Letteratura scientifica selezionata sul tema "Fossil Geographical distribution"

É descrito um novo blatóide fóssil (Insecta) Amazonina purperae Pinto, sp. nov., do Estado de Minas Gerais, encontrado em argilito arrocheado associado a uma tafoflora atribuída ao Pleistoceno. O material é proveniente do km 30,25 da Rodovia BR-262, Belo Horizonte – Uberaba. A amostra contém um único élitro. Trata-se do primeiro blatídeo fóssil de Amazonina, Hebard, 1929, gênero de ampla distribuição na América do Sul e América Central. O élitro apresenta extraordinária semelhança com os élitros de Amazonina rehni Albuquerque, 1964, dos quais se diferencia pelo número de ramos e pela bifurcação mais proximal do ramo posterior de R. Outrossim, A. rehni apresenta uma bifurcação distal de M que não existe na nova espécie.

The latitudinal distributions in Devonian–Cretaceous ammonoids were analyzed at the genus level, and were compared with the hatchling sizes (i.e., ammonitella diameters) and the geological durations. The results show that (1) length of temporal ranges of ammonoids effected broader ranges of fossil distribution and paleobiogeography of ammonoids, and (2) the hatchling size was not related to the geographical range of fossil distribution of ammonoids. Reducing the influence of geological duration in this analysis implies that hatchling size was one of the controlling factors that determined the distribution of ammonoid habitats at any given period in time: ammonoids with smaller hatchling sizes tended to have broader ammonoid habitat ranges. These relationships were somewhat blurred in the Devonian, Carboniferous, Triassic, and Jurassic, which is possibly due to (1) the course of development of a reproductive strategy with smaller hatchling sizes in the Devonian and (2) the high origination rates after the mass extinction events.

Abstract Remains of teiids assignable to the Tupinambinae (Tupinambis sp. or Crocodilurus sp.) are here described from the middle Miocene Collón Curá Formation at Cañadón del Tordillo, in Neuquén province, Argentina. No tupinambine species presently inhabits the region of the fossil locality. The fossils represent the westernmost distribution of fossil tupinambine teiids in Patagonia, enlarging the known geographical distribution of the teiids through the Miocene in a longitudinal range. Also, they constitute the first record of lizards from the Colloncuran SALMA, partially filling the record of tupinambine teiids for the South American Miocene.

Dinosaur migration patterns are very difficult to determine, often relying solely on the geographical distribution of fossils. Unfortunately, it is generally not possible to determine if a fossil taxon's geographical distribution is the result of migration or simply a wide distribution. Whereas some attempts have been made to use isotopic systems to determine migratory patterns in dinosaurs, these methods have yet to achieve wider usage in the study of dinosaur ecology. Here, we have used strontium isotope ratios from fossil enamel to reconstruct the movements of an individual hadrosaur from Dinosaur Provincial Park in Alberta, Canada. Results from this study are consistent with a range or migratory pattern between Dinosaur Provincial Park and a contemporaneous locality in the South Saskatchewan River area, Alberta, Canada. This represents a minimum distance of approximately 80 km, which is consistent with migrations seen in modern elephants. These results suggest the continent-wide distribution of some hadrosaur species in the Late Cretaceous of North America is not the result of extremely long-range migratory behaviours.

A checklist of published records of coronuloid barnacles (Cirripedia: Thoracica: Coronuloidea) attached to marine vertebrates is presented, with 44 species (including 15 fossil species) belonging to 14 genera (including 3 fossil genera) and 3 families recorded. Also included is information on their geographical distribution and the hosts with which they occur.

Four new fossil species of the genus Priacma, P. latidentata sp. nov., P. tuberculosa sp. nov., P. clavata sp. nov. and P. renaria sp. nov., are described from the Yixian Formation of western Liaoning, China. This finding documents the first record of fossil Priacma in China and extends the geographical distribution of this genus.

Abstract Gymnophiona, popularly known as caecilians, the most poorly known major taxon of extant amphibians, are elongate and limbless tetrapods, with compact ossified skulls and reduced eyes, mainly adapted to fossorial life as adults. Caecilians are poorly represented in the fossil record, but despite the scarcity of fossil specimens described (only four named taxa, in addition to indeterminate fragmentary material), their fossils play a key role in our knowledge of the origin and evolution of Lissamphibia, as well as contribute directly to a better understanding of the phylogeny, taxonomy and biogeography of extant gymnophionan taxa. These records are scattered throughout geological time (from the Jurassic to the sub-Recent) and space (North and South America and Africa). Here, we revisit the caecilian fossil record, providing a brief description of all known extinct taxa described so far, along with general remarks about their impact on systematics, time range, and geographical distribution of the clade, as well as prospects for future research. Possible calibration constraints based on the caecilian fossil record are provided.

