bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin and early radiation of terebratuloid brachiopods: thoughts provoked byProrensselaeriaandNanothyris
Authors: Boucot A. J. , Wilson R. A. 
Published: August 2016

The ontogenies ofProrensselaeriaandNanothyris, described here for the first time, suggest that Cloud's Dielasmatidae are closely affiliated phylogenetically with Cloud's Centronellidae. This is based on the fact that the type species ofNanothyrisgoes through an initial mutationellinid (Cloud's Dielasmatidae) growth stage before reaching its adult rensselaerinid (Centronellidae) growth stage. The ontogeny ofProrensselaeriarequires that it be transferred from the Globithyrinae (Rhipidothyrididae) to the Mutationellinae (Meganteridae [=Cloud's Dielasmatidae = Stehli's Mutationellidae]). Further consideration of their ontogenies permits the transfer ofMeganteris, Meganterella, andReeftonellato the Meganterinae of the Meganteridae. It is recommended, because of the placement ofMeganterisin the Meganterinae, that the term Meganteridae replace Mutationellidae, and Mutationellinae be restricted to costate Meganteridae. The subfamily Adreninae of the Meganteridae (=Stehli's Mutationellidae) is proposed to includeAdrenia, Cydimia, Micidus, Sturtella, Barbarothyris, andLingshanella.The information developed here permits one to conclude that there are two kinds of families: 1) those generated by directional selection, involving major adaptive radiations, the type generated by quantum evolution in Simpson's sense; and 2) those generated by minor developmental changes, that do not involve major adaptive radiations, although they do result in morphological and biogeographical differences great enough to warrant the erection of families.
Extinction of inoceramid bivalves in Maastrichtian strata of the Bay of Biscay region of France and Spain
Authors: MacLeod Kenneth G. 
Published: August 2016

Maastrichtian strata of the Zumaya-Algorta Formation of southwestern France and northeastern Spain record a major pulse of extinction among inoceramid bivalves well before the Cretaceous–Tertiary (K–T) boundary. Inoceramids are the most abundant macrofossils preserved in the study sections; at least six species ofInoceramus[I. (Endocostea)aff.I.(En.) balticusGiers,I.(En.) pteroidesGiers,I.(Platyceramus)aff.I.(Pl.) cycloidesWegner,I.(Trochoceramus) nahorianensisKociubynskij,I.(Tr.) morganiSornay, andI.(?)goldfussianusd'Orbigny] are common to abundant in lower Maastrichtian strata. However, all six species disappear over a few tens of meters of section near the base of the upper Maastrichtian, as defined by the first appearance of the planktonic foraminiferAbathomphalus mayaroensis. Tenuipteria argentea(Conrad), which has not been recovered from the lower Maastrichtian portions of the sections, occurs at low abundances through the upper Maastrichtian, disappearing within 10 cm of the K–T boundary.The mid-Maastrichtian extinction interval among inoceramids occurs within the upperGlobotruncana gansserito lowerAbathomphalus mayaroensisplanktonic foraminiferal zone, in nannofossil zone 24 to 25A, in theAnapachydiscus fresvillensisammonite zone, in magnetochron 31N, and near the base of a change in slope of the seawater strontium curve, all as recognized by previous studies in one or more of the study sections. Whereas the new data presented here are not global in extent, the observed distribution of inoceramids may be the local manifestation of global oceanic changes during the mid-Maastrichtian.
Origin and spread ofPudoproetus, a survivor of the Late Devonian trilobite crisis
Authors: Feist Raimund , Petersen Morris S. 
Published: August 2016

