bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endemism and extinction of a new genus of Chionine (Veneridae: Chioninae) bivalve from the Late Neogene of Venezuela
Authors: Roopnarine Peter D. 
Published: August 2016

Liromissus,a new genus of chionine bivalve from the Neogene of Venezuela, serves as an example of the link between geographic range, endemism and extinction susceptibility. Unlike other Neogene tropical American chionine genera,Liromissuswas not widespread in the tropical Western Atlantic and Eastern Pacific, but was instead restricted to the Atlantic Gatunian region. Late Neogene extinctions in tropical America affected taxa with restricted geographic ranges, and regions with higher degrees of endemism more severely. Accordingly,Liromissusis the only tropical chionine genus to suffer extinction during the Neogene.The type species ofLiromissus, L. quirosensis,was originally described as a member of the genusLirophora.Morphological considerations preclude this assignment, but also demonstrate thatLiromissuspossesses all the characters diagnostic of the Chioninae.
In situ earliest Cambrian tube worms and the oldest metazoan-constructed biostrome (Placentian Series, southeastern Newfoundland)
Authors: Landing Ed 
Published: August 2016

“Ladatheca” cylindrica (Grabau, 1900) was a eurytopic metazoan with a calcareous operculum and an elongate, gently tapering conch up to 15+ cm long and with an apical angle of approximately 0.75–2.0°. This apparent polychaete was geographically widespread in the sub-trilobitic Lower Cambrian of middle latitude, siliciclastic (middle and upper Placentian Series, Avalon Zone) and low latitude, carbonate platform (Tommotian Stage, Siberia(?) and Kazakhstan; and, probably, the upper Meishucunian Stage, southwestern China) sequences.In situ conchs (vertically to steeply inclined, apex down) of “Ladatheca” cylindrica are common in deep subtidal, siliciclastic mudstones (Chapel Island Formation) and in a peritidal algal mud mound(?) limestone (West Centre Cove Formation) in southeastern Newfoundland. Closely juxtaposed conchs locally form a worm reef at the top of the West Centre Cove Formation. This structure is older than the oldest archaeocyathan build-ups and is the earliest known metazoan-constructed biostrome. “Ladatheca” cylindrica was a dominant element of the sessile benthos prior to its apparent ecological displacement by Coleoloides typicalis Walcott, 1889, in the upper Placentian Series.
Halysitid and auloporid tabulate corals from the Gascons and West Point Formations (Silurian), Gaspé, Québec, Canada
Authors: Young Graham A. , Lee Dong-Jin , Noble James P. A. 
Published: August 2016

The uppermost Lower Silurian and Upper Silurian Gascons and West Point Formations of the southern Gaspé Peninsula were deposited under a broad range of environmental conditions from deep offshore-shelf to reef facies. Halysitid and auloporid tabulate corals occur in a number of facies and show a high degree of endemism.Two species of Halysitidae and three species of Auloporida are found in these formations. Both halysitids have been previously described from this region. The auloporids include the new speciesSyringopora minutaand another species that may represent the first known Silurian occurrence of the fletcheriellid genusPseudofletcheria. A neotype for the halysitidCystihalysites amplitubulatus(Lambe) is proposed.
Discussion of the systematic placement of the Ordovician brachiopod generaCoopereaandCraspedeliaby Cocks and Rong (1989)
Authors: Potter A. W. 
Published: August 2016

Cocks and Rong (1989) subdivided the species of the Ordovician brachiopod genusBimuriainto two groups, those with a simple, or not undercut, cardinal process and those with an undercut cardinal process. They placed the second group in a new genus,Cooperea, and groupedCoopereawithCraspedeliain the new subfamily Craspedeliinae of the family Sowerbyellidae. However, the cardinal process ofBimuriaranges from not undercut to undercut within at least two species.Coopereais therefore placed in synonymy withBimuria, andCraspedeliais returned to the Bimuriidae.Cocks and Rong (1989) inferred that, with rare exceptions, the cardinal process of the Plectambonitacea evolved from simple to trifid to undercut. The evidence fromBimuriaindicates, however, that the undercut process developed more than once and, inBimuria, directly from the simple type.As an adjunct to the above discussion three new species are described:Bimuria gilbertella, Craspedelia intonsa, andCraspedeliasp. 1.Craspedeliais a rarely reported genus documented here for the first time in western North America (northern California). Additional evidence is introduced that the ratio Lmusbv/Lebv decreased from middle to late Ordovician species ofBimuria.
Uppermost Cambrian slope deposits at Highgate Gorge, Vermont: a minor miscorrelation with major consequences for conodont- and trilobite-based chronocorrelation
Authors: Taylor J. F. , Kennedy D. J. , Miller J. F. , Repetski J. E. 
Published: August 2016

