bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ontogenetic adaptations in some Pennsylvanian crinoids
Authors: Peters Janet , Lane N. Gary 
Published: August 2016

Three species of Upper Pennsylvanian crinoids, two inadunates and one flexible, exhibit a sufficiently complete growth series to describe and quantify their ontogeny. Apographiocrinus typicalis (Moore and Plummer), Erisocrinus typus (Meek and Worthen), and Euonychocrinus simplex (Strimple and Moore) were collected from the middle shale of the Millersville Limestone Member of the Bond Formation at the Charleston Stone Quarry, Coles County, Illinois. Ten other crinoid species were collected in insufficient numbers for growth studies. Both bivariate and multivariate statistical procedures were used to analyze the growth of these crinoids.In the inadunate crinoids skeletal growth was highly coordinated in the dorsal cup and cup plates. Arm length increased by addition of secundibrachials. Food groove width increased almost three times from immature to adult stages, thus allowing a larger range of food particles to be consumed by adults. Growth of the cup is isometric in E. typus and slightly anisometric in A. typicalis. Primibrachials in both species develop anisometrically. Immature specimens possess long, slender primibrachials, with the A ray plate being longest. In maturity, the primibrachials become equidimensional and equalized in all rays. The A ray arm is followed by the C and D ray arms, and finally the B and E ray arms, in sharp contrast to arm development in disparid inadunates. Pinnules appear late in the immature stage of growth. Primary emphasis on the expansion of the arms in young inadunates demonstrates a rapid establishment of a filtration-fan mode of feeding. Subsequent development involves widening of the plates for strength and support of the arms and to accommodate wider food grooves that permit a larger array of food particles to be captured.The flexible crinoid, E. simplex, experienced a less correlated pattern of growth. Cup plates and arms grew isometrically and all arms were added simultaneously. Development suggests that flexibles fed differently than the associated inadunates and the cup may have played a less important role in functioning of the calyx.The upright, elevated growth pattern of stalked crinoids exposed them to a sequence of competitive interactions with other epifaunal animals that had important adaptational ramifications for their evolution, diversity, and extinction. The fact that most living crinoids, stalked and unstalked, have abandoned a permanently fixed place of growth may have been an advantageous factor in their survival.
Uintan land mammals (excluding rodents) from an estuarine facies of the Laredo Formation (Middle Eocene, Claiborne Group) of Webb County, Texas
Authors: Westgate James W. 
Published: August 2016

A newly discovered vertebrate fossil assemblage, the Casa Blanca local fauna, comes from the Laredo Formation, Claiborne Group, of Webb County, Texas, and is the first reported Eocene land-mammal fauna from the coastal plain of North America. The mammalian fauna is correlated with the Serendipity and Candelaria local faunas of west Texas, the Uinta C faunas of the Rocky Mountains, the Santiago Formation local fauna of southern California, and the Swift Current Creek local fauna of Saskatchewan. The vertebrate-bearing deposit lies approximately 32 m above a horizon containing the marine gastropodTurritella cortezi, which ranges from east Texas to northeast Mexico in the lower half of the Cook Mountain and Laredo Formations and is a guide fossil for the Hurricane Lentil in the Cook Mountain Formation. Nannoplankton found in these middle Eocene formations belong to the upper half of Nannoplankton Zone 16 and allow correlation with European beds of late Lutetian to early Bartonian age.Over 700 specimens represent at least 30 species of 28 mammal genera. The Casa Blanca fauna is the southernmost and easternmost North American land-mammal fauna of definite Eocene age, and is the westernmost Paleogene vertebrate fauna from the Gulf Coastal Plain.
Middle Jurassic inoceramids from Argentina
Authors: Damborenea Susana E. 
Published: August 2016

