bluuebunny/crossref_metadata_2025 huggingface dataset:
Artificial time-averaging of marsh foraminiferal assemblages: linking the temporal scales of ecology and paleoecology
Authors: Martin Ronald E. , Hippensteel Scott P. , Nikitina Daria , Pizzuto James E.
Published: July 2006

Multiple regression models were developed for seasonal test inputs to, and preservation of, marsh foraminiferal assemblages for a two-year period at Bombay Hook National Wildlife Refuge (BHNWR; Smyrna, Delaware). Seasonal assemblages were quite variable and yielded poor regression models. However, signal/noise ratios were amplified using artificially time-averaged (ATA) assemblages, in which separate dead and live abundances of the most abundant species were summed for all seasons. Regression models that used ATA species abundances to retrodict original sample depths accounted for up to ~99% (p < 0.0001) and ~91% (p < 0.023) of the variation of dead and live ATA assemblages, respectively, and usually retrodicted sample depths within 2–3 cm of actual depths.

Artificially time-averaged assemblages were also used to extract multidecadal- to centennial-scale sea-level signals from near-surface assemblages at BHNWR formed during the past few centuries. The BHNWR sea-level curve closely resembles one previously published for marshes in Clinton, Connecticut (also based on foraminifera). The technique of artificial time-averaging therefore links the temporal scales of ecology and paleobiology by extracting high-resolution paleoenvironmental signals preserved in the fossil record.
The synthesis marches on - From DNA to Diversity: Molecular Genetics and the Evolution of Animal Design. Sean B. Carroll, Jennifer K. Grenier, and Scott D. Weatherbee. Blackwell Science, Maiden, Massachusetts. 2001. 214 pages. Paper $44.95.
Authors: Valentine James W.
Published: July 2006

In the late 1930s and early 1940s, a professionally disparate group of biologists forged an evolutionary synthesis that placed natural selection at the center of the changes in genes and in morphology that have produced the diversity of organisms in the biosphere. The chief architects of this famous synthesis included population geneticists, zoologists, botanists, and paleontologists, but not developmental biologists. Among the tenets of the synthesis was the finding that evolution generally proceeded in populations by selection from among a variety of alleles of structural genes that were provided by various forms of mutation, and which had small but cumulative effects. Some workers concluded that even the evolution of major novelties, such as the distinctive body-plans of different animal phyla, could be produced by the accumulation of such small changes in gene products. Whether the high rates of morphological change inferred from the fossil record could have actually been achieved by these processes alone was not clear.
Testing for bias in the evolution of coloniality: a demonstration in cyclostome bryozoans
Authors: McShea Daniel W. , Venit Edward P.
Published: July 2006

Colonial organisms vary in the degree to which they are individuated at the colony level, i.e., in the degree to which the colony constitutes a unified whole, as opposed to a group of independent lower-level entities. Various arguments have been offered suggesting that evolutionary change along this continuum may be biased, that increases may be more probable than decreases. However, counterarguments can be devised, and the existing evidence is meager and inconclusive. In this paper, we demonstrate how the question can be addressed empirically by conducting a test for bias in a group of stenolaemate bryozoans, the cyclostomes. More specifically, we suggest three criteria for colony individuation: degree of connectedness among lower-level entities (in this case, zooids), degree of differentiation among lower-level entities, and number of intermediate-level parts. And we show how these criteria can be used together with a phylogeny and ancestral-state reconstruction methods to test for bias. In this case, results do not unambiguously support any single interpretation but are somewhat supportive of a null hypothesis of no bias in favor of increase.

As part of the demonstration, we also show how results can be transformed into a quantitative estimate of an upper limit on bias. Finally, we place the question of bias in a larger context, arguing that the same criteria and methods we employ here can be used to test for bias in other colonial taxa, and also at other hierarchical levels, for example, in the transitions from free-living eukaryotic cells to multicellular organisms.
Inferring predation intensity in the marine fossil record
Authors: Leighton Lindsey R.
Published: July 2006

Accurate estimates of predation intensity, the frequency of mortality from predation, are critical to studies of the evolution of species in response to predation, and to studies of predator-prey systems in general. Most commonly used indirect proxies for predation intensity in the fossil record have logistical or theoretical problems. Direct proxies, using actual traces of predatory activity, such as drilling and repair scars, may hold more promise. However, these direct proxies often have been used in conjunction with optimal foraging models, and in this context, the underlying assumptions and predictions of optimal foraging are examined.

Results from theoretical models using optimal foraging suggest that (1) the ratio of internal shell volume to shell thickness of prey (benefit/cost ratio) may be a questionable measurement of prey “value” to the predator, as it fails to account adequately for energetic cost to the predator during pursuit and grappling; (2) drilling and repair frequency are invalid measures of prey preference, because optimal foraging predicts that specific prey types are either always taken or always ignored; (3) pooled drilling frequency will not be a useful metric of predation intensity in systems in which the predator need not always drill; and (4) an increase in repair frequency can be a consequence of either an increase or a decrease in predation intensity.

