scholarly journals The biostratigraphy of the Upper Pliensbachian-Toarcian (Lower Jurassic) sequence at Ilminster, Somerset

2009 ◽  
Vol 28 (1) ◽  
pp. 67-85 ◽  
Author(s):  
I. Boomer ◽  
A. R. Lord ◽  
K. N. Page ◽  
P. R. Bown ◽  
F. M. D. Lowry ◽  
...  
Keyword(s):  
Lower Jurassic ◽  
Calcareous Nannofossils ◽  
Marked Contrast ◽  
Evolutionary Patterns ◽  
Southern England ◽  
Carbonate Deposit ◽  
Temporary Road ◽  
Insight Into ◽  
Jurassic Sequence

Abstract. Temporary road sections for the A303 bypass at Ilminster, Somerset, revealed Upper Pliensbachian and Toarcian sediments from an alternating limestone–marl facies, in marked contrast to the limestone-dominated Dorset coast succession. The lithostratigraphy is described, with the standard ammonite zonation providing chronostratigraphical correlation. The uppermost Pliensbachian (Spinatum Chronozone) and much of the Toarcian (Serpentinum, Bifrons, Variabilis, Thouarsense and Pseudoradiosa chronozones) of the classic Dorset coast Lower Jurassic sequence are represented by the Beacon Limestone Formation, formerly the ‘Junction Bed’ (a highly condensed carbonate deposit). The Tenuicostatum Chronozone is largely missing from the sequence. Elsewhere in southern and eastern England this interval is poorly or rarely exposed. The argillaceous units have yielded rich microfaunas and -floras (foraminifera, ostracods, calcareous nannofossils and palynomorphs), the biostratigraphical distributions of which are analysed and discussed in relation to contemporary evolutionary patterns and other UK records. This study provides an insight into the micro-biostratigraphy of the Late Pliensbachian to Toarcian interval for onshore southern England.

scholarly journals High resolution integrated microbiostratigraphy of the Lower Jurassic (late Pliensbachian–early Toarcian) of central Italy

1998 ◽  
Vol 17 (2) ◽  
pp. 153-172 ◽  
Author(s):  
Raffaella Bucefalo Palliani ◽  
Emanuela Mattioli
Keyword(s):  
High Resolution ◽  
Evolutionary History ◽  
Central Italy ◽  
Lower Jurassic ◽  
High Potential ◽  
Calcareous Nannofossils ◽  
Calcareous Nannofossil ◽  
Dinoflagellate Cyst ◽  
History Of ◽  
Global Events

Abstract. The integrated use of calcareous nannofossil and dinoflagellate cyst events in a study of the late Pliensbachian–early Toarcian interval in central Italy has yielded a high resolution biostratigraphy. The use of both the first and last occurrences of selected taxa belonging to the two phytoplankton groups allows the dating of the sediments with a very refined detail, even when lithologies are unfavourable to the preservation of one fossil group. The evolutionary history of calcareous nannofossils and dinoflagellate cysts during the early Jurassic and its links with global events are responsible for the high potential of this integrated biostratigraphy.

scholarly journals John H. Herz: realism and the fragility of the international order

2005 ◽  
Vol 31 (2) ◽  
pp. 285-306 ◽  
Author(s):  
Peter Stirk
Keyword(s):  
United States ◽  
International Relations ◽  
The United States ◽  
International Order ◽  
The State ◽  
Marked Contrast ◽  
Insight Into

John H. Herz is a significant, but comparatively neglected, figure in the development of International Relations (IR) as a discipline. Although he contributed to the emergence of realism as the dominant approach to international relations in the United States, his thought is characterised by an insight into the fragility of the international order and the state which stands in marked contrast to the emphasis upon durability and persistence evident in recent surveys of a self-avowed American realism.

scholarly journals Maniraptoran pelvic musculature highlights evolutionary patterns in theropod locomotion on the line to birds

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10855
Author(s):  
Matthew M. Rhodes ◽  
Donald M. Henderson ◽  
Philip J. Currie
Keyword(s):  
Hind Limb ◽  
Soft Tissues ◽  
Morphological Features ◽  
Fundamental Aspect ◽  
Evolutionary Patterns ◽  
Theropod Dinosaurs ◽  
Relative Differences ◽  
Insight Into

