bluuebunny/crossref_metadata_2025 huggingface dataset:
Interference of Common Cocklebur (Xanthium strumarium) and Cotton (Gossypium hirsutum)
Authors: Byrd John D. , Coble Harold D.
Published: January 2018

An area of influence method with biweekly destructive harvests 5 through 19 wk after planting (WAP) was used to monitor the reciprocal interference of common cocklebur and cotton in 1987 and 1988. Plant heights, leaf area, and leaf, stem, boll, fiber, and total plant biomass dry weights were measured in 15-cm increments away from common cocklebur or from a randomly selected cotton plant out to 105 cm. Data indicated that cotton less than 60 cm from common cocklebur was shorter, had less leaf area and lower leaf, stem, boll, and biomass dry weights than cotton beyond 60 cm from common cocklebur or cotton grown without common cocklebur interference. Differences in leaf area and biomass between cotton grown with and without common cocklebur interference were greater at and beyond 13 WAP sample dates than before 13 WAP. By 15 WAP, cotton leaf area and biomass were reduced an estimated 11% and 15%, respectively, averaged over the entire 105 cm of row. Cotton yield, harvested 27 WAP, was reduced an estimated 31% on plants grown with one common cocklebur plant per 2.1 m. Cotton yield was reduced on plants out to 99 cm from common cocklebur. Common cocklebur and cotton plants grown alone were taller, had greater leaf area, and greater leaf, stem, and biomass dry weight than those respective plants grown adjacent to cotton. Common cocklebur grown alone produced 67% more biomass than did cotton grown alone. Cotton plants grown adjacent to other cotton plants produced 89% and 96% less boll and fiber weight, respectively, than plants grown alone.
A Chlorophyll Assay to Assess Sethoxydim Activity in Two Grass Species
Authors: Smith Anne M. , Vanden Born William H.
Published: January 2018

The influence of ammonium sulfate on the activity of sethoxydim on wild oats and barley was examined under field conditions in 1989 and 1990. A chlorophyll assay, together with plant height and dry weight determinations, was used to quantify the visual ratings for sethoxydim activity. Ammonium sulfate enhanced the activity of 75 and 150 g ai ha-1sethoxydim in 1989. In 1990, ammonium sulfate increased the activity of the lower rate of sethoxydim only. Of the three quantitative assays, chlorophyll concentration alone differentiated the more rapid development of injury symptoms with added ammonium sulfate that was observed in the visual ratings. The chlorophyll assay was not better than the visual rating assessment, however, and appears to offer no advantages that would justify the time required.
Vegetation Management in the Cross Timbers: Response of Woody Species to Herbicides and Burning
Authors: Stritzke Jimmy F. , Engle David M. , McCollum F. Ted
Published: January 2018

Brush control and woody plant community structure in the Cross Timbers of Oklahoma resulting from treatments with herbicides and fire were compared. Tebuthiuron and triclopyr were applied alone and in combination with burning at 2.2 kg ai ha-1in March and June of 1983, respectively. The burned pastures were burned with strip headfires in late spring of 1985, 1986, and 1987. Both herbicides were effective on the dominant overstory brush species, blackjack oak and post oak, and this resulted in good reduction of canopy cover of brush initially. However, effects of triclopyr were short-lived because of ineffectiveness on many of the other hardwood species (American elm, gum bumelia, hackberry, roughleaf dogwood, and buckbrush). Crown reduction and tree kill of these hardwood species was usually better with tebuthiuron than with triclopyr. Neither herbicide was effective on eastern redcedar. Better brush control, associated with tebuthiuron, resulted in better fine fuel release and by 1988, burning was having a significant effect on woody plants in the tebuthiuron-treated plots.
Field Bindweed (Convolvulus arvensis) Control in Winter Wheat (Triticum aestivum) With Herbicides
Authors: Heering David C. , Peeper Thomas F.
Published: January 2018

Field experiments were conducted in Oklahoma to evaluate the effect of three imidazolinone herbicides and metsulfuron on established field bindweed and hard red winter wheat followcrops. Imazapyr at 280 g ai ha-1and imazethapyr at 560 g ai ha-1controlled field bindweed from 78 to 100% for 48 wk, but imazaquin at 560 g ai ha-1, metsulfuron at 17.5 g ai ha-1, and 2,4-D plus picloram at 1120 plus 280 g ae ha-1did not. Imidazolinone herbicides reduced forage and grain yield of wheat seeded 8 to 14 wk after herbicide application. Only imazapyr reduced grain yield of wheat seeded 15 mo after treatment.
Effect of Glyphosate on Introduced and Native Grasses
Authors: Lym Rodney G. , Kirby Donald R.
Published: January 2018

