Spatio‐temporal transitions in Paleozoic Bivalvia: A field comparison of upper Ordovician and upper Paleozoic bivalve‐dominated fossil assemblages

Because of the uncertain relationship between relative abundance and taxonomic richness, abundance data are potentially critical components in any analysis of faunal dominance within fossil assemblages. However, such data are often not available in the literature. In this paper, relative abundance data collected during field work at 25 Upper Ordovician and 22 Upper Pennsylvanian to mid‐Permian localities are used to evaluate Paleozoic transitions in the environmental distributions of bivalve molluscs. On the basis of multivariate analyses of these data, it is shown that even early in their history, during the Ordovician, bivalves were generally not restricted in abundance to just marginal environments. They apparently thrived in terrigenous—dominated regions, both nearshore and offshore, but were less abundant in carbonate settings. However, by the late Paleozoic, bivalve abundances had increased in some carbonate environments, in part because of the growing abundances of free‐burrowing suspension‐feeders, which had been substantially less abundant even in terrigenous environments earlier in the Paleozoic. The results of this study corroborate those of a companion analysis, using literature‐derived data, of paleoenvironmental diversity transitions exhibited by Paleozoic Bivalvia.     

Ethnonationalism,ethnic nationalism,and mini‐nationalism: A comparison of Connor,Smith and Snyder

Some terms have been coined to highlight the important relation between nationalism and ethnicity. However, there has been much confusion as to the meaning of such concepts as ‘ethnonationalism’, ‘ethnic nationalism’ and ‘mini‐nationalism’. This article compares the three terms, as used respectively in the works of Walker Connor, Anthony Smith and Louis Snyder. These scholars are selected not only because of their well‐respected position in the study of nationalism but also because their works are representative of each of the three concepts. The comparison finds that since both Connor and Smith emphasized the ethnic dimension of nationalism, their ideas can be presented in one analytical framework. In fact, Connor's ‘ethnonationalism’ and Smith's ‘ethnic nationalism’ overlap with each other. However, Smith's theory of nationalism is comprehensive enough to take care of the fact that the nationalisms of many new states of today's world have no ethnic base at all, whereas Connor's analysis makes no mention of this. In this respect, Smith's model is preferred to that of Connor. Finally, Snyder's ‘mini‐nationalism’ is seen as the least useful concept, since the use of size rather than ethnicity to classify nationalisms does not increase our understanding of the concept.     

Volcanic impacts on the Holocene vegetation history of Britain and Ireland? A review and meta-analysis of the pollen evidence

Volcanic ash layers show that the products of Icelandic volcanism reached Britain and Ireland many times during the Holocene. Historical records suggest that at least one eruption, that of Laki in a.d. 1783, was associated with impacts on vegetation. These results raise the question: did Icelandic volcanism affect the Holocene vegetation history of Britain and Ireland? Several studies have used pollen data to address this issue but no clear consensus has been reached. We re-analyse the palynological data using constrained ordination with various representations of potential volcanic impacts. We find that the palynological evidence for volcanic impacts on vegetation is weak but suggest that this is a case of absence of evidence and is not necessarily evidence of absence of impact. To increase the chances of identifying volcanic impacts, future studies need to maximise temporal resolution, replicate results, and investigate a greater number of tephras in a broader range of locations, including more studies from lake sediments.     

Ontogenetic sequence comparison of extant and fossil tadpole shrimps: no support for the “living fossil” concept

