bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aspects of Gulf Coast late Neogene sequence stratigraphy
Authors: Shaffer Bernard L. , Pacht Jory A. , Bowen Bruce E. 
Published: January 2018

With its vast well and seismic data base, coupled with expanded sedimentary and biostratigraphic cycles that apparently were driven by glacial eustacy, the Gulf Coast offshore region provides a unique opportunity to develop and test sequence models. Virtually every major oil company and a number of academic institutions are currently engaged in some form of sequence analysis.Regional studies incorporating biostratigraphic analyses of more than 120 wells integrated with a seismic grid exceeding 24,000 line smiles, have shown the Gulf Coast to be an unstable prograding margin, and that characteristic seismic criteria developed for stable progradational margin models do not always apply. Biostratigraphic approaches consistent with the procedures and objectives of sequence analysis thus play a preeminent role in providing a chronostratigraphic framework, and in utilizing biotic patterns to aid in the delineation of systems tracts.For the pre- Wisconsin Plio-Pleistocene, 15 biostratigraphically and seismically resolvable and regionally mappable sequences are documented. Those for the past one million years approximate 100,000 year cycles. All of the sequences are calibrated by highest occurrence datums (HOD) which almost invariably occur within condensed sections developed either during maximum flooding events or on lowstand slope fans. This association with condensed sections begs the question whether or not these HOD are true extinctions, and whether or not sediment accumulation rates, or similar techniques, derived from them, can reliably be used to establish the position and absolute age of sequence bounding unconformities.Seismic and well data suggest that sequence bounding surfaces in this province are usually subtle, and that the hiatus they may represent is, except in extreme cases, beyond the resolution of the biostratigraphic framework. Sequence boundary placement can be routinely interpreted through integration of bioistratigraphic data, including condensed sections, wireline log patterns, and seismic character. In slope paleo-environments, condensed sections commonly are temporally equivalent to both the trasgressive and highstand systems tracts on the shelf, and their upper surface may coincide with the sequence boundary. In paleo-shelf settings, condensed sections frequently are restricted to the transgressive systems tract, and their contained HOD may be suppressed by succeeding highstand deposits. In such cases, sequence boundaries are best placed by wireline log and seismic criteria.Pitfalls and limitations to the proposed biostratigraphic approach to sequence stratigraphy are discussed and illustrated.
A new method for the determination of the δ18O composition of bone phosphate: applications to the thermal physiology of vertebrates
Authors: Showers William J. , Genna Bernard , Barrick Reese E. , Fischer Alfred G. 
Published: January 2018

A new method for the preparation of bone samples for δ18O-PO4 analysis has been developed. The phosphate from bone samples is separated and purified using ion exchange chromatography, and then precipitated as silver phosphate using the Firsching method. O2 is then extracted by reaction with bromine pentafluoride and converted to CO2 for isotopic analysis. Advantages of the silver phosphate technique over the bismuth phosphate technique are (1) the simplicity of the method, (2) silver phosphate is not hygroscopic so atmospheric water is not an oxygen contaminate, and (3) very small samples (2 mg to 10 mg) can be analyzed with an increase of precision compared to previous techniques. Iron and silica oxides added to Ag3PO4 standards produce no offset, which suggests that this new technique is not sensitive to interferences from cements commonly found in fossil bone material. Analyses have been performed on standards ranging in size from 30 mg to 2 mg with a σ1 of ± 0.05 per mil.The δ18O-PO4 compositional pattern of the bones of modern vertebrates have been analyzed to provide a base for the interpretation of the δ18O-PO4 pattern of fossil vertebrates. The average %PO4 in modern mammals and reptiles is approximately 15% with a σ1 of 2-3 %. The average %PO4 of fossil reptiles range from 10 to 25% with σ1 variations of up to 10%. The %PO4 variation can be related to cementation of void spaces in the bone material. XRD analysis reveals that calcite, dolomite, ankerite, and silica cements are commonly present. FTIR (Fourier Transform Infrared Spectroscopy) yields low indices calculated according to the formula of Shemesh, 1990 [GCA 54(9):2433]. Thin sections of the fossil bone material show detailed structures. All this evidence suggests that the fossil bone δ18O-PO4 composition is pristine and not altered by diagenesis. The total δ18O-PO4 σ1 variation of 10 or more skeletal elements analyzed for each individual specimen varies from 0.1 per mil for a domestic cow (Bos) to 0.8 per mil for a Komodo dragon (Varanus). Variations in between appear to be related to thermal physiology and variations in drinking water δ18O due to seasonality or migration.
Morphological and molecular rates of evolution in post-Paleozoic echinoids
Authors: Smith Andrew B. , Christen R. 
Published: January 2018