The effect of glyphosate applied alone and with 2,4-D as a commercial mixture on 30 native or introduced grass species was evaluated. Grass yield averaged 98 and 87% of the untreated controls when glyphosate was applied in the fall at 0.2 or 0.4 kg ae ha-1, respectively, alone or with 2,4-D at 0.35 or 0.7 kg ae ha-1. Western wheatgrass production decreased more than any other species present in a native rangeland site following either a spring or fall glyphosate application. In seeded plots, intermediate wheatgrass was the most and ‘Fairway’ crested wheatgrass the least susceptible to glyphosate plus 2,4-D with average yields of 57 and 97% compared with untreated controls of each species, respectively. Glyphosate reduced the yield of ‘Nordan’ standard crested wheatgrass more than that of Fairway crested wheatgrass or other diploid cultivars. The greater the spring precipitation following a fall application of glyphosate, the less effect of glyphosate on forage yield. Glyphosate plus 2,4-D can be used for weed control in pasture and rangeland provided some yield reduction is acceptable.
The Paleosol Record of Increasing Plant Diversity and Depth of Rooting and Changes in Atmospheric pCO2 in the Siluro-Devonian
Authors: Driese Steven G. , Mora Claudia I. , Elick Jennifer M.
Published: January 2018

Paleosols Crop Out extensively in the Appalachian region of eastern North America, from the Canadian Maritime Provinces southward to the Tennessee-Alabama border along the western side of the Appalachian Orogen (Fig. 1). The paleosols occur primarily in terrigenous clastic redbed deposits ranging in age from Late Ordovician to Early Permian (Mora and Driese, 1999; Driese and Mora, in press), which encompass a time interval characterized by rapid evolution and diversification of terrestrial ecosystems (Table 1). These Appalachian paleosols formed under relatively constant sediment-source area and pedogenic environments (Table 1); thus they share generally uniform physical and chemical properties. As such, they are suitable particularly for investigating evolutionary advances in the gross morphology of plant roots and rhizomes, preserved as traces, and their relationship to physical and chemical features in the paleosols (Table 2). Important changes in plant abundance, rhizome and root systems, and adaptive capabilities are recorded in the paleosols, concurrent with a proxy record of changing environmental conditions. Paleosols represent a still-underutilized record of the terrestrial ecosystem (Retallack, 1990).
Evolution and Expansion of Flowering Plants
Authors: Wing Scott L.
Published: January 2018

Flowering plants are a classic example of a group arising late in Earth history and yet achieving very high diversity, abundance, and ecological and morphological variety in a great array of environments and climatic conditions on all continents. Thus, the success of flowering plants raises basic questions about how new lineages become inserted into existing terrestrial ecosystems. To what degree did flowering plants replace older lineages competitively, and to what extent did their expansion depend on large-scale environmental disruption or extinction of older groups? Is the higher taxonomic diversity of flowering plants a consequence of higher rates of speciation, lower rates of extinction, or both? Have flowering plants expanded the total area and range of habitats occupied by terrestrial vegetation? What were the effects of the diversification and spread of flowering plants on the structure of habitats and the types of resources available to terrestrial heterotrophs?
Welcome to the C4 World
Authors: Cerling Thure E. , Ehleringer James R.
Published: January 2018

There are two principal mechanisms of photosynthesis amongst the plants of the world. One produces a 3-carbon compound as the primary photosynthate and is called C3 photosynthesis. The other produces a 4-carbon compound as its primary photosynthate and is called C4 photosynthesis. This latter method is of rather recent origin, and its inception had important consequences for the flora and fauna of the world. The C4 plants make up a significant portion of global net primary productivity, especially in low latitudes. C4 plants are predominantly warm-season grasses, while C3 plants include most dicotyledons and cool-season monocotyledons. In this review we answer the questions about how C4 photosynthesis differs from C3 photosynthesis, where C4 plants are found, and review the paleoecological history of C4 photosynthesis.
Current issues in Scandinavian acute psychiatric wards
Authors: Ruud Torleif , Lindefors Nils , Lindhardt Anne
Published: January 2018

The aim of the paper is to provide an overview of some of the most important issues faced by acute inpatient facilities in three Scandinavian countries, including reflections and critical remarks for discussion in this field. Information was drawn from scientific articles and official reports published in recent years, as well as the authors' own knowledge of acute facilities in their home countries. Acute inpatient facilities, including General Hospital Psychiatric Units (GHPUs), in all Scandinavian countries have several issues and problems in common, which include the organisation and capacity of acute services, the assessment of dangerousness and suicidality, the use of coercion and efforts to reduce coercion, the need to define and improve the quality of acute services, and the necessity to improve collaboration and continuity between acute services and other services. Although the emphasis some of these issues receive can vary across the three countries, Scandinavian mental health professionals (and policy makers) have begun to systematically share their experiences in developing a growing spirit of collaboration. Despite the role of welfare state and the deployment of substantial resources in Scandinavian countries, mental health practitioners are struggling to implement best practices in acute wards, to develop differentiated forms of acute services, and to reach the right balance and coordination between acute services and other services.
Developing and implementing clinical guidelines: lessons from the NICE Schizophrenia Guideline
Authors: Pilling Stephen , Price Katy
Published: January 2018

This paper describes the development of the clinical practice guideline on schizophrenia from the National Institute for Clinical Excellence (NICE) and outlines its main recommendations. It reviews the evidence on effective implementation of guidelines generally and examines issues specific to the schizophrenia guideline. It describes NICE'S approach to supporting implementation alongside that developed by the National Collaborating Centre for Mental Health (NCCMH) and looks at local implementation examples for schizophrenia.