Although drilling frequency may not indicate prey preference, it is a valid proxy for selection due to predation. An approach using size classes, in which the minimum size at which a predation refuge is achieved, is suggested for use with repair frequency.
Morphometric analysis of ontogeny and allometry of the Middle Ordovician trilobite Triarthrus becki
Authors: Kim Keonho , Sheets H. David , Haney Robert A. , Mitchell Charles E.
Published: July 2006

Traditionally, the distinction between meraspis and holaspis among trilobites has been based on the achievement of the full adult complement of thoracic segments. Using a large sample (over 700 specimens collected from a single bed) we explore the utility of employing the ontogenetic trajectory of the cranidium as an alternative means to differentiate trilobite growth stages. This method is particularly useful for species represented solely by exuviae and disarticulated individuals. We use geometric morphometrics to examine shape change among cranidia ranging in size from 0.9 mm to 11.6 mm in cephalic length. The 114 measured specimens exhibit a rather continuous gradation in size in which no distinct instars are evident.

The meraspid and holaspid specimens exhibit allometry when partial warp scores and uniform components of shape derived from thin-plate spline analysis are regressed onto log centroid size. To describe allometric shape change, deformation vectors from the smallest to the largest specimen in both ontogenetic stages are presented in three different superimposition settings by using a new software program. We have concluded that a new superimposition method (the Sliding Baseline Registration) is a useful tool for visualizing allometry in organisms that contain an axis of symmetry. As a result, we conclude that allometry is evident in meraspides and holaspides, but the degree of allometry in holaspides is very small relative to that in meraspides. The boundary between meraspis and holaspis in Triarthrus becki appears to correspond to a large change in the rate of ontogenetic change, but neither to a change in the direction of that trajectory nor to a cessation of ontogenetic change. This boundary also corresponds to a cranidium centroid size that matches well previous determinations that holaspis begins at about 2.8 mm in cephalic length.
New evidence for the lack of C4 grassland expansions during the early Pliocene at Langebaanweg, South Africa
Authors: Franz-Odendaal Tamara A. , Lee-Thorp Julia A. , Chinsamy Anusuya
Published: July 2006

Major C4 grass expansions during the late Miocene in both the Northern and Southern Hemispheres had a major impact on biological communities. We report that the diverse terrestrial fauna of Langebaanweg, South Africa, existed in a local environment that remained C3-dominated during the late Neogene (~5 Ma). In contrast, other Southern Hemisphere sites at similar latitudes show a clear shift to C4 grasslands well before 5 Ma. Our results are based on stable isotope analyses of enamel carbonate from four artiodactyl and two perissodactyl families from this locality. We also provide insight into the evolution of the current Mediterranean climate system in this part of South Africa.
Paleoecology of Dominican amber preservation: spider (Araneae) inclusions demonstrate a bias for active, trunk-dwelling faunas
Authors: Penney David
Published: July 2006

The Dominican Republic amber, as a data set for ecological investigation, is subject to unique biases. To understand the paleoecology of Hispaniola during the Miocene it is not sufficient only to identify the amber inclusions, the biases of entrapment also need to be elucidated. This study compares the spider (Araneae) fauna from Recent Neotropical rainforests with assemblages from Dominican Republic amber deposits. This comparison demonstrates that the site of the original resin secretion is farther removed from the ground layer than has previously been suggested. In many spider families, particularly the web weavers, mature males lead an active lifestyle as they roam in search of the more sedentary females. Male spiders are significantly more common as amber inclusions than females. When the sex ratios of preserved spiders are examined in relation to the predation strategies of their extant relatives, at family level, wandering spiders appear more susceptible to entombment than sedentary spiders. This implies that spiders, and presumably other co-occurring organisms, were trapped primarily by wandering onto sticky resin rather than by being engulfed passively by less viscous, flowing resin.
Size patterns through time: the case of the Early Jurassic ammonite radiation
Authors: Dommergues Jean-Louis , Montuire Sophie , Neige Pascal
Published: July 2006

The shell size of 1236 ammonite species representing all known Early Jurassic faunas is analyzed. Size patterns are studied for the entire period and then at the biozone scale for the first four stages of the Jurassic (28 Myr), during which ammonites recovered from the crisis at the Triassic/Jurassic (T/J) boundary. Our analysis reveals that (1) a size continuum (normal distribution from “dwarfs” to “giants”) exists for all Early Jurassic ammonites; (2) although there are no sustained trends (e.g., no Cope's rule), the succession is not monotonous and patterns may differ conspicuously from one biozone to the next; and (3) increases and decreases in size range are the most frequent evolutionary styles of size change. The only pattern that can be connected with a particular episode of Early Jurassic ammonite history is the initial increase in size disparity during the first four biozones attributable to phyletic radiation after the T/J crisis. Subsequent correlations with environmental constraints (e.g., sea-level changes), although suspected, cannot be shown.
Variation and covariation of skulls and teeth: modern carnivores and the interpretation of fossil mammals
Authors: Dayan Tamar , Wool David , Simberloff Daniel
Published: July 2006

