title: Heating element

text: Resistance wire: Metallic resistance heating elements may be wire or ribbon, straight or coiled. They are used in common heating devices like toasters and hair dryers, furnaces for industrial heating, floor heating, roof heating, pathway heating to melt snow, dryers, etc. The most common classes of materials used include:


title: Heating element

text: Thick film heaters are a type of resistive heater that can be printed on a thin substrate. Thick film heaters exhibit various advantages over the conventional metal-sheathed resistance elements. In general, thick film elements are characterized by their low profile form factor, improved temperature uniformity, quick thermal response due to low thermal mass, low energy consumption, high watt density and wide range of voltage compatibility. Typically, thick film heaters are printed on flat substrates, as well as on tubes in different heater patterns. These heaters can attain watt densities of as high as 100 W/cm depending on the heat transfer conditions. The thick film heater patterns are highly customizable based on the sheet resistance of the printed resistor paste.


title: Heating element

text: These heaters can be printed on a variety of substrates including metal, ceramic, glass, polymer using metal/alloy-loaded thick film pastes. The most common substrates used to print thick film heaters are aluminum 6061-T6, stainless steel and muscovite or phlogopite mica sheets. The applications and operational characteristics of these heaters vary widely based on the chosen substrate materials. This is primarily attributed to the thermal characteristics of the heater substrate.


title: Heating element

text: There are several conventional applications of thick film heaters. They can be used in griddles, waffle irons, stove-top electric heating, humidifiers, tea kettles, heat sealing devices, water heaters, clothes irons and steamers, hair straighteners, boilers, 3D printer heated beds, thermal print heads, glue guns, laboratory heating equipment, clothes dryers, baseboard heaters, warming trays, heat exchangers, deicing/defogging devices for car windshields, side mirrors, etc., refrigerator defrosting, etc.


title: Heating element

text: For most applications, the thermal performance and temperature distribution are the two key design parameters. In order to avoid any hotspots and to maintain a uniform temperature distribution across a substrate, the circuit design can be optimized by changing the localized power density of the resistor circuit. An optimized heater design helps to control the heater output and modulate the local temperatures across the heater substrate. In cases where there is a requirement of 2 or more heating zones with different output power over a relatively small area, a thick film heater can be designed to achieve a zonal heating pattern on a single substrate.


title: Heating element

text: Thick film heaters can largely be characterized under two subcategories- negative temperature coefficient (NTC) or positive temperature coefficient (PTC) based on the effect of temperature increase on the element's resistance. The NTC type heaters are characterized by a decrease in resistance as the heater temperature increases and thus have a higher output power at higher temperatures for a given input voltage. The PTC heaters behave in an opposite manner with an increase of resistance and decreasing heater power at elevated temperatures. This characteristic of the PTC heaters make them self regulating too, as their output power saturates at a fixed temperature. On the other hand, NTC type heaters generally require a thermostat or a thermocouple in order to control the heater runaway. These heaters are used in applications which require a quick ramp-up of heater temperature to a predetermined set-point as they are usually faster acting than the PTC type heaters.


title: Heating element

text: Resistive heaters can be made of conducting PTC rubber materials where the resistivity increases exponentially with increasing temperature. Such a heater will produce high power when it is cold, and rapidly heat up itself to a constant temperature. Due to the exponentially increasing resistivity, the heater can never heat itself to warmer than this temperature. Above this temperature, the rubber acts as an electrical insulator. The temperature can be chosen during the production of the rubber. Typical temperatures are between .


title: Heating element

text: It is a point-wise self-regulating heater and self-limiting heater. Self-regulating means that every point of the heater independently keeps a constant temperature without the need of regulating electronics. Self-limiting means that the heater can never exceed a certain temperature in any point and requires no overheat protection.


title: Henry Adams

text: Henry Brooks Adams (February 16, 1838 – March 27, 1918) was an American historian and a member of the Adams political family, descended from two U.S. Presidents.


title: Henry Adams

text: As a young Harvard graduate, he served as secretary to his father, Charles Francis Adams, Abraham Lincoln's ambassador to the United Kingdom. The posting influenced the younger man through the experience of wartime diplomacy, and absorption in English culture, especially the works of John Stuart Mill. After the American Civil War, he became a political journalist who entertained America's foremost intellectuals at his homes in Washington and Boston.


title: Henry Adams

text: During his lifetime, he was best known for "The History of the United States of America During the Administrations of Thomas Jefferson and James Madison", a nine-volume work, praised for its literary style, command of the documentary evidence, and deep (family) knowledge of the period and its major figures.


title: Henry Adams

text: His posthumously published memoir, "The Education of Henry Adams", won the Pulitzer Prize and went on to be named by the Modern Library as the best English-language nonfiction book of the 20th century.