Phylogenetic analysis of a data matrix of 86 skeletal characteristics, and of the first 400 bases of the 5’ end of the large subunit ribosomal RNA gene produce congruent cladograms for 11 extant echinoids. Based on these cladistic analyses the great majority of morphologic and molecular apomorphies can be placed in one of 18 independent geological time intervals. When the cladogram is calibrated using the fossil record of post-Paleozoic echinoids, rates of molecular change in 28S rRNA can be calculated and compared with estimated rates of morphological evolution.Morphological and molecular apomorphies acquired in each time interval both correlate moderately strongly with time elapsed, but less strongly with one another. As expected, morphological rates vary considerably over time and between sister groups, but so too do molecular rates. When averaged over all echinoids studied, the number of morphological apomorphies accrued yields a slightly higher Spearman Rank correlation coefficient with time elapsed than does the number of molecular apomorphies accrued. This is because there is a three-fold difference in the rate of molecular change amongst the echinoid lineages studied.
Exotic terranes, late Paleozoic to early Mesozoic fossils and circum-Pacific events
Authors: Stanley George D. 
Published: January 2018

In addition to the breakup of Pangea, other major events occurring in the ancient Pacific during late Paleozoic and early Mesozoic time were the development and dispersal of exotic terranes which now characterize large portions of the eastern and western Pacific margins. While the terrane concept made sense out of the geologic crazy quiltwork pattern of these regions, considerable uncertainties still exist concerning terrane origins and their paleogeographic histories. Did terranes of the eastern and western pacific merely border Pangea or did they once exist within far-flung reaches of the ancient Pacific Ocean? Paleontology is now exploring and seeking answers to such issues based on benthic invertebrate fossils.Like examples in the western Pacific rim of Asia, the American Cordillera contains volcanic terranes with fossil content and history quite different from coeval rocks of the adjacent craton. Some terranes may have developed close to ancient North America, but others show evidence of having existed in settings far-removed from the craton. Over time, some terranes could have experienced considerable geographic displacement via tectonic processes (faulting, rift volcanism, seafloor spreading).Many terranes experienced protracted volcanic episodes of oceanic history during Permian and Triassic time. Terrane amalgamations occurred during Triassic and Jurassic time, and later in the Mesozoic were followed by accretion to the North American Craton. Some terranes such as Quesnellia, Cache Creek, Stikine, Wallowa, Eastern Klamath, and Wrangellia yield excellent benthic marine fossils—many of tropical Tethyan derivation, but other fossil assemblages are of mixed paleogeographic affiliations. Two island arc terranes, Stikinia and Wallowa, contribute to evolutionary and biogeographic issues with Triassic and Jurassic, tropical to temperate marine fossils. These include calcareous algae, sponges and corals occurring in reef sequences which can be related to better known examples from Asia and the former Tethys region. Continuing paleontological investigations into fossils from exotic terranes of the Cordilleran region, offer promise in the resolution of late Paleozoic and early Mesozoic circum-Pacific events and in the attainment of unified views of global paleogeography.
Evolution and development in the origin of major groups of vascular plants
Authors: Stein William E. 
Published: January 2018