Teeth are generally the best-preserved elements among mammal fossil remains and are highly diagnostic characters. Consequently, much mammalian paleontological, systematic, and evolutionary research focuses on teeth, so it is important to understand how they vary and covary with other characters. Dental traits within populations of carnivores appear to be more variable than cranial traits, a pattern that results only partly from their usually smaller size. Furthermore, dental traits, although highly correlated with one another, are not highly correlated with cranial traits, which are also highly correlated with one another. Thus, teeth and cranial bones may be subject to quite different selective pressures and genetic/developmental constraints and may suggest different microevolutionary scenarios. Vestigial teeth show significantly greater variability than expected, reflecting the absence of stabilizing selection.
Dinosaurian and mammalian predators compared
Authors: Van Valkenburgh Blaire , Molnar Ralph E.
Published: July 2006

Theropod dinosaurs were, and mammalian carnivores are, the top predators within their respective communities. Beyond that, they seem distinct, differing markedly in body form and ancestry. Nevertheless, some of the same processes that shape mammalian predators and their communities likely were important to dinosaurian predators as well. To explore this, we compared the predatory adaptations of theropod dinosaurs and mammalian carnivores, focusing primarily on aspects of their feeding morphology (skulls, jaws, and teeth). We also examined suites of sympatric species (i.e., ecological guilds) of predatory theropods and mammals, emphasizing species richness and the distribution of body sizes within guilds. The morphological comparisons indicate reduced trophic diversity among theropods relative to carnivorans, as most or all theropods with teeth appear to have been hypercarnivorous. There are no clear analogs of felids, canids, and hyaenids among theropods. Interestingly, theropods parallel canids more so than felids in cranial proportions, and all theropods appear to have had weaker jaws than carnivorans. Given the apparent trophic similarity of theropods and their large body sizes, it was surprising to find that species richness of theropod guilds was as great as or exceeded that observed among mammalian carnivore guilds. Separation by body size appears to be slightly greater among sympatric theropods than carnivorans, but the magnitude of size difference between species is not constant in either group. We suggest that, as in modern carnivoran guilds, smaller theropod species might have adapted to the threats posed by much larger species (e.g., tyrannosaurs) by hunting in groups, feeding rapidly, and avoiding encounters whenever possible. This would have favored improved hunting skills and associated adaptations such as agility, speed, intelligence, and increased sensory awareness.
Lack of a pheromonal sense in phytosaurs and other archosaurs, and its implications for reproductive communication
Authors: Senter Phil
Published: July 2006

The vomeronasal (VN) system is a pheromone-processing sensory system of tetrapods. Tetrapods use pheromones to communicate territorial boundaries, reproductive status, sex, and species identity. Presumed impressions of VN bulbs on phytosaur frontals led to a claim that phytosaurs possessed the VN system. However, in extant crocodilians, which lack the VN system, the corresponding impressions are associated not with cerebral tissue but with the ophthalmic nerves. Phytosaur head morphology was not conducive to pheromone collection. The extant phylogenetic bracket suggests that all extinct archosaurs, including phytosaurs, lacked the VN system. Without the pheromonal sense, they would not have used chemical means to convey territorial boundaries, reproductive status, sex, and species identity. Instead, they would have used visual, acoustic, and tactile cues, as in extant archosaurs and other tetrapods in which the VN sense is reduced or absent.
Does global diversity mean anything?
Authors: Vermeij Geerat J. , Leighton Lindsey R.
Published: July 2006

A major goal of paleobiological research since the early 1960s has been the reconstruction in quantitative terms of the history of biological diversity. Spearheaded by Valentine (1969), Raup (1972, 1976a, b), and Sepkoski (1979, 1981, 1984, 1990, 1993), this effort has yielded estimates of global diversity through time, as well as calculations of global rates and magnitudes of extinction and diversification. A consensus emerging in the early 1980s (Sepkoski et al. 1981) indicated that global marine invertebrate diversity rose through the Cambrian and Ordovician periods to a plateau, which with brief extinction-related interruptions was maintained from the mid-Paleozoic to the mid-Mesozoic. Beginning in the Cretaceous, diversity rose again, reaching a peak in the late Neogene. The five mass extinctions of the Phanerozoic, and more or less distinct episodes of diversification, were identified and distinguished from many lesser events (Raup and Sepkoski 1982). Comparable studies, with varying results, were conducted on land vertebrates (Benton 1985, 1989), land plants (Knoll et al. 1979; Niklas et al. 1980, 1983; Tiffney 1981; Knoll 1984), early protistans (Knoll 1994), insects (Labandeira and Sepkoski 1993), and life as a whole (Van Valen 1984, 1985; Van Valen and Maiorana 1985; Signor 1990; Valentine et al. 1991; Benton 1995; Courtillot and Gaudemer 1996; Miller and Foote 1996).
In praise of the big picture
Authors: Nee Sean
Published: July 2006