The paper highlights key considerations for the forthcoming revision of the NICE schizophrenia guideline. It makes recommendations concerning the scope of the guideline and the quality and type of data available to the guideline developers: the lack of data on outcomes such as quality of life and social functioning, the challenges presented by unpublished papers and areas where evidence is limited. Since publication of the schizophrenia guideline, the NICE development process has undergone significant methodological improvements. The grading of evidence has been refined and more recently NICE proposed that grading of recommendations be dropped. Consensus methods are increasingly and more effectively used to deal with areas where the evidence-base is limited. NICE and the NCCMH have developed a more implementation-ready range of guideline products.

The initial NICE guideline on schizophrenia was positively received nationally and internationally. This paper highlights challenges that will be involved in updating the guideline and ways to refine the methodology of development. Ultimately the impact of the guideline will be measured not in its methodological rigor but in how its successful implementation improves patient care.

Declaration of Interest: Stephen Pilling in receipt of funding from NICE for the production of clinical guidelines.
Quality of mental health services: a self audit in the South Verona mental health service
Authors: Allevi Liliana , Salvi Giovanni , Ruggeri Mirella
Published: January 2018

Aims – To start a process of Continuous Quality Improvement (CQI) in an Italian Community Mental Health Service by using a quality assurance questionnaire in a self audit exercise. Methods – The questionnaire was administered to 14 key workers and clinical managers with different roles and seniority. One senior manager's evaluation was used as a benchmark for all the others. Changes were introduced in the service practice according to what emerged from the evaluation. Meetings were scheduled to monitor those changes and renew the CQI process. Results – There was a wide difference in the key workers' answers. Overall, the senior manager's evaluation was on the 60th percentile of the distribution of the other evaluations. Those areas that required prompt intervention were risk management, personnel development, and CQI. The CQI process was followed up for one year: some interventions were carried out to change the practice of the service. Conclusions – A self audit exercise in Community Mental Health Services was both feasible and useful. The CQI process was easier to start than to carry on over the long term.
Public health psychopharmacology: a new research discipline comes of age?
Authors: Barbui C. , Ostuzzi G. , Godman B.
Published: January 2018

Research evidence guiding the identification of pragmatic and effective actions aimed at improving the selection, availability, affordability and rational prescribing of medicines for mental disorders is sparse and inconsistent. In order to boost the development of new research, in this commentary we suggest to organise and classify all the activities in this area under a common theoretical framework and nomenclature, adopting the term ‘public health psychopharmacology’. Public health psychopharmacology is proposed as a research discipline, based on contributions from the fields of regulatory science, health services research and implementation science. Implementing the term public health psychopharmacology may offer advantages, as the scientific community would be more focused on common goals and objectives, with, likely, an increasing body of research evidence of practical use.
Conservation Introductions for Biodiversity Adaptation under Climate Change
Authors: McCormack Phillipa C.
Published: January 2018

Anthropogenic climate change represents a wicked problem, both for the Earth’s natural systems and for biodiversity conservation law and policy. Legal frameworks for conservation have a critical role to play in helping species and ecosystems to adapt as the climate changes. However, they are currently poorly equipped to regulate adaptation strategies that demand high levels of human intervention. This article investigates law and policy for conservation introductions, which involve relocating species outside their historical habitat. It takes as a case study Australian law on conservation introductions, demonstrating theoretical and practical legal hurdles to these strategies at international, national and subnational levels. The article argues that existing legal mechanisms may be repurposed, in some cases, to better regulate conservation introduction projects. However, new legal mechanisms are also needed, and soon, to effectively conserve species and ecosystems in a period of unprecedented ecological change.
Floodplains and paleosols in the Wyoming Eocene sequence: implications for the taphonomy and paleoecology of faunas
Authors: Bown Thomas M. , Kraus Mary J. , Aslan Andres
Published: January 2018

The Willwood Fm. of the southern Bighorn Basin of Wyoming, U.S.A., comprises 700 m of lower Eocene alluvial molasse, nearly all of which contains relict pedogenic features. These rocks are grouped into pedofacies–alluvial sediment prisms, thick with immature paleosols proximal to streams and thinner with mature paleosols distally. Pedofacies are bounded by either trunk-stream channel or crevasse-splay deposits, which represent time-stratigraphic markers. The floodplain widths of the Willwood rivers varied from 15 to 20+ km. Paleosols occur throughout the Willwood Formation and the most mature paleosols required about 60 Ka to form whereas the least mature, required 0.5 to 1.0 Ka. Paleosol thicknesses vary from about 0.3–8.0 m and are directly related to net sediment accumulation rate (NSAR) and profile maturity. Pedofacies also reflect NSAR controls; pedofacies are continuously superposed, 15–35-m-thick, and represent time intervals of 30–60 Ka.

In the earliest Eocene, paleosol maturity rose sharply, and NSAR plummeted (Fort Union Fm./Willwood Fm. contact), after which maturity gradually declined (and NSAR rose) throughout the early Eocene. This decline was punctuated by two episodes of severe decline, each corresponding with major increases in NSAR, increased tectonism, and episodes of faunal turnover (“Biohorizons” A and B). Above the biohorizons, species earlier tied to particular paleosol maturities were replaced by closely related though more generalized species with no marked paleosol preferences. Time-stratigraphic reconstruction of the Willwood Fm. shows that “Biohorizons” B and C record the same faunal event; B the extinctions, and C the immigrations.