The current distributions of widespread groups of terrestrial animals and plants are supposedly the result of a mixture of either vicariance owing to continental split or more recent trans-oceanic dispersal. For organisms exhibiting a vicariant biogeographic pattern—achieving their current distribution by riding on the plates of former supercontinents—this view is largely inspired by the belief that Pangaea lacked geographical or ecological barriers, or that extinctions and dispersal would have erased any biogeographic signal since the early Mesozoic. We here present a time-calibrated molecular phylogeny of Onychophora (velvet worms), an ancient and exclusively terrestrial panarthropod group distributed throughout former Pangaean landmasses. Our data not only demonstrate that trans-oceanic dispersal does not need be invoked to explain contemporary distributions, but also reveal that the early diversification of the group pre-dates the break-up of Pangaea, maintaining regionalization even in landmasses that have remained contiguous throughout the history of the group. These results corroborate a growing body of evidence from palaeontology, palaeogeography and palaeoclimatic modelling depicting ancient biogeographic regionalization over the continuous landmass of Pangaea.

"April 2002" Includes bibliographical references and list of the publications and papers submitted. Pt. 1: section 1. Ostracod taxonomy and ecology -- section 2. Limnology of salt lakes -- section 3. Ostracod palaoecology - Quaternary environments -- section 4. Palaolimnology - Quaternary paleoenvironments and geology -- pt. 2: section 5. Geochemistry of ostracod shells -- section 6. Palaeoceanography Contains the majority of the author's scientific publications. Aims at reconstructing Quaternary paleoenvironments, mostly from the Australian region, using the fossil remains of organisms as well as new geochemical techniques.