One of the most severe restrictions in taxonomic diversity of trilobites coincides with the Late Devonian “Hangenberg” Event, which is characterized by a pronounced eustatic low-stand. One of the survivors of this event isPudoproetus, which, being adapted to shallow water conditions, experienced an opportunistic worldwide spread during this time. The oldest representatives of this genus are reported from the pre-Hangenberg Late Famennian of the Urals and Kazakhstan. Other known occurrences of this genus, midcontinent U.S.A., Utah, southern China, and southern France, occur at the Devonian-Carboniferous boundary, shortly after the Hangenberg event, and in the earliest Carboniferous. This pattern of distribution suggests that neither climatic nor geographic migration barriers existed around the Old Red landmass at that time. On the other hand, the Hangenberg crisis severely affected outer shelf benthic habitats, whereas nearshore trilobites were largely unaffected by the event.A proetine origin ofPudoproetus, as originally proposed by Hessler (1963), is emphasized on the basis of paleoecologic, stratigraphic, and morphological arguments. In particular, the presence of ancestral features, such as the possession of 10 thoracic segments and lateral occipital lobes still occurring in earlyPudoproetusspecies, points to a phylogenetic link with proetines rather than with phillipsiids. Within this group two new species are named:P. priscusandP. mediterraneus.
The rise and fall of late Paleozoic trilobites of the United States
Authors: Brezinski David K. 
Published: August 2016

Based on range data and generic composition, four stages of evolution are recognized for late Paleozoic trilobites of the contiguous United States. Stage 1 occurs in the Lower Mississippian (Kinderhookian-Osagean) and is characterized by a generically diverse association of short-ranging, stenotopic species that are strongly provincial. Stage 2 species are present in the Upper Mississippian and consist of a single, eurytopic, pandemic genus,Paladin.Species of Stage 2 are much longer-ranging than those of Stage 1, and some species may have persisted for as long as 12 m.y. Stage 3 is present within Pennsylvanian and Lower Permian strata and consists initially of the eurytopic, endemic generaSevilliaandAmeuraas well as the pandemic genusDitomopyge.During the middle Pennsylvanian the very long-ranging speciesAmeura missouriensisandDitomopyge scitulasurvived for more than 20 m.y. During the late Pennsylvanian and early Permian, a number of pandemic genera appear to have immigrated into what is now North America. Stage 4 is restricted to the Upper Permian (late Leonardian-Guadalupian) strata and is characterized by short-ranging, stenotopic, provincial genera.The main causal factor controlling the four-stage evolution of late Paleozoic trilobites of the United States is interpreted to be eustacy. Whereas Stage 1 represents an adaptive radiation developed during the Lower Mississippian inundation of North America by the Kaskaskia Sequence, Stage 2 is present in strata deposited during the regression of the Kaskaskia sea. Stage 3 was formed during the transgression and stillstand of the Absaroka Sequence and, although initially endemic, Stage 3 faunas are strongly pandemic in the end when oceanic circulation patterns were at a maximum. A mid-Leonardian sea-level drop caused the extinction of Stage 3 fauna. Sea-level rise near the end of the Leonardian and into the Guadalupian created an adaptive radiation of stentopic species of Stage 4 that quickly became extinct with the latest Permian regression.
Burrow distribution of thalassinidean shrimp on a Fraser Delta tidal flat, British Columbia
Authors: Swinbanks David D. , Luternauer John L. 
Published: August 2016

Burrows of the thalassinidean shrimp Callianassa californiensis and Upogebia pugettensis, which resemble the trace fossils Thalassinoides and Ophiomorpha, respectively, occur on the southern tidal flats at the western front of the Fraser Delta. Burrow densities for both shrimp species are highest at lower intertidal levels immediately inshore of an extensive bed of Zostera marina eelgrass, but the high-density shrimp populations are segregated: the highest densities of C. californiensis burrows (350–450 burrow openings/m2) occur in a strip of clean sandy sediments, whereas U. pugettensis burrows are most abundant (30–80 burrow openings/m2) in a patch of muddy sands and sandy muds. On the tidal flats of the Fraser Delta as a whole, however, textural properties of the sediment show no consistent correlation with the burrow density of either shrimp.In the eelgrass bed, eelgrass root mats appear to markedly restrict the density of C. californiensis burrows. Towards the shore, the well-lined dwelling burrows of U. pugettensis occur no higher than mean sea level where maximum continuous exposure is ≤0.5 days. In contrast, C. californiensis, which has an unlined feeding burrow and a higher tolerance for anoxia, is present up to the margin of the local salt marsh which lies near the mean higher high water level where the flats can be exposed continuously up to 5 days.In situ experiments indicate that C. californiensis extrudes 18 ± 9 ml of wet sediment/shrimp/ day onto the substrate surface, while U. pugettensis seldom forms a mound around its burrow entrance. Burial of filter-feeding postlarval U. pugettensis under the mounds produced by C. californiensis may increase postlarval mortality and reduce adult populations of U. pugettensis in areas of high C. californiensis burrow density.The results of this study suggest that in distinguishing Ophiomorpha from Thalassinoides more emphasis should be placed on the presence of an extensive burrow lining in Ophiomorpha than on the presence of a knobby burrow exterior, because the former characteristic has a more profound bearing on burrow function, physiology of the occupant organism, and, consequently, burrow distribution.
A Bohemian-type Silurian (Wenlockian) pelecypod faunule from Arctic Canada
Authors: Pojeta John , Norford B. S. 
Published: August 2016

