Paleontology or palaeontology is the scientific study of life that existed prior to, sometimes including, the start of the Holocene Epoch. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments. Paleontological observations have been documented as far back as the 5th century BC; the science became established in the 18th century as a result of Georges Cuvier's work on comparative anatomy, developed in the 19th century. The term itself originates from Greek παλαιός, palaios, "old, ancient", ὄν, on, "being, creature" and λόγος, logos, "speech, study". Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of anatomically modern humans, it now uses techniques drawn from a wide range of sciences, including biochemistry and engineering. Use of all these techniques has enabled paleontologists to discover much of the evolutionary history of life all the way back to when Earth became capable of supporting life, about 3.8 billion years ago.
As knowledge has increased, paleontology has developed specialised sub-divisions, some of which focus on different types of fossil organisms while others study ecology and environmental history, such as ancient climates. Body fossils and trace fossils are the principal types of evidence about ancient life, geochemical evidence has helped to decipher the evolution of life before there were organisms large enough to leave body fossils. Estimating the dates of these remains is essential but difficult: sometimes adjacent rock layers allow radiometric dating, which provides absolute dates that are accurate to within 0.5%, but more paleontologists have to rely on relative dating by solving the "jigsaw puzzles" of biostratigraphy. Classifying ancient organisms is difficult, as many do not fit well into the Linnaean taxonomy classifying living organisms, paleontologists more use cladistics to draw up evolutionary "family trees"; the final quarter of the 20th century saw the development of molecular phylogenetics, which investigates how organisms are related by measuring the similarity of the DNA in their genomes.
Molecular phylogenetics has been used to estimate the dates when species diverged, but there is controversy about the reliability of the molecular clock on which such estimates depend. The simplest definition of paleontology is "the study of ancient life"; the field seeks information about several aspects of past organisms: "their identity and origin, their environment and evolution, what they can tell us about the Earth's organic and inorganic past". Paleontology is one of the historical sciences, along with archaeology, astronomy, cosmology and history itself: it aims to describe phenomena of the past and reconstruct their causes. Hence it has three main elements: description of past phenomena; when trying to explain the past and other historical scientists construct a set of hypotheses about the causes and look for a smoking gun, a piece of evidence that accords with one hypothesis over the others. Sometimes the smoking gun is discovered by a fortunate accident during other research. For example, the discovery by Luis and Walter Alvarez of iridium, a extra-terrestrial metal, in the Cretaceous–Tertiary boundary layer made asteroid impact the most favored explanation for the Cretaceous–Paleogene extinction event, although the contribution of volcanism continues to be debated.
The other main type of science is experimental science, said to work by conducting experiments to disprove hypotheses about the workings and causes of natural phenomena. This approach cannot prove a hypothesis, since some experiment may disprove it, but the accumulation of failures to disprove is compelling evidence in favor. However, when confronted with unexpected phenomena, such as the first evidence for invisible radiation, experimental scientists use the same approach as historical scientists: construct a set of hypotheses about the causes and look for a "smoking gun". Paleontology lies between biology and geology since it focuses on the record of past life, but its main source of evidence is fossils in rocks. For historical reasons, paleontology is part of the geology department at many universities: in the 19th and early 20th centuries, geology departments found fossil evidence important for dating rocks, while biology departments showed little interest. Paleontology has some overlap with archaeology, which works with objects made by humans and with human remains, while paleontologists are interested in the characteristics and evolution of humans as a species.
When dealing with evidence about humans and paleontologists may work together – for example paleontologists might identify animal or plant fossils around an archaeological site, to discover what the people who lived there ate. In addition, paleontology borrows techniques from other sciences, including biology, ecology, chemistry and mathematics. For example, geochemical signatures from rocks may help to discover when life first arose on Earth, analyses of carbon isotope ratios may help to identify climate changes and to explain major transitions such as the Permian–Triassic extinction event. A recent discipline, molecular phylogenetics, compares the DNA and RNA of modern organisms to re-construct the "family trees" of their
Vertebrate paleontology is the subfield of paleontology that seeks to discover, through the study of fossilized remains, the behavior and appearance of extinct animals with vertebrae or a notochord. It tries to connect, by using the evolutionary timeline, the animals of the past and their modern-day relatives; the fossil record shows aspects of the meandering evolutionary path from early aquatic vertebrates to mammals, with a host of transitional fossils, though there are still large blank areas. The earliest known fossil vertebrates were armored fish discovered in rocks from the Ordovician Period about 500 to 430 Ma; the Devonian Period brought in the changes that allowed primitive air-breathing fish to remain on land as long as they wished, thus becoming the first terrestrial vertebrates, the amphibians. Amphibians developed forms of reproduction and locomotion and a metabolism better suited for life on land, becoming more reptilian. Full-fledged reptiles appeared in the Carboniferous Period.