Locomotion is a fundamental aspect of palaeobiology and often investigated by comparing osteological structures and proportions. Previous studies document a stepwise accumulation of avian-like features in theropod dinosaurs that accelerates in the clade Maniraptora. However, the soft tissues that influenced the skeleton offer another perspective on locomotory adaptations. Examination of the pelvis for osteological correlates of hind limb and tail musculature allowed reconstruction of primary locomotory muscles across theropods and their closest extant relatives. Additionally, the areas of pelvic muscle origins were quantified to measure relative differences within and between taxa, to compare morphological features associated with cursoriality, and offer insight into the evolution of locomotor modules. Locomotory inferences based on myology often corroborate those based on osteology, although they occasionally conflict and indicate greater complexity than previously appreciated. Maniraptoran pelvic musculature underscores previous studies noting the multifaceted nature of cursoriality and suggests that a more punctuated step in caudal decoupling occurred at or near the base of Maniraptora.

scholarly journals Darwin review: angiosperm phylogeny and evolutionary radiations

2019 ◽  
Vol 286 (1899) ◽  
pp. 20190099 ◽  
Author(s):  
Pamela S. Soltis ◽  
Ryan A. Folk ◽  
Douglas E. Soltis
Keyword(s):  
Plant Evolution ◽  
Plant Biology ◽  
Evolutionary Patterns ◽  
Genealogical Tree ◽  
Evolutionary Origins ◽  
New Directions ◽  
Evolutionary Radiations ◽  
Plant Phylogenetics ◽  
Insight Into ◽  
Rapid Radiations

Darwin's dual interests in evolution and plants formed the basis of evolutionary botany, a field that developed following his publications on both topics. Here, we review his many contributions to plant biology—from the evolutionary origins of angiosperms to plant reproduction, carnivory, and movement—and note that he expected one day there would be a ‘true’ genealogical tree for plants. This view fuelled the field of plant phylogenetics. With perhaps nearly 400 000 species, the angiosperms have diversified rapidly since their origin in the Early Cretaceous, often through what appear to be rapid radiations. We describe these evolutionary patterns, evaluate possible drivers of radiations, consider how new approaches to studies of diversification can contribute to our understanding of angiosperm diversity, and suggest new directions for further insight into plant evolution.

OBSERVATION OF QUANTUM OSCILLATIONS IN FOUR-LAYER BaRuO3

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3285-3288 ◽  
Author(s):  
C. S. ALEXANDER ◽  
Y. XIN ◽  
Z. X. ZHOU ◽  
S. MCCALL ◽  
G. CAO ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Layer Structure ◽  
Relaxation Times ◽  
Marked Contrast ◽  
Crystallographic Form ◽  
Quasi Particle ◽  
Quantum Oscillations ◽  
Lattice Coupling ◽  
Substantial Change ◽  
Insight Into

Well characterized single crystals of the four layer crystallographic form of BaRuO3 were studied at low temperatures (20 < T < 850 mK) and high magnetic fields (0 < H < 30 T). Quantum oscillations have been observed via the Shubnikov - de Haas and de Haas - van Alphen effects. In marked contrast, BaRuO3 with the nine-layer structure shows no similar behavior, suggesting a substantial change in the Fermi surface or quasi-particle relaxation times. The quantum oscillations provide insight into the ground state which, like those of other layered ruthenates, is characteristically sensitive to electron-lattice coupling. This observation is significant in that it represents the first example of quantum oscillations in a non-Ruddlesden–Popper type ruthenate and provides some insight into the Fermi surface even though a psuedo-gap is evident in other studies.

The origin of celestine–quartz–calcite geodes associated with a basaltic dyke, Makhtesh Ramon, Israel

2013 ◽  
Vol 151 (5) ◽  
pp. 798-815 ◽  
Author(s):  
MICHAEL ANENBURG ◽  
OR M. BIALIK ◽  
YEVGENY VAPNIK ◽  
HAZEL J. CHAPMAN ◽  
GILAD ANTLER ◽  
...  
Keyword(s):  
Low Temperature ◽  
Fluid Inclusions ◽  
Lower Cretaceous ◽  
Meteoric Water ◽  
Hydrothermal Activity ◽  
Lower Jurassic ◽  
Specific Location ◽  
Melting Temperatures ◽  
Jurassic Sequence