Extensive collections from stratigraphically controlled sections allow reassessment and systematic revision of Middle Jurassic inoceramids from Argentina. Two species are doubtfully referred toParainoceramusVoronetz, includingP.?westermannin. sp. Five species ofRetroceramusKoshelkina, includingR.cf.R. marwicki(Speden),R. patagonicus(Philippi) andR. stehnin. sp., are present. The Bajocian–early Callovian species ofRetroceramusshow strong affinities with Aalenian–Bathonian inoceramids from the Northern Hemisphere, and also with the South Pacific forms of thegaloi–haastigroup of Heterian–Ohauan age, except for minor differences in outline, ornamentation, and the umbonal region.The time range of each species in Argentina was determined by associated ammonoids. There is strong morphological evidence, supported by the stratigraphic distribution of species, thatRetroceramuscf.R. marwicki, R. patagonicus, andR. stehnibelong to a single clade, which developed from the late Bajocian to the early Callovian in the Andean region.
Systematics and phylogeny of the late Osagean and Meramecian crinoids Platycrinites and Eucladocrinus from the Mississippian stratotype region
Authors: Ausich William I. , Kammer Thomas W. 
Published: August 2016

Late Osagean to Meramecian Platycrinites and Eucladocrinus from Illinois, Iowa, and Missouri are redescribed and redefined from study of type material. Three of the oldest species were incorrectly synonymized with P. sarae, and this correction leads to a realignment of species systematics within Platycrinites. Accordingly, six species of Platycrinites and one species of Eucladocrinus are considered valid in the Keokuk Limestone through St. Louis Limestone of the stratotype area. Valid species include Platycrinites saffordi (Hall), P. sarae (Hall), P. georgii (Hall), P. pumilus (Hall), P. brevinodus (Hall), P. niotensis (Meek and Worthen), and Eucladocrinus millebrachiatus Wahsmuth and Springer. Nomenclatoral changes include the following: 1) P. sarae is redescribed and all junior synonyms are removed; 2) P. georgii is a valid senior synonym of P. bonoensis (White), P. aeternalis (Miller), P. boonvillensis (Miller), and P. cauducus; 3) P. pentagonus (Miller) is a junior synonym of P. niotensis; 4) P. pumilus is a valid senior synonym of P. prattenanus (Meek and Worthen), and P. monroensis (Worthen); 5) P. bloomfieldensis (Miller) is designated as a nomen dubium; and 6) Eucladocrinus millebrachiatus immaturus is a junior synonym of E. millebrachiatus.The evoluton of new species in Platycrinites was by a combination of cladogenesis and possibly anagenesis. Platycrinites sarae evolved from P. saffordi possibly through anagenesis, P. pumilus evolved from P. niotensis through cladogenesis, and P. hemisphaericus evolved through cladogenesis from P. brevinodus, although P. hemisphaericus does not occur in the geographic area of this study.
Early Permian colonial rugose corals from the Stikine River area, British Columbia, Canada
Authors: Stevens Calvin H. , Rycerski Barbara 
Published: August 2016

Twenty-two species of Early Permian colonial rugose corals belonging to 12 genera from 10 locations in the Stikine River area in northwestern British Columbia, Canada, are described. These include three new species ofFomichevella(F. magna, F. southeri, F. bamberi); two species ofHeintzella; five species ofHeritschioides, of which three are new (H. bagleyae, H. garvinae, H. hoganae); two new species ofParaheritschioides(P. jennyi, P. wickenae); one new species questionably assigned toKleopatrina(K.?stikinensis); two new species ofPetalaxis(P. guaspariniae, P. neriae); and two new species ofLytvophyllum(L.?mongeri, L. wersoni). In addition, five new species assigned to five new genera are here namedEastonastraea complexa, Fedorowskiella simplex, Pararachnastraea lewisi, Stikineastraea thomasi, andWilsonastraea rigbyi.These corals occur in rocks forming part of the Stikine terrane, the largest tectonostratigraphic unit in western Canada. This coral fauna shows a very close affinity with that of the Lower Permian McCloud Limestone of the eastern Klamath Mountains of northern California, and there is some similarity to the Coyote Butte fauna of central Oregon. Several species compare most closely with species from Spitsbergen, but there are few similarities with any cratonal North American faunas and none with Tethyan faunas.
Heritability and intraspecific heterochrony in Ordovician bryozoans from environments differing in diversity
Authors: Pachut Joseph F. 
Published: August 2016