The 1,300 Willwood fossil vertebrate localities, which are distributed throughout the entire formation, occur in the surface horizons of cumulative alluvial paleosols. All fossil accumulations in paleosols are attritional and formed during pedogenesis. The most complete remains occur in immature paleosols, whereas the most abundant remains are found in mature paleosols. Within the large-scale Willwood ecologic setting, studies of discrete (m's to tens of m's thick) stratigraphic intervals suggest that the paleontology and sedimentology of these intervals can be significantly influenced by lateral differences in paleosol hydromorphy (soil wetness) and maturity (lateral position of a fossil-bearing paleosol with respect to an ancient river channel). These smaller-scale controls on fossil occurrences are important for distinguishing between real and apparent changes in faunal compositions over time and emphasize the value of three-dimensional stratigraphic analysis for interpreting paleontologic events.

Supported by National Geographic Society grant 3985-89.
Biotic and sedimentologic comparison of patch reefs on the north and south shelf of Belize, Central America
Authors: Burke C. D. , Mazzullo S. J.
Published: January 2018

Holocene patch-reefs occur throughout the shallow marine platform, to the lee of the barrier reef in northern and southern Belize, Central America. Patch reefs on the northern shelf that occur within an areally extensive patch reef complex (Mexico Rocks) indicate that differences exist between reefs here and well-studied patch reefs on the southern shelf that have been used by workers as a general model for patch reef development throughout Belize. This model proposes that patch reefs on the Belizean shelf are dominated by typical Atlantic-Caribbean, biotically-zoned coral assemblages of Acropora palmata and A. cervicornis that kept up or caught up with Holocene sea level rise during the last 8000 years to form large “keep up” or in some instances “catch up” reefs.

In contrast to those in the south, the northern patch reefs are not biotically zoned, are dominated by Montastrea annularis rather than Acropora spp., and are much younger (400 years old) than those in the south. In addition, northern shelf patch reefs developed predominantly by lateral growth in a milieu of static sea level and are herein called “accretion” type reefs. These differences in biotic and sedimentologic parameters between reefs on the northern and southern shelves imply fundamentally different ecologic and sea level history controls on patch reef formation from north to south. A leading contributor to the variation among the reefs along the Belizean shelf may be species-specific growth rates of the coral species that initiate each patch reef, and response to sea level fluctuation versus stasis through time.
Isotopic evidence for climatic, ecologic, and faunal change in the Siwaliks of Pakistan
Authors: Cerling Thure E. , Quade Jay
Published: January 2018

The biggest replacement of fauna in the Siwaliks of Pakistan takes place between 7.5 and 7.0 million years (Ma) ago. By 5 Ma, almost the entire fauna that existed at 8 Ma had been replaced by a different fauna. Although other important faunal changes occurred at about 13.5, 12, and 9.5 Ma those changes are small compared to that between 7.5 and 7.0 Ma. What event caused the wholesale local extinction of fauna which was replaced by another?

The stable isotopic composition of paleosol carbonate shows two important “events” in the Siwalik sequence. First, at 8 Ma a big shift in the δ18O of soil carbonate indicates that a major shift in climate occurred. We have found a similar change in Europe and East Africa in soil carbonates on those continents, suggesting a major change in global circulation patterns. The second event is a change in the isotopic composition of carbon-bearing phases which shows that the pre-7.5 Ma vegetation was dominated by C3 plants which were completely replaced by C4 plants between 7 and 6 Ma. This is most likely a replacement of woody plants by tropical (C4) grasses.

The carbon isotopic composition of tooth enamel from Siwalik mammals shows that prior to 7.5 Ma they consumed C3 plants, and by 5 Ma consumed only C4 plants. While it comes as no surprise that animals eat local vegetation, this study shows that isotopic reconstruction of paleo-diets can be traced back into the Tertiary.

Global climatic change in the late Miocene resulted in the invasion of tropical grasslands into the Indian subcontinent. The resulting change in habitat and diet caused the migration of many species of mammals, which is manifested as an almost complete turnover in the fauna fo the Siwaliks.
A new stage in the Upper Cenozoic of Southern South America
Authors: Cione Alberto L. , Tonni Eduardo P.
Published: January 2018

Former workers developed in South America a chronostratigraphic system not essentially different to that of European stage/age system. However, the authors of this paper believe that accurate biostratigraphic studies have to be done in southern South America for establishing the precise boundary stratotypes of most stage/ages. A new South American Upper Cenozoic continental stage/age is recognized. The stratotype is located in the fossiliferous southeastern Buenos Aires Province marine cliffs between Mar del Plata and Miramar. The outcrops in the area are the best continental representation of Plio-Pleistocene times in South America. It is younger than Chapadmalalan and older than Ensenadan and replaces the “Uquian”. We consider that the “Uquian” actually emcopasses Chapadmalalan and Ensenadan times. The Uquía outcrops are here considered inadequate as stratotype especially by the dearth of micromanmals, the relatively poor fossil record and the comparatively inadequate geographic location. The new stage would be correlated with the Gauss Chron and possibly with the lower Matuyama Chron. The lower boundary is tentatively stated. For so doing, a biostratigraphic scheme is proposed. This lower boundary approximately corresponds to the base of the Barranca de los Lobos “Formation” of Kraglievich (1952) and a new (unpublished) unconformity bounded unit (Zárate, 1989). Some taxa that apparently ranges from the base are candidates to define it after a detailed biostratigraphic study.