The pelecypod generaSlavaandRhombopteriaare reported for the first time from Canada, where they occur in a limestone concretion within the Cape Phillips Formation, Cornwallis Island, Arctic Archipelago. These genera are characteristic of Silurian rocks in Bohemia, Czechoslovakia. Graptolites from the same concretion indicate theMonograptus ludensisZone (uppermost Wenlockian); this age is substantiated by associated conodonts, trilobites, vertebrates, and pelecypods but with less precision. It is difficult to explain the occurrence of Slava andRhombopteriain the middle of Laurentia on the basis of some map reconstructions of the Wenlockian world.The Canadian material ofSlava novaterran. sp. andRhombopteriacf.R. mira(Barrande) is described.Leptodesma(Leptodesma) sp. A and an indeterminate grammysiid pelecypod from the same concretion are illustrated. Information is provided to show thatNewsomellaFoerste, from Wenlockian–Ludlovian rocks of Illinois, Wisconsin, and Tennessee, is not a subgenus ofRhombopteriaJackson.
Lithofacies and biofacies of the Middle and Upper Devonian Sultan Formation at Mountain Springs, Clark County, Nevada: implications for stromatoporoid paleoecology
Authors: Harrington Robert J. 
Published: August 2016

The Sultan Formation is a Middle and Upper Devonian inner shelf carbonate sequence in southern Nevada containing four stromatoporoid-dominated biofacies. Reported herein is a study of the Ironside Dolomite and Valentine Limestone Members exposed at Mountain Springs, Nevada. Eight lithofacies are distinguished and interpreted as a transgressive sequence, with deposition ranging from the supratidal zone to just below wave base. Each of the biofacies is unique and confined to a specific depositional environment as interpreted from the lithofacies reconstructions. The purpose of the study was to gain a better understanding of the range of ecologic conditions—physical, chemical, and biological—to which these stromatoporoids were adapted.Based on the research, it is concluded that stromatoporoids flourished in a variety of nonreef habitats which ranged from highly stressful peritidal environments where only stromatoporoids were accommodated to less stressful offshore habitats where other organisms may have been in direct competition. Although habitat generalists are usually poor competitors, these stromatoporoids appear to have been an exception. Their ability to colonize a variety of substrata, their broad tolerances to chemical conditions and circulation patterns, and their emphasis on high rates of lateral growth have permitted them to simultaneously occupy unstable tidal channel embayments and more benign offshore habitats.
Middle OrdovicianLophospira(Archaeogastropoda) from the Upper Mississippi Valley
Authors: Tofel Jane Evans , Bretsky Peter W. 
Published: August 2016

A detailed morphological study of over 2,500 Middle Ordovician (Black Riveran) lophospirid archaeogastropods from the lower half of the Platteville Formation (Pecatonica Member and Mifflin Submember of the McGregor Member), principally as it is exposed in southern Wisconsin, has permitted the definition of five species ofLophospira. Lophospira perangulata(Hall),L. milleri(Hall),L. serrulata(Salter),L. helicteres(Salter), andL. delicata(n. sp.) are preserved throughout a three-meter interval of fine-grained, heavily bioturbated carbonates, now dolomitized. Deposition took place on a broad, shallow tropical shelf, which was characterized by low rates of deposition and low physical energy. The sampled interval represents about 500,000 years. The benthic marine invertebrate fauna is well preserved, diverse, and characteristic of an environment of normal marine salinity.Of the fiveLophospiraspecies, only one,L. perangulata, has been positively identified in older strata (late Whiterockian, eastern North America). The other four species were endemic to the interior seas, and apparently at least two of these,L. serrulataandL. helicteres, did not survive into post-Platteville (post-Black Riveran) environments. Changes in the proportions of lophospirid species from the Pecatonica into the Mifflin strata probably reflect subtle changes in the distribution of carbonate shelf habitats but no major alteration in the kinds of habitats available for colonization.
Changes in Permian marine ostracode faunas during regression, Florena Shale, northeastern Kansas
Authors: Costanzo Gary V. , Kaesler Roger L. 
Published: August 2016

