1.
Antiarchi
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Antiarchi is an order of heavily armored placoderms. The antiarchs form the second-most successful group of placoderms after the arthrodires in terms of numbers of species, the pair of pectoral fins were modified into a pair of caliper-like, or arthropod-like limbs. In primitive forms, such as Yunnanolepis, the limbs were thick and short, while in advanced forms, such as Bothriolepis, below is a cladogram from Jia et al. Review of Antiarcha at Paleos Long, John A, the Rise of Fishes,500 Million Years of Evolution Baltimore, The Johns Hopkins University Press,1996. A compendium of fossil marine animal genera
2.
Ediacaran
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The Ediacaran Period, spans 94 million years from the end of the Cryogenian Period 635 million years ago, to the beginning of the Cambrian Period 541 Mya. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon and it is named after the Ediacara Hills of South Australia. The Ediacaran Period overlaps, but is shorter than the Vendian Period, the Vendian concept was formed stratigraphically top-down, and the lower boundary of the Cambrian became the upper boundary of the Vendian. Paleontological substantiation of this boundary was worked out separately for the siliciclastic basin, the lower boundary of the Vendian was suggested to be defined at the base of the Varanger tillites. The Ediacaran Period represents the time from the end of global Marinoan glaciation to the first appearance worldwide of somewhat complicated trace fossils. Although the Ediacaran Period does contain soft-bodied fossils, it is unusual in comparison to later periods because its beginning is not defined by a change in the fossil record. Rather, the beginning is defined at the base of a chemically distinctive carbonate layer that is referred to as a cap carbonate and this bed is characterized by an unusual depletion of 13C that indicates a sudden climatic change at the end of the Marinoan ice age. The lower boundary GSSP of the Ediacaran is at the base of the cap carbonate, immediately above the Elatina diamictite in the Enorama Creek section, Brachina Gorge, Flinders Ranges, South Australia. In the history of stratigraphy it was the first case of usage of bioturbations for the System boundary definition, nevertheless, the definitions of the lower and upper boundaries of the Ediacaran on the basis of chemostratigraphy and ichnofossils are disputable. Also, the Shuram excursion is prolonged and is estimated to last for ~9.0 Myrs. pedum in Namibia, Spain and Newfoundland, the stratigraphic range of T. pedum overlaps the range of the Ediacaran fossils in Namibia, and probably in Spain. The dating of the type section of the Ediacaran Period in South Australia has proven uncertain. Therefore, the age range assigned those rocks from 635 to 542 million years, is based on more precice dating in other locations is possible, the base age of approximately 635 million years is based on U-Pb isochron dating from Namibia and China. The fossil record from the Ediacaran Period is sparse, as more easily fossilized hard-shelled animals had yet to evolve, the Ediacaran biota include the oldest definite multicellular organisms, the most common types of which resemble segmented worms, fronds, disks, or immobile bags. Ediacara biota bear little resemblance to modern lifeforms, and their relationship even with the immediately following lifeforms of the Cambrian explosion is rather difficult to interpret. More than 100 genera have been described, and well known forms include Arkarua, Charnia, Dickinsonia, Ediacaria, Marywadea, Onega, Pteridinium, there is evidence that Earths first mass extinction happened during this period when early animals changed the environment. The relative proximity of the Moon at this time meant that tides were stronger, the day was 21. 9±0.4 hours, and there were 13. 1±0.1 synodic months/year and 400±7 solar days/year. A few English language documentaries have featured the Ediacaran era and biota, the Geological History of Canada, as part of The Nature of Things series, CBC-SRC,2011, Eastern Canada. The first episode of a BBC documentary titled Life on Earth, with David Attenborough as narrator, another documentary narrated by David Attenborough titled First Life featuring Charnia, Dickinsonia, Spriggina, Funisia, and Kimberella animated in CGI
3.