Additionally, a different timing for the arrival of North American mammals to southern South America is given.
New occurrences of Silurian eurypterids (Carcinosomatidae) in Pennsylvania, Ohio and New York
Authors: Ciurca Samuel J.
Published: January 2018

Carcinosomatids are rare among the Silurian eurypterid faunas of northeastern United States. New discoveries, discussed below, extend the geographic and stratigraphic ranges of two important types:

Paracarcinosoma, known primarily from the Bertie Group of western New York, and

Rhinocarcinosoma, known only from the Illion Shale of eastern New York. PENNSYLVANIA: The very distinctive Rhinocarcinosoma was obtained from rocks of the McKenzie Fm., below Bloomsburg redbeds, just east of Lock Haven. Remains consist of a well preserved carapace with characteristic 'shovel’ developed as an extension of the anterior portion of the carapace. This occurrence is analogous to the occurrence in the New York stratigraphic sequence 185 miles (285 km) to the northeast in the type area of the Illion Shale. At the New York localities, the eurypterid-bearing beds are overlain by the redbeds of the Vernon Fm. (Salina Group).

OHIO: The Maumee Quarry east of Toledo has been studied extensively by many geologists. The stratigraphic sequence exposed consists of “Niagaran reefs” overlain by the Greenfield Fm. (Bass Islands Group) but with an impressive array of stromatolitic beds transitionally developed between the two units.

In the transitional beds occur the scattered remains of Paracarcinosoma. Specimens are fragmentary, but a small well preserved carapace was obtained showing the intramarginal position of the compound eyes characteristic of this carcinosomatid. The specimens were obtained from fine-grained dolostone with no evidence of other fossils.

NEW YORK: The original discovery of Rhinocarcinosoma, as described in 1912 by Clarke and Ruedemann, is here supplemented by new finds in the Illion Shale east of the type area and particularly by the discovery of this eurypterid in rocks of the Lockport Group near Sodus Center, N.Y. Exposures of the Sconondoa Fm. in the Sodus Quarry and in the streambed just to the north yielded numerous specimens. Particularly noteworthy is an operculum of the size and structure illustrated by Clarke and Ruedemann. The new occurrences in the Sodus Center area extend the geographic range of Rhinocarcinosoma westward about 100 miles (160 km).

The carcinosomatid occurrences just described are intimately associated with stromatolitic or thrombolitic biostromes or “reefs.” It would appear that both types of eurypterids, Paracarcinosoma and Rhinocarcinosoma, preferred a niche in backreef areas in peculiar algal-lagoonal settings little understood today. Eurypterus, the common form in the Bertie Group, is generally found in rocks having much evidence of hypersalinity (salt hopper structures, etc.), presumably a more supratidal setting.
Putting our science to work in the 21st Century: new directions in applied paleobiology?
Authors: Cohen Andrew S.
Published: January 2018

The scientific community is in great need of input from paleontologists today in two key areas of societal concern: the historical basis of global change and losses of biodiversity. Paleontologists, with their unique perspective on rates of change in biotic communities and their training in filtering signal from noise in the fossil record, are the best placed scientists in biology to approach these problems from an historical viewpoint. In the classroom we give lip service to the central role of paleontology in understanding these problems. Yet with the exclusion of Quaternary (and particularly Recent) paleoecology from the mainstream of our field, we have abrogated this responsibility to other disciplines. Paleontologists are in danger of losing the opportunity to provide guidance on the very issues in paleontology where political interest and funding will lie in the not too distant future. As opportunities for employment of paleontologists in the petroleum industry fade, it is critical that academic paleontologists define new directions for graduate education in our field.

The paleontological community needs to reincorporate Quaternary paleoecology into its mainstream, emphasizing the importance of a paleobiological perspective in environmental problem solving. As the developers of theory and methodology in the interpretation of the fossil record it is our responsibility to set the agenda as to how paleobiology should be utilized. Our professional societies should provide leadership as advocates for funding research and training in the new areas of applied paleobiology, lest paleobiology (as we define it) be marginalized and traditional paleontology programs be viewed by their home institutions as increasingly irrelevant. Employment opportunities in biostratigraphy are a thing of the past; applied paleontology must redefine itself for career opportunities at the top of the column, in such areas as recent climate change or the fossil record of human-induced ecological disturbances. The PIRLA Project (Paleoecological Investigation of Recent Lake Acidification) provides an excellent example of applying paleobiology to such problems, using the Recent diatoms, crustaceans, insects and pollen fossils to understand the chronology of the acid rain problem in eastern North America.

