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Mark McMenamin
Mark A. S. McMenamin (born c. 1957) is an American paleontologist and professor of geology at Mount Holyoke College. He has contributed to the study of the Cambrian explosion and the Ediacaran biota. He is the author of several books, most recently ''Deep Time Analysis'' (2018) and ''Dynamic Paleontology'' (2016). His earlier works include ''The Garden of Ediacara: Discovering the Earliest Complex Life'' (1998), one of the only popular accounts of research on the Ediacaran biota, and ''Science 101: Geology'' (2007). He is credited with co-naming several geological formations in Mexico, describing several new fossil genera and species, and naming the Precambrian supercontinent Rodinia. The Cambrian archeocyathid species ''Markocyathus clementensis'' was named in his honor in 1989. Early life and career McMenamin was born in Oregon, earned his B.S. at Stanford University in 1979 and his PhD at the University of California, Santa Barbara in 1984. In 1980, while at Santa Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oregon
Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. The 42° north parallel delineates the southern boundary with California and Nevada. Oregon has been home to many indigenous nations for thousands of years. The first European traders, explorers, and settlers began exploring what is now Oregon's Pacific coast in the early-mid 16th century. As early as 1564, the Spanish began sending vessels northeast from the Philippines, riding the Kuroshio Current in a sweeping circular route across the northern part of the Pacific. In 1592, Juan de Fuca undertook detailed mapping and studies of ocean currents in the Pacific Northwest, including the Oregon coast as well as the strait now bearing his name. Spanish ships – 250 in as many years – would typically not land before reaching Cape Mendoci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnostida
Agnostida is an order of arthropod which have classically been seen as a group of highly modified trilobites, though some recent research has doubted this placement. Regardless, they appear to be close relatives as part of the Artiopoda. They are present in the Lower Cambrian fossil record along with trilobites from the Redlichiida, Corynexochida, and Ptychopariida orders, and were highly diverse throughout the Cambrian. Agnostidan diversity severely declined during the Cambrian-Ordovician transition, and the last agnostidans went extinct in the Late Ordovician. Systematics The Agnostida are divided into two suborders — Agnostina and Eodiscina — which are then subdivided into a number of families. As a group, agnostids are isopygous, meaning their pygidium is similar in size and shape to their cephalon. Most agnostid species were eyeless. The systematic position of the order Agnostida within the class Trilobita remains uncertain, and there has been continuing de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exergue
A coin is a small, flat (usually depending on the country or value), round piece of metal or plastic used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in order to facilitate trade. They are most often issued by a government. Coins often have images, numerals, or text on them. ''Obverse'' and its opposite, ''reverse'', refer to the two flat faces of coins and medals. In this usage, ''obverse'' means the front face of the object and ''reverse'' means the back face. The obverse of a coin is commonly called ''heads'', because it often depicts the head of a prominent person, and the reverse ''tails''. Coins are usually made of metal or an alloy, or sometimes of man-made materials. They are usually disc shaped. Coins, made of valuable metal, are stored in large quantities as bullion coins. Other coins are used as money in everyday transactions, circulating alongside banknotes. Usually the highest val ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stater
The stater (; grc, , , statḗr, weight) was an ancient coin used in various regions of Greece. The term is also used for similar coins, imitating Greek staters, minted elsewhere in ancient Europe. History The stater, as a Greek silver currency, first as ingots, and later as coins, circulated from the 8th century BC to AD 50. The earliest known stamped stater (having the mark of some authority in the form of a picture or words) is an electrum turtle coin, struck at Aegina that dates to about 650 BC. It is on display at the Bibliothèque Nationale in Paris. According to Robin Lane Fox, the stater as a weight unit was borrowed by the Euboean stater weighing from the Phoenician shekel, which had about the same weight as a stater () and was also one fiftieth of a mina.Lane Fox, Robin. ''Travelling Heroes: Greeks and Their Myths in the Epic Age of Homer''. P. 94. London: Allen Lane, 2008. The silver stater minted at CorinthSmith, William. ''A Dictionary of Greek an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carthage
Carthage was the capital city of Ancient Carthage, on the eastern side of the Lake of Tunis in what is now Tunisia. Carthage was one of the most important trading hubs of the Ancient Mediterranean and one of the most affluent cities of the classical world. The city developed from a Canaanite Phoenician colony into the capital of a Punic empire which dominated large parts of the Southwest Mediterranean during the first millennium BC. The legendary Queen Alyssa or Dido, originally from Tyre, is regarded as the founder of the city, though her historicity has been questioned. According to accounts by Timaeus of Tauromenium, she purchased from a local tribe the amount of land that could be covered by an oxhide. As Carthage prospered at home, the polity sent colonists abroad as well as magistrates to rule the colonies. The ancient city was destroyed in the nearly-three year siege of Carthage by the Roman Republic during the Third Punic War in 146 BC and then re-developed as Roma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phoenicia
Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their history, and they possessed several enclaves such as Arwad and Tell Sukas (modern Syria). The core region in which the Phoenician culture developed and thrived stretched from Tripoli and Byblos in northern Lebanon to Mount Carmel in modern Israel. At their height, the Phoenician possessions in the Eastern Mediterranean stretched from the Orontes River mouth to Ashkelon. Beyond its homeland, the Phoenician civilization extended to the Mediterranean from Cyprus to the Iberian Peninsula. The Phoenicians were a Semitic-speaking people of somewhat unknown origin who emerged in the Levant around 3000 BC. The term ''Phoenicia'' is an ancient Greek exonym that most likely described one of their most famous exports, a dye also known as Tyrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New World
The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 33: "[16c: from the feminine of ''Americus'', the Latinized first name of the explorer Amerigo Vespucci (1454–1512). The name ''America'' first appeared on a map in 1507 by the German cartographer Martin Waldseemüller, referring to the area now called Brazil]. Since the 16c, a name of the western hemisphere, often in the plural ''Americas'' and more or less synonymous with ''the New World''. Since the 18c, a name of the United States of America. The second sense is now primary in English: ... However, the term is open to uncertainties: ..." The term gained prominence in the early 16th century, during Europe's Age of Discovery, shortly after the Italian explorer Amerigo Vespucci concluded that America (now often called ''the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbiogenesis
Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory,) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes (more closely related to the Bacteria than to the Archaea) taken one inside the other in endosymbiosis. Mitochondria appear to be phylogenetically related to Rickettsiales bacteria, while chloroplasts are thought to be related to cyanobacteria. The idea that chloroplasts were originally independent organisms that merged into a symbiotic relationship with other one-celled organisms dates back to the 19th century, when it was espoused by researchers such as Andreas Schimper. The endosymbiotic theory was articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lynn Margulis
Lynn Margulis (born Lynn Petra Alexander; March 5, 1938 – November 22, 2011) was an American evolutionary biologist, and was the primary modern proponent for the significance of symbiosis in evolution. Historian Jan Sapp has said that "Lynn Margulis's name is as synonymous with symbiosis as Charles Darwin's is with evolution." In particular, Margulis transformed and fundamentally framed current understanding of the evolution of cells with nuclei – an event Ernst Mayr called "perhaps the most important and dramatic event in the history of life" – by proposing it to have been the result of symbiotic mergers of bacteria. Margulis was also the co-developer of the Gaia hypothesis with the British chemist James Lovelock, proposing that the Earth functions as a single self-regulating system, and was the principal defender and promulgator of the five kingdom classification of Robert Whittaker. Throughout her career, Margulis' work could arouse intense objection (one grant applic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodarwinism
Neo-Darwinism is generally used to describe any integration of Charles Darwin's theory of evolution by natural selection with Gregor Mendel's theory of genetics. It mostly refers to evolutionary theory from either 1895 (for the combinations of Darwin's and August Weismann's theories of evolution) or 1942 ( "modern synthesis"), but it can mean any new Darwinian- and Mendelian-based theory, such as the current evolutionary theory. Original use Darwin's theory of evolution by natural selection, as published in 1859, provided a selection mechanism for evolution, but not a trait transfer mechanism. Lamarckism was still a very popular candidate for this. August Weismann and Alfred Russel Wallace rejected the Lamarckian idea of inheritance of acquired characteristics that Darwin had accepted and later expanded upon in his writings on heredity. The basis for the complete rejection of Lamarckism was Weismann's germ plasm theory. Weismann realised that the cells that produce the germ plas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columbia University Press
Columbia University Press is a university press based in New York City, and affiliated with Columbia University. It is currently directed by Jennifer Crewe (2014–present) and publishes titles in the humanities and sciences, including the fields of literary and cultural studies, history, social work, sociology, religion, film, and international studies. History Founded in May 1893, In 1933 the first four volumes of the ''History of the State of New York'' were published. In early 1940s revenues rises, partially thanks to the ''Encyclopedia'' and the government's purchase of 12,500 copies for use by the military. Columbia University Press is notable for publishing reference works, such as ''The Columbia Encyclopedia The ''Columbia Encyclopedia'' is a one-volume encyclopedia produced by Columbia University Press and, in the last edition, sold by the Gale Group. First published in 1935, and continuing its relationship with Columbia University, the encyclopedi ...'' (1935†... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notochord
In anatomy, the notochord is a flexible rod which is similar in structure to the stiffer cartilage. If a species has a notochord at any stage of its life cycle (along with 4 other features), it is, by definition, a chordate. The notochord consists of inner, vacuolated cells covered by fibrous and elastic sheaths, lies along the anteroposterior axis (''front to back''), is usually closer to the dorsal than the ventral surface of the embryo, and is composed of cells derived from the mesoderm. The most commonly cited functions of the notochord are: as a midline tissue that provides directional signals to surrounding tissue during development, as a skeletal (structural) element, and as a vertebral precursor. In lancelets the notochord persists throughout life as the main structural support of the body. In tunicates the notochord is present only in the larval stage, being completely absent in the adult animal. In these invertebrate chordates, the notochord is not vacuolated. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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