Embryo
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An embryo is an early stage of development of a multicellular diploid eukaryotic organism. In general, in organisms that reproduce sexually, an embryo develops from a zygote, the zygote possesses half the DNA of each of its two parents. In plants, animals, and some protists, the zygote will begin to divide by mitosis to produce a multicellular organism, the result of this process is an embryo. First attested in English in the mid-14c, the word embryon derives from Medieval Latin embryo, itself from Greek ἔμβρυον, lit. Young one, which is the neuter of ἔμβρυος, lit, growing in, from ἐν, in and βρύω, swell, be full, the proper Latinized form of the Greek term would be embryum. In animals, the development of the zygote into an embryo proceeds through specific stages of blastula, gastrula. The blastula stage typically features a fluid-filled cavity, the blastocoel, surrounded by a sphere or sheet of cells, in a placental mammal, an ovum is fertilized in a fallopian tube through which it travels into the uterus. An embryo is called a fetus at an advanced stage of development. In humans, this is from the week of gestation. During gastrulation the cells of the blastula undergo coordinated processes of cell division, invasion, in triploblastic organisms, the three germ layers are called endoderm, ectoderm, and mesoderm. The position and arrangement of the layers are highly species-specific, however. For example, in neurogenesis, a subpopulation of cells is set aside to become the brain, spinal cord. Modern developmental biology is extensively probing the molecular basis for every type of organogenesis, including angiogenesis, chondrogenesis, myogenesis, osteogenesis, and many others. In botany, a plant embryo is part of a seed, consisting of precursor tissues for the leaves, stem. Once the embryo begins to germinate — grow out from the seed — it is called a seedling, bryophytes and ferns also produce an embryo, but do not produce seeds. In these plants, the embryo begins its existence attached to the inside of the archegonium on a parental gametophyte from which the egg cell was generated, the structure and development of the rest of the embryo varies by group of plants. Once the embryo has expanded beyond the enclosing archegonium, it is no longer termed an embryo, embryos are used in various fields of research and in techniques of assisted reproductive technology. An egg may be fertilized in vitro and the embryo may be frozen for later use
4.
Doushantuo Formation
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The whole sequence sits on an unconformity with the underlying Liantuo Formation, which is free of fossils, an unconformity usually being interpreted as a period of erosion. This latest Cryogenian glacial level is dated ca 654 —635 Ma. The Doushantuo formation itself has three layers representing aquatic sediments that formed as sea levels rose with the melting of worldwide glaciation. Biomarkers indicate highly saline conditions, such as might be found in a lagoon, low oxygen levels, the richest finds lie at the bottom of the middle stratum, with a date about 570 Ma, thus from some time after the great Gaskiers glaciation of. Doushantuo fossils are all aquatic, microscopic, and preserved to a degree of detail. A nearly microscopic fossil animal, Vernanimalcula was announced in October 2005, an alternative interpretation suggests that it was created by non-biological rock-forming processes. The discovery was made when the phosphate deposits were being mined. The documented biota now includes phosphatized microfossils of algae, multicellular thallophytes, acritarchs, ciliates, there also seem to be what scientists cautiously report as bilateral animal embryos, termed Parapandorina, and eggs. An alternative possibility is that the embryos and eggs are in fact fossils of giant sulfur bacteria resembling Thiomargarita, the interpretation would also provide a mechanism for phosphatic fossilization through microbially mediated phosphate precipitation by the bacteria, which has been observed in modern environments. If dark spots in the fossil transpire to be fossilised nuclei - an unlikely claim - this would refute the Thiomargarita hypothesis. That being said, recent comparisons of the Doushantuo fossils to modern decaying Thiomargarita, the formation was laid down on a carbonate shelf, whose rim enclosed a lagoon between tidal flats on the shore, and the deeper ocean. The most recent Doushantuo rocks show a decrease in the 13C/12C carbon isotope ratio. Phosphatic fossilization Hagadorn, J. W. Xiao, S, Donoghue, PC, Bengtson, S, Gostling, NJ, Pawlowska, M, Raff, EC, Raff, RA, cellular and Subcellular Structure of Neoproterozoic Animal Embryos. Knoll, A. H. Three-dimensional preservation of algae and animal embryos in a Neoproterozoic phosphorite
5.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
6.
Eukaryote
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A eukaryote is any organism whose cells contain a nucleus and other organelles enclosed within membranes. Eukaryotes belong to the taxon Eukarya or Eukaryota, the presence of a nucleus gives eukaryotes their name, which comes from the Greek εὖ and κάρυον. Eukaryotic cells also contain other membrane-bound organelles such as mitochondria and the Golgi apparatus, in addition, plants and algae contain chloroplasts. Eukaryotic organisms may be unicellular or multicellular, only eukaryotes form multicellular organisms consisting of many kinds of tissue made up of different cell types. Eukaryotes can reproduce asexually through mitosis and sexually through meiosis and gamete fusion. In mitosis, one cell divides to produce two identical cells. In meiosis, DNA replication is followed by two rounds of division to produce four daughter cells each with half the number of chromosomes as the original parent cell. These act as sex cells resulting from genetic recombination during meiosis, the domain Eukaryota appears to be monophyletic, and so makes up one of the three domains of life. The two other domains, Bacteria and Archaea, are prokaryotes and have none of the above features, eukaryotes represent a tiny minority of all living things. However, due to their larger size, eukaryotes collective worldwide biomass is estimated at about equal to that of prokaryotes. Eukaryotes first developed approximately 1. 6–2.1 billion years ago, in 1905 and 1910, the Russian biologist Konstantin Mereschkowsky argued three things about the origin of nucleated cells. Firstly, plastids were reduced cyanobacteria in a symbiosis with a non-photosynthetic host, secondly, the host had earlier in evolution formed by symbiosis between an amoeba-like host and a bacteria-like cell that formed the nucleus. Thirdly, plants inherited photosynthesis from cyanobacteria, the split between the prokaryotes and eukaryotes was introduced in the 1960s. The concept of the eukaryote has been attributed to the French biologist Edouard Chatton, the terms prokaryote and eukaryote were more definitively reintroduced by the Canadian microbiologist Roger Stanier and the Dutch-American microbiologist C. B. van Niel in 1962. In his 1938 work Titres et Travaux Scientifiques, Chatton had proposed the two terms, calling the bacteria prokaryotes and organisms with nuclei in their cells eukaryotes. However he mentioned this in one paragraph, and the idea was effectively ignored until Chattons statement was rediscovered by Stanier. In 1967, Lynn Margulis provided microbiological evidence for endosymbiosis as the origin of chloroplasts and mitochondria in cells in her paper. In the 1970s, Carl Woese explored microbial phylogenetics, studying variations in 16S ribosomal RNA and this helped to uncover the origin of the eukaryotes and the symbiogenesis of two important eukaryote organelles, mitochondria and chloroplasts
7.