When ambitious large-scale projects are proposed, like the Paleobiology Database (Alroy et al. 2001) and Panama Paleontology Projects (Jackson and Johnson 2001), there is inevitably a negative reaction from various quarters, which is quickly forgotten when the projects start to yield results. Given that, it may be useful to sing the praises of “big picture” science more generally and I will do so after briefly addressing this discussion starter in the context of my own research.
The multiple scales of biodiversity
Authors: Badgley Catherine
Published: July 2006

The claim that measures of global biodiversity dynamics are meaningless is based upon several methodological problems, including underrepresentation of tropical regions in “global” Phanerozoic data sets, inaccuracies in taxonomic data, non-equivalence of higher taxa among groups of organisms, and uneven sampling intensity across groups, environments, and time intervals. Some of these problems are inherent in the fossil record, whereas others lie in documentation and interpretation of the subject. But the subject of global biodiversity is perfectly legitimate, even if problems persist in evaluating its full history. Moreover, recognition of the methodological problems has resulted in notable improvements in the Phanerozoic diversity database (e.g., Adrain and Westrop 2000; Alroy et al. 2001).
On global biodiversity estimates
Authors: Wilson Edward O.
Published: July 2006

All measurements and estimates have meaning, if consistent with peer-reviewed data and gifted with heuristic value. In pure science, we judge measures and estimation techniques by their importance to theory. We devise them for maximum relevance, and advance their reliability and precision by successive approximations. If better measures and estimation techniques come along, either by shifts in theoretical context or advances in technology, we discard the old and use the new.
On the importance of global diversity trends and the viability of existing paleontological data
Authors: Miller Arnold I.
Published: July 2006

Regardless of the macroevolutionary issues at stake, most students of biodiversity would agree that there is value in calibrating global biodiversity trends through critical intervals. To cite one obvious example, given the overwhelming interest in mass extinctions, we would certainly like to know the extent to which diversity declined during these events. Just as significantly, if we are to argue that any mass extinction was truly a global phenomenon, we must demonstrate definitively that its biotic effects reached around the world. Clearly, “standard” global compendia (e.g., Sepkoski 1992, 2002) are insufficient for the latter objective, because they contain no geographic or environmental information. At the least, a database that compares biodiversity transitions among different regions or paleoenvironments is required. Such analyses have the added benefit of providing opportunities to evaluate geographic and environmental selectivity in extinctions, an important facet of any attempt to understand what caused them (e.g., Raup and Jablonski 1993; Jablonski and Raup 1995).
New data for old questions
Authors: Johnson Kenneth G.
Published: July 2006

Global biodiversity dynamics result in large-scale patterns of change in the variety of life on earth. One deceptively simple measure of global biodiversity is the total count of species or supraspecific taxa that have been described from each subinterval of the Phanerozoic record. These tallies usually are obtained from data compilations based on extensive literature searches supplemented with examination of collections in museums (Sepkoski 1993; Alroy et al. 2001). Such measures of global biodiversity dynamics are probably not meaningless, but it is difficult to understand what they mean. The number of taxa alive on Earth at any one time is a function of innumerable ecological factors acting at the full range of temporal and spatial scales (Willis and Whittaker 2002). Changes in global richness might result from increasing local richness as local communities become more complex (Valentine 1969; Bambach 1977). At the regional scale, changing oceanographic conditions, climate, and the relative positions of continents and shallow seas might alter global taxonomic diversity by changing the size and arrangement of biogeographic units (Valentine 1970). Therefore, the best hope for understanding global diversity patterns is to collect information on local assemblages. These hierarchically organized data can then be integrated to test alternate hypothetical mechanisms of change. Data compiled as the endpoints of stratigraphic or geographic ranges are useless for this purpose. This has been known at least since Bambach (1977) explored patterns of change in alpha diversity of level-bottom marine communities.
Paleobiodiversity: we need new data
Authors: Adrain Jonathan M. , Westrop Stephen R.
Published: July 2006

Very different questions are involved when we attempt to assess modern versus ancient global biodiversity. Because of the megabiases of taphonomy, eustasy, and tectonics, our estimates of paleobiodiversity can never be absolute; whether or not we can accurately estimate total diversity in the modern world is an open question, but we certainly cannot in the fossil record. The issues are whether we have any way of studying relative change in biodiversity through time, and how best this might be accomplished. That is, can we meaningfully estimate the shape of a global temporal diversity curve?
Global databases will yield reliable measures of global biodiversity
Authors: Alroy John
Published: July 2006

For decades, paleobiologists have treated global diversity estimation as a straightforward problem (Miller 2000): count up the known higher taxa in each geological time interval, make a diversity curve, and go straight ahead to analyzing and interpreting the trends. However, global diversity curves recently have come under attack from all sides. Some researchers argue that although traditional curves are strongly affected by sampling biases (e.g., Smith 2001; Peters and Foote 2002), these biases can be corrected by assembling large, locality-level databases with detailed contextual information (Alroy et al. 2001). Others point to the large gap between true total global richness and the meager head counts the fossil record has to offer, and conclude that workers should focus exclusively on local and regional diversity (Jackson and Johnson 2001). Here I argue that although further fieldwork surely is needed, understanding global diversity in the short term remains a tractable goal—as long as we move quickly to build a discipline-wide, globally extensive paleontological database.
Challenges to understanding dynamics of biodiversity in time and space
Authors: Willig Michael R.
Published: July 2006