The reptilian changes and adaptations to diet and geography are chronicled in the fossil record of the varying forms of therapsida. True mammals showed up in the Triassic Period around the same time as the dinosaurs, which sprouted from the reptilian line. Birds first diverged from dinosaurs between 60 Ma. One of the people who helped figure out the vertebrate progression was French zoologist Georges Cuvier, who realized that fossils found in older rock strata differed from more recent fossils or modern animals, he published his findings in 1812 and, although he steadfastly refuted evolution, his work proved the contested theory of extinction of species. Thomas Jefferson is credited with initiating the science of vertebrate paleontology in the United States with the reading of a paper to the American Philosophical Society in Philadelphia in 1797. Jefferson presented fossil bones of a ground sloth found in a cave in western Virginia and named the genus; the species was named Megalonyx jeffersonii in his honor.
Jefferson corresponded with Cuvier, including sending him a shipment of desirable bones of the American mastodon and the woolly mammoth. Paleontology got started though, with the publication of Recherches sur les poissons fossiles by Swiss naturalist Louis Agassiz, he studied and listed hundreds of species of fossil fish, beginning the serious study into the lives of extinct animals. With the publication of the Origin of Species by Charles Darwin in 1849, the field got a theoretical framework. Much of the subsequent work has been to map the relationship between fossil and extant organisms, as well as their history through time. In modern times, Alfred Romer wrote what has been termed the definitive textbook on the subject, called Vertebrate Paleontology, it shows the progression of evolution in fossil fish, amphibians and reptiles through comparative anatomy, including a list of all the known fossil vertebrate genera. Romer became the first president of the Society of Vertebrate Paleontology in 1940, alongside co-founder Howard Chiu.
An updated work that carried on the tradition from Romer, by many considered definitive book on the subject was written by Robert L. Carroll of McGill University, the 1988 text Vertebrate Paleontology and Evolution. Carroll was president of the Society of Vertebrate Paleontology in 1983; the Society keeps its members informed on the latest discoveries through newsletters and the Journal of Vertebrate Paleontology. The "traditional" vertebrate classification scheme employ evolutionary taxonomy where several of the taxa listed are paraphyletic, i.e. have given rise to another taxa that have been given the same rank. For instance, birds are considered to be the descendants of reptiles, but in this system both are listed as separate classes. Under phylogenetic nomenclature, such an arrangement is unacceptable, though it offers excellent overview; this classical scheme is still used in works where systematic overview is essential, e.g. Benton and Goslow and Knobill and Neill. While seen in general works, it is still used in some specialist works like Fortuny & al..
Kingdom Animalia Phylum Chordata Class Agnatha Subclass Cyclostomata Subclass Ostracodermi † Class Chondrichthyes Subclass Elasmobranchii Subclass Holocephali Class Placodermi † Class Acanthodii † Class Osteichthyes Subclass Actinopterygii Subclass Sarcopterygii Class Amphibia Subclass Labyrinthodontia † Subclass Lepospondyli † Subclass Lissamphibia Class Reptilia Subclass Anapsida Order Cotylosauria † Order Testudines Subclass Synapsida Order Pelycosauria † Order Therapsida † Subclass Euryapsida Order Sauropterygia † Order Ichthyosauria † Subclass Diapsida Order Crocodilia Order Sphenodontia Order Squamata Order Thecodonts † Order Pterosauria † Order Saurischia † Order Ornithischia † Class Aves Subclass Archaeornithes † Subclass Neornithes Superorder Odontognathae † Superorder Palaeognathae Superorder Neognathae Class Mammalia Subclass Prototheria Order Monotremata Subclass Theria Infraclass Metatheria
A thesis or dissertation is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings. In some contexts, the word "thesis" or a cognate is used for part of a bachelor's or master's course, while "dissertation" is applied to a doctorate, while in other contexts, the reverse is true; the term graduate thesis is sometimes used to refer to both master's theses and doctoral dissertations. The required complexity or quality of research of a thesis or dissertation can vary by country, university, or program, the required minimum study period may thus vary in duration; the word "dissertation" can at times be used to describe a treatise without relation to obtaining an academic degree. The term "thesis" is used to refer to the general claim of an essay or similar work; the term "thesis" comes from the Greek θέσις, meaning "something put forth", refers to an intellectual proposition. "Dissertation" comes from the Latin dissertātiō, meaning "discussion".