Uppermost Cambrian and lowest Ordovician slope deposits in Highgate Gorge, northwestern Vermont, yield a succession of conodont faunas (and a few associated trilobite species) similar to that observed in coeval North American carbonate-platform sequences. Decimeter-scale sampling of a 15-m-interval in two sections comprising thin-bedded limestone–shale rhythmites alternating with thick-bedded debris flow conglomerates yielded 60 trilobite specimens and more than 5,000 conodont elements from 48 productive horizons. The new biostratigraphic control does not support earlier claims that the lowest occurrence ofCordylodus proavusin the Gorge Formation and presumably in other slope sequences is significantly older than the base of theC. proavusZone in platform deposits; rather, it demonstrates the isochronous persistence of this boundary across the North American (Laurentian) shelf margin into Iapetan slope deposits. The common occurrence of the deep, cool-water conodontEoconodontus alisonaeand the agnostoid trilobiteLotagnostus hediniin theEoconodontusZone at Highgate Gorge makes it possible to extend the correlation even farther from the Laurentian platform into uppermost Cambrian strata in Kazakhstan and China. This new information greatly strengthens arguments in favor of using this zonal boundary for defining the international boundary between the Cambrian and Ordovician Systems.In earlier studies of Highgate Gorge strata, composite treatment of biostratigraphic data from similar but non-correlative intervals (Zones 2 and 3) in two sections created an illusion of significant stratigraphic overlap ofC. proavuswith older faunas and direct association of some trilobite species for which overlap has never been established. Composite treatment of data from Zones 2 and 3 under designations such as “main zone’ or “upper zone’ should be discontinued and species that have been reported as occurring together in the “main zone’ should not be assumed (on the basis of that association alone) to have come from the same stratigraphic level.
Trilobites from the upper part of the Deadwood Formation (Upper Franconian and Trempealeauan stages, Upper Cambrian), Black Hills, South Dakota
Authors: Stitt James H. , Straatmann Wendy Metcalf 
Published: August 2016

Trilobites assigned to 29 genera and 39 species are reported from the Deadwood Formation in the Black Hills of South Dakota. Two new species,Prosaukia lochmaniandArcifimbria pahasapaensis,are described. Brachiopods are reported from theTaenicephalusZone.A biostratigraphic zonation is established for the upper part of the Deadwood Formation. TheTaenicephalusZone in the lower part of the study interval is succeeded upsection by theEllipsocephaloidesZone, both of which are assigned to the Franconian Stage. These two zones are overlain in turn by theIllaenurusandSaukiaZones of the Trempealeauan Stage. These zones are used to correlate this part of the Deadwood with coeval strata in Montana and Wyoming, central Texas, Oklahoma, and Alberta, Canada. The lowstand of sea level that occurred in the Great Basin at the time of the deposition of theSaukiella juniaSubzone of theSaukiaZone probably extended eastward into the Black Hills, resulting in the absence of this fauna in the Black Hills.
Thermophilic dinoflagellate assemblages from the mid Pliocene of eastern England
Authors: Head Martin J. 
Published: August 2016

Dinoflagellate cysts from the classic mid-Pliocene Coralline Crag locality of Rockhall Wood, Suffolk are described, representing the first systematic treatment of mid-Pliocene dinoflagellates from the North Sea region. The dinoflagellates broadly reflect warm-temperate surface waters whose temperatures were considerably higher than today. Two assemblages are recognized: an older assemblage (late early Pliocene or earliest late Pliocene, possibly not younger than 3.3 Ma) confined to the Ramsholt Member, and a younger assemblage (predating 2.6 Ma) confined to the overlying Sudbourne Member. Assemblages are characterized by quantitative differences and their succession indicates either: 1) slight cooling within a probable warm-temperate range; 2) a slight increase in open marine influence; or 3) a taphonomic effect perhaps related to a change in bottom currents.Specimens have been observed using light (LM) and scanning electron (SEM) microscopy, and cyst wall ultrastructure is emphasized as a valuable but underutilized character for Neogene dinoflagellate taxonomy.Operculodinium?eirikianumHead et al. is emended and the following new taxa are proposed:Achomosphaera andalousiensis suttonensisnew subspecies,Ataxiodinium zevenboomiinew species,Bitectatodinium raedwaldiinew species, andOperculodinium tegillatumnew species.Geonettia? sp. is new to science but formal description awaits detailed analysis of tabulation.
Silurian Odontopleurinae (Trilobita) from the Cape Phillips Formation, Arctic Canada
Authors: Adrain Jonathan M. , Ramsköld Lars 
Published: August 2016