Environmental conditions affect both the character and variability of developmental patterns (=astogeny) within each of four species of Ordovician bryozoans. Regressions between pairs of stereological measurements for populations from both high-and low-diversity habitats differ significantly in 79 percent of all comparisons. Deviations from a rigid pattern of development, measured as dispersion from regression, were greater in species populations from low diversity settings in 77 percent of comparisons. Therefore, both developmental patterns and their variability differ intraspecifically along a diversity gradient in representatives of four bryozoan families. Additionally, dispersion values were larger in younger rather than older colonies in two species irrespective of diversity level, thus suggesting an age-related reduction in variation.Changes in developmental trajectories indicate that colonies from low-diversity settings are generally paedomorphic relative to conspecific populations from high-diversity habitats. The heritability of these characters and developmental patterns, estimated using variance partitioning techniques, is greater in high-diversity associations. These findings suggest that character state modifications dependent upon astogeny, or a consequence of astogenetic modifications, are more heritable in high-diversity settings. However, if the environment can cause facultative heterochrony, the possibility of fixing such patterns in subsequent generations is increased, although the mechanism for accomplishing this is presently unknown.
Frasnian species of the Late Devonian conodont genus Ancyrognathus
Authors: Klapper Gilbert 
Published: August 2016

Detailed qualitative analysis of the Pa element and multielement analysis emphasizing the associated Pb element have led to the present revision of the Frasnian species of Ancyrognathus. Diagnostic characters of the Pa element, such as the platform outline, carinal pattern, and shape of the pit, as well as salient features of the Pb element, are the basis of this revision. As a consequence, the restriction in the definition of A. triangularis, formerly a heterogeneous concept including several discrete species, has in turn led to the recognition of a substantially increased number of species of Ancyrognathus.The lowest occurrence of Ancyrognathus primus is used here to delimit the base of Zone 6 of the Montagne Noire Frasnian sequence. The exact relationship of the Montagne Noire zonation to the published standard zonation is problematical. For example, the base of the range of A. triangularis is possibly above the zone for which it is the nominal species in the standard zonation. Two new species are named herein, A. coeni and A. seddoni, both of which have been widely illustrated in the literature, and three new species are recognized in open nomenclature.
Vincular furrows in some Early Silurian and Devonian Phacopidae (Trilobita), predominantly from North America
Authors: Lespérance Pierre J. 
Published: August 2016

The vincular furrow morphology of 19 species of Phacopidae is critically examined. The anterior part of the vincular furrow is much less variable than the posterior part of the vincular furrow, but it can be absent, shallow, deep, or have a slightly ventrally elongated boss. The posterior part of the vincular furrow can have pleurovincular pits (for reception of the thoracic pleural tip processes) or indentations for these processes, plus bounding walls that are variably indented laterally and very variable in vertical elongation. The functional morphology of the various elements of the vincular furrow is best explained by a paradigm of resistance to lateral shearing.All elements of the vincular furrow in Devonian taxa had already appeared in the Early Silurian, but Early Silurian taxa are richer in diversity of elements. Some Devonian subspecies, essentially based on dorsal morphologies, show distinctly different vincular furrows. Cluster analysis of the data gathered on the vincular furrow complexes regroups the distinctly different Devonian subspecies and some Silurian subgenera. Other vincular furrows within the Phacopidae suggest that Reedops is near the Phacops logani complex and that the Phacopidellinae is a valid subfamily, but formal emendations within the family are not suggested because of incomplete data, notably on our knowledge of the distribution of vincular furrows. The use of the widely conceived genus Phacops Emmrich, 1839, over more recently described taxa such as Paciphacops Maximova, 1972, is presently favored, as this reflects more clearly current understanding of the systematics within the family Phacopidae.Primary types of the North American taxa Phacops cristata, P. cristata gaspensis, and Acernaspis (Acernaspis) orestes are critically reviewed; significant changes of previous interpretations are suggested. Phacops cristata vitrea n. subsp. is erected. Thoracic pleural tip processes and anterolateral ventral pygidial processes are described in detail within Phacops rana rana and Acernaspis (Acernaspis) orestes. A pathological specimen of Phacops rana rana, with an injured eye, demonstrates that the individual did not revert to a primitive type of lens packing.
Morphological integration and covariance during astogeny of an Ordovician trepostome bryozoan from communities of different diversities
Authors: Pachut Joseph F. 
Published: August 2016