The Florena Shale (Permian, Wolfcampian) of the Midcontinent of North America was deposited in a restricted marine basin. Shifting environments due to marine regression caused a gradual change in the ostracode fauna. Cluster analysis and ordination by nonmetric multidimensional scaling of data on ostracode relative abundances revealed three ostracode assemblages, each characteristic of a different environment. TheCryptobairdia seminalisassemblage from the lowest Florena Shale is characteristic of deeper water, offshore, marine environments with only minor influx of terrigenous mud. TheAmphissites centronotusassemblage found above theC. seminalisassemblage occupied a similar environment, but with greater influx of terrigenous mud and intervals of increased turbidity. TheKnightina texanaassemblage occurs stratigraphically highest and probably represents a quiet-water, very shallow, nearshore, marine environment. Although protected from strong wave and current activity, the water mass was occasionally turbid.Species diversity of ostracodes is high both at the base of the Florena Shale, which was deposited in the most offshore position, and again at the top of the lower part of the Florena Shale, which was deposited nearer to the shore. In contrast to diversities of assemblages of ostracodes from similar environments in other stratigraphic units, theK. texanaassemblage has an anomalously high diversity. This is due in part to time averaging of adjacent ostracode assemblages and a strong taphonomic overprint.
Mandalacystis, a new rhipidocystid eocrinoid from the Whiterockian Stage (Ordovician) in Oklahoma and Nevada
Authors: Lewis Ronald D. , Sprinkle James , Bailey J. Bowman , Moffit John , Parsley Ronald L. 
Published: August 2016

Mandalacystis dockeryi n. gen. and sp. is known from seven complete or nearly complete thecae, six partial thecae, and numerous separate plates from the Oil Creek Formation in south-central Oklahoma, and a single thecal plate from the Antelope Valley Limestone in Nevada. Details of skeletal microstructure (stereom) are well preserved, permitting scanning electron microscopy for the first time in the Eocrinoidea, and demonstrating that plate thickness on thecal faces is only 60–70 μm. Mandalacystis is characterized by labyrinthine ridges on both faces of the theca, relatively short brachioles, and a normal stem with holdfast (at least in juvenile stages). Based on the normal biserial arrangement of brachiolar plates in the brachioles and the possession of a normal stem, Mandalacystis appears to be one of the most primitive rhipidocystids, closely related to Petalocystites.Mandalacystis dockeryi lived in a storm-dominated, shallow-water offshore habitat on patches of skeletal debris surrounded by soft, terrigenous mud. This setting may have been conducive to the transition from an erect, attached mode of life to the prone, unattached lifestyle of later rhipidocystids.
Cretaceous brachiopods from James Ross Island, Antarctic Peninsula, and their paleobiogeographic affinities
Authors: Sandy Michael R. 
Published: August 2016