title: Henry Adams

text: He was born in Boston on February 16, 1838, into one of the country's most prominent families. His parents were Charles Francis Adams Sr. (1807–1886) and Abigail Brooks (1808–1889). Both his paternal grandfather, John Quincy Adams, and great-grandfather, John Adams, one of the most prominent among the Founding Fathers, had been U.S. Presidents. His maternal grandfather, Peter Chardon Brooks, was one of Massachusetts' most successful and wealthiest merchants. Another great-grandfather, Nathaniel Gorham, signed the Constitution.


title: Henry Adams

text: After his graduation from Harvard University in 1858, he embarked on a grand tour of Europe, during which he also attended lectures in civil law at the University of Berlin.


title: Henry Adams

text: In his 50s, he was initiated into the Phi Kappa Psi fraternity as an honorary member at the 1893 Columbian Exposition by Harris J. Ryan, a judge for the exhibit on electrical engineering. Through that organization, he was a member of the Irving Literary Society.


title: Henry Adams

text: Adams returned home from Europe in the midst of the heated presidential election of 1860. He tried his hand again at law, taking employment with Judge Horace Gray's Boston firm, but this was short-lived.


title: Henry Adams

text: His father, Charles Francis Adams Sr., was also seeking re-election to the US House of Representatives. After his successful re-election, Charles Francis asked Henry to be his private secretary, continuing a father-son pattern set by John and John Quincy and suggesting that Charles Francis had chosen Henry as the political scion of that generation of the family. Henry shouldered the responsibility reluctantly and with much self-doubt. "[I] had little to do", he reflected later, "and knew not how to do it rightly."


title: Henry Adams

text: During this time, Adams was the anonymous Washington correspondent for Charles Hale's "Boston Daily Advertiser".


title: Henry Adams

text: On March 19, 1861, Abraham Lincoln appointed Charles Francis Adams Sr. United States Ambassador to the United Kingdom. Henry accompanied his father to London as his private secretary. He also became the anonymous London correspondent for "The New York Times". The two Adamses were kept very busy, monitoring Confederate diplomatic intrigues and trying to obstruct the construction of Confederate commerce raiders by British shipyards (see Alabama Claims). Henry's writings for the "Times" argued that Americans should be patient with the British. While in Britain, Adams was befriended by many noted men, including Charles Lyell, Francis T. Palgrave, Richard Monckton Milnes, James Milnes Gaskell, and Charles Milnes Gaskell. He worked to introduce the young Henry James to English society, with the help of his closest and lifelong friend Charles Milnes Gaskell and his wife Lady Catherine ("nee" Wallop).


title: Henry Adams

text: While in Britain, Henry read and was taken with the works of John Stuart Mill. For Adams, Mill's "Considerations on Representative Government" showed the necessity of an enlightened, moral, and intelligent elite to provide leadership to a government elected by the masses and subject to demagoguery, ignorance, and corruption. Henry wrote to his brother Charles that Mill demonstrated to him that "democracy is still capable of rewarding a conscientious servant." His years in London led Adams to conclude that he could best provide that knowledgeable and conscientious leadership by working as a correspondent and journalist.


title: Henry Adams

text: In 1868, Adams returned to the United States and settled in Washington, DC, where he began working as a journalist. Adams saw himself as a traditionalist longing for the democratic ideal of the 17th and 18th centuries. Accordingly, he was keen on exposing political corruption in his journalism.


title: Henry Adams

text: In 1870, Adams was appointed professor of medieval history at Harvard, a position he held until his early retirement in 1877 at 39. As an academic historian, Adams is considered to have been the first (in 1874–1876) to conduct historical seminar work in the United States. Among his students was Henry Cabot Lodge, who worked closely with Adams as a graduate student.


title: Henry Adams

text: Adams's "The History of the United States of America (1801 to 1817)" (9 vols., 1889–1891) is a highly detailed history of the Jefferson and Madison administrations with a focus on diplomacy. Wide praise was given for its literary merit, especially the opening five chapters of volume 1, describing the nation in 1800. These chapters have also been criticized; Noble Cunningham states flatly, "Adams misjudged the state of the nation in 1800." In striving for literary effect, Cunningham argues, Adams ignored the dynamism and sophistication of the new nation. Such arguments aside, historians have long recognized it as a major and permanent monument of American historiography. It has been called "a neglected masterpiece" by Garry Wills, and "a history yet to be replaced" by the great historian C. Vann Woodward.


title: Henry Adams

text: In the 1880s, Adams wrote two novels, starting with "", which was published anonymously in 1880 and immediately became popular in literary circles in England and Europe as well as in America. (Only after Adams's death did his publisher reveal his authorship.) His other novel, published under the "nom de plume" of Frances Snow Compton, was "Esther", whose heroine was believed to be modeled after his wife.