AbstractSpectacular celestine geodes occur in a Jurassic peri-evaporitic sequence (Ardon Formation) exposed in Makhtesh Ramon, southern Israel. The geodes are found only in one specific location: adjacent to an intrusive contact with a Lower Cretaceous basaltic dyke. Celestine, well known in sedimentary associations worldwide and considered as a low temperature mineral, may therefore be associated with magmatic-induced hydrothermal activity. Abundant fluid inclusions in celestine provide valuable information on its origin: gas-rich inclusions in celestine interiors homogenized at T≥200°C whereas smaller liquid-rich inclusions record the growth of celestine rims at T≤200°C. Near 0°C melting temperatures of some fluid inclusions and the occurrence of hydrous Ca-sulphate solid crystals in other inclusions indicate that celestine precipitated from variably concentrated Ca-sulphate aqueous solutions of meteoric origin. Celestine crystallized from meteoric water heated by the cooling basaltic dyke at shallow levels (c. 160 m) during a Lower Cretaceous thermal perturbation recorded by regional uplift and magmatism. The 87Sr/86Sr ratio of geode celestine, 0.7074, is similar to that measured in the dolostones of the host Jurassic sequence, but differs markedly from the non-radiogenic ratio of the dyke. Strontium in celestine was derived from dolostones preserving the 87Sr/86Sr of Lower Jurassic seawater, while sulphur (δ34S = 19.9‰) was provided by in situ dissolution of precursor marine gypsum (δ34S = 16.8‰) indicated by relict anhydrite inclusions in celestine. Low-temperature meteoric fluid flow during the Campanian caused alteration of the dyke into secondary clays and alteration of geodal celestine into quartz, calcite and iron oxides.

scholarly journals Lower Jurassic biostratigraphy and ostracods of the Danish Embayment

1975 ◽  
Vol 104 ◽  
pp. 1-287
Author(s):  
Olaf Michelsen
Keyword(s):  
New Genus ◽  
Lower Jurassic ◽  
Ontogenetic Development ◽  
Muscle Scar ◽  
Scar Area ◽  
European Area ◽  
Ostracod Species ◽  
Jurassic Sequence

The Lower Jurassic sequence and ostracods from 36 borings within the Danish Embayment are analysed and described.Hettangian, Sinemurian and Pliensbachian are demonstrated on the basis of extensive ostracod faunas, whilst only weak indications of Aalenian have been found.The following ostracod zones are defined as a basis for a biostratigraphical subdivision of the Lower Jurassic series in the Danish Embayment:The Ogmoconchella adenticulata - Nanacythere (Nanacythere) simplex Zone (Upper Pliensbachian).The Ogmoconchella danica Zone (Upper Sinemurian and Lower Pliensbachian).The Gramannella apostolescui - Kinkelinella (Klinglerella ) foveolata Subzone (Lower Pliensbachian).The Progonoidea reticulata Subzone (lowest Upper Sinemurian, Lias Beta-1a).The Cristacythere betzi - C. crassireticulata Zone (upper Lower Sinemurian).The Ogmoconchella aspinata Zone (Hettangian and lower Lower Sinemurian).The chronostratigraphical subdivision of the Lower Jurassic sequence in the Danish Embayment is presented, based upon the ostracod faunas described here and upon previous investigations of sediments, foraminifera and megafossils.The conditions prevailing in the basin are discussed, with descriptions of the sedimentary and faunal developments, and an evaluation of the relationships with other parts of the Northwest European area.124 ostracod species are described; 23 are described as new, whilst 30 species which cannot be referred to any known species are described with open nomenclature owing to limited or badly preserved material. The remaining 71 species have all been described previously and are more or less well-known. The 124 species fall into 27 genera or subgenera, of which 2 genera (Pseudomacrocy pris and Cristacythere) and 1 subgenus (Nanacythere (Goniocythere)) are established as new.A subdivision is made of the described Lower Jurassic "Procytheridea". The genus Klinglerella Anderson, 1964 is placed as a subgenus under Kinkelinella Martin, 1960. Pleurifera Gramann, 1962 and Progonoidea Gramann, 1962 are regarded as independent genera placed together with Kinkelinella and the new genus Cristacythere.The family Healdiidae is regarded as being represented by only three genera in the Lower Jurassic: Ogmoconcha, Ogmoconchella and Pseudohealdia. The Ontogenetic development of the muscle scar area in Ogmoconchella is shown to be a development from a simple muscle scar of the Pseudohealdia-type to a typical Ogmoconchella-scar.ree genera in the Lower Jurassic: Ogmoconcha, Ogmoconchella and Pseudohea!dia. The Ontogenetic development of the muscle scar area in Ogmoconchella is shown to be a development from a simple muscle scar of the Pseudohea/dia-type to a typical Ogmoconchella-scar.

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