Academic departments bear a responsibility to bring the important new applications of paleobiology into the classroom, demonstrating its societal relevance and training students to avail themselves of potential opportunities for paleobiologists in global change and biodiversity research. Recent developments in taphonomy or stratigraphic ordering of fossils could be extremely powerful tools if applied to environmental change problem solving. We need to make our students marketable by spending more time in the classroom teaching them about Recent diatom paleoecology and less on brachiopod biostratigraphy. Otherwise paleobiology may go the way of Egyptology.
Ediacaran survivors
Authors: Conway Morris Simon
Published: January 2018

Ediacaran taxa are a characteristic element of latest Precambrian biotas, with an effectively global distribution. Their time range is not well understood, but with one possible exception from western Canada Ediacaran faunas appear always to post-date the late Precambrian glaciations. There is also growing evidence that many Ediacaran taxa disappeared before the Precambrian-Cambrian boundary. These disappearances traditionally have been ascribed to changes in taphonomic circumstances, but a series of extinctions is a plausible alternative. Ediacaran fossils pose two major problems: Notwithstanding the reasons for their disappearance shortly before the Precambrian-Cambrian boundary, was their demise total or did some forms persist into the Cambrian? Second, is the traditional view that Ediacaran taxa are metazoans, many of a cnidarian grade, correct? Recently Seilacher, Bergström and others have argued that the Ediacaran organisms have a distinctive bauplan, difficult to reconcile with known phyla and possibly different from any metazoan.

In the Cambrian, Burgess Shale-type faunas are the principal source of information on soft-bodied metazoans. The differences between them and Ediacaran assemblages are largely self-evident, but there is now unequivocal evidence for at least one Ediacaran survivor from the Middle Cambrian Burgess Shale of British Columbia. This is a sea-pen-like animal, known from three specimens (one adult about 20 cm in length, and two juveniles). The fossils consist of a broad frond, with branches arising from a central axis on one side, while the opposite side is smooth apart from longitudinal ridges. The frond extends into a blunt holdfast that presumably was embedded in the muddy silt of the sea floor. This fossil is strikingly similar to the Ediacaran taxon Charniodiscus, best known from South Australia. The Burgess Shale example shows two important features. The first are pustule-like structures, possibly zooids, both on the branches and adjacent to the axis. The second feature is evidence for connections between the branches and axis, possibly representing canals. These features both support a comparison with extant pennatulaceans, and suggest that at least some Ediacaran taxa are correctly assigned to the metazoans.

Also occurring in the Burgess Shale is an enigmatic bag-like organism Mackenzia costalis. Clear evidence exists for it being benthic, but its mode of feeding is uncertain. The interior appears to have consisted largely of a spacious cavity, probably sub-divided by longitudinal partitions. In addition, an elongate strand may represent a discrete organ, perhaps connected with digestion or reproduction. No exact equivalent to Mackenzia appears to occur in Ediacaran assemblages, but bag-like taxa are a common component. These include erniettids, best known from Namibia, and Platypholina, from the White Sea region of Russia.
Evolution of high-latitude biotas
Authors: Crame J. Alistair
Published: January 2018

With the recent rapid improvement in the quality of the fossil record in both polar regions it has become possible to examine critically the development of high-latitude faunas and floras through time. Within arctic regions, distinctive biotas have been present, at least intermittently, since the early Permian, and in antarctic regions they can be traced back to the early Middle Devonian. It would appear that, whenever continents (and continental shelves) moved into the high latitudes they were the sites of significant biotic differentiation.

To investigate the ways in which taxa may have accumulated in the high latitudes through time, three simple global models have been proposed. In the first of these it is envisaged that major groups of plants and animals arose in the low latitudes and disseminated subsequently into the polar regions. Here they would become relicts and the latter would be regarded as refugia. The second model is almost exactly the reverse of the first in that it proposes that certain taxa arose in the polar regions and then spread, through time, into the low latitudes. Such a process may at first sight seem less likely, but the Antarctic fossil record in particular is providing important evidence to suggest that certain major groups of both plants and animals had a high-latitude origin. The third model differs substantially from the previous two in that it makes no a priori assumptions about either centres of origin or the process of dispersal. It merely states that, at certain times in the past, widespread distribution patterns have been disrupted in the low latitudes to form disjunct populations in the northern and southern hemispheres. It results in the classic bipolar pattern, which can now be traced back to at least the Early Jurassic period.

A major phase of Jurassic - Cretaceous bipolarity can be attributed to tectonic vicariance as the Pangean supercontinent disintegrated, and a major late Paleogene - early Neogene one can be related to climatic vicariance. Such hypotheses are attractive as they are testable by cladistic analysis. Although data available so far are limited, both fossil and living benthic molluscs offer considerable scope for future work.
Mid to Late Cretaceous diversity of angiosperm floral structure and implications for the history of pollination mechanisms
Authors: Crepet William L. , Hortorium L.H. Bailey , Nixon Kevin C. , Hortorium L.H. Bailey , Brenner Gilbert J.
Published: January 2018