Odontopleurids are a diverse component of rich silicified trilobite faunas recovered from the Wenlock and Ludlow of the Cape Phillips Formation, central Canadian Arctic. Odontopleurinae and Acidaspidinae are common, but Ceratocephalinae and Koneprusiinae are also represented. This work treats all of the Odontopleurinae, with the exception of the genusAcanthalominaPrantl and Přibyl, 1949.New species ofKettneraspisPrantl and Přibyl, 1949, include the upper SheinwoodianK. wrightae,the lower HomerianK. lindoei,and the GorstianK. caldwelli.Rare specimens assigned toOdontopleuraEmmrich, 1839, andRadiaspisRichter and Richter, 1917, occur in the Sheinwoodian of the central Arctic.Edgecombeaspis(type speciesE. johansonaenew species) is proposed for an odontopleurine clade endemic to Laurentia, and in the Silurian restricted to northern Laurentia. Cladistic analysis yields a hypothesis of ingroup structure that is in general calibrated with stratigraphic sequence. An exception is a group of Telychian species from the Mackenzie Mountains, whose stratigraphic sequence was used to support a previous hypothesis of an ancestral-descendant lineage. The cladistic result indicates that the stratigraphic pattern is the inverse of the phylogenetic pattern: the stratigraphically lowest species in the proposed lineage is the most derived, and the highest is most primitive. In addition to the type, new species ofEdgecombeaspisinclude the mid-SheinwoodianE. jahansiand the lower HomerianE. soehni. Edgecombeaspisapparently became extinct in the Homerian.The speciesKettneraspis lenzi(Chatterton and Perry, 1983) andRadiaspiscf.R. norfordi(Chatterton and Perry, 1983) occur in the central Arctic, and further strengthen previous correlations with strata in the central Mackenzie Mountains, Northwest Territories.
Phylogeny of calceocrinid crinoids (Paleozoic: Echinodermata): Biogeography and mosaic evolution
Authors: Harvey Erik W. , Ausich William I. 
Published: August 2016

A structured evolutionary pattern emerges from cladistic and stratocladistic analyses of the Calceocrinidae (Echinodermata). These Paleozoic disparid crinoids were dominated by three long-ranging genera, and other genera were derived during endemic radiations in North America and in Europe. Calceocrinid evolution was highly mosaic, including the repetition of morphological transitions, numerous character reversals, and evolutionary independence of characters.As a family, the calceocrinids make up a highly derived, unique family because the crown is bilaterally symmetrical, is reflexed onto the stem by a hinge between the radial and basal circlets, and was normally situated just above the substratum. The analysis included 23 genera with 17 characters; three were coded as ordered based on previously observed evolutionary trends. Standard cladistic analysis yielded a total of 17,000 equally parsimonious trees. The addition of stratigraphic data through the use of stratocladistic methodology reduced this number to 16 equally parsimonious trees.
Streptognathodus (Conodonta) succession at the proposed Carboniferous-Permian boundary stratotype section, Aidaralash Creek, Northern Kazakhstan
Authors: Chernykh Valery V. , Ritter Scott M. 
Published: August 2016