Aristotle was the first philosopher to define the term thesis. "A'thesis' is a supposition of some eminent philosopher that conflicts with the general opinion...for to take notice when any ordinary person expresses views contrary to men's usual opinions would be silly". For Aristotle, a thesis would therefore be a supposition, stated in contradiction with general opinion or express disagreement with other philosophers. A supposition is a statement or opinion that may or may not be true depending on the evidence and/or proof, offered; the purpose of the dissertation is thus to outline the proofs of why the author disagrees with other philosophers or the general opinion. A thesis may be arranged as a thesis by publication or a monograph, with or without appended papers though many graduate programs allow candidates to submit a curated collection of published papers. An ordinary monograph has a title page, an abstract, a table of contents, comprising the various chapters, a bibliography or a references section.
They differ in their structure in accordance with the many different areas of study and the differences between them. In a thesis by publication, the chapters constitute an introductory and comprehensive review of the appended published and unpublished article documents. Dissertations report on a research project or study, or an extended analysis of a topic; the structure of a thesis or dissertation explains the purpose, the previous research literature impinging on the topic of the study, the methods used, the findings of the project. Most world universities use a multiple chapter format: a) an introduction, which introduces the research topic, the methodology, as well as its scope and significance. Degree-awarding institutions define their own house style that candidates have to follow when preparing a thesis document. In addition to institution-specific house styles, there exist a number of field-specific and international standards and recommendations for the presentation of theses, for instance ISO 7144.
Other applicable international standards include ISO 2145 on section numbers, ISO 690 on bibliographic references, ISO 31 on quantities or units. Some older house styles specify that front matter must use a separate page number sequence from the main text, using Roman numerals; the relevant international standard and many newer style guides recognize that this book design practice can cause confusion where electronic document viewers number all pages of a document continuously from the first page, independent of any printed page numbers. They, avoid the traditional separate number sequence for front matter and require a single sequence of Arabic numerals starting with 1 for the first printed page. Presentation requirements, including pagination, layout and color of paper, use of acid-free paper, paper size, order of components, citation style, will be checked page by page by the accepting officer before the thesis is accepted and a receipt is issued. However, strict standards are not always required.
Most Italian universities, for example, have only general requirements on the character size and the page formatting, leave much freedom for the actual typographic details. A thesis or dissertation committee is a committee. In the US, these committees consist of a primary supervisor or advisor and two or more committee members, who supervise the progress of the dissertation and may act as the examining committee, or jury, at the oral examination of the thesis. At most universities, the committee is chosen by the student in conjunction with his or her primary adviser after completion of the comprehensive examinations or prospectus meeting, may consist of members of the comps committee; the committee members are doctors in their field (whether a PhD or other des
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters are at Broadcasting House in Westminster, it is the world's oldest national broadcasting organisation and the largest broadcaster in the world by number of employees, it employs over 20,950 staff in total. The total number of staff is 35,402 when part-time and fixed-contract staff are included; the BBC is established under a Royal Charter and operates under its Agreement with the Secretary of State for Digital, Culture and Sport. Its work is funded principally by an annual television licence fee, charged to all British households and organisations using any type of equipment to receive or record live television broadcasts and iPlayer catch-up; the fee is set by the British Government, agreed by Parliament, used to fund the BBC's radio, TV, online services covering the nations and regions of the UK. Since 1 April 2014, it has funded the BBC World Service, which broadcasts in 28 languages and provides comprehensive TV, online services in Arabic and Persian.
