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Cambrian Explosion
The Cambrian explosion, Cambrian radiation, Cambrian diversification, or the Biological Big Bang refers to an interval of time approximately in the Cambrian Period when practically all major animal phyla started appearing in the fossil record. It lasted for about 13 – 25 million years and resulted in the divergence of most modern metazoan phyla. The event was accompanied by major diversification in other groups of organisms as well. Before early Cambrian diversification, most organisms were relatively simple, composed of individual cells, or small multicellular organisms, occasionally organized into colonies. As the rate of diversification subsequently accelerated, the variety of life became much more complex, and began to resemble that of today. Almost all present-day animal phyla appeared during this period, including the earliest chordates. A 2019 paper suggests that the timing should be expanded back to include the late Ediacaran, rather than just the na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Life
The history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to present day. Earth formed about 4.5 billion years ago (abbreviated as ''Ga'', for ''gigaannum'') and evidence suggests that life emerged prior to 3.7 Ga. Although there is some evidence of life as early as 4.1 to 4.28 Ga, it remains controversial due to the possible non-biological formation of the purported fossils. The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor. Only a very small percentage of species have been identified: one estimate claims that Earth may have 1 trillion species. * However, only 1.75–1.8 million have been named "A version of this article appears in print on Nov. 9, 2014, Section SR, Page 6 of the New York edition with the headline: Prehistory's Brilliant Future." and 1.8 million documented in a central database. These currentl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fauna
Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is '' flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. Zoologists and paleontologists use ''fauna'' to refer to a typical collection of animals found in a specific time or place, e.g. the " Sonoran Desert fauna" or the " Burgess Shale fauna". Paleontologists sometimes refer to a sequence of faunal stages, which is a series of rocks all containing similar fossils. The study of animals of a particular region is called faunistics. Etymology '' Fauna'' comes from the name Fauna, a Roman goddess of earth and fertility, the Roman god Faunus, and the related forest spirits called Fauns. All three words are cognates of the name of the Greek god Pan, and ''panis'' is the Greek equivalent of fauna. ''Fauna'' is also the word for a book that catalogues the animals in such a manner. The term wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grypania
''Grypania'' is an early, tube-shaped fossil from the Proterozoic eon. The organism, with a size over one centimeter and consistent form, could have been a giant bacterium, a bacterial colony, or a eukaryotic alga. The oldest probable ''Grypania'' fossils date to about 2100 million years ago (redated from the previous 1870 million)Schneider, D. A., Bickford, M. E., Cannon, W. F., Schulz, K. J., & Hamilton, M. A. (2002)Age of volcanic rocks and syndepositional iron formations, Marquette Range Supergroup: implications for the tectonic setting of Paleoproterozoic iron formations of the Lake Superior region Canadian Journal of Earth Sciences, 39(6), 999-1012. and the youngest extended into the Ediacaran The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and t ... period.Wang, Y., Wang, Y., & Du, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microorganism
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in older texts. The informal synonym ''microbe'' () comes from μικρός, mikrós, "small" and βίος, bíos, "life". is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from sixth century BC India. The scientific study of microorganisms began with their observation under the microscope in the 1670s by Anton van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s, Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera, diphtheria, and anthrax. B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stromatolite
Stromatolites () or stromatoliths () are layered sedimentary formations ( microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). These microorganisms produce adhesive compounds that cement sand and other rocky materials to form mineral " microbial mats". In turn, these mats build up layer by layer, growing gradually over time. A stromatolite may grow to a meter or more. Although they are rare today, fossilized stromatolites provide records of ancient life on Earth. Morphology Stromatolites are layered, biochemical, accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains in biofilms (specifically microbial mats), through the action of certain microbial lifeforms, especially cyanobacteria. They exhibit a variety of forms and structures, or morphologies, including conical, stratiform, domal, columnar, and branchi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Warrawoona, Australia
Warrawoona is a region of Western Australia in the Pilbara province. The region is home to the Warrawoona belt, a geological area and discovery site of the Warrawoona Group of fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...s. These fossils, which are over 3.5 billion years old, are considered to be the oldest known geological record of life on earth. References {{reflist Pilbara Geology of Western Australia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossils Of The Burgess Shale