Incertae sedis
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Incertae sedis is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are referred to as enigmatic taxa. In the system of nomenclature, uncertainty at specific taxonomic levels is indicated by incertae familiae, incerti subordinis, incerti ordinis. The fossil plant Paradinandra suecica could not be assigned to any family, the fossil Gluteus minimus, described in 1975, could not be assigned to any known animal phylum. The genus is therefore incertae sedis within the kingdom Animalia, while it was unclear to which order the New World vultures should be assigned, they were placed in Aves incertae sedis. It was later agreed to them in a separate order. Bocages longbill, Amaurocichla bocagei, a species of passerine bird, since it is unclear to which family it belongs, it is classified as Passeroidea incertae sedis. HeLa cells, descended from human cervical cancer cells, may diverge genetically from normal human cells sufficiently to be categorized as a new species with largely incertae sedis taxonomy, when formally naming a taxon, uncertainty about its taxonomic classification can be problematic. Their reduced status was attributed largely to poor or inadequate descriptions and it is also evident that a proportion of the characters used in the analysis, or their given states for particular taxa, were inappropriate or invalid. Additional complexity, and factors that have misled earlier authorities, are intrusion by extensive homoplasies, apparent character state reversals and convergent evolution. If a formal analysis is conducted that does not include a certain taxon. This is particularly common when molecular phylogenies are generated, since tissue for many rare organisms is hard to obtain and it is also a common scenario when fossil taxa are included, since many fossils are defined based on partial information. If conflicting results exist or if there is not a consensus among researchers as to how a taxon relates to other organisms, for example, if a new species was given the specific epithet album by Anton and attributed with uncertainty to Agenus, it could be denoted Agenus. Album Anton, the indicates the author that assigned the question mark, so if Anton described Agenus album, and Bruno called the assignment into doubt, this could be denoted Agenus. Album, with the parentheses around Anton because the original assignment was modified by Bruno
8.
Synonym (taxonomy)
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For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies. This name is no longer in use, it is now a synonym of the current scientific name which is Picea abies, unlike synonyms in other contexts, in taxonomy a synonym is not interchangeable with the name of which it is a synonym. In taxonomy, synonyms are not equals, but have a different status, for any taxon with a particular circumscription, position, and rank, only one scientific name is considered to be the correct one at any given time. A synonym cannot exist in isolation, it is always an alternative to a different scientific name, given that the correct name of a taxon depends on the taxonomic viewpoint used a name that is one taxonomists synonym may be another taxonomists correct name. Synonyms may arise whenever the same taxon is described and named more than once, independently. They may also arise when existing taxa are changed, as when two taxa are joined to one, a species is moved to a different genus. To the general user of scientific names, in such as agriculture, horticulture, ecology, general science. A synonym is a name that was used as the correct scientific name but which has been displaced by another scientific name. Thus Oxford Dictionaries Online defines the term as a name which has the same application as another. In handbooks and general texts, it is useful to have mentioned as such after the current scientific name. Synonyms used in this way may not always meet the strict definitions of the synonym in the formal rules of nomenclature which govern scientific names. Changes of scientific name have two causes, they may be taxonomic or nomenclatural, a name change may be caused by changes in the circumscription, position or rank of a taxon, representing a change in taxonomic, scientific insight. A name change may be due to purely nomenclatural reasons, that is, based on the rules of nomenclature, the earliest such name is called the senior synonym, while the later name is the junior synonym. One basic principle of zoological nomenclature is that the earliest correctly published name, synonyms are important because if the earliest name cannot be used, then the next available junior synonym must be used for the taxon. Objective synonyms refer to taxa with the type and same rank. For example, John Edward Gray published the name Antilocapra anteflexa in 1855 for a species of pronghorn, however, it is now commonly accepted that his specimen was an unusual individual of the species Antilocapra americana published by George Ord in 1815. Ords name thus takes precedence, with Antilocapra anteflexa being a subjective synonym. Objective synonyms are common at the level of genera, because for various reasons two genera may contain the type species, these are objective synonyms
9.