The negative consequences of anthropogenic activities such as agriculture and urbanization (e.g., deforestation, greenhouse gas emissions, and pollution) have become exacerbated by rapid rates of human population increase (see Pimm et al. 2001). Subsequent habitat loss and modification has accelerated rates of extinction, creating a biodiversity crises which arguably is one of the most pressing problems of the twenty-first century. Although causative agents are unclear, the fossil record suggests that biotas undergo periods of massive extinction as well as considerable diversification (Alroy et al. 2001; Jackson and Johnson 2001) at the global scale, even in the absence of human activities. As such, quantifying the spatial and temporal dynamics of biodiversity in past and contemporary times, and understanding their mechanistic bases represent disciplinary emphases of evolutionary and environmental biology. Equally important, such understanding is a critical step in informing regional as well as global management strategies and conservation efforts. Nonetheless, considerable controversy or uncertainty exists surrounding the patterns, underlying mechanisms, and strategies of conservation (Willig 2000; Andelman and Willig 2002). The past may provide important insights into a number of relevant issues regarding contemporary biodiversity (and vice versa), but only recently has the dialogue between neontologists and paleontologists charted productive areas of collaboration. Indeed, a growing body of work has questioned the meaning of global measures of biodiversity (past or present) and has suggested that only detailed studies at local sites provide resolution to important issues about biodiversity. This is due, in part, to considerable sampling problems associated with broad-scale estimation, including the averaging of local and regional patterns.
Getting the measure of diversity
Authors: Smith Andrew B.
Published: July 2006

Paleontological data have for long been paramount in providing a long-term perspective on global biodiversity. But all is not as simple and secure as it once seemed. Apparently rapid diversification events recorded in the fossil record have been challenged by new molecular data (Bromham et al. 1999; Wray 2001; reviewed in Smith and Peterson 2002), certain mass extinctions are not as well founded as was previously supposed (Smith et al. 2001; Peters and Foote 2002b), and even such a deeply cherished belief as the long-term trend of increasing diversity through the Phanerozoic is once again under question (Alroy et al. 2001; Peters and Foote 2002a). Why is the fossil record not currently providing us with reliable, clear-cut data, and what can be done to correct the situation?
Applicability and resolving power of statistical tests for simultaneous extinction events in the fossil record
Authors: Payne Jonathan L.
Published: July 2006

The recognition that past catastrophic events may have caused the simultaneous extinction of many taxa has prompted the development of statistical tests to determine the compatibility of the fossil record with such scenarios. Statistical tests necessitate simplifying assumptions, the most significant of which are continuous (as opposed to discrete) data in the sampling of the fossil record and random distribution of fossil occurrences because constant preservation potential and collecting intensity of fossils are assumed. The assumption of random distribution of fossil occurrences has been addressed quantitatively, but the continuity of data has not. The assumption of continuous data is not trivial, for although collecting may appear continuous, the resulting data are never strictly continuous because the stratigraphic positions of fossils are known with limited precision. For one test of simultaneous extinction, simulations demonstrate that the data behave in a less continuous manner as the occurrence rate increases, decreasing the reliability of the test at higher occurrence rates. Out of mathematical simplicity, nearly all tests use simultaneous extinction as the null hypothesis. However, even under ideal sampling circumstances, gradual extinctions that occurred over a sufficiently short stratigraphic interval are likely to be statistically indistinguishable from extinction occurring at a single horizon. Therefore, a range of gradual extinction scenarios will also be compatible with the fossil record even if the null hypothesis is not rejected. Because direct tests of gradual extinction scenarios have not yet been developed, simulations were used to determine the probability that an extinction occurring over a given stratigraphic distance with a given number of taxa will be statistically indistinguishable from extinction at a single horizon. The simulation results allow the test results to be used to define a range of extinction scenarios compatible with the fossil record. Finally, the simulation results were applied to two Late Cretaceous ammonite data sets. Although both data sets sufficiently approximate continuous sampling for the use of statistical tests, the method shows that the data are not always sufficient to rule out either stratigraphically simultaneous extinction or a literal reading of extinction rate as representing gradual or episodic extinction.
Taphonomy and ecology of modern avifaunal remains from Amboseli Park, Kenya
Authors: Behrensmeyer Anna K. , Stayton C. Tristan , Chapman Ralph E.
Published: July 2006