The tadpole shrimp Triops cancriformis (Branchiopoda, Eucrustacea) is often referred to as a “living fossil.” This term implies that the morphology of a species has barely changed for hundreds of millions of years; in the case of T. cancriformis, for about 200 million years. In 1938, Trusheim documented fossil notostracans from the Upper Triassic of southern Germany (237–200 million years) and named them T. cancriformis minor due to their small size compared to modern forms of T. cancriformis. We compared the ontogenetic sequence of the fossil forms to that of modern forms. Fossil material came from the Museum Terra Triassic in Euerdorf and originated from the same geological formation (the Hassberge Formation) as the Trusheim material, which is considered to be nearly entirely lost. The specimens were documented using cross-polarized light and processed into high-resolution images. Fluorescence microscopy was used to document exuviae and carcasses of extant representatives of T. cancriformis. Both forms showed an elongation and similar trends in the length/width ratio of the shield during ontogeny. However, differences were found in the starting point of the developmental processes. Fossil forms start out with a more roundly shaped shield, which becomes more elliptical, while extant forms already start with a more elliptical shield shape. Further differences between extant and fossil forms were found upon comparing shield to trunk ratios. All differences are highly significant statistically. These differences in ontogeny cast severe doubt on the interpretation that T. cancriformis has been static for 237 million years. While the term “living fossil” is misleading and its use should be discouraged in general, it seems to be especially inappropriate to apply it to T. cancriformis.     

Holocene vegetation of the Van area: palynological and chronological evidence from Söğütlü, Turkey

Evidence of the terrestrial pollen precipitation in the Van area, obtained from the marsh of Söütlü, is compared with the lacustrine record from Lake Van, eastern Turkey. The radiocarbon chronology of the vegetation history of the Van area is compared with that from varve counting. The first method produced the most probable results, supported by palynological investigations in other parts of Turkey and Iran. The combination of radiocarbon dating and palynological correlation dates the sediments of Lake Van 1100 to 2200 years older than the varve dating.The indicator value of Cerealia-type pollen as evidence of prehistoric agriculture is discussed and compared with results from observations on modern crops. In the present study, Cerealia-type pollen may have been produced by wild grasses growing in the marsh.     

Mammalian predator–prey relationships and reoccupation of burrows in the Pliocene of the Pampean Region (Argentina): new ichnological and taphonomic evidence

Here we describe an unusual fossil assemblage found inside a crotovine from the late Pliocene Chapadmalal ‘Formation’ (Buenos Aires Province). This assemblage contains the greatest vertebrate diversity recovered inside an ichnofossil of this type, including skeletal remains of dasypodids, didelphids, procyonids, anurans and caviomorph rodents within coprolites and disaggregated scatological waste. We describe four general size types for crotovines and palaeoburrows found in the Pliocene to Holocene of Argentina and Brazil, of which the structure found corresponds to the ‘mid-large’ size type and is linked to the activity of the large dasypodid Ringueletia simpsoni. The scatological remains are assigned to a small-sized carnivorous mammal with a body mass of between 1 and 6 kg. Within the guild of Chapadmalalan omnivorous–carnivorous mammals, this inferred mass range is restricted to large didelphids and mid-sized procyonids (represented in the assemblage by Thylophorops chapadmalensis and Cyonasua lutaria, respectively). The data gathered here confirms that the reoccupation of burrows is a common behaviour in small-sized carnivorous mammals at least since the early Pliocene. In addition, we suggest a predator–prey relationship between the studied carnivores and the most abundant small fossorial mammals of the Pampean Pliocene.     

Corimbatichnus fernandezi: A cluster of fossil bee cells from the late cretaceous‐early tertiary of Uruguay

Corimbatichnus fernandezi n.igen, n. isp. is a cluster of fossil bee cells from the Uruguayan Late Cretaceous‐early Tertiary Asencio Formation. It is composed of rows of small excavated cells contained in paleosol peds. Cells have inner surfaces somewhat rough and are closed with loose material. Separation among cells is very thin, and the cells are orientated uniformly, showing a great economy of space as in some halictine constructions. Corimbatichnus can be distinguished from Rosellichnus and Uruguay by its convex face, excavated cells and the spatial arrangement of them.     