Among multicellular organisms, the fossil record of vascular plants is, perhaps, uniquely informative about pattern and process leading to the establishment of major groups. Although classifications above the family level remain highly debatable, especially with regard to level, important insight has been gained into external morphology and internal anatomy of the earliest members of the clade, as well as into general patterns of diversification and change in form through time. Despite these advantages, cladistic methods have brought into sharp focus significant problems with important characters at high taxonomic levels. Putative synapomorphies used to diagnose major groups often have conflicting phylogenetic implications which, according to the cladistic paradigm, must be interpreted as homoplasy. From a biological standpoint, however, unrecognized instances of homoplasy in the character set often seem unlikely due to the complexity of the features involved, and the lack of plausible mechanisms producing multiple parallelisms or reversals by means of “known” processes such as adaptation, homeosis, heterochrony, or functional constraint. Added to this are conceptual and practical problems concerning morphological gaps (and what might bridge them) between recognized groups. One of the most interesting challenges to current approaches are enigmatic fossils early in the history of apparent clades exhibiting unprecedented variability in expression of supposedly diagnostic features. As a result, terminology originally developed to circumscribe alternative morphological states within clades completely breaks down. Perhaps, what's needed here is a more dynamic model of evolutionary change linking hypotheses of synapomorphy with specific changes in the structuring “rules” (or capacities) of development.Among characters used to diagnose major groups of vascular plants, differences in stelar architecture remain among the most important. Comparative evidence suggests that early vascular plants have essentially the same relatively well-understood developmental mechanisms as living plants; vascular tissues differentiate according to hormone (primarily auxin) gradient signals, that are the more-or-less the passive consequence of shoot geometry during growth. Because early plants have an extremely simple organography (dichotomizing stems with no leaves), an unparalleled opportunity exists to understand historical changes leading to establishment of major stelar morphs in the fossil record terms of changed dynamics of continuous serial development at the shoot apex. A computer simulation of vascular tissue patterning under hormone influence will be presented, and suggestions offered regarding the relative plausibility of alternate routes of evolutionary change between major groups.
Paleoecologic implications of epibionts on the Silurian lichid trilobite

Arctinurus
Authors: Tetreault Denis K. 
Published: January 2018

The Wenlockian lichid trilobite Arctinurus boltoni has been regarded as a classic example of a “snow-shoe” type adaptation. That is, the broad flat doublure has been interpreted as a resting surface, with well-developed terrace ridges serving as either sensory or frictional devices. New data from the Rochester Shale of western New York State indicate that this interpretation is incorrect The discovery of the small, calcareous worm tube Cornulites on complete, articulated specimens of Arctinurus indicates that these trilobites seldom rested their doublure on the sediment surface. Apertures of all specimens of Cornulites are oriented posteriorly, suggesting a rheophilic response to persistent water circulation patterns beneath the trilobite. The presence of suspension feeding organisms on the doublure also indicates that the water currents beneath the trilobite were free of suspended mud, so that Arctinurus may not have processed sediment in search of food.Large specimens of Arctinurus also have numerous epibionts on the dorsal shield, including cyclostome bryozoans, brachiopods (Stegerhynchus) and Cornulites. The presence of these suspension feeders indicates that Arctinurus did not burrow or even partially cover itself with mud. The large number of epibionts on adult specimens of Arctinurus, including several age classes for Stegerhynchus, indicates that molting stopped or at least slowed greatly once a certain size was attained, and that these trilobites may have had fairly long life spans.
A new dinoflagellage cyst sequence biostratigraphic framework for the Miocene of the Baltimore Canyon Trough and adjacent Salisbury Embayment
Authors: Verteuil Laurent De , Norris Geoffrey 
Published: January 2018