title: Henry Adams

text: During the late 1860s and early 1870s, Adams edited, with the assistance of his brother Charles Francis Adams, the major American intellectual-literary journal, The North American Review. During his tenure it published a number of articles exposing corrupt malpractices in finance, corporations and government, anticipating the work of the "muckrakers" by a generation. The brothers collected several of their most important essays in "Chapters Of Erie" (1871). This experience marked the public commencement of Henry Adams' critical observation of, and radical disenchantment with, the operations and ascendancy of corporations and centralized finance in the economic, social and political life of America. Summarizing the observations of a lifetime, he wrote to his brother Brooks on September 20, 1910 (vol. 6, pp. 369-370, "Letters", ed. Levenson et al.): "Our system of protection [of industry and commerce]... is fatal to our principles... Railways, trusts, banking-system, manufactures, capital and labor, all rest on the principle of monopoly ... The suggestion that these great corporate organisms, which now perform all the vital functions of our social life, should behave themselves decently, gives away our contention that they have no right to exist. Nor am I prepared to admit that more decency can be attained through a legislature made up of similar people exercising similar illegal powers... From top to bottom the whole system is a fraud... The conviction of having reached this point where we have no choice but to go on in our own rot, drove me out of all share in public affairs twenty years ago.. Every one who has assumed such a share since then has only muddled and made the matter worse."


title: Henry Adams

text: In 1884, Adams was elected a member of the American Antiquarian Society. In 1892, he received the degree LL.D., from Western Reserve University. In 1894, Adams was elected president of the American Historical Association. His address, entitled "The Tendency of History," was delivered "in absentia". The essay predicted the development of a scientific approach to history, but was somewhat ambiguous as to what this achievement might mean.


title: Henry Adams

text: During the 1890s, Adams exercised a profound and fruitful influence over the thought and writings of his younger brother Brooks. Brooks' essay, "The Degradation of the Democratic Dogma," an offshoot of their decades long conversations and correspondence, was published years later.


title: Henry Adams

text: Adams was an accomplished poet and in later life a friend of young poets—notably George Cabot Lodge and Trumbull Stickney—but published nothing in his lifetime. His important poems "Buddha and Brahma" and "Prayers to the Virgin and the Dynamo" are included (respectively) in the Library of America's Nineteenth and Twentieth Century Anthologies, and a half dozen sonnets, a Troubadour translation, and one lyric are scattered through the letters. It is an open question whether the Massachusetts Historical Society or other archives preserve more.


title: Henry Adams

text: In 1904, Adams privately published a copy of his "Mont Saint Michel and Chartres", a pastiche of history, travel, and poetry that celebrated the unity of medieval society, especially as represented in the great cathedrals of France. Originally meant as a diversion for his nieces and "nieces-in-wish", it was publicly released in 1913 at the request of Ralph Adams Cram, an important American architect, and published with support of the American Institute of Architects.


title: Henry Adams

text: He published "The Education of Henry Adams" in 1907, in a small private edition for selected friends. Only following Adams's death was "The Education" made available to the general public, in an edition issued by the Massachusetts Historical Society. It ranked first on the Modern Library's 1998 list of 100 Best Nonfiction Books and was named the best book of the 20th century by the Intercollegiate Studies Institute, a conservative organization that promotes classical education. It was awarded the Pulitzer Prize in 1919.


title: Henry Adams

text: Some center-right intellectuals view the book critically. Conservative journalist Fred Siegel considered the worldview expressed therein to be rooted in resentment of America's middle class. "Henry Adams," wrote Siegel, "grounded the intellectual's alienation from American life in the resentment that superior men feel when they are insufficiently appreciated in America's common-man culture." Others view Adams's critique of the commercialism, corruption and pecuniolatry of American mercantile culture as central.


title: Henry Adams

text: John Quincy Adams II (1833–1894) was a graduate of Harvard (1853), practiced law, and was a Democratic member for several terms of the Massachusetts general court. In 1872, he was nominated for vice president by the Democratic faction that refused to support the nomination of Horace Greeley.


title: Henry Adams

text: Charles Francis Adams Jr. (1835–1915) fought with the Union in the Civil War, receiving in 1865 the brevet of brigadier general in the regular army. He became an authority on railway management as the author of "Railroads, Their Origin and Problems" (1878), and as president of the Union Pacific Railroad from 1884 to 1890. He collaborated with Henry on the editing of The North Atlantic Review and other projects.


title: Henry Adams

text: Brooks Adams (1848–1927) practiced law and became a writer. His books include "The Gold Standard" (1894), "The Law of Civilization and Decay" (1895), "America's Economic Supremacy" (1900), "The New Empire" (1902), "The Theory of Social Revolutions" (1914), and "The Emancipation of Massachusetts" (1919). Henry's influence on and involvement with his youngest brother's thought and writing was profound and enduring.


title: Henry Adams

text: Louisa Catherine Adams Kuhn Her brother describes her death in 1870 from tetanus following a carriage accident in Bagni di Lucca in his Chaos Chapter of "The Education of Henry Adams". She is buried in Florence's 'English' Cemetery.


title: Henry Adams

text: Adams was a member of an exclusive circle, a group of friends called the "Five of Hearts" that consisted of Henry, his wife Clover, geologist and mountaineer Clarence King, John Hay (assistant to Lincoln and later Secretary of State), and Hay's wife Clara.


