Late Devonian

Middle-Late Devonian Radiolarians are recorded for the first time in the southern Ural Mountains in Bashkortostan, in a section of Kariukmas Mountain (Upper Eifelian) and on the southern slope of Argagan Mountain (Middle Frasnian). The new Late Eifelian assemblage is composed of 17 species of 11 genera, and Middle Frasnian radiolarians comprise 13 species of 7 genera of spherical, discoidal, pylomate, and spiny radiolarians. A new species, Primaritripus kariukmasensis, sp. nov., is described. The prevalence of discoidal forms in the oryctocenosis suggests shallow marine conditions in the Late Eifelian and Middle Frasnian basins. Two new biostratons, the Upper Eifelian beds with Primaritripus kariukmasensis and Middle Frasnian beds with Primaritripus chuvashovi, are established based on radiolarians.     

Root evolution at the base of the lycophyte clade: insights from an Early Devonian lycophyte

Background and Aims The evolution of complex rooting systems during the Devonian had significant impacts on global terrestrial ecosystems and the evolution of plant body plans. However, detailed understanding of the pathways of root evolution and the architecture of early rooting systems is currently lacking. We describe the architecture and resolve the structural homology of the rooting system of an Early Devonian basal lycophyte. Insights gained from these fossils are used to address lycophyte root evolution and homology.Methods Plant fossils are preserved as carbonaceous compressions at Cottonwood Canyon (Wyoming), in the Lochkovian–Pragian (∼411 Ma; Early Devonian) Beartooth Butte Formation. We analysed 177 rock specimens and documented morphology, cuticular anatomy and structural relationships, as well as stratigraphic position and taphonomic conditions.Key Results The rooting system of the Cottonwood Canyon lycophyte is composed of modified stems that bear fine, dichotomously branching lateral roots. These modified stems, referred to as root-bearing axes, are produced at branching points of the above-ground shoot system. Root-bearing axes preserved in growth position exhibit evidence of positive gravitropism, whereas the lateral roots extend horizontally. Consistent recurrence of these features in successive populations of the plant preserved in situ demonstrates that they represent constitutive structural traits and not opportunistic responses of a flexible developmental programme.Conclusions This is the oldest direct evidence for a rooting system preserved in growth position. These rooting systems, which can be traced to a parent plant, include some of the earliest roots known to date and demonstrate that substantial plant–substrate interactions were under way by Early Devonian time. The morphological relationships between stems, root-bearing axes and roots corroborate evidence that positive gravitropism and root identity were evolutionarily uncoupled in lycophytes, and challenge the hypothesis that roots evolved from branches of the above-ground axial system, suggesting instead that lycophyte roots arose as a novel organ.     

Carboniferous reef succession of the Panthalassan open-ocean setting: example from Omi Limestone, central Japan

Summary The Carboniferous-Permian (Visean-Midian) Omi Limestone in the Akiyoshi Terrane, central Japan is a large carbonate unit developed on a seamount in the Panthalassa Ocean. As the seamount subsided during Carboniferous and Permian time, the carbonate deposition at the top of a seamount was almost continous. Terrigenous siliciclastic sediments are absent, because the seamount was situated in an open-ocean setting. The lower part of this seamount-type limestone records a nearly continuous Carboniferous reef succession. Sedimentary facies in the Carboniferous part of the Omi Limestone are generally highly diverse, but their diversity varies in each age. The Upper Carboniferous part consists of highly diversified facies including fore reef, reef front, reef crest, sand shoal, and lagoon facies, while a simple facies assemblage, composed only of fore reef, reef front, and sand shoal facies, occurs in the Lower Carboniferous. The Carboniferous reef succession consists of four phases characterized, in ascending order, by the coralbryozoan-crinoid community, problematic skeletal organism-microencruster community, chaetetid-microencruster community, and calcareous algal community. The first phase, comprising the coral-bryozoan-crinoid community, occurs in theEndothyra spp. Zone to theEostaffella kanmerai Zone (Visean to Serpukhovian). This community acted only as sediment-bafflers and/or contributors. The second phase, represented by the problematic skeletal organism-microencruster community, is developed in theMillerella sp. Zone to theAkiyoshiella ozawai Zone (Bashkirian to lowermost Moscovian), and the third phase, comprising the chaetetid-microencruster community, occurs in the overlyingFusulinella biconica Zone (Lower Moscovian). These two communities are characterized by highly diversified reef-building organisms that had the ability to build rigid frameworks. Calcareous algae and incertae sedis such asHikorocodium, solenoporaceans and phylloid algae characterize the fourth phase, which occurs in theBeedeina sp. Zone (Upper Moscovian). The changes of the reef communities were sucessive for a long period of more than 40 m.y., and each community was distributed in various environments. In addition, the continuous subsidence of the isolated seamount resulted in environmental stability. These properties indicate that this succession represents the biotic evolution of reef-building organisms. The problematic skeletal organism-microencruster community and chaetetid-microencruster community of the Late Carboniferous formed wave-resistant and rigid frameworks along with abundant submarine cements. The growth of these reef frameworks resulted in the formation of highly diversified sedimentary facies comparable to those of a modern reef complex. Such reefs are also recognized in the seamount-type Akiyoshi Limestone, but rare on Carboniferous Pangean shelves. Therefore, the formation of these types of reefs appear to be characteristic of open-ocean seamount settings, which differed from epicontinental shelf settings in having no siliciclastic input, being exposed to relatively strong openocean waves and swells, and probably more environmental stability resulting from the relatively continuous subsidence of the seamount.     

A new specimen ofWeinbergina opitzi (Chelicerata: Xiphosura) from the Lower Devonian Hunsriick Slate, Germany

A new specimen of the synziphosurine arthropodWeinbergina opitzi is described from the Lower Devonian (Lower Emsian) Hunsrück Slate of Germany (Rhenish Slate Mountains). It is the smallest and only the fifth specimen of this taxon to be described and is preserved in ventral aspect with exceptional preservation of prosomal and opisthosomal appendages. This specimen confirms the presence of a seventh appendage, similar in morphology to the preceding prosomal appendages, associated with opisthosomal segment one. In addition, at least three opisthosomal plates fringed with teeth are confirmed. Correlation of prosomal appendage podomeres betweenWeinbergina and selected chelicerate taxa shows that appendage structure is most similar to eurypterid appendages III–IV and Araneae appendages III–VI. This is in contrast to modern horseshoe crabs which have fewer podomeres in appendages II–V due to an undifferentiated tibiotarsus.