Over the past two decades, extensive seismic mapping of the Baltimore Canyon Trough off New Jersey, Delaware and Virginia, has documented a succession of progradational Miocene stratigraphic sequences. Understanding the depositional timing of these sequences is critical in evaluating the role of eustasy in their development, but has until now been hampered by the lack of suitably high resolution biostratigraphic data. Attempts to produce an integrated Neogene basin history have previously been frustrated by an inability to directly correlate individual shelf-based seismic sequences, with regionally mapped onshore, unconformity-bound, stratigraphic units. This study addresses both problems using data comprising the stratigraphic distribution of dinoflagellate cysts in two composited outcrop and ten subsurface sections from the Salisbury Embayment and adjacent Baltimore Canyon Trough. The result is a detailed age model for the entire Miocene depositional history of the area. Onshore samples are from the type sections of the Chesapeake Group in Maryland and Virginia. Offshore COST B-2 & B-3, Exxon 684 & 902 and Mobil 500 wells are directly tied to the regional seismic grid.According to our model, the magnitude and timing of mapped sequences in the Baltimore Canyon Trough compare well with Miocene third order cycles of the Exxon Cycle Chart. With the exception of the 22 Ma sequence (Cycle 1.5 of Haq et al., 1988), all of the other postulated eustatically controlled sequences are potentially present in the study area. In addition, on the basis of seismic mapping and integrated biostratigraphy, our model predicts one additional lower Serravalian sequence between 15.5 Ma and 13.8 Ma, and two additional lower Tortonian sequences between 10.5 Ma and 8.2 Ma. The onshore expression of these sequences are, respectively, the Calvert Beach Member of the Calvert Formation and parts of the Little Cove Point Beds of the Saint Marys Formation. An important implication of the age model is that the entire Fairhaven Member and “beds 4-9” of the Plum Point Marl Member, of the Calvert Formation, are lower Miocene strata.These dinocyst data were not available when the Exxon model of Miocene eustatic cycles was developed and therefore represent a critical independent test of that model. This is particularly so because the tectonically quiescent, mature, divergent-margin setting of the basin limits the role of causative variables other than eustasy, in the development and architecture of third order depositional sequences. Our model should be further tested by detailed sedimentological and taphonomic field studies of the Chesapeake Group.
Towards a pattern recognition approach for stratophenetics
Authors: Wei Kuo-Yen 
Published: January 2018

Stratophenetics has been widely adopted in paleontology to reconstruct phylogenetic trees. Despite the easy access to powerful computing facility amongst paleontologists, there is a shortage of integrated statistical procedures in such approach. This report is to (1) introduce a pattern recognition technique, Soft Independent Modeling of Class Analogy (SIMCA), for an objective stratophenetic approach, and (2) demonstrate its applicability by tracing two planktic foraminiferal lineages through a deep-sea sedimentary sequence.Stratophenetics proceeds in three steps: (1) recognizing phena (groups of morphologically similar specimens) from each stratigraphic sample, (2) ordering stratigraphic levels in each local section, and (3) linking phena in adjacent chronostratigraphic intervals on the basis of overall morphological similarity. The Plio-Pleistocene planktic foraminiferal sequence of the Globorotalia (Globoconella) puncticulata-inflata plexus obtained from the Deep Sea Drilling Project site 588 serves a good illustration case. This sequence, dated at 3.66 Ma to the Recent, is relatively complete and furnished with a good chronostratigraphy. It records the branching history of G, inflata form the G. puncticulata lineage. The gradation nature of the divergence and the enormous morphological variability in G. inflata have caused difficulty in achieving a consensus of taxonomy and phylogeny in this plexus.Typical specimens of the two species, G. puncticulata and G. inflata, were identified from a stratigraphic level dated at 2.76 Ma. Principal component models were built to characterize the morphometric patterns of the two morphotypes using SIMCA. The Globoconella specimens of the two adjacent stratigraphic intervals, one above and one below (dated 2.74 Ma and 2.83 Ma, respectively), were evaluated against the models and classified into one of the two morphotypes. The newly classified specimens were then used to build new models for further tracing specimens in the next adjacent stratigraphic levels. Progression such training and classification procedures through the stratigraphic intervals resulted in a reconstruction of the evolutionary patterns of the two lineages. The cladogenesis is inferred to occur at about 3.5 Ma and is characterized by a gigantism in the G. inflata lineage. The two lineages differ only in size and show similarity in all other characters in the beginning of the divergence, A disparity in allometric heterochrony further differentiated the two lineages after 2.8 Ma and the trend continued until G. puncticulata became extinct at 2.35 Ma.
Anatomy of the forelimb in