title: Henry Adams

text: One of Adams's frequent travel companions was the artist John La Farge, with whom he journeyed to Japan and the South Seas.


title: Henry Adams

text: From 1885 until 1888, Theodore Frelinghuysen Dwight (1846–1917), the State Department's chief librarian, lived with Adams at his home at 1603 H Street in Washington, D.C., where he served as Adams's literary assistant, personal secretary, and household manager. Dwight would go on to serve as archivist of the Adams family archives in Quincy, Massachusetts; director of the Boston Public Library; and U.S. Consul at Vevey, Switzerland.


title: Henry Adams

text: On June 27, 1872, Adams married Clover Hooper in Beverly, Massachusetts. They spent their honeymoon in Europe, much of it with Charles Milnes Gaskell at Wenlock Abbey, Shropshire. While there, exemplifying the New England civic conscience she and Henry shared, Clover wrote "England is charming for a few families but hopeless for most ... Thank the Lord that the American eagle flaps and screams over us." Upon their return, Adams went back to his position at Harvard, and their home at 91 Marlborough Street, Boston, became a gathering place for a lively circle of intellectuals. In 1877, his wife and he moved to Washington, DC, where their home on Lafayette Square, across from the White House, again became a dazzling and witty center of social life. He worked as a journalist and continued working as a historian.


title: Henry Adams

text: On Sunday morning, December 6, 1885, after a late breakfast at their home, 1607 H Street on Lafayette Square, Clover Hooper Adams went to her room. Henry, troubled by a toothache, had planned to see his dentist. While departing his home, he was met by a woman calling to see his wife. Adams went upstairs to her room to ask if she would receive the visitor and found his wife lying on a rug before the fire; an opened vial of potassium cyanide, which Clover had frequently used in processing photographs, lay nearby. Adams carried his wife to a sofa, then ran for a doctor. Shortly thereafter, Dr. Charles E. Hagner pronounced Clover dead.


title: Henry Adams

text: Much speculation and numerous theories have been given concerning the causes of Clover Adams's suicide. Her death has been attributed to depression over her father's death. Her suicide was also related to a family history of mental depression and suicide, a sense of frustration and lack of fulfillment as a cultured person and as a woman, and a feeling of intellectual inferiority over her husband's interest in and attention to another woman. The possibility of determining the validity of any or all of these causes was made more difficult by Henry Adams's destruction of most of Clover's letters and photos following her death. His autobiography maintains a profound silence about his wife after her suicide. Adams's grief was profound and enduring. The event was life-shattering for Adams and profoundly altered the course of his life.


title: Henry Adams

text: Henry, his brother, Charles Francis Adams, Clover's brother Edward, and her sister Ellen, with her husband Ephraim Gurney, were the attendees at a brief funeral service held on December 9, 1885, at the house on Lafayette Square. Interment services followed at Rock Creek Cemetery, but the actual burial was postponed until December 11, 1885, because of the inclement weather. A few weeks later, Adams ordered a modest headstone as a temporary marker. Later he commissioned a monument for her tomb from his friend, the sculptor Augustus Saint-Gaudens, who created a masterpiece for her memorial.


title: Henry Adams

text: Henry Adams first met Elizabeth Cameron in January 1881 at a reception in the drawing room of the house of John and Clara Hay. Elizabeth was considered to be one of the most beautiful and intelligent women in the Washington area. Elizabeth had grown up as Lizzie Sherman, the daughter of Judge Charles Sherman of Ohio, the niece of Secretary of the Treasury John Sherman in Hayes's cabinet, and the niece of General William Tecumseh Sherman. Her family had pressured Lizzie into a loveless marriage with Senator J. Donald Cameron, brokering a prenuptial agreement that provided her with the income from $160,000 worth of securities, a very large amount in 1878, equivalent to about $ million in . The arranged marriage on May 9, 1878, united the reluctant 20-year-old beauty with a 44-year-old widower with six children. Eliza, his eldest, who had served as her father's hostess, was now displaced by a stepmother the same age. The children never accepted her. The marriage was further strained by the Senator's coarseness and indifference and his fondness for bourbon and the world of political corruption he inhabited, which is reflected in Adams's novel "Democracy".


title: Henry Adams

text: Henry Adams initiated a correspondence with Lizzie on May 19, 1883, when she and her husband departed for Europe. That letter reflected his unhappiness with her departure and his longing for her return. It was the first of hundreds to follow for the next 35 years, recording a passionate yet unconsummated relationship. On December 7, 1884, one year before Clover's suicide, Henry Adams wrote to Lizzie, "I shall dedicate my next poem to you. I shall have you carved over the arch of my stone doorway. I shall publish your volume of extracts with your portrait on the title page. None of these methods can fully express the extent to which I am yours."