Avian skeletal remains occur in many fossil assemblages, and in spite of small sample sizes and incomplete preservation, they may be a source of valuable paleoecological information. In this paper, we examine the taphonomy of a modern avian bone assemblage and test the relationship between ecological data based on avifaunal skeletal remains and known ecological attributes of a living bird community. A total of 54 modern skeletal occurrences and a sample of 126 identifiable bones from Amboseli Park, Kenya, were analyzed for weathering features and skeletal part preservation in order to characterize preservation features and taphonomic biases. Avian remains, with the exception of ostrich, decay more rapidly than adult mammal bones and rarely reach advanced stages of weathering. Breakage and the percentage of anterior limb elements serve as indicators of taphonomic overprinting that may affect paleoecological signals. Using ecomorphic categories including body weight, diet, and habitat, we compared species in the bone assemblage with the living Amboseli avifauna. The documented bone sample is biased toward large body size, representation of open grassland habitats, and grazing or scavenging diets. In spite of this, multidimensional scaling analysis shows that the small faunal sample (16 out of 364 species) in the pre-fossil bone assemblage accurately represents general features of avian ecospace in Amboseli. This provides a measure of the potential fidelity of paleoecological reconstructions based on small samples of avian remains. In the Cenozoic, the utility of avian fossils is enhanced because bird ecomorphology is relatively well known and conservative through time, allowing back-extrapolations of habitat preferences, diet, etc. based on modern taxa.
Origins and escalation of herbivory in fishes: a functional perspective
Authors: Bellwood David R.
Published: July 2006

One of the central goals in paleoecology is to understand the nature and consequences of biotic interactions. In marine systems, it has been argued that one of the major steps in the escalation of biotic interactions was marked by the origins of grazing fishes in the Cenozoic. Here I investigate the origins of herbivory and grazing in marine fishes using analyses of functional morphospace. Closing and opening lever ratios and relative length of the lower jaw are used to construct a plot of functional morphospace, a quantitative description of the potential feeding modes of fishes. Four fish faunas were examined, spanning the Mesozoic and Cenozoic (Triassic, Jurassic, Eocene and Recent). All three fossil faunas are from conservation Lagerstätten in the central Tethys, in the vicinity of coral reefs or coral-bearing hardgrounds. Changes in functional morphospace occupation reveal a marked shift in the Cenozoic, with the appearance of fishes with relatively small forceful jaws. In Recent faunas, this functional morphospace is occupied almost exclusively by grazing herbivores. This taxon-independent morphological signal of herbivory was lacking in the Mesozoic faunas, was first recorded in the Eocene, and persisted throughout the Cenozoic. This suggests that the Cenozoic did indeed witness the appearance and proliferation of herbivory and grazing by marine fishes. The arrival of these piscine herbivores had the potential to fundamentally alter the dynamics of benthic marine communities.
Ecological conservatism in the “living fossil”Ginkgo
Authors: Royer Dana L. , Hickey Leo J. , Wing Scott L.
Published: July 2006

The living speciesGinkgo bilobais phylogenetically isolated, has a relictual distribution, and is morphologically very similar to Mesozoic and Cenozoic congenerics. To investigate what adaptations may have allowed this lineage to persist with little or no morphological change for over 100 Myr, we analyzed both sedimentological and floral data from 51 latest Cretaceous to middle MioceneGinkgo-bearing fossil plant sites in North America and northern Europe. The resulting data indicate that throughout the late Cretaceous and CenozoicGinkgowas largely confined to disturbed streamside and levee environments, where it occurred with a consistent set of other plants. These inferred habitats are surprising because the life-history traits ofGinkgo(e.g., slow growth rate, late reproductive maturity, extended reproductive cycle, large and complex seeds, large and slowly developing embryos) are counter to those considered advantageous in modern disturbed habitats. Many flowering plant lineages first appeared or became common in disturbed riparian habitats, and are inferred to have had reproductive and growth traits (e.g., rapid reproduction, small easily dispersed seeds, rapid growth) suited to such habitats. Paleoecological inferences based on both morphology and sedimentary environments thus support the idea thatGinkgowas displaced in riparian habitats by angiosperms with better adaptations to frequent disturbance.
Evidence for advanced carnivory in fossil armadillos (Mammalia: Xenarthra: Dasypodidae)
Authors: Vizcaíno Sergio F. , De Iuliis Gerardo
Published: July 2006

The euphractine Macroeuphractus outesi, from the late Pliocene Chapadmalalan SALMA of Buenos Aires Province, Argentina, is one of the largest dasypodids known. Its skull preserves features remarkable for an armadillo. Its complete dental arcade and large caniniform teeth have received attention in the literature as indicative of scavenging behavior. This report considers the degree of carnivory within the context of the generally omnivorous feeding behavior of euphractine armadillos through morphological and biomechanical analyses. Morphological analyses reveal that the main differences between M. outesi and other euphractines are the enlargement of the cranium, particularly of the temporal fossa; more prominent muscular scars for origin of the temporalis muscle; a more expanded rostrum, particularly in dorsoventral height; a more powerful anterior dentition, especially in the great enlargement and caniniform modification of M2; and a deeper and more robust zygomatic arch. Biomechanical analyses indicate that the moment arm of the temporalis musculature is greater than that recorded for other armadillos. These analyses indicate that the temporalis was probably larger and played a more important role in Macroeuphractus than in other euphractines, a pattern that is more usual for carnivorous mammals. Combined with the second upper molariform, which is caniniform, the features suggest that Macroeuphractus occupied an extreme position in the carnivorous-omnivorous feeding behavior of euphractines. Its large size indicates that it could have easily preyed on hare-sized vertebrates.
The ontogenetic dynamics of shape disparity
Authors: Zelditch Miriam Leah , Sheets H. David , Fink William L.
Published: July 2006