Correlations exist between diversity and colonial growth pattern and variability in Paleozoic stenolaemate bryozoans. Habitats occupied by diverse communities contained colonies whose growth trajectories were different and were more highly constrained than those of low-diversity habitats. Because previous studies have not examined variability during colony growth, it was unclear whether observed variabilities were constant during growth (astogeny) or whether variability changed with age. Astogenetic trajectories and growth variability are here reexamined in populations of colonies ofHeterotrypa ulrichifrom the same high-diversity and low-diversity communities examined by Pachut (1989).Growth trajectories of populations differ in both intermonticular and monticular regions of colonies for fundamental stereological characters. Total zooidal surface areas generally decrease during astogeny whereas zooidal densities increase. Surface areas per zooid also decrease with increasing age, but are consistently larger in monticular zooecia and in populations from low-diversity communities irrespective of the colony region sampled. These patterns of declining values are caused by increasing wall thicknesses, larger and more abundant mesozooecia and acanthostyles, and the development of maculae during colony growth. Larger values in low-diversity settings may have provided reproductive and feeding benefits necessary for survival.Covariances reflect levels of morphological integration and are larger in populations from high-diversity communities in both intermonticular and monticular regions. Values differ more during early stages of growth (1–3) than later in astogeny (stages 4–5), and are consistently higher in intermonitulcar than in monticular zooecia. Lower levels of integration in monticules may be caused by spatial adjustments as the number of monticules increases across the expanding colony surface during growth. In general, stabilizing selection may have been weaker and less effective in establishing character covariance patterns in populations from low-diversity communities, perhaps because of greater environmental stress. These findings suggest that evaluations of astogenetic patterns and age-related changes in levels of morphological integration within a paleoenvironmental context are important in measuring species richness, in determining the direction of character evolution, and in assessing tempo and mode of evolutionary changes.
Alternative methods for dealing by nonnormality and heteroscedasticity in paleontological data
Authors: Hageman Steven J. 
Published: August 2016

Although numerical methods are highly useful in paleontological studies, potential problems arise with application of parametric statistical methods to paleontological data. Most common statistical tests assume data are normally distributed and that multiple populations have equal variances (homoscedasticity). Paleontological data frequently do not satisfy these assumptions, thereby affecting results of tests and potentially misleading scientific interpretations. Nonparametric tests should be used when assumptions of parametric tests are violated. Normal scores tests, which utilize expected normal deviates (rankits) substituted for original data, are the most powerful nonparametric tests. Despite their potential utility, normal scores tests have received little attention, primarily because of difficulties encountered with rankit conversion.Recent advances in microcomputer technology provide viable methods for rankit conversion, thus making normal scores tests accessible for routine application. Normal scores tests provide a practical method of dealing with nonnormality and heteroscedasticity common in paleontological data.
New Late Ordovician solitary rugose coral with perforate septa
Authors: Elias Robert J. 
Published: August 2016

Neotryplasma flowerin. sp. is an epizoic solitary rugose coral characterized by two orders of perforate, monacanthine, carinate septa, a complex axial structure of septal lobes and lamellae, and a well developed broad dissepimentarium. It occurs in the Late Ordovician (late Edenian to earliest Maysvillian; late Caradoc) Upham Dolomite Member of the Second Value Dolomite, Montoya Group, at El Paso, Texas, U.S.A.NeotryplasmaKaljo, 1957, also includes two Late Ordovician species from the Estonian S.S.R. and one from the late Middle and Late Ordovician of the northern and middle Ural region, U.S.S.R. This genus is assigned to the Neotryplasmatidae n. fam., which is placed in the Suborder Monacanthina Neuman, 1984.Neotryplasmaappears to be closest toSumsarophyllumLavrusevich, 1971a, from the Late Ordovician of the Zeravshan-Gissar region, U.S.S.R. This is noteworthy because Erina (1978) and Erina and Kim (1980) suggested that the latter may be a scleractinian coral of the Order Fungiida Verrill, 1865. The rugosan mode of septal insertion has been confirmed inNeotryplasma. N. floweriseems to bear close resemblance to a poorly known Ordovician coral,Cyathophyllum(?)kjerulfiKiaer, 1932, from Caradoc–Ashgill strata in the Trondheim region of Norway.
Biostratinomy of ostracode assemblages from a small reef flat in Maunalua Bay, Oahu, Hawaii
Authors: Izuka Scot K. , Kaesler Roger L. 
Published: August 2016