Classified in the Lissamphibia, modern amphibians are the only non-amniote tetrapods living today. They consist of three morphologically distinct groups: the tailless frogs and toads (Anura), the limbless caecilians (Gymnophiona), and the tailed salamanders and newts (Urodela). With 205 species, the caecilians are highly specialized worm-like forms that live a fossorial lifestyle, with a relatively narrow distribution in the tropic rainforests of South America, Africa and Asia (Duellman and Trueb, 1994; Amphibiaweb, 2015). Salamanders, with 683 species, are widely distributed in the North America, Asia and Europe, with a few plethodontids extending to Central and South America (Duellman and Trueb, 1994; Amphibiaweb, 2015). Frogs are the most diverse amphibian groups, with 6644 species distributed over all continents except Antarctica (Duellman and Trueb, 1994; Amphibiaweb, 2015). Both frogs and salamanders develop a wide array of lifestyles, ranging from terrestrial, aquatic, fossorial to aboreal lifestyles (Duellman and Trueb, 1994). During ontogeny, amphibian larvae usually undergo a drastic post-embryonic shift into an adult form, a term known as metamorphosis. In salamanders, another developmental pathway – neoteny – also occurs, in which the larval morphology is retained in sexually mature adults (Duellman and Trueb, 1994; Rose, 2003). Because of the diverse lifestyles and developmental pathways, frogs and salamanders are often used as model systems in many fields of biology (e.g., evo-devo). Over a century, but especially in the past two decades, a wealth of frog and salamander fossils has been discovered from the Mesozoic and Cenozoic of East Asia (e.g., Noble, 1924; Young, 1936; Borsuk-Bialynicka, 1978; Gao, 1986; Dong and Wang, 1998; Gao and Shubin, 2001, 2003, 2012; Gao and Wang, 2001; Gao and Chen, 2004; Wang and Rose, 2005; Wang and Evans, 2006b; Zhang et al., 2009; Chen et al., 2016; this study). Some of these fossils represent the earliest members of many crown clades, including the earliest crown salamanders from the Middle Jurassic (~165 Ma, Gao and Shubin, 2003), the earliest salamandroid from the Late Jurassic, the earliest sirenid from the Late Jurassic (this study), and the earliest spadefoot toads from the late Paleocence (Chen et al., 2016). Other fossils also bear important anatomical, temporal and geographical information in understanding their evolution. Unfortunately, the importance of many of these fossils remains obscure in a phylogenetic context. For example, an early-middle Oligocene Mongolian spadefoot toad Macropelobates osborni (Noble, 1924) was discovered outside the current distribution of spadefoot toads, yet its phylogenetic position and its implication on spadefoot toad biogeography remain not well understood. A major reason for the poor understanding of these fossils can be attributed to a trend of dichotomy between morphological and molecular phylogenies on amphibians. Whereas morphologists and paleontologists sometimes use a relatively small morphological dataset to reconstruct relationships (e.g., Gao and Shubin, 2012; Henrici, 2013), large-scale phylogenies are almost always conducted with molecular data with only living taxa (e.g., Roelants and Bossuyt, 2005; Pyron and Wiens, 2011). Very few studies on amphibian phylogeny have combined morphological and molecular data together, and even fewer also combined fossils. Because of this, the positions of many important fossils remains unclear, and the evolutionary scenarios inferred from only living species can sometimes be inconsistent with fossil evidence. In this thesis, I adopt a total-evidence approach to understand the evolution of amphibians, especially frogs and salamanders. I will incorporate information from fossils, morphology and molecules together to reconstruct the relationships. Compared with studies with each individual datasets, this approach incorporates all available data in a single analysis, with a goal to reach robust and congruent results that allow further discussions on character evolution and biogeographic reconstruction. The inclusion of fossils directly into the combined analysis provides the time dimension that is independent from molecular data (Norell, 1992). The anatomical combination of fossils can represent intermediate forms that help to solve the “long branch” problems caused by highly specialized modern taxa. The morphological dataset, despite its much smaller size with molecular data, is the only link between fossils and modern taxa. The inclusion of key morphological characters in both reconstructing phylogenetic hypotheses and examining character evolution provide consistent results that allow discussion on the homology/homoplasy of a certain character without ambiguity. The molecular sequence data provides overwhelmingly large data on modern taxa for phylogenetic reconstructions compared with morphological data, which helps to reach a robust hypothesis. Although fossils contain no molecular data, the inclusion of molecular sequence data into the combined analysis does have an effect on the positions of fossil taxa. By altering the relationship “framework” of modern taxa, the character optimization of fossils and other taxa of a combined analysis also varies compared with results of morphology-only analysis, thus changing the positions of fossils. In the following five chapters, I will describe a number of fossil amphibian species, reconstruct three combined phylogenies, and use the results for discussions on character evolution and biogeography. In Chapter 1 and Chapter 2, I focus on a frog clade called spadefoot toads (Anura: Pelobatoidea). In Chapter 1, I provide descriptions on three important fossil spadefoot toads from the Cenozoic of East Asia and North America: Macropelobates osborni from the early-middle Oligocene of Mongolia, Prospea holoserisca from the latest Paleocene of Mongolia, and Scaphiopus skinneri from the middle Oligocene of the United States. In Chapter 2, I conduct a combined phylogenetic analysis of archaeobatrachian frogs, and discuss the evolution of the bony spade and the historical biogeography of spadefoot toads based on the results of the phylogeny. In Chapter 3, I describe a new fossil frog from the Early Cretaceous of Inner Mongolia, China. The unique morphology of the new fossil is distinct from previous Early Cretaceous frogs from the Jehol Biota of China. Results of the combined analysis show that the new frog represents a basal member of the Pipanura. Comparisons between the Early Cretaceous frogs from China, Spain and Brazil show a high diversity of species coupled with a high degree of endemism during the Early Cretaceous. I discuss in the phylogenetic context how early frogs gradually reach their postcranial body plan with a shortened vertebral column, loss of ribs, and specialized pelvic regions. In Chapter 4, I provide a brief review of Mesozoic fossil salamanders from northern China, and describe a new fossil from the Late Jurassic of Liaoning Province, China. I conduct a combined phylogeny of higher-level relationships of salamanders. The new fossil, despite its general-looking appearance, represents a basal member of the highly specialized eel-like neotenic family Sirenidae on the cladogram. I discuss character evolutions in the Sirenidae, and how the neotenic developmental pathway evolved in early salamanders. In Chapter 5, I conduct a combined phylogenetic analysis of the salamander suborder Cryptobranchoidea, consisting of the neotenic giant salamanders (Cryptobranchidae) and the metamorphic Asiatic salamanders (Hynobiidae). The new morphological matrix includes new characters that were previously less sampled in the hynobranchial region. The monophyly of the Hynobiidae are confirmed by the new analysis, and four unequivocal synapomorphies are found for the clade. An S-DIVA biogeographic reconstruction is conducted to disscuss the distributional patterns of the Hynobiidae.