Articulate brachiopods from the Aptian–Coniacian (Kotick Point and Whisky Bay Formations, Gustav Group) and the Santonian–Campanian (Santa Marta Formation, Marambio Group) of James Ross Island are described. A new terebratulid species,Rectithyris whiskyin. sp., is described from the late Albian–early Coniacian of the Whisky Bay Formation. The record from the late Albian is supported by palynological evidence making it contemporaneous with other species ofRectithyrisfrom Europe. The relative abundance ofRectithyris whiskyin. sp. in late Turonian to early Coniacian sections indicates an extended biohorizon that may aid biostratigraphic correlation in the James Ross Island region.The brachiopods have some affinities with faunas described from Europe, northern Siberia, North America, Madagascar, southern India, Western Australia, and Alexander Island, Antarctic Peninsula. Elements of the James Ross Island brachiopod fauna probably migrated by the following routes: 1) from northern high latitudes via the Eastern Pacific; 2) from Europe via the north and central Atlantic and opening south Atlantic Ocean; and 3) via Eastern Tethys, the East African Seaway, to the south Atlantic Ocean. Brachiopod evidence supports a fully marine connection between the central Atlantic and south Atlantic Ocean (Route 2) possibly as early as the late Albian (as do ammonite faunas from western Africa), and certainly by the late Turonian. Route 3 was established in the Cretaceous by the Aptian?–Albian to eastern Africa and Madagascar and to the Antarctic Peninsula by the late Turonian. Faunal links between James Ross Island and Western Australia support the Late Cretaceous juxtaposition of these plates.A distinct austral brachiopod fauna may be present in the Cretaceous from the Aptian onwards (although current evidence is scant). Antarctic Peninsular and Western Australian faunas yield five brachiopod genera (and their species) endemic to Gondwanaland's southern marine fauna. Other genera known from the Antarctic Peninsula (Kingena, Ptilorhynchia, andRectithyris) and the Northern Hemisphere may have species endemic to Gondwanaland.
New Late Eocene mollusks from localized limestone deposits formed by subduction-related methane seeps, southwestern Washington
Authors: Squires Richard L. , Goedert James L. 
Published: August 2016

The trochid archaeogastropodMargarites(Pupillaria)columbianan. sp., the mytilid bivalveModiolus(Modiolus)willapaensisn. sp., and the vesicomyid bivalveCalyptogena chinookensisn. sp. are described from the earliest known fossil communities associated with subduction-related methane seeps. The communities are in very localized limestones of late middle to late Eocene age along the southwestern margin of Washington. These limestones contain large numbers of chemosynthetic bivalves and worm tubes, as well as other macrobenthos, that colonized around cool-temperature methane seeps along the landward slopes of an ancient subduction-zone complex.Calyptogena chinookensisn. sp.is the earliest known species of this genus, which was previously known from Miocene to Recent.
Size-related evolutionary patterns among species and subgenera in the Strombina group (Gastropoda: Columbellidae)
Authors: Budd Ann F. , Johnson Kenneth G. 
Published: August 2016

This study represents a preliminary analysis of variation in size and shape in a large and diverse molluscan clade, the Strombina group, over the past 20 million years. Restored height and width were measured on 5,099 individuals of 72 species and 5 genera. Size was estimated by adding height and width, and shape was estimated by dividing height by width. Patterns of variation were analyzed quantitatively among species, subgenera, and genera using univariate statistical tests comparing means and variances and linear regression.
Results of univariate tests show that both shape and size vary among species within subgenera (the specific level) and among genera (the generic level). However, only shape varies among subgenera within genera (the subgeneric level). Regression analyses for each species show that the relationship between height and width is linear, indicating that growth is never allometric with respect to these characters. Because of this nonallometric growth, rates of shape relative to size change can never vary, imposing a severe constraint on shape change and, in turn, shape evolution. Regression models for species within subgenera have equal slopes but differ slightly in intercept. Subgeneric models differ more in intercept. Generic level models differ in slope. These results suggest that formation of species within subgenera primarily involves extension or contraction of trajectories between height and width within species (=static vectors), resulting in size change without shape change. Shape change is more important in the evolution of higher categories.
To examine overall morphologic change in the clade through time, mean sizes and shapes of species were analyzed using nonparametric statistics. Only a slight tendency exists within the clade for increase in species size, and this tendency is best expressed within two species-rich subgenera having long stratigraphic ranges. No directional trends exist for change in species shape. No relationship is found between species size and probability of speciation or extinction, or between species size and species duration, thus negating the role of species selection. Nevertheless, species are smaller in size in the northern Caribbean, a region characterized by extreme fluctuations in temperature. Larger species occurred only after a taxonomic radiation in the eastern Pacific, a more restricted region possibly characterized by reduced environmental disturbance. During this radiation, normal patterns of morphologic change associated with speciation appear to have been disrupted.