Balanoglossites Mägdefrau, 1932 from the middle triassic of Germany: part of a complex trace fossil probably produced by burrowing and boring polychaetes

The ichnogenusBalanoglossites Mägdefrau, 1932 is re-described from its type area and is interpreted as part of a complex trace fossil comprising both burrow and boring components. The type ichnospecies,B. triadicus, consists of predominantly deep U- or Y-shaped tunnel elements, whereasB. ramosus n. isp. encompasses irregularly ramified galleries. Both ichnospecies occur frequently in firmground and hardground substrates with sporadic epikarst features. In the underlying softground, they may integrate intoLabyrintichnus terrerensis Uchman &; Álvaro, 2000, a network of irregular galleries and communicating shafts. On the omission surface, the tunnels are linked to elongated or winding grooves in hard or firm substrates. Further elements of the complex trace fossil include lobate burrows similar toZoophycos andRhizocorallium, mainly occurring in firmground and softground, shallow to deep U-shaped pouches and winding tunnels (Maeandropolydora sulcans Voigt, 1965) in hard and firm substrates. Finally, some tunnel portions and well preserved top surfaces of the ichnofabrics are scattered with the faecal pelletsCoprulus oblongus Mayer, 1952.C. oblongus has a rounded shape and a homogeneous structure and belongs to the Coprulidae n. ichnofam. Based on the numerous fingerprints preserved in the complex trace fossil, polychaete worms are identified as possible tracemakers. This is in accordance with the close combination of borings and burrows, a tunnel system highly variable in shape and size, blind ending side-branches and tunnel terminations, association with scolecodonts and exceptionally preserved polychaete remains. In addition, different commensals may have contributed to the modification of the complex trace fossil.     

Classification,nomenclature and identification of lime swallowtail butterflies: A post‐cladistic analysis (Lepidoptera: Papilionidae)

Specimens taxonomically treated in the Fauna Hawaiiensis were associated by cluster analysis, thereby reconstructing assemblages of Hawaiian carabid beetle species (Coleoptera: Carabidae) observed during the late 19th century. Associations among specimens representing 193 species permit concise hypotheses of habitat preferences for many of the 32 carabid species collected during the early period of European scientific exploration (1872–1902), but not observed since. These associations are consistent with data derived from contemporary biological surveys of Hawai'i. Absence of entire clusters of associated species from recent collections suggests actions of common agents leading to extinction or extreme population reduction. The candidate list of threatened and endangered species of the US. Fish and Wildlife Service established prior to 1994 included one Hawaiian carabid species missing since 1902, versus eight other species collected at various times over the past century. Improvements in knowledge of carabid beetle species’ spatial distribution and temporal persistence derived from recent field survey and taxonomic research demonstrate that the types of criteria used to construct that list must be rejected. Future consideration of official conservation status for any Hawaiian carabid beetle species must take into account the status of ecologically associated species, and the limited likelihood that individuals of all extant species can be consistently observed in nature due to their natural relative rarity or their secretive habits within restricted geographic and ecological distributions. Historical specimen associations serve as the best guides for continuing efforts to monitor known faunal members and to rediscover long‐missing species. These associations also serve to link information concerning individual species with particular habitats.     

The effects of progressive hypoxia on the crustacean cardiovascular system: a comparison of the freshwater crayfish, (Procambarus clarkii ), and the lobster (Homarus americanus)

The heart rate of crayfish (Procambarus clarkii) and lobsters (Homarus americanus) decreased (bradycardia) as partial pressure of O₂ (P O ₂) decreased, yet cardiac output (V _b) was maintained via an increased stroke volume (S _v) to P O ₂s of 40 mmHg and 75 mmHg for crayfish and lobsters, respectively. V _b was redistributed in both animals. Flow through the anterior aorta increased while flow dropped through the posterior aorta and sternal artery to a P O ₂ of 30 mmHg; below this flow was no longer maintained in crayfish. In the lobster, flow increased to the lateral arteries and the ventral thoracic artery while flow through the anterior and posterior aortas, sternal artery and ventral abdominal artery decreased to a P O ₂ of 75 mmHg. Anterior hemolymph flow was maintained or increased in both animals presumably to supply nervous tissue and cephalic sense organs better. Crayfish showed an increase in intracardiac and mean arterial hemolymph pressures as P O ₂ declined. The increased pressures combined with the net increase in cardiac filling pressure and diastolic filling time could have accounted for the increased S _V. The cardiovascular response exhibited by both the crayfish and lobster was P O ₂ dependent; below a critical water P O ₂ active compensation was no longer observed. Accepted: 26 November 1997     