Around a quarter of BBC revenues come from its commercial arm BBC Studios Ltd, which sells BBC programmes and services internationally and distributes the BBC's international 24-hour English-language news services BBC World News, from BBC.com, provided by BBC Global News Ltd. From its inception, through the Second World War, to the 21st century, the BBC has played a prominent role in British culture, it is known colloquially as "The Beeb", "Auntie", or a combination of both. Britain's first live public broadcast from the Marconi factory in Chelmsford took place in June 1920, it was sponsored by the Daily Mail's Lord Northcliffe and featured the famous Australian soprano Dame Nellie Melba. The Melba broadcast caught the people's imagination and marked a turning point in the British public's attitude to radio. However, this public enthusiasm was not shared in official circles where such broadcasts were held to interfere with important military and civil communications. By late 1920, pressure from these quarters and uneasiness among the staff of the licensing authority, the General Post Office, was sufficient to lead to a ban on further Chelmsford broadcasts.
But by 1922, the GPO had received nearly 100 broadcast licence requests and moved to rescind its ban in the wake of a petition by 63 wireless societies with over 3,000 members. Anxious to avoid the same chaotic expansion experienced in the United States, the GPO proposed that it would issue a single broadcasting licence to a company jointly owned by a consortium of leading wireless receiver manufactures, to be known as the British Broadcasting Company Ltd. John Reith, a Scottish Calvinist, was appointed its General Manager in December 1922 a few weeks after the company made its first official broadcast; the company was to be financed by a royalty on the sale of BBC wireless receiving sets from approved domestic manufacturers. To this day, the BBC aims to follow the Reithian directive to "inform and entertain"; the financial arrangements soon proved inadequate. Set sales were disappointing as amateurs made their own receivers and listeners bought rival unlicensed sets. By mid-1923, discussions between the GPO and the BBC had become deadlocked and the Postmaster-General commissioned a review of broadcasting by the Sykes Committee.
The Committee recommended a short term reorganisation of licence fees with improved enforcement in order to address the BBC's immediate financial distress, an increased share of the licence revenue split between it and the GPO. This was to be followed by a simple 10 shillings licence fee with no royalty once the wireless manufactures protection expired; the BBC's broadcasting monopoly was made explicit for the duration of its current broadcast licence, as was the prohibition on advertising. The BBC was banned from presenting news bulletins before 19.00 and was required to source all news from external wire services. Mid-1925 found the future of broadcasting under further consideration, this time by the Crawford committee. By now, the BBC, under Reith's leadership, had forged a consensus favouring a continuation of the unified broadcasting service, but more money was still required to finance rapid expansion. Wireless manufacturers were anxious to exit the loss making consortium with Reith keen that the BBC be seen as a public service rather than a commercial enterprise.
The recommendations of the Crawford Committee were published in March the following year and were still under consideration by the GPO when the 1926 general strike broke out in May. The strike temporarily interrupted newspaper production, with restrictions on news bulletins waived, the BBC became the primary source of news for the duration of the crisis; the crisis placed the BBC in a delicate position. On one hand Reith was acutely aware that the Government might exercise its right to commandeer the BBC at any time as a mouthpiece of the Government if the BBC were to step out of line, but on the other he was anxious to maintain public trust by appearing to be acting independently; the Government was divided on how to handle the BBC but ended up trusting Reith, whose opposition to the strike mirrored the PM's own. Thus the BBC was granted sufficient leeway to pursue the Government's objectives in a manner of its own choosing; the resulting coverage of both striker and government viewpoints impressed millions of listeners who were unaware that the PM had broadcast to the nation from Reith's home, using one of Reith's sound bites inserted at the last moment
Permian–Triassic extinction event
The Permian–Triassic extinction event, colloquially known as the Great Dying, the End-Permian Extinction or the Great Permian Extinction, occurred about 252 Ma ago, forming the boundary between the Permian and Triassic geologic periods, as well as between the Paleozoic and Mesozoic eras. It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct, it was the largest known mass extinction of insects. Some 57% of all biological families and 83% of all genera became extinct; because so much biodiversity was lost, the recovery of land-dwelling life took longer than after any other extinction event up to 10 million years. Studies in Bear Lake County, near Paris, showed a quick rebound in a localized marine ecosystem, taking around 2 million years to recover, suggesting that the impact of the extinction may have been felt less in some areas than others. There is evidence for phases, of extinction. Suggested mechanisms for the latter include one or more large meteor impact events, massive volcanism such as that of the Siberian Traps, the ensuing coal or gas fires and explosions, a runaway greenhouse effect triggered by sudden release of methane from the sea floor due to methane clathrate dissociation according to the clathrate gun hypothesis or methane-producing microbes known as methanogens.