The fossils of the Burgess Shale, like the Burgess Shale itself, formed around 505 million years ago in the Mid Cambrian period. They were discovered in Canada in 1886, and Charles Doolittle Walcott collected over 65,000 specimens in a series of field trips up to the alpine site from 1909 to 1924. After a period of neglect from the 1930s to the early 1960s, new excavations and re-examinations of Walcott's collection continue to reveal new species, and statistical analysis suggests that additional discoveries will continue for the foreseeable future. Stephen Jay Gould's book '' Wonderful Life'' describes the history of discovery up to the early 1980s, although his analysis of the implications for evolution has been contested. The fossil beds are in a series of shale layers, averaging and totalling about in thickness. These layers were deposited against the face of a high undersea limestone cliff. All these features were later raised up above current sea level during the cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Doolittle Walcott
Charles Doolittle Walcott (March 31, 1850February 9, 1927) was an American paleontologist, administrator of the Smithsonian Institution from 1907 to 1927, and director of the United States Geological Survey. Wonderful Life (book) by Stephen Jay Gould published in 1989, Chapter 4 He is famous for his discovery in 1909 of well-preserved fossils, including some of the oldest soft-part imprints, in the Burgess Shale of British Columbia, Canada. Early life Charles Doolittle Walcott was born on March 31, 1850 in New York Mills, New York. His grandfather, Benjamin S. Walcott, moved from Rhode Island in 1822. His father, also Charles Doolittle Walcott, died when Charles Jr. was only two. Walcott was the youngest of four children. He was interested in nature from an early age, collecting minerals and bird eggs and, eventually, fossils. He attended various schools in the Utica area but left at the age of eighteen without completing high school, the end of his formal education. His int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Lyell
Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geology'' (1830–33), which presented to a wide public audience the idea that the earth was shaped by the same natural processes still in operation today, operating at similar intensities. The philosopher William Whewell termed this gradualistic view "uniformitarianism" and contrasted it with catastrophism, which had been championed by Georges Cuvier and was better accepted in Europe. The combination of evidence and eloquence in ''Principles'' convinced a wide range of readers of the significance of "deep time" for understanding the earth and environment. Lyell's scientific contributions included a pioneering explanation of climate change, in which shifting boundaries between oceans and continents could be used to explain long-term variations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods ( myriapods, arachnids and hexapods) became fully terrestrialized. A significant evolutionary milestone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roderick Murchison
Sir Roderick Impey Murchison, 1st Baronet, (19 February 1792 – 22 October 1871) was a Scottish geologist who served as director-general of the British Geological Survey from 1855 until his death in 1871. He is noted for investigating and describing the Silurian, Devonian and Permian systems. Early life and work Murchison was born at Tarradale House, Muir of Ord, Ross-shire, the son of Barbara and Kenneth Murchison. His wealthy father died in 1796, when Roderick was four years old, and he was sent to Durham School three years later, and then the Royal Military College, Great Marlow to be trained for the army. In 1808 he landed with Wellesley in Portugal, and was present at the actions of Roliça and Vimeiro in the Peninsular War as an ensign in the 36th Regt of Foot. Subsequently under Sir John Moore, he took part in the retreat to Corunna and the final battle there. After eight years of service Murchison left the army, and married Charlotte Hugonin (1788–1869 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adam Sedgwick
Adam Sedgwick (; 22 March 1785 – 27 January 1873) was a British geologist and Anglican priest, one of the founders of modern geology. He proposed the Cambrian and Devonian period of the geological timescale. Based on work which he did on Welsh rock strata, he proposed the Cambrian period in 1835, in a joint publication in which Roderick Murchison also proposed the Silurian period. Later in 1840, to resolve what later became known as the Great Devonian Controversy about rocks near the boundary between the Silurian and Carboniferous periods, he and Murchison proposed the Devonian period. Though he had guided the young Charles Darwin in his early study of geology and continued to be on friendly terms, Sedgwick was an opponent of Darwin's theory of evolution by means of natural selection. He strongly opposed the admission of women to the University of Cambridge, in one conversation describing aspiring female students as "nasty forward minxes." Life and career Sedgwick ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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