theropithecus oswaldi
Authors: Whitehead Paul F. 
Published: January 2018

A sample of over 170 hand, wrist, forearm and upper arm bones, from Olorgesailie DE/89 Horizon B and from Olduvai Gorge, was examined in this study. Elements include a trapezoid and centrale, capitates, hamates, scaphoids, lunates, pisiforms, triquetra and second, third, fourth and fifth metacarpals, ulnae, radii, humerii and scapulae.The fossils are different in several functionally significant ways from modern papionids. The angulation between the dorsal and palmar halves of the scaphoid is less acute. The helicoidal facet of the hamate, for articulation with the triquetrum, is radio-ulnarly shorter than in modern cercopithcoids; this would limit ulnar deviation. The hamulus is disto-proximally shorter, relative to the hamate body, than in digitigrade cercopithecoids, knuckle-walkers or fist-walkers. The distal hamate surface has the division into distinct, separate fourth and fifth metacarpal facets that is present in palmigrade cercopithecoids. Intermetacarpal facets are generally bissected by deep grooves, indicating strong intermetacarpal ligaments. The facet on the capitate for articulation with the second metacarpal, and the corresponding facet on the metacarpal, indicate that there was a functional division between the second and third metacarpals. The two extremes of retroflexion of the medial epicondyle of the humerus are present in the sample of humerii; some specimens closely resemble the angulation found in arboreal Colobus guereze and Cercopithecus albogularis, while others are similar to terrestrial Papio and Erythrocebus. The extremes of bifurcation and angulation of the radial notch are present in the sample of ulnae. Some specimens have the arboreal condition of a single, basically lateral-facing facet; others have the terrestrial split radial notch. The terrestrial condition is found where movement is confined to the parasaggital plane, with the arm in full pronation. The more lateral orientation of the radial notch appears to indicate more capacity for pronation/supination. The retroflexed olecranon is indicative of terrestriality; all of the examined ulnae have the short, grooved, angled olecranon typical of terrestrial monkeys. The associated specimens from MCK II illustrate that the features can appear as a mosaic: “terrestrial” olecranon, retroflexed medial epicondyle but “arboreal” radial notch. The brachialis mark is more anteriorly-oriented than in modern cercopithecoids.
Early ordovician assemblages and their possible relation to communities and biofacies – with an example from the Nittany Dolomite of central Pennsylvania
Authors: Zell Paul D. , Cuffey Roger J. 
Published: January 2018

Historically, six Early Ordovician fossil-bearing facies have been recognized in North America, based on both their lithology and the most abundant types of fossils: the cryptalgal facies, cherty-carbonate - molluscan facies, thrombolite mound facies, sponge-algal mound facies, limestone-brachiopod facies, and graptolitic shale facies. However, complete or representative fossil assemblages characterizing these facies have not yet been defined. Paleogeographic controls on the distribution of these facies are primarily water depth and circulation; much of the North American continent exhibits a progression from dolomite to limestone to shale as one goes from shoreline out across the shelf to deep sea deposits.Current study shows that the cherty-carbonate - molluscan facies as developed in the Nittany Dolomite of central Pennsylvania contains diverse assemblages consisting of, in decreasing order of abundance, gastropods, cephalopods, pelmatozoans, brachiopods, trilobites, sponges, polyplacophorans, rostroconchs, conodonts, encrusting and burrowing worms, and several types of algal structures. Within the mollusc dominated facies, different assemblages can be recognized which vary in the types of gastropods which predominate and in the abundance of cephalopods. These different assemblages appear limited enough that they approach the concept of fossil communities, although some might prefer to regard them as local biofacies. The assemblages are inferred to be related to current energy, water depth, salinity, and substrate texture. Intriguingly, diversity of the Nittany molluscs is highest where sponges and algal structures occur; comparison with the published literature also suggests a greater-than-expected faunal similarity and geographic proximity between the mollusc dominated facies and the sponge-algal mound facies.