For most of the Twentieth Century the angiosperm archetypal flower has been viewed as relatively large, multiparted, with spirally arranged fleshy appendages, and as being probably beetle pollinated as in some extant Magnoliales. However, the preponderance of fossil evidence indicates that flowers with such characters do not appear until the mid-Cretaceous, well after smaller simpler fossil flowers such as platanoids and chloranthoids. Winteraceous and Chloranthaceous pollen appears more or less simultaneously in the Lower Cretaceous, but rapidly mounting evidence for mosaicism in Cretaceous taxa makes it unwise to extrapolate floral structure on the basis of dispersed pollen. Mid-Late Cretaceous fossils illustrate an increasing proportion of simple flowered Rosidae in the angiosperm flora. We report new fossil evidence of charcoalified flowers and fruits representing at least 20–30 diverse angiosperm taxa from the Cenomanian and Turonian deposits of the Atlantic Coastal Plain. These fossil flowers include representatives with hypanthia and floral cups, sympetaly, syncarpy, inferior ovaries, campylotropous ovules, nectaries of various forms, specialized anther dehiscence, epipetalous stamens, and connate filament tubes. Major taxonomic groups (as defined by Cronquist) represented by these fossils include Dilleniidae, Magnoliidae, Rosidae, monocots, and possibly Caryophyllidae. Thus, the early Late Cretaceous angiosperm flora had greater floral diversity than has previously been documented. This array of floral structures includes features that are now associated with bees and other specialized insect pollinators, thus providing a new perspective on the evolution of insect pollination.
Potential effect of climate change on terrestrial biota
Authors: Crowley Thomas J.
Published: January 2018

There are several important changes in Phanerozoic climates that may have influenced terrestrial biota. Prior to the time of the terrestrial invasion in the early Paleozoic, an unvegetated landscape would have been associated with a larger seasonal cycle and decreased precipitation. Albedo and transpiration changes associated with the first appearance of plants should have changed this pattern, reducing the seasonal cycle and increasing precipitation. Enhanced soil weathering associated with vegetation should also have lowered atmospheric CO2 levels. During Pangaea time the giant landmass should again have caused very large seasonal cycles and decreased precipitation. Climate models invariably simulate below-freezing temperatures in winter on the supercontinent, a result at variance with inferred “equable” climates of the Jurassic. The large landmass should also have had very large Milankovitch variations. Seasonal warming during precession half-cycles of 10,000 years duration may have been associated with intermittent occupation of high-latitude sites that could bias interpretation of warmth in high latitudes. During the later Mesozoic (140–80 Ma) CO2 levels may have been several times higher than present. High CO2 levels should have affected the cycles of temperature and precipitation on land and also affected plants through the CO2 fertilization pathway. Subsequent decreased CO2 levels and continued breakup of landmasses may have influenced location of tropical rainbelts and perhaps the distribution of tropical rainforests. Numerous studies indicate that these changes, combined with expanded ice cover in the later Cenozoic, resulted in increasingly drier conditions in higher latitude land areas. The situation in the tropics is more uncertain, because there are conflicting signals from the marine realm as to the Cenozoic history of tropical sea-surface temperatures (SSTs). If early Cenozoic SSTs were in fact low (as indicated by some δ18O records), then tropical temperature and moisture levels may not have been high enough to sustain tropical rainforests. This summary highlights some of the excellent opportunities for interactions between paleontologists and paleoclimatologists in assessing the effects of climate change on terrestrial biota.
A Rhuddanian (Silurian: Lower Llandovery) echinoderm fauna from Haverfordwest, Southwest Wales
Authors: Donovan Stephen K. , Veltkamp Cornelis J.
Published: January 2018

Llandovery (Lower Silurian) echinoderm faunas are uncommon, an observation which has important implications for our understanding of the patterns of evolution and extinction over the Ordovician/Silurian boundary interval. For example, only two crinoid faunas of Rhuddanian or Rhuddanian+Aeronian age have so far been described, both from North America (Cataract Group, Ontario; Brassfield Formation, Ohio). A third echinoderm fauna of Rhuddanian age is now recognized from the Gasworks Mudstones (=upper Haverford Mudstone Formation) and, less certainly, the Gasworks Sandstone Formation of Haverfordwest, Dyfed, southwest Wales. Recent fieldwork has failed to relocate the precise horizon that produced this fauna and the taxa discussed herein are all based on specimens in the Turnbull Collection of the Sedgwick Museum, Cambridge. There is no published analysis of this fauna, but Ramsbottom, in his Ph.D. thesis, identified Pisocrinus sp., Macrostylocrinus sp. and Dimerocrinites sp. from this horizon.

A disarticulated thecal plate has been identified as the rhombiferan Homocystites? sp., confirming that the cheirocrinids survived the end Ordovician extinction. This is only the second British Llandovery cystoid. All other specimens are crinoids. Crowns of calceocrinid disparids are assigned to two species of Calceocrinus (=“Pisocrinus sp.” of Ramsbottom). A dendrocrinid cladid is interpreted as a smmoth-cupped Dendrocrinus? A unique internal mould is a monobathrid, possibly Macrostylocrinus. Distinctive petaloid columnals of Floricolumnus (col.) sp. cf. F. girvanensis Donovan and Clark, possibly derived from a rhodocrinitid diplobathrid, are congeneric with ossicles from the Newlands Formation of southwest Scotland (latest Rhuddanian-earliest Aeronian) and the Brassfield Formation of Ohio (‘Bead Bed’). A new species of rhodocrinitid diplobathrid (=“Dimerocrinites sp.” of Ramsbottom) has low infrabasals just apparent in lateral view; a moderately bowl-shaped dorsal cup; prominent ray ridges; 2, 3 or 5 plates, respectively, in the first three tiers of interprimibrachials; and uniserial arms that branch isotomously once and heterotomously thereafter. Two further crinoid species are indeterminate. At the familial level, this fauna shows strong similarities with coeval, but more diverse, crinoid assemblages from North America.
Trilobite vision: a comparison of schizochroal and holochroal eyes with the compound eyes of modern arthropods
Authors: Fordyce David. , Cronin Thomas W.
Published: January 2018