Disparity appears to decrease or remain stable over geological time in numerous groups. This pattern is sometimes explained in terms of developmental constraints, but labile developmental systems might produce the same pattern should novelties interact, counterbalancing their individual effects. We test the hypothesis that counterbalancing can reduce disparity by comparing ontogenies of shape among nine species of piranhas to identify the developmental novelties. All three parameters examined change multiple times, sometimes dramatically. By comparing levels of disparity between species at two developmental phases, at the transition from larval to juvenile phases, and at maximum adult body size, we find that disparity decreases significantly and substantially over ontogeny. That reduction occurs because of, rather than despite, novelties of postlarval morphogenesis. Some interacting novelties are historically independent and affect different developmental phases, others are historically independent and affect the same developmental phase, and still others are historically correlated and affect either the same or different developmental phases. By modeling hypothetical ontogenies, constraining developmental parameters mathematically to one of the observed values, we find that variation in each parameter, taken by itself, and combinations of them taken two at a time, tend to increase disparity. It is the interactions among all three that reduce disparity. In this group divergent ontogenies transform disparate larvae into similar adults.
An Integrated Anaerobic/Aerobic Bioprocess for the Remediation of Chlorinated Phenol‐Contaminated Soil and Groundwater
Authors: Ehlers George A. , Rose Peter D.
Published: July 2006

An investigation of biodegradation of chlorinated phenol in an anaerobic/aerobic bioprocess environment was made. The reactor configuration used consisted of linked anaerobic and aerobic reactors, which served as a model for a proposed bioremediation strategy. The proposed strategy was studied in two reactors before linkage. In the anaerobic compartment, the transformation of the model contaminant, 2,4,6‐trichlorophenol (2,4,6‐TCP), to lesser‐chlorinated metabolites was shown to occur during reductive dechlorination under sulfate‐reducing conditions. The consortium was also shown to desorb and mobilize 2,4,6‐TCP in soils. This was followed, in the aerobic compartment, by biodegradation of the pollutant and metabolites, 2,4‐dichlorophenol, 4‐chlorophenol, and phenol, by immobilized white‐rot fungi. The integrated process achieved elimination of the compound by more than 99% through fungal degradation of metabolites produced in the dechlorination stage. pH correction to the anaerobic reactor was found to be necessary because acidic effluent from the fungal reactor inhibited sulfate reduction and dechlorination.
Managing Dual-Use Technology in an Age of Uncertainty
Authors: Reppy Judith
Published: July 2006

'Dual use' refers to those technologies that can, with some adaptation, have both military and civilian applications. It is a concept rooted in the dichotomies of the Cold War. Over the last 55 years it has served both to structure an export control regime aimed at limiting the diffusion of advanced technology to hostile states and to underpin a range of domestic defense acquisition policies aimed at increasing the utilization of civilian technologies by the military. With the end of the Cold War and the erosion of the boundaries between civil and military technologies, U.S. policy to control the spread of military-related technology is in disarray. A more workable policy would replace open-ended support for new military technology with a realistic assessment of the security risks and needs, and limit export controls to a few, highly dangerous technologies.
Back to the Future: Transforming the Army Officer Development System
Authors: Meese Michael , Calkins Samuel
Published: July 2006

As a closed labor force, with limited lateral entry, the military must build officers from within. This means that when significant changes in operating environments occursuch as the end of the Cold War or the aftermath of 9/11changes in the military personnel system can take significant time to affect the composition of the officer corps. Changes at the end of the Cold War in the Army officer development system created greater specialization of officers in their specific career fields, which is both understandable and supportable when viewed in historical context. As the nation addresses the officer development system today, the Army should consider returning to some practices implemented during the Cold War to enhance flexibility and versatility among its officer corps in the post-9/11 environment.
The Effects of a Decoction Prepared from the Leaves and Unripe Fruits of Crataegus aronia in Streptozotocin-Induced Diabetic Rats
Authors: Ljubuncic Predrag , Azaizeh Hassan , Cogan Uri , Bomzon Arieh
Published: July 2006