title: Henry Adams

text: Adams's wife, Clover, who had written a weekly letter to her father throughout her marriage except for the brief hiatus during her breakdown along the Nile, never mentioned concerns or suspicions about Henry's relationship with Lizzie. Nothing in the letters of her family or circle of friends indicates her distrust or unhappiness with her husband in this matter. Indeed, after her death, Henry found a letter from Clover to her sister Ellen which had not been posted. The survival of this letter was assured by its contents which read, "If I had one single point of character or goodness, I would stand on that and grow back to life. Henry is more patient and loving than words can express—God might envy him—he bears and hopes and despairs hour after hour—Henry is beyond all words tenderer and better than all of you even."


title: Henry Adams

text: On Christmas Day 1885, Adams sent one of Clover's favorite pieces of jewelry to Cameron, requesting that she "sometimes wear it, to remind you of her."


title: Henry Adams

text: Just before the end of 1885, Adams moved into his newly completed mansion next door at 1603 H Street designed by his old friend, Henry Hobson Richardson, one of the most prominent architects of his day.


title: Henry Adams

text: Following his wife's death, Adams took up a restless life as a globetrotter, traveling extensively, spending summers in Paris and winters in Washington, where he commissioned the Adams Memorial, designed by sculptor Augustus Saint-Gaudens and architect Stanford White for her grave site in Rock Creek Cemetery.


title: Henry Adams

text: In 1912, Adams suffered a stroke, perhaps brought on by news of the sinking of the , for which he had return tickets to Europe. After the stroke, his scholarly output diminished, but he continued to travel, write letters, and host dignitaries and friends at his Washington, DC, home.


title: Henry Adams

text: In the first volume of her autobiography Eleanor Roosevelt offers this vignette of Adams in old age: "Occasionally we received one of the much-coveted invitations to lunch or dine at his house... My first picture of this supposedly stern, rather biting Mr. Adams is of an old gentleman in a victoria outside of our house on N Street. [His secretary] Aileen Tone and I were having tea inside, but Mr. Adams never paid calls. He did, however, request that the children of the house come out and join him in the victoria; ... and they brought their Scottie dog and sat and chatted and played all over the vehicle. No one was ever able thereafter to persuade me that Mr. Adams was quite the cynic he was supposed to be. One day after lunch with him, my husband [the future President] mentioned something which at the time was causing him deep concern in the Government, and Mr. Adams looked at him rather fiercely and said: 'Young man, I have lived in this house many years and seen the occupants of that White House across the square come and go, and nothing that you minor officials or the occupant of that house can do will affect the history of the world for long!' ... Henry Adams loved to shock his hearers, and I think he knew that those who were worth their salt would understand him and pick out of the knowledge which flowed from his lips the things which might be useful, and discard the cynicism as an old man's defense against his own urge to be [still] an active factor in the work of the world."


title: Henry Adams

text: Henry Adams died at age 80 in Washington, DC. on March 27, 1918. He is interred beside his wife in Rock Creek Cemetery, Washington, DC.


title: Henry Adams

text: Considered a prominent Anglo-Saxonist of particularly the nineteenth-century, Adams has been portrayed by modern historians as anxious about the immigration of the era into the United States, particularly from Eastern Europe. More starkly put, Adams also wrote of his belief that "the dark races are gaining on us". He considered the U.S. Constitution itself as belonging to the Anglo-Saxon "race", and as an expression of "Germanic freedom". He went so far as to criticize fellow scholars for not being absolute enough in their Anglo-Saxonism, such as William Stubbs, whom he criticized for downplaying the significance, as he saw it, of "Germanic law" or hundred law in its contribution to English common law.


title: Henry Adams

text: Adams was nevertheless highly critical of the English. He referred to them as a "besotted race" from whom nothing good could come and "wanted nothing so much as to wipe England off the earth."


title: Henry Adams

text: Adams's attitude towards Jews has been described as one of loathing. John Hay said that when Adams "saw Vesuvius reddening ... [he] searched for a Jew stoking the fire."


title: Henry Adams

text: Adams wrote: "I detest [the Jews], and everything connected with them, and I live only and solely with the hope of seeing their demise, with all their accursed Judaism. I want to see all the lenders at interest taken out and executed." To one friend, he wrote: "Bombard New York. I know no place that would be more improved by it. The chief population is Jew, and the rest is German Jew."


title: Henry Adams

text: His letters were "peppered with a variety of antisemitic remarks", according to historian Robert Michael, as in the following citations from historian Edward Saveth:


title: Henry Adams

text: "We are in the hands of the Jews", Adams lamented. "They can do what they please with our values." He advised against investment except in the form of gold locked in a safe deposit box. "There you have no risk but the burglar. In any other form you have the burglar, the Jew, the Czar, the socialist, and, above all, the total irremediable, radical rottenness of our whole social, industrial, financial and political system."