Taphonomic signatures,ichnofacies analysis and depositional dynamics of fossil macro-invertebrate assemblages of the San Juan Raya Formation,Zapotitlán Basin,Puebla, Mexico

In this paper, we describe the taphofacies and ichnofacies from Aptian strata of the San Juan Raya Formation in the Santa Ana Teloxtoc area, Puebla, Mexico. A composite stratigraphic section was analysed on a bed-by-bed scale up to a total thickness of 765.5 m. Our results show the presence of 10 taphofacies and 3 ichnofacies. The taphofacies and ichnofacies interpretation, and its correlation with the sedimentary lithofacies, enabled the determination of a palaeoenvironmental model for the study area that corresponds to a shallow marine, open-coast, clastic system with episodic sedimentation as a product of storm events. This system had several variations in sub-environments, from foreshore to offshore. Foreshore and shoreface environments are characterised by taphofacies Tf1, Tf2, Tf3 and Tf10 and PsI and SkI ichnofacies, representing lower faunal diversity moments (with the exception of Tf3 taphofacies). Meanwhile, taphofacies Tf4, Tf5, Tf6, Tf7, Tf8 and Tf9 were representative of shelf environments and are described as moments of medium-to-high faunal diversity (with the exception of Tf5 taphofacies).     

Holocene thecideide brachiopods from the north‐western Pacific Ocean: Systematics,life habits and ontogeny

Abstract

A new species of the lacazelline brachiopod genus Ospreyella is described from shallow cryptic habitats in Palau, western Caroline Islands and Arnd Atoll, Pohnpei, eastern Caroline Islands, north‐western Pacific Ocean. This new taxon, here named Ospreyella palauensis, and representing the third discovery of a species of Ospreyella from the Indo‐Pacific region, is compared with the other two recently described extant species of the genus, O. depressa Lüter from the Great Barrier Reef, Australia, and O. maldiviana Logan from the Maldive Islands, northern Indian Ocean. An ontogenetic sequence is described for the new species and compared with those previously described for other Holocene lacazellines. Additionally, a study of ontogenetic stages in Thecidellina congregata from Saipan in the Northern Mariana Islands shows early‐stage similarities to those of the new species and other lacazellines. These observations on development in extant forms provide important analogies for comparison with ontogenetic stages in ancestral fossil forms and information which may be useful in reconstructing thecideide phylogenetic history.     

Facies and diagenetic evaluation of the Permian–Triassic boundary interval and basal Triassic carbonates: shallow and deep ramp sections,Hungary

The Permian–Triassic boundary and basal Triassic shallow-marine successions were studied and correlated in sections of two structural units in Hungary (Transdanubian Range and Bükk units). Core sections in the Transdanubian Range unit recovered inner ramp deposits whereas outcrops in the Bükk unit expose deposits of the deeper ramp area of the western Tethys. The inner ramp section (studied ca. 10 m in thickness) is characterized by a succession of dolomites overlain by bioclastic limestones, peloidal grainstones (which recorded the biotic decline) and oolites with finely crystalline limestone interlayers. The deeper ramp section (studied ca. 15 m in thickness) is characterized by a succession of bioclastic limestones and marlstones, mudstone beds (recording the first biotic decline), the ‘boundary shales’ (recording the second biotic decline and the stable carbon isotope marker), mudstones with wackestone laminae, and stromatolite boundstones. Accordingly, oolite formation and microbial micrite precipitation represent carbonate sedimentary responses of end-Permian mass extinction on the carbonate shelf. In both successions, mudstones predominate the upsection, suggesting a relative sea-level rise. The succession of the deep ramp area exhibits a continuous sediment accumulation and the diagenesis here was influenced by marine and marine-derived pore water. The δ¹³C curve shows a continuous change towards more negative values, starting in bioclastic limestones, followed by a sharp symmetric negative peak at the second biotic decline that is a chemostratigraphic marker of the boundary event. Facies and microfacies trend of the inner ramp carbonates in the Transdanubian Range unit exhibits close similarities to that found in many South Alpine sections. Relict peloidal deposits, formed cemented submarine hardground substrate, indicate the extinction level. Sedimentary and diagenetic features of the overlying oolite bedset revealed slightly different depositional environments in the two studied Transdanubian Range unit sections. Petrography of the oolites highlighted shallow burial diagenetic alterations which includes marine cementation, marine-burial replacement and dolomitization. A lack of the specific negative peak in the δ¹³C values is most likely due to the multiple redeposition events of the sedimentary grains. This led to the conclusion that the deeper ramp deposits (e.g., in Bükk unit) have greater potential for recognizing trends in processes, affecting the marine environments and related to the end-Permian mass extinction, at the western Tethys.     