Conventional power generation stations used to be centralized and located far from customers. The transport and distribution infrastructure incur power losses that are mainly due to cabling resistance. Distributed power generation resources located close to customers are sought as a solution to minimize transport power losses. They are also good alternatives in situations where connection to the grid is not possible due to geographical or economical reasons. Furthermore, the adoption of renewable energies as alternatives for the scarce fossil energy sources paves the way to more distributed energy production. These Distributed energy resources, when located in a limited region, can be interconnected with loads and eventually storages to form a microgrid. A microgrid can operate in off-grid, on-grid, or alternate between these modes while optimizing power quality and cost. Multi-Agent Systems (MAS) and Petri nets could be put into contribution for high level planning of energy exchanges within a microgrid. This strategy has been validated on the basis of a dynamic model for the simulation and optimization of power exchanges between different DERs.

Over the next two or three decades a new energy economy should begin to take shape in the developed industrial countries. This will not be a post-fossil fuel economy. But it could be an economy in which non-fossil sources play a more important role; where efficiency in the production, distribution, and use of energy is significantly enhanced; where new storage and carrier technologies are being adopted; and where the fossil sector is being transformed by the imperative of carbon sequestration. Such an energy economy would represent a critical staging post in a much longer transition towards a carbon neutral, low-environmental impact, energy system. The extent to which a new energy economy actually materializes will depend on many factors including the pace and orientation of international economic development, the rate and direction of technological innovation and diffusion, as well as patterns of geo-strategic cooperation and conflict. But there is no doubt the trajectory will be significantly influenced by political decisions and government action on the energy file. This is the issue with which this chapter is concerned. At the moment there are two main political drivers for the move to look beyond oil. First, there are supply concerns. Increasing global demand, production bottlenecks, and political instability have pushed oil prices towards historic highs. Although the oil intensity (oil consumption per unit of GDP) of the OECD economies is less than during the oil crises of the 1970s (IMF, 2005), there is no doubt that the long term economic impact of high oil prices would be considerable. There are also critical issues associated with the geographic distribution of reserves. Production from areas opened up following the turbulence of the early 1970s (such as the North Sea) is peaking. In coming years the United States will be more heavily dependent on imported oil, with an increasing percentage of these imports destined to come from politically volatile areas in the Middle East and Asia. And this presents a serious risk of supply disruption.

The major source of energy is fossil fuels, known as hydrocarbon containing C and H as the main elements. The heat generated from combustion of these fuels is used in power generation cycles to generate electricity. Main products of a hydrocarbon combustion reaction are water and carbon dioxide, but due to some reasons such as excessive temperature and inappropriate air-fuel mixing, always some pollutants are formed. One of the major concerns of recent years are NOx pollutants, which is mostly generated in the high temperature combustions. According to the geographical and economic issues, most countries are using coal as fuel and many researches have been conducted about pollutant formation and temperature distribution in coal fired boilers (H. Y. Park, et al,. J. R. Fan, et al, and many others), but in Middle Eastern countries, the dominant fuel for the power generation cycles is natural gas. In this paper, pollutant formation and temperature distribution is numerically studied in a power generation boiler using natural gas as fuel. NOx formation mechanisms are introduced and discussed about the main source of NOx pollutants in this boiler. The natural gas burners are appropriate for non-premixed flame, so the goal of this study is to achieve the desired temperature distribution and minimize NOx pollutants through the variation of inlet angle of fuel and air in the burner. A case study is presented for boiler with 156MW power, equipped with natural gas burners. Numerical simulation is applied for the mentioned system and optimization consideration on pollutant is discussed.

To limit the global temperature rise to 1.5°C in 2100 compared to mid nineteenth century, net post 2015 emissions should amount maximum 200 Gigaton Carbon (GTC) or 734 GT CO2 emissions [Millar, 2017]. Annual world CO2 emission rate was 36.2GT, and CO2_eq (the combined impact of all emissions on global warming, translated to the equivalent impact of CO2 emissions) emission rate was 49 GT in 2016, [Carbonatlas, 2017]. Currently only 685 GT CO2 emission quota is left, or 14 years of emitting at the current emission rate. Estimates vary widely: IPCC thinks we only have 485 GT CO2 emission quota left, while the most pessimistic estimates talk about only 200 GT CO2. With this in mind, the ambition of the Dutch Operational Energy Strategy [Schulten 2017] to reduce the dependency on fossil fuels (and hence CO2 emissions) by 20 % in 2030, is not sufficient to meet the objectives of the Treaty of Paris. We have to choose whether to keep this ambition, defining much stricter ambitions, or invest differently to keep global warming within acceptable limits. This paper discusses CO2 emissions and their distribution both over different sectors and geographical, worldwide. Next the paper discusses the options we have on short and medium term to reduce emissions, and their impact on emission reduction.