Pro parte
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For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies. This name is no longer in use, it is now a synonym of the current scientific name which is Picea abies, unlike synonyms in other contexts, in taxonomy a synonym is not interchangeable with the name of which it is a synonym. In taxonomy, synonyms are not equals, but have a different status, for any taxon with a particular circumscription, position, and rank, only one scientific name is considered to be the correct one at any given time. A synonym cannot exist in isolation, it is always an alternative to a different scientific name, given that the correct name of a taxon depends on the taxonomic viewpoint used a name that is one taxonomists synonym may be another taxonomists correct name. Synonyms may arise whenever the same taxon is described and named more than once, independently. They may also arise when existing taxa are changed, as when two taxa are joined to one, a species is moved to a different genus. To the general user of scientific names, in such as agriculture, horticulture, ecology, general science. A synonym is a name that was used as the correct scientific name but which has been displaced by another scientific name. Thus Oxford Dictionaries Online defines the term as a name which has the same application as another. In handbooks and general texts, it is useful to have mentioned as such after the current scientific name. Synonyms used in this way may not always meet the strict definitions of the synonym in the formal rules of nomenclature which govern scientific names. Changes of scientific name have two causes, they may be taxonomic or nomenclatural, a name change may be caused by changes in the circumscription, position or rank of a taxon, representing a change in taxonomic, scientific insight. A name change may be due to purely nomenclatural reasons, that is, based on the rules of nomenclature, the earliest such name is called the senior synonym, while the later name is the junior synonym. One basic principle of zoological nomenclature is that the earliest correctly published name, synonyms are important because if the earliest name cannot be used, then the next available junior synonym must be used for the taxon. Objective synonyms refer to taxa with the type and same rank. For example, John Edward Gray published the name Antilocapra anteflexa in 1855 for a species of pronghorn, however, it is now commonly accepted that his specimen was an unusual individual of the species Antilocapra americana published by George Ord in 1815. Ords name thus takes precedence, with Antilocapra anteflexa being a subjective synonym. Objective synonyms are common at the level of genera, because for various reasons two genera may contain the type species, these are objective synonyms
10.
Micropaleontology
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Micropaleontology is the branch of palaeontology that studies microfossils, or fossils that require the use of a microscope to see the organism, its morphology and its characteristics details. Microfossils are fossils that are generally between 0. 001mm and 1 mm in size, the study of which requires the use of light or electron microscopy. Fossils which can be studied with the eye or low-powered magnification. For example, some organisms, such as Bryozoa have relatively large colonies. In another example, many genera of Foraminifera, which are protists are known from shells that were as big as coins. Microfossils are a feature of the geological record, from the Precambrian to the Holocene. They are most common in deposits of marine environments, but also occur in water, fresh water. This division reflects differences in the mineralogical and chemical composition of microfossil remains rather than any strict taxonomic or ecological distinctions, most researchers in this field, known as micropaleontologists, are typically specialists in one or more taxonomic groups. Calcareous microfossils include coccoliths, foraminifera, calcareous dinoflagellate cysts, phosphatic microfossils include conodonts, some scolecodonts, Shark spines and teeth, and other Fish remains. Siliceous microfossils include diatoms, radiolarians, silicoflagellates, ebridians, phytoliths, some scolecodonts, the study of organic microfossils is called palynology. Organic microfossils include pollen, spores, chitinozoans, scolecodonts, acritarchs, dinoflagellate cysts, the resulting concentrated sample of microfossils is then mounted on a slide for analysis, usually by light microscope. Taxa are then identified and counted, the enormous numbers of microfossils that a small sediment sample can often yield allows the collection of statistically robust datasets which can be subjected to multivariate analysis. A typical microfossil study will involve identification of a few hundred specimens from each sample, Microfossils are especially noteworthy for their importance in biostratigraphy. Since microfossils are often abundant, widespread, and quick to appear and disappear from the stratigraphic record. Microfossils, particularly from deep-sea sediments, also some of the most important records of global environmental change on long. Across vast areas of the floor, the shells of planktonic micro-organisms sinking from surface waters provide the dominant source of sediment. Study of changes in assemblages of microfossils and changes in their shell chemistry are fundamental to research on change in the geological past. Micropaleontology is also a tool of geoarchaeology used in the reconstruction of human habitation sites