Streptognathodus Pa elements dominate conodont faunas from the proposed Carboniferous-Permian boundary stratotype at Aidaralash Creek, northern Kazakhstan. The phyletic development of this genus provides the means for subdividing the late Gzhelian to early Sakmarian prodeltaic section (Beds 9-37) into six zones. The preferred Global Stratotype Section and Point (GSSP) for the base of the Permian System is 27 m above the base of Bed 19 at the first occurrence of Streptognathodus isolatus Chernykh, Ritter, and Wardlaw, 1996. This arbitrarily chosen point in the evolutionary continuum of nodose streptognathodids is recognizable in basinal rocks elsewhere in the Ural trough (lower part of Bed 16 at Usolka) as well as the cyclic shelf succession of the American Midcontinent (Glenrock Limestone Member of the Red Eagle Limestone).Eight new species of Streptognathodus occur in the Aidaralash collections: S. bellus n. sp., S. costaeflabellus n. sp., S. flexuosus n. sp., S. glenisteri n. sp., S. longilatus n. sp., S. rectangularis n. sp., S. sigmoidalis n. sp., and S. tenuialveus n. sp. In addition, three morphotypes with limited occurrence (S. sp. A-C) are left in open nomenclature. New collections of topotype material from the nearby Tabantal River section permit clarification of S. barskovi (Kozur).
Ontogenies of trilobites from the lower Ordovician Garden City Formation of Idaho and their implications for the phylogeny of the Cheirurina
Authors: Lee Dong-Chan , Chatterton Brian D. E. 
Published: August 2016

Ontogenies of three trilobites from the Garden City Formation (Tremadocian to early Arenigian; equivalent to Ibexian) are described: Tesselacauda depressa (Pilekiidae), Rossaspis pliomeris (Protopliomeropsinae), and Protopliomerella contracta (Cybelopsinae).Comparison of both larval and adult features of the described trilobites with those of cheirurids and encrinurids suggests that three lineages of the Cheirurina existed during the Early and Middle Ordovician. Members of the first lineage show the following hierarchical relationships; (Tesselacauda depressa (Cheirurinae (Acanthoparyphinae (two separate Sphaerexochinae groups)))). Within the second lineage, the following internested relationships of its members are recognized; (Protopliomeropsinae (“early” cybelines (“advanced” cybelines and Encrinurinae))). The Cybelopsinae constitute the third lineage that is considered as an immediate outgroup to the above two lineages. Pattern of nested distribution of synapomorphies within all these lineages reveals that the two pliomerid subfamilies (Protopliomeropsinae and Cybelopsinae) do not share a recent common ancestor, suggesting that the Pliomeridae is a paraphyletic group.
Indications of polypides in feeding zooids and polymorphs in Lower Paleozoic trepostomata (Bryozoa)
Authors: Boardman Richard S. 
Published: August 2016

Delicate symmetrical structures in living chambers of autozooecia of some lower Paleozoic species of the order Trepostomata have been interpreted as indications of polypides with little further elaboration. Applications of the anatomy, mode of skeletal growth, and functional requirements basic to living species permit recognition of a few organs of these partially preserved polypides, their functions, and their relationships to enclosing skeletons. Only one basic polypide anatomy is indicated in lower Paleozoic trepostome species, in contrast to the wide diversity of polypide anatomy and their lack of correlation with skeletal characteristics in living stenolaemates. In general, the longer the evolutionary history, the greater the diversity of skeletal morphology in stenolaemates. Apparently, polypide diversity and lack of correlation with skeletal morphology also have increased over time.The complex skeletal septa in autozooecial apertures of the lower Paleozoic trepostome Hallopora have been interpreted as reflecting an organ of full-sized feeding polypides. Applications of the basic biological concepts of living species suggest that the septa provided reduced skeletal apertures to fit smaller polypides of polymorphs that secondarily occupied the living chambers of full-sized degenerated feeding polypides.
Proconchidium fromLate Ordovician strata of Brodeur Peninsula, Baffin Island, Arctic Canada
Authors: Jia-Yu Rong , Jones Brian , Nentwich F. W. 
Published: August 2016

Proconchidium brodeurensisn. sp. occurs 212 m above the base of member B of the Baillarge Formation on Brodeur Peninsula, Baffin Island, 8 m below the Ordovician–Silurian boundary. Study ofProconchidiumshows that it can be easily distinguished fromEoconchidiumbut possesses many characters that are similar to those inTcherskidium. Analysis of internal structures suggests that the three genera can be distinguished from each other and belong to Virgianidae. Tcherskidiidae is a synonym of Virgianidae and should be abandoned.This represents the first recorded occurrence ofProconchidiumin North America. Although this genus and its related generaTcherskidiumSapelnikov, 1972, andEoconchidiumRozman, 1967, are common in Ashgill strata of Eurasia, they have not been recorded or illustrated from North America. This led to the suggestion that distinct brachiopod biogeographic provinces may have existed during the Ashgill. The occurrence of these genera probably indicates that they may have lived in mostly tropical and subtropical zones.
Clinal variation in the evolution of Ectenocrinus simplex
Authors: Titus Robert 
Published: August 2016