Possible contributing gradual changes include sea-level change, increasing anoxia, increasing aridity, a shift in ocean circulation driven by climate change. Until 2000, it was thought that rock sequences spanning the Permian–Triassic boundary were too few and contained too many gaps for scientists to reliably determine its details. However, it is now possible to date the extinction with millennial precision. U–Pb zircon dates from five volcanic ash beds from the Global Stratotype Section and Point for the Permian–Triassic boundary at Meishan, establish a high-resolution age model for the extinction – allowing exploration of the links between global environmental perturbation, carbon cycle disruption, mass extinction, recovery at millennial timescales; the extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 Ma ago, a duration of 60 ± 48 ka. A large, abrupt global decrease in the ratio of the stable isotope 13C to that of 12C, coincides with this extinction, is sometimes used to identify the Permian–Triassic boundary in rocks that are unsuitable for radiometric dating.
Further evidence for environmental change around the P–Tr boundary suggests an 8 °C rise in temperature, an increase in CO2 levels by 2000 ppm. There is evidence of increased ultraviolet radiation reaching the earth, causing the mutation of plant spores, it has been suggested that the Permian–Triassic boundary is associated with a sharp increase in the abundance of marine and terrestrial fungi, caused by the sharp increase in the amount of dead plants and animals fed upon by the fungi. For a while this "fungal spike" was used by some paleontologists to identify the Permian–Triassic boundary in rocks that are unsuitable for radiometric dating or lack suitable index fossils, but the proposers of the fungal spike hypothesis pointed out that "fungal spikes" may have been a repeating phenomenon created by the post-extinction ecosystem in the earliest Triassic; the idea of a fungal spike has been criticized on several grounds, including: Reduviasporonites, the most common supposed fungal spore, may be a fossilized alga.
The reduviasporonites may represent a transition to a lake-dominated Triassic world rather than an earliest Triassic zone of death and decay in some terrestrial fossil beds. Newer chemical evidence agrees better with a fungal origin for Reduviasporonites, diluting these critiques. Uncertainty exists regarding the duration of the overall extinction and about the timing and duration of various groups' extinctions within the greater process; some evidence suggests that there were multiple extinction pulses or that the extinction was spread out over a few million years, with a sharp peak in the last million years of the Permian. Statistical analyses of some fossiliferous strata in Meishan, Zhejiang Province in southeastern China, suggest that the main extinction was clustered around one peak. Recent research shows. In a well-preserved sequence in east Greenland, the decline of animals is concentrated in a period 10,000 to 60,000 years long, with plants taking an additional several hundred thousand years to show the full impact of the event.
An older theory, still supported in some recent papers, is that there were two major extinction pulses 9.4 million years apart, separated by a period of extinctions well above the background level, that the final extinction killed off only about 80% of marine species alive at that time while the other losses occurred during the first pulse or the interval between pulses. According to this theory one of these extinction pulses occurred at the end of the Guadalupian epoch of the Permian. For example, all but one of the surviving dinocephalian genera died out at the end of the Guadalupian, as did the Verbeekinidae, a family of large-size fusuline foraminifera; the impact of the end-Guadalupian extinction on marine organisms appears to have varied between locations and between taxonomi
University of Bristol
The University of Bristol is a red brick research university located in Bristol, United Kingdom. It received its royal charter in 1909, although like the University of the West of England and the University of Bath, it can trace its roots to the Merchant Venturers' Technical College, founded as a school in 1595 by the Society of Merchant Venturers, its key predecessor institution, University College, had been in existence since 1876. Bristol is organised into six academic faculties composed of multiple schools and departments running over 200 undergraduate courses situated in the Tyndalls Park area of the city; the university had a total income of £642.7 million in 2017/18, of which £164.0 million was from research grants and contracts. It is the largest independent employer in Bristol; the University of Bristol is ranked 44th by the QS World University Rankings 2018, is ranked amongst the top 10 of UK universities by QS, THE, ARWU. A selective institution, it has an average of 6.4 to 13.1 applicants for each undergraduate place.