title: Henry Adams

text: Edward Chalfant's definitive three-volume biography of Adams includes an exhaustive, well-documented examination of Adams's "antisemitism" in its second volume, "Improvement of the World". He shows that most of the time when Adams says "Jews" he means "financiers." This accords with the historical English usage referenced by the second definition under the Oxford English Dictionary entry, a usage that was common in Adams's time and social milieu. It also accords with Adams's frequent laments that "the eighteenth-century fabric of a priori, or moral, principles" had been replaced with "a bankers' world" and that the "banking mind was obnoxious".


title: Henry Adams

text: Adams esteemed individual Jewish personages. In the "Dilettantism" chapter of "The Education of Henry Adams" he wrote of historian Francis Palgrave that "the reason of his superiority lay in his name, which was Cohen, and his mind which was Cohen also". (Palgrave, the son of a Jewish stockbroker, had changed his name from Cohen upon marriage.) In the "Political Morality" chapter of the same volume he praises the Jewish statesman Benjamin Disraeli over the Gentiles Palmerston, Russell and Gladstone, writing: "Complex these gentlemen were not. Disraeli alone might, by contrast, be called complex."


title: Henry Adams

text: In 1910, Adams printed and distributed to university libraries and history professors the small volume "A Letter to American Teachers of History" proposing a "theory of history" based on the second law of thermodynamics and the principle of entropy. This, essentially, states that all energy dissipates, order becomes disorder, and the earth will eventually become uninhabitable. In short, he applied the physics of dynamical systems of Rudolf Clausius, Hermann von Helmholtz, and William Thomson to the modeling of human history.


title: Henry Adams

text: In his 1909 manuscript "The Rule of Phase Applied to History", Adams attempted to use Maxwell's demon as a historical metaphor, though he seems to have misunderstood and misapplied the principle. Adams interpreted history as a process moving towards "equilibrium", but he saw militaristic nations (he felt Germany pre-eminent in this class) as tending to reverse this process, a "Maxwell's Demon of history."


title: Henry Adams

text: Adams made many attempts to respond to the criticism of his formulation from his scientific colleagues, but the work remained incomplete at Adams's death in 1918. It was published posthumously.


title: Henry Adams

text: Adams said, "I think that Lee should have been hanged. It was all the worse that he was a good man and a fine character and acted conscientiously. It's always the good men who do the most harm in the world."


title: Henry Adams

text: In "Mont Saint-Michel and Chartres", Adams argues that the previous nineteen hundred years of civilization dating from the birth of Christ had been dominated by the feminine, fertile image of the Blessed Virgin, and that the industrial "dynamo" was a masculine, destructive force which would upend history.


title: Essar Group

text: Essar Group is an Indian multinational conglomerate company, founded by Shashi Ruia and Ravi Ruia in 1969. As Essar Global Fund Limited (EGFL), the company controls a number of assets across the core sectors of energy (oil refining, oil and gas exploration, and production, power), infrastructure & logistics (ports, projects), metals & mining, technology and retail (oilfield services, IT, food retail). EGFL holds nearly 100% stake in all its investments.


title: Essar Group

text: Significant Essar Group companies include Essar Oil UK, Essar Ports, Essar Oil & Gas Exploration & Production, Essar Shipping, Essar Power, and Essar Projects.


title: Essar Group

text: In 1969, Shashi Ruia won a major contract worth Rs. 2.3 crore for the construction of an outer breakwater for Chennai port, thus laying the foundation of Essar Group.


title: Essar Group

text: In 1995, Essar Group entered the telecom sector with a Swiss PTT joint venture partnership branded as the Essar Cellphone. In the same year, Essar Group started GSM operations from Delhi. Essar independently, and in partnership with Hutchison (Hutchison Essar), subsequently acquired more telecom circles in India. By 2006, all the circles were under Hutchison Essar Limited.


title: Essar Group

text: In 2017, Essar Steel India Ltd. (ESIL) was on the defaulter's list disclosed by the Reserve Bank of India. Essar Oil was acquired by a consortium led by Rosneft, Trafigura, and UCP for US$12.9 billion, and Essar Oil was rebranded as Nayara Energy.


title: Essar Group

text: In November 2019, ArcelorMittal won approval from Supreme Court to takeover Essar Steel and pay the creditors with equal rights.


title: Essar Group

text: In March 2020, Essar Group was successful in cutting down the residual debt by 70% to about Rs. 12,000 crore.


title: Essar Group

text: In February 2021, Essar Power entered into the renewable energy venture by setting up a 90 MW solar plant in Madhya Pradesh.


title: Essar Group

text: In December 2021, Essar has set up Vertex Hydrogen under UK's HyNet project with Progressive Energy to help drive energy transition in the UK.


title: Essar Group

text: In 2003, Essar Group acquired Aegis Communication and spread across 13 countries. In 2014, Essar did the part sale of Aegis USA Inc. with annual revenue of $400 million to Teleperformance and in 2017 Essar left the outsourcing business by selling Aegis’ operations to Capital Square Partners (CSP).