A new Mastodonsauroid Temnospondyl from the Triassic of Algeria: Implications for the biostratigraphy and palaeoenvironments of the Zarzaïtine Series,northern Sahara

We describe a new species of mastodonsauroid temnospondyl from Algeria, Stanocephalosaurus amenasensis nov. sp., on the basis of two exquisite skulls from a Lagerstätte found in the lowermost formation of the Zarzaïtine Series, Illizi Basin, in the area of “La Reculée”, In Amenas region, Algeria. The new species is characterized by subtriangular nostrils with concave lateral borders; small orbits; postfrontals posteriorly very wide; very elongate parietals; smoothly concave posterior margin of the skull; ovoid anterior palatal vacuities; very posteriorly pointed choanae; oval interpterygoid fenestrae; and a short anterior extension of the cultriform process of the parasphenoid. S. amenasensis is different than the Algerian taxa previously erected by Lehman (1971)–“Parotosaurus lapparenti” and “Wellesaurus bussoni”–which we consider nomina dubia. It enlarges the distribution of the genus in northern Gondwana and supports the Early-Middle Triassic age of the lowermost formation of the Zarzaïtine Series. It also suggests that the local palaeoclimate was very seasonal and these aquatic amphibians died massively in a dewatering sebkha.     

Building cross‐cultural coalitions: A case‐study of the Black‐Korean Alliance and the Latino‐Black Roundtable

A case‐study is presented of two Los Angeles‐based cross‐cultural coalitions, the Black‐Korean Alliance [BKA] and the Latino‐Black Roundtable [LBR]. An analysis of the development and eventual dissolution of these two coalitions is presented against the backdrop of the history of relations between the African‐American, Korean‐American and Latino communities of Los Angeles. The central issues leading to the breakup of the two coalitions were: lack of resources, internal power dynamics between coalition partners, nationalistic factions within the broader communities, cross‐cultural dynamics between coalition members, the use of a dialogue model to frame coalition activities, and the analysis of intergroup relations underlying the formation of the coalitions. The applied and theoretical implications of the research are discussed.     

A comparison of the in vitro binding of α-tocopherol to microsomes of lung,liver, heart and brain of the rat

The in vitro binding of α-tocopherol to microsomes of lung, liver, heart and brain of the rat was studied with the insoluble tocopherol ligand presented as a complex with bovine serum albumin. Under these conditions, all microsomes showed nonsaturable binding of α-tocopherol and the amount bound to microsomes was linearly proportional to the concentration of albumin-complexed tocopherol. Increasing the amount of α-tocopherol bound to microsomes in this manner reduced the extent of lipid peroxidation induced by added ferrous iron. The apparent affinities of the microsomes for α-tocopherol, as indicated by the amount bound at a given concentration of albumin-complexed tocopherol, decreased in the order brain > liver ≈ heart > lung. The differences in affinity did not correlate with total fatty acid content (r = − 0.39), total unsaturated fatty acid content (r = − 0.26), or with the content of fatty acids containing two or more double bonds (r = − 0.01). A high positive correlation was found with the content of fatty acids containing three or more double bonds (r = + 0.96). Since lung microsomes contain approx. 6-times the tocopherol levels of liver and brain and about twice that of heart microsomes, these results show that the in vivo levels of microsomal tocopherol do not reflect microsomal affinity for this biological antioxidant.     