The compound eyes of trilobites provide the best examples of fossilized sensory organs for which the function in life can be worked out today, because the optical array of their corneal lenses preserves the geometry with which the eye originally sampled the visual world. An analysis of trilobite vision is strengthened by the use of new mathematical approaches to compound eye design. In particular, the product of the facet diameter (D) and the interommatidial angle (Δϕ) gives the value of the eye parameter, DΔϕ, which is a reliable indicator of the photic conditions in which the eye was used. In modern arthropods, DΔϕ values range from 0.3 for animals active in bright sunlight to 20 or more for nocturnal or deep-sea animals.

Three types of compound eyes existed in trilobites: schizochroal, holochroal, and abathochroal. We examined the schizochroal and holochroal types. Schizochroal eyes were studied in the phacopid species Phacops rana crassituberculata and Phacops rana milleri. We measured the diameter of every corneal lens, and estimated its optical axis by taking the normal to the plane of the lens's diameter. In both species, each eye covered almost exactly 180° of visual space in azimuth with no binocular overlap, from directly anterior to directly posterior. Vertically, the visual field extended from the horizon to about 40° in elevation. Facet diameters and interommatidial angles were large, giving eye parameter values ranging from 10 to > 150. These are much greater than in any living arthropod, implying that modern compound eye theory does not apply to schizochroal eyes. We believe that each ommatidium of the schizochroal eye served as a miniature lens eye. If so, phacopid vision must have been unique, with multiply overlapping visual fields. Such a design would have required considerable central processing, but could have provided exceptional opportunities for spatial, spectral, and polarizational analysis.

We examined holochroal compound eyes in Asaphus cornutus and Isotelus “gigas”. Here, visual field coverage was greater than in the schizochroal eye type, with a small amount of frontal binocular overlap. Holochroal eyes contain far more ommatidia than do schizochroal types, reducing both facet diameter (D) and interommatidial angle (Δϕ). Thus, DΔϕ values in these species fall into the same range as in modern compound eyes. This implies that function of the holochroal eye was similar to that of modern crustaceans and insects.

This material is based on research supported by the National Science Foundation under Grants No. BNS-8518769 and BNS-8917183.
Phylogenetic history of major trilobite clades in relation to paleoenvironment
Authors: Fortey Richard A. , Owen Robert M.
Published: January 2018

Because trilobites occupied a wide a range of Paleozoic marine habitats they are a good group to examine hypotheses concerning the sites in which new major clades first appear, and their subsequent history of diversification and decline. There are several problems in this endeavour. The first concerns classification. Until a complete phylogenetic classification is available, there is no objective way to assess the equivalence or otherwise of groups which have been claimed as orders. For example, Odontopleurida and Lichida are treated as separate orders in some classifications, but are considered as a single major clade - presumably of ordinal status - in others. Some of the most commonly accepted groups (Olenellida, Ptychopariida) are paraphyletic. The second problem is taphonomic. The first appearance of a major group often coincides with a major extrinsic change, such as a regressive-transgressive couplet. Does the event initiate the novelty, or simply permit it to be preserved? Does such an event “punctuate” the fossil record, such that earlier, ancestral taxa belonging to the same clade go unrecognised?

Trilobites are already paleogeographically diversified when they make their first appearance in the Lower Cambrian. Since trilobites constitute a true clade, this implies an earlier phase of vicariance of dispersal which is not recorded in the rocks. In China, Siberia, North America, and North Africa these first occurrences are in rocks of inshore origin: still earlier trilobites may have had thin cuticles which militated against their being preserved in the highest energy environments where “small shelly” fossils occurred. The groups Olenellida, Redlichiida, Corynexochida, Ptychopariina (?Lichida) appear in the early Cambrian. The earliest polymerids with morphology corresponding to deep water, atheloptic, is latest Lower Cambrian (Atops, Australia): there are many such in the mid-Cambrian.

Opinions differ on the classification of Agnostida. Our own view relates Agnostina to Eodiscina, and on this view the early representatives of the clade (Lower Cambrian, China) are inshore compared with later agnostid occurrences, which typify outer shelf to slope. Ordovician agnostids are comparatively rare; the youngest agnostids were not confined to deep water sites.

There is good evidence of early occurrences of Odontopleurida, Lichida s.s., Illaenina, Proetida and Phacopida in shallow water deposits. Evidence from Asaphida is more equivocal. Colonisation of deeper water habitats from shallow is rapid, although not achieved at the same time in each group. The scenario is of repeated production of deeper water forms from shelf taxa rather than wholesale movement of clades into that environment. After the demise of other groups in the late Devonian, for example, in the youngest Devonian and Carboniferous proetides radiated into deep water habitats. But the last trilobites of all in the Permian were shallow shelf inhabitants.