title: Essar Group

text: In 2011, Essar Energy purchased Stanlow Refinery in North West England for $350 million. Under Essar's leadership, the first phase of the turnaround of Stanlow refinery has been started during the financial year 2015–16 with $187 million net profit. Essar plans a £250 million expansion of Stanlow refinery, with over 16% production of transport fuels in the UK.


title: Essar Group

text: During COVID-19 pandemic, Essar Foundation opened Covid Care Centre at Devbhumi Dwarka, Gujarat, organized vaccination drives, and provided meals to needy people.


title: Hahm Eun-jung

text: Hahm Eun-jung (born December 12, 1988), known professionally as Eunjung and also Elsie, is a South Korean singer and actress. In 1995, she won "Little Miss Korea" competition at the age of seven and debuted as a child actress in the same year with the television drama "A New Generation of Adults" (1995). Since then, she has taken on several minor roles in movies, television series and also being cast in various commercial films. After three years of training, she debuted as a member of South Korean girl group T-ara in July 2009. She debuted as a solo artist by the name Elsie with her EP, "I'm Good", on May 7, 2015.


title: Hahm Eun-jung

text: Hahm was born in Seoul, South Korea. Her mother, a graduate of Ewha Womans University, is a former piano teacher who works as Hahm's agent. While attending seventh grade, Hahm started taekwondo lessons and won three different competitions. Her mother made the decision to quit teaching and manage her career upon her high school graduation in 2007. Later that year, Hahm enrolled in Dongguk University, where she took performance courses. She is an only child and has been quoted as explaining, "My mother had me 10 years after she was married to my father, which seems more hurtful. Upon watching several famous performers in the past, she wanted to become an actress. Now that I have, she is very pleased I have acting as a priority. She believes her original prayers were answered."


title: Hahm Eun-jung

text: In 1995, when Hahm was seven years old, she participated in the "Little Miss Korea" pageant and won. That same year, she appeared in the youth drama "", which aired on KBS. Afterwards, she had several minor roles in movies and Korean dramas, along with being cast in a handful of commercial films.


title: Hahm Eun-jung

text: In 2007, Hahm appeared in various music videos, namely SG Wannabe's music video "Gasiri" ("가시리") from their 2007 album "Story In New York". Later that year, she would also be seen in FT Island's music videos "Thunder" ("천둥"), "Only One Person" ("한사람만"), and "A Man's First Love Follow Him To The Grave" ("남자의 첫사랑은 무덤까지 간다").


title: Hahm Eun-jung

text: She also appeared in the 2008 horror film "Death Bell", where she plays a student who was murdered by her teacher.


title: Hahm Eun-jung

text: Hahm originally trained to be an actress, and later debuted as a member of T-ara in July 2009. She was the first leader of the group, until September 2010.


title: Hahm Eun-jung

text: Hahm featured in Davichi's music video "Time, Please Stop" ("시간아 멈춰라") which was released on May 6, 2010.


title: Hahm Eun-jung

text: Her first major acting role since joining T-ara was in SBS drama "Coffee House", which aired on from May 17, 2010, to July 17, 2010. That same year, she was cast in the horror film "".


title: Hahm Eun-jung

text: Hahm's popularity began to rise in 2011, when she starred in the teen drama "Dream High". The drama was a success, and brought high domestic viewership ratings, and also gaining popularity in other countries and winning several international awards. From 2011 to 2012, she joined MBC's variety program "We Got Married", pairing up with actor Lee Jang-woo. She won the Best Newcomer Award at the MBC Entertainment Awards. Hahm then starred in historical dramas "The King of Legend" and "Insu, The Queen Mother".


title: Hahm Eun-jung

text: In June 2012, Hahm was confirmed to star in the drama "Five Fingers". However, on August 22, it was revealed that she had been dropped from the drama. The Korean Actors Labor Union demanded that Hahm be issued an apology by the producer and crew. In February 2013, Yein E&M issued a formal apology for firing Hahm without notice.


title: Hahm Eun-jung

text: In 2015, it was announced that Hahm would play the lead role in the Thai romantic comedy "Micro Love", making her the first female idol to star in a Thai movie. In May 2015, Hahm made her solo debut under the stage name ELSIE. She released her first mini album "I'm Good", with the lead single of the same name featuring K.Will. The Chinese version of her music video peaked at #2 on the Chinese "YinYueTai"'s music video charts. On October 14, Hahm released the song "Goodbye", as the soundtrack of T-ara's web-drama "Sweet Temptation". The song was also included in her repackaged mini album, "Goodbye", released on October 30.


title: Hahm Eun-jung

text: In 2016, Hahm was cast in "Flowers of Evil", a thriller directed by Cho Sung-kyu. In 2017, Hahm was cast in MBC's daily drama, "Sisters-in-Law," which premiered in April that year.


title: Hahm Eun-jung

text: In January 2018, Hahm confirmed her departure from MBK after her contract expired. In February 2018, Hahm signed an exclusive management contract with UFO Production, making her the company's first-ever artist. UFO Production, a subsidiary of technology company Pobis TNC, is more known for producing the MBC TV weekend drama "Money Flower". On May 24, 2018, it was confirmed that Hahm was cast in the upcoming KBS's drama "Lovely Horribly", starring Park Si-hoo and Song Ji-hyo.