Fixed,free, and fixed: The fickle phylogeny of extant Crinoidea (Echinodermata) and their Permian–Triassic origin

Although the status of Crinoidea (sea lilies and featherstars) as sister group to all other living echinoderms is well-established, relationships among crinoids, particularly extant forms, are debated. All living species are currently placed in Articulata, which is generally accepted as the only crinoid group to survive the Permian–Triassic extinction event. Recent classifications have recognized five major extant taxa: Isocrinida, Hyocrinida, Bourgueticrinina, Comatulidina and Cyrtocrinida, plus several smaller groups with uncertain taxonomic status, e.g., Guillecrinus, Proisocrinus and Caledonicrinus. Here we infer the phylogeny of extant Crinoidea using three mitochondrial genes and two nuclear genes from 59 crinoid terminals that span the majority of extant crinoid diversity. Although there is poor support for some of the more basal nodes, and some tree topologies varied with the data used and mode of analysis, we obtain several robust results. Cyrtocrinida, Hyocrinida, Isocrinida are all recovered as clades, but two stalked crinoid groups, Bourgueticrinina and Guillecrinina, nest among the featherstars, lending support to an argument that they are paedomorphic forms. Hence, they are reduced to families within Comatulida. Proisocrinus is clearly shown to be part of Isocrinida, and Caledonicrinus may not be a bourgueticrinid. Among comatulids, tree topologies show little congruence with current taxonomy, indicating that much systematic revision is required. Relaxed molecular clock analyses with eight fossil calibration points recover Articulata with a median date to the most recent common ancestor at 231–252 mya in the Middle to Upper Triassic. These analyses tend to support the hypothesis that the group is a radiation from a small clade that passed through the Permian–Triassic extinction event rather than several lineages that survived. Our tree topologies show various scenarios for the evolution of stalks and cirri in Articulata, so it is clear that further data and taxon sampling are needed to recover a more robust phylogeny of the group.     

Breast‐feeding,social variables,and infant mortality: A hazards model analysis of the case of Malaysia

Abstract

This study is an attempt to use a hazards model to estimate the relative risks of mortality experienced at different periods during the first year of life among Malaysian infants breast‐fed for various durations. Data on mortality, breast‐feeding, and social variables were obtained from the retrospective Malaysian Family Life Survey and were used after checking for quality and consistency. Using LOGLIN to calculate hazards models, essentially multidimensional life‐tables, we found that breast‐feeding had an effect on mortality independent of socio‐economic variables and birth cohort. There was a monotonic relationship between breastfeeding duration and lower infant mortality during each of four subdivisions of the first year of life. Breast‐feeding was a statistically significant predictor of mortality in the first six months. The results are compared with those from the Rand study, which employed regression rather than hazards models.     

Holocene sea level instability in the southern Great Barrier Reef,Australia: high-precision U–Th dating of fossil microatolls

Three emergent subfossil reef flats from the inshore Keppel Islands, Great Barrier Reef (GBR), Australia, were used to reconstruct relative sea level (RSL). Forty-two high-precision uranium–thorium (U–Th) dates obtained from coral microatolls and coral colonies (2σ age errors from ±8 to 37 yr) in conjunction with elevation surveys provide evidence in support of a nonlinear RSL regression throughout the Holocene. RSL was as least 0.75 m above present from ~6500 to 5500 yr before present (yr BP; where “present” is 1950). Following this highstand, two sites indicated a coeval lowering of RSL of at least 0.4 m from 5500 to 5300 yr BP which was maintained for ~200 yr. After the lowstand, RSL returned to higher levels before a 2000-yr hiatus in reef flat corals after 4600 yr BP at all three sites. A second possible RSL lowering event of ~0.3 m from ~2800 to 1600 yr BP was detected before RSL stabilised ~0.2 m above present levels by 900 yr BP. While the mechanism of the RSL instability is still uncertain, the alignment with previously reported RSL oscillations, rapid global climate changes and mid-Holocene reef “turn-off” on the GBR are discussed.