A decoction of leaves and unripe fruits prepared from C. aronia syn. azarolus (L) (Rosaceae), the indigenous Israeli hawthorn, is used to treat diabetes in Arab traditional medicine. There is a growing body of evidence reporting the presence of systemic oxidative stress in insulin-dependent and non-insulin dependent diabetes. We have already reported that this decoction has antioxidant properties in vitro. In this report, we extended these in vitro observations to study its antioxidant action in the streptozotocin (STZ)-induced diabetic rat in which we measured its effect on plasma and tissue indices of oxidative stress, as well as blood glucose levels. In an experiment lasting 24 days, 30 diabetic and 30 control rats were each subdivided into three separate groups. Group 1 rats drank tap water, group 2 rats drank the decoction containing 50 mg grounded dried plant/mL and group 3 rats drank the decoction containing 350 mg grounded dried plant/mL. Upon completion of the treatment period, the rats were anesthetized and blood glucose was measured using a drop of blood obtained by tail vein puncture. The abdomen was opened and aortic blood was withdrawn for measurement of the plasma levels of lipid peroxides, glutathione, cholesterol and triglycerides and the livers were harvested for determination of the extent of lipid peroxidation. The results of these experiments show that a decoction prepared from the leaves and unripe fruits of C. aronia normalizes plasma lipid peroxide levels and lowers blood glucose levels in diabetic rats. These findings indicate that the therapeutic benefit of the decoction could be due to these two actions, thereby providing a basis for its use in treating diabetes in traditional Arab medicine.
Survey of the Peace Economics Literature: Recent Key Contributions and a Comprehensive Coverage Up to 1992 (Part I)
Authors: Isard Walter , Anderton Charles H.
Published: July 2006

In this paper we wish to make generally available a comprehensive survey of the peace economics literature up to 1992, printed at that time in a very high-priced book unaffordable by most scholars and university and college libraries. This survey constitutes Part II of this paper. To this survey we wish to add contributions on certain topics of continuing major concern, and cover somewhat extensively new literature on intra-national conflict, a subject which recently has become of critical, world-wide importance. These additions are in Part I of this paper.
An Economic Analysis of Health Plan Conversions: Are They in the Public Interest?
Authors: Beaulieu Nancy Dean
Published: July 2006

Over the last decade, managed-care companies have been consolidating on both a regional and national scale. More recently, nonprofit health plans have been converting to for-profit status, and this conversion has frequently occurred as a step to facilitate merger or acquisition with a for-profit company. Some industry observers attribute these managed-care marketplace trends to an industry shakeout resulting from increased competition in the sector. At the same time, these perceived competitive pressures have led to questions about the long-run viability of nonprofit health plans. Furthermore, some industry and government leaders believe that some nonprofits are already conducting themselves like for-profit health plans and question the state premium tax exemption ordinarily accorded to such plans. This paper examines related health policy issues through the lens of a case study of the proposed conversion of the CareFirst Blue Cross Blue Shield company to a for-profit public-stock company and its merger with the Wellpoint Corporation. Company executives and board members argued that CareFirst lacked access to sufficient capital and faced serious threats to its viability as a financially healthy nonprofit health care company. They also argued that CareFirst and its beneficiaries would benefit from merger through enhanced economies of scale and product-line extensions. Critics of the proposed conversion and merger raised concerns about the adverse impacts on access to care, coverage availability, quality of care, safety-net providers, and the cost of health insurance. Analyses demonstrate that CareFirst wields substantial market power in its local market, that it is unlikely to realize cost savings through expanded economies of scale, and that access to capital concerns are largely driven by the perceived need for further expansion through merger and acquisition. Although it is impossible to predict future changes in quality of care for CareFirst, analyses suggest that quality appears to be somewhat lower in for-profit national managed-care companies. Additional research is needed to assess the viability of true nonprofits, the potential effects of nonprofits and for-profit national managed-care plans on the evolution of local insurance andprovider markets, and methods for effective oversight of nonprofit healthplans.
Novel soluble aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties: characterization and optical properties
Authors: Schab-Balcerzak Ewa , Grabiec Eugenia , Jarząbek Bożena , Grobelny Łukasz , Kurcok Małgorzata , Mazurak Zbigniew
Published: July 2006

A series of aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties and the amide units in the main chain have been synthesized by solution polycondensation reaction of newly prepared diamidedianhydride with several aromatic diamines: 1,3-phenylenediamine, 3,3′-dimethoxy-biphenyl-4,4′-diamine, 4,4′-oxydianiline, 4,4′-(1,3-phenylenedioxy)dianiline, 4,4′-(9-fluorenylidene)dianiline and 1,5-diaminonaphthalene. Molecular structures of the polymers obtained have been characterized using 13C NMR, 1H NMR and FTIR spectroscopies. The polymers prepared are readily soluble in aprotic polar solvents, and form optically transparent films by solution casting. The resultant poly(amideimide)s have been analyzed by differential scanning calorimetry (DSC), thermogravimetry (TG) and wide-angle X-ray diffraction measurements. They exhibited high levels of thermal stability, with decomposition temperatures in the range 452–494 °C, and high glass transition temperatures (181–278 °C). The optical behavior of these polymers has been investigated in NMP solution as well as in the films. The photoluminescence (PL) spectra of the free-standing films prepared from the poly(amideimide)s exhibited maximum emission bands around 506–525 nm in the green region.