It was ranked 9th in the UK amongst multi-faculty institutions for the quality of its research and for its Research Power in the 2014 Research Excellence Framework. Current academics include 21 fellows of the Academy of Medical Sciences, 13 fellows of the British Academy, 13 fellows of the Royal Academy of Engineering and 44 fellows of the Royal Society; the university has been associated with 13 Nobel laureates throughout its history, including Paul Dirac, Sir William Ramsay, Cecil Frank Powell, Sir Winston Churchill, Dorothy Hodgkin, Hans Albrecht Bethe, Max Delbrück, Gerhard Herzberg, Sir Nevill Francis Mott, Sir Paul Nurse, Harold Pinter, Jean-Marie Gustave Le Clézio and most 2015 Economics Nobel Prize winner Angus Deaton. Bristol is a member of the Russell Group of research-intensive British universities, the European-wide Coimbra Group and the Worldwide Universities Network, of which the university's previous vice-chancellor, Eric Thomas, was chairman from 2005 to 2007. In addition, the university holds an Erasmus Charter, sending more than 500 students per year to partner institutions in Europe.
The earliest antecedent of the university was the engineering department of the Merchant Venturers' Technical College which became the engineering faculty of Bristol University. The university was preceded by Bristol Medical School and University College, founded in 1876, where its first lecture was attended by only 99 students; the university was able to apply for a royal charter due to the financial support of the Wills and Fry families, who made their fortunes in tobacco plantations and chocolate, respectively. The Wills Family made a vast fortune from the tobacco industry and gave generously to the city and university; the royal charter was gained in May 1909, with 288 undergraduates and 400 other students entering the university in October 1909. Henry Overton Wills III became its first chancellor; the University College was the first such institution in the country to admit women on the same basis as men. However, women were forbidden to take examinations in medicine until 1906. Since the founding of the university itself in 1909, it has grown and is now one of the largest employers in the local area, although it is smaller by student numbers than the nearby University of the West of England.
Bristol is spread over a considerable geographic area. Most of its activities, are concentrated in the area of the city centre, referred to as the "University Precinct", it is a member of the Russell Group of research-led UK universities, the Coimbra Group of leading European universities and the Worldwide Universities Network. After the founding of the University College in 1876, Government support began in 1889. After mergers with the Bristol Medical School in 1893 and the Merchant Venturers' Technical College in 1909, this funding allowed the opening of a new medical school and an engineering school—two subjects that remain among the university's greatest strengths. In 1908, gifts from the Fry and Wills families £100,000 from Henry Overton Wills III, were provided to endow a University for Bristol and the West of England, provided that a royal charter could be obtained within two years. In December 1909, the King erected the University of Bristol. Henry Wills became Conwy Lloyd Morgan the first vice-chancellor.
Wills died in 1911 and in tribute his sons George and Harry built the Wills Memorial Building, starting in 1913 and finishing in 1925. Today, it houses parts of the academic provision for earth sciences and law, graduation ceremonies are held in its Great Hall; the Wills Memorial Building is a Grade II* listed building. In 1920, George Wills bought the Victoria Rooms and endowed them to the university as a Students' Union; the building now is a Grade II * listed building. At the point of foundation, the university was required to provide for the local community; this mission was behind the creation of the Department of Extra-Mural Adult Education in 1924 to provide courses to the local community. This mission continues today. Among the famous names associated with Bristol in this early period is Paul Dirac, who graduated in 1921 with a degree in engineering, before obtaining a second degree in mathematics in 1923 from Cambridge. For his subsequent pioneering work on quantum mechanics, he was awarded the 1933 Nobel Prize for Physics.