Comparisons of biotopes based on ternary plots and cluster analyses of living ostracode assemblages with those from subfossil assemblages from a small reef flat show that biostratinomic processes modify the assemblages before they are incorporated into the sediment of the reef flat. Selective preservation changes the assemblages by preferentially preserving robust carapaces over fragile carapaces. The thin-shelled Paradoxostomatidae, which are abundant in the algae-dwelling assemblages, are largely destroyed by biostratinomic processes and are represented by only a few individuals in the subfossil assemblages.Mixing of algae-dwelling assemblages and sediment-dwelling assemblages results in a lower relative proportion of many species in the subfossil assemblages than in the living assemblages. The Leptocytheridae, which comprise a large portion of the sediment-dwelling fauna, are reduced in relative proportion in the subfossil assemblages as a result of dilution of the sediment-dwelling fauna with an abundant, algae-dwelling fauna.Transportation of ostracode remains by wave-induced currents removes the patchiness that is characteristic of the biotopes of the living ostracode assemblages but does not completely homogenize the assemblage despite the close spacing of sampling and the small areal extent of the biotopes studied.
Form of the trilobite digestive system: alimentary structures in Pterocephalia
Authors: Chatterton Brian D. E. , Johanson Zerina , Sutherland George 
Published: August 2016

Three types of alimentary canals (=midgut) occur in the Annelida and non-trilobite Arthropoda: 1) a sagittal tube with metamerically paired diverticula related to the number of somites; 2) a tube that is constricted slightly between somites; and 3) a simple tubular gut that may taper slightly backwards to the anus. At least two of these three types (1 and 3) occur in the Trilobita. Pterocephalia and Olenoides share the first type with the probable sister taxon to the Trilobita, Naraoia (Nectaspida), and this is probably the plesiomorphic condition for the class. Varying feeding habits may well have made this character homoplastic within each of these groups. The preservation of parts of the alimentary tract in specimens of Upper Cambrian Pterocephalia n. sp. (McKay Group, British Columbia) was probably a function of taphonomic and/or very early diagenetic changes that resulted from the type of food preferred by that trilobite. Other trilobites from the same beds do not have their soft parts preserved. The alimentary structures are preserved in a different fashion from, apparently unattached to, and an order of magnitude larger than genal caeca that occur in this taxon. Thus, genal caeca are regarded as imprints of circulatory rather than alimentary structures.Energy dispersive analysis of a fragment of preserved alimentary tract of Pterocephalia n. sp. showed the presence of Ca, Si, Al, Fe, P, K, Na, and Cl. These alimentary tracts are composed of a complex mixture of minerals that probably includes clays, detrital quartz, carbonates, phosphates, and oxides or hydroxides. The structure of these dark fillings is microcrystalline. The presence of detrital minerals as part of this mixture would suggest that this trilobite was a deposit feeder.
Conodonts from the Bromide Formation (Middle Ordovician), south-central Oklahoma
Authors: Bauer Jeffrey A. 
Published: August 2016

Forty-seven samples of the Bromide Formation (Simpson Group) of south-central Oklahoma produced a collection of 10,216 conodonts assigned to 46 species. The conodont fauna is dominated by species ofPhragmodusandPlectodinaand indicates a latest Whiterockian to early Mohawkian (Black Riveran) or late Llandeilian to early Caradocian age. Five new species are named includingAnsella crassa, Bryantodina aequalis, Plectodina edentula, Walliserodus declivis, andPharagmodus ambiguus.The latter species is distinct fromPhragmodus flexuosusMoskalenko, a species to which it has been assigned in past reports.Analysis of conodont distribution with respect to the shallow-water Bromide lithofacies distinguishes shallow to deeper water conodont associations. Samples from shallower water facies containAnsella crassan. sp.,Cahabagnathus sweeti(Bergström),Curtognathusspp.,Eoplacognathus elongatus(Bergström),Erismodus typusBranson and Mehl,Oneotodus?ovatus(Stauffer),Phragmodus ambiguusn. sp.,Phragmodus flexuosus, andStaufferella falcata(Stauffer). Samples from deeper water facies contain forms such asAnsella nevadensis(Ethington and Schumacher) andBaltoniodus gerdae(Bergström).