The crinoid Ectenocrinus has unusual trimeric columnals which make it instantly recognizable. In northern New York State such columnals first appear in the deep shelf facies of the lower Trenton Group (the Sugar River Limestone). In these strata the columnals display nearly triangular shapes with triangular lumina and represent a new species, E. triangulus. A small minority of the columnals of these early forms are round with five-pointed lumina.A definite cline had developed by middle Trentonian time. Deep-water columnals display the ancestral triangular form, whereas adjacent, shallow-water forms are rounder and have the five-pointed or pentagonal lumina. These round types came to be the beneficiaries of middle Trentonian facies changes. This was a time when the eastern bank margin steepened and narrowed. The deep shelf habitat shrank to the east and disappeared. Trapped in this shrinking sea floor setting, the populations of the deep-water members of the cline dwindled and disappeared before late Trentonian time. Only the round form with a pentagonal lumen survived. This form, Ectenocrinus simplex, was a great success; its numbers increased and its range expanded throughout the remainder of Trentonian time.The transition from Ectenocrinus triangulus to E. simplex is seamless. No boundary, other than an arbitrary one, can be recognized. A simple and gradual shift of phenotype abundance characterized the event.
New archaeocyathan occurrences in the upper Harkless Formation (Lower Cambrian of western Nevada)
Authors: Savarese Michael , Signor Philip W. 
Published: August 2016

A newly discovered assemblage of archaeocyathans, dominated by the unusual genus Retilamina, occurs in outcrops of the upper Harkless Formation in Esmeralda County, Nevada. These rock units have been correlated with the Saline Valley Formation in the Bonnia–Olenellus Zone (late Early Cambrian) of eastern California, making this the youngest known occurrence of archaeocyathans in the White–Inyo region.Although the assemblage contains a variety of different organisms (including the alga Renalcis, trilobite and echinoderm debris, bivalves?, and Chancelloria spines), it is dominated by archaeocyathans. Diplocyathellus, a conical form with a complex inner wall, is the only genus of regular archaeocyathan in the assemblage. The irregular archaeocyathans Arrythmocricus and Metaldetes exhibit dendroid branching and cylindroconical morphologies, respectively. A third irregular, Retilamina debrennei n. sp., is an atypical archaeocyathan with a sheetlike or shallow convex dome morphology. Retilamina formed natural cavities that sheltered cryptobionts. Unlike coelobiont communities reported from other Lower Cambrian cavities where the diversity of the supported biota is relatively high, the Harkless cavities contain only the alga Renalcis. While the undersurfaces of Retilamina are consistently encrusted by Renalcis, the upper, exposed surfaces typically lack epibionts. Similar morphologies and associations for Retilamina have been reported from bioherms and biostromes from southern Labrador and western Newfoundland. Unlike most archaeocyathans, Retilamina had a solitary, free-lying life habit. Retilamina's broad base and low profile provided stability in episodically turbulent conditions or on biologically disturbed substrates.This occurrence demonstrates that the disappearance of archaeocyathans from the stratigraphic record of the southern Great Basin in the late Early Cambrian is a paleoecological artifact. Archaeocyathans were extant in the region in the late Early Cambrian but the habitats conducive to archaeocyathan growth or preservation are, for the most part, not represented in the preserved strata.
Silurian Heliolitidae (Anthozoa, Tabulata) from the Chaleurs Bay region, Canada
Authors: Young Graham A. , Noble James P. A. 
Published: August 2016

The Early to Late Silurian sedimentary rocks of the Limestone Point and La Vieille Formations of northern New Brunswick and the Anse à Pierre-Loiselle, La Vieille, and Gascons Formations of the Gaspé Peninsula possess diverse and abundant tabulate coral faunas that include six species of Heliolitidae distributed amongHeliolitesandStelliporella.Two species,Heliolites laxusandHeliolites distinctus, are new. A revised concept of the genusHeliolitesis proposed. The Heliolitidae from this region show a substantial degree of endemism and are most similar to northern European faunas.The distribution of individual heliolitid species was under a high degree of facies control. The heliolitids are more restricted in distribution than are other groups of Tabulata in this region and are most abundant in open shelf and carbonate bank facies.