title: Hahm Eun-jung

text: On February 26, 2019, it was announced that Hahm would be the narrator for the Korea-Vietnam co-production documentary named "The Muse Story", which will be broadcast on KBS World. On October 14, 2020, her label announced that Hahm will star in upcoming film called “I will sing” as a singer.


title: Hahm Eun-jung

text: As of February 2021, she is cast in the leading role of the upcoming TV drama "A Fool's Dream", which will be aired on KBS1 on March 29, 2021. On July 15, 2021, Hahm left Cabin 74 after her contract expired. On September 27, 2021, Hahm signed an exclusive contract with Management Koo.


title: Hahm Eun-jung

text: Eunjung has modeled for several brands since before her debut as a singer. Her first ever advertisement was a print-in ad for Korea's No.1 mineral water "Jeju Samdasoo" in 1998.


title: Hahm Eun-jung

text: In February 2011, Eunjung was chosen, along with actor Kim Soo-hyun, as exclusive models for clothing brand SPRIS. The brand is known to be the most preferred brand among young people with previous models including Lee Joon-gi, Kim Beom and 2PM. The brand was promoted with a series of TV commercial films including a 3-minute music-drama video which featured a newly recorded song by both Eunjung and Kim Soo-hyung called ""Crazy4s"," the song was never officially released.


title: Hahm Eun-jung

text: In 2015, posters featuring Eunjung as a model for "Burger King" were released all over Korea, Hahm became the third T-ara member to endorse the restaurant after her Hyomin and Jiyeon in 2014.


title: Hahm Eun-jung

text: In 2016, Eunjung was selected as a model for "Coca Cola" along with Yubin, Park Yoon and Jo Se-hyeon. She attended several promotional events for the brand for 2 years since 2015 including its 130th anniversary exhibition event.


title: The Dream-Quest of Unknown Kadath

text: The Dream-Quest of Unknown Kadath is a novella by American writer H. P. Lovecraft. Begun probably in the autumn of 1926, the draft was completed on January 22, 1927 and it remained unrevised and unpublished in his lifetime. It is both the longest of the stories that make up his Dream Cycle and the longest Lovecraft work to feature protagonist Randolph Carter. Along with his 1927 novel "The Case of Charles Dexter Ward", it can be considered one of the significant achievements of that period of Lovecraft's writing. "The Dream-Quest" combines elements of horror and fantasy into an epic tale that illustrates the scope and wonder of humankind's ability to dream.


title: The Dream-Quest of Unknown Kadath

text: The story was published posthumously by Arkham House in 1943. Currently, it is published by Ballantine Books in an anthology that also includes "The Silver Key" and "Through the Gates of the Silver Key". The definitive version, with corrected text by S. T. Joshi, is published by Arkham House in "At the Mountains of Madness and Other Novels" and by Penguin Classics in "The Dreams in the Witch-House and Other Weird Stories".


title: The Dream-Quest of Unknown Kadath

text: In his dreams, Randolph Carter sees a majestic city, but is unable to approach it. After the third time the city appears in his dreams, he prays to the gods of dream to reveal the city's whereabouts, but then the city vanishes from his dreams altogether. Undaunted, Carter resolves to beseech the gods in person at Kadath, the mountain above which the gods of dream live. In dream, Carter consults priests in a temple that borders the Dreamlands. They tell Carter that nobody knows the location of Kadath, and warn him of great danger should he continue with his quest to reach the city and suggest that the gods purposefully stopped his visions.


title: The Dream-Quest of Unknown Kadath

text: Carter's knowledge of Dreamlands customs and languages makes his quest comparatively less risky than if done by an amateur, but he must consult entities with a dangerous reputation. The Zoogs, a race of predatory rodents, direct him to Ulthar to find the priest Atal. In the cat-laden city of Ulthar, Atal mentions a huge mountainside carving of the gods' features. Carter realizes the gods' mortal descendants will share those features and presumably be near Kadath. While seeking passage there, Carter is kidnapped by turbaned slavers, who take him to the moon and deliver him to horrible moon-beasts, the servants of malevolent god Nyarlathotep. The cats of Ulthar, Carter's allies, rescue him and return him to a port city.


title: The Dream-Quest of Unknown Kadath

text: After a long journey, Carter finds the carving, recognizing the visage of the gods in traders who dock at Celephaïs. Before he can act on his knowledge, faceless, winged creatures called nightgaunts capture him and leave him to die in the underworld. Friendly ghouls, including Carter's friend Richard Pickman, assist him in returning to the surface by sneaking through the terrible city of the man-eating Gugs. After assisting the cats in repelling a Zoog sneak attack, Carter buys passage to Celephaïs and learns from the sailors that the traders come from Inganok, a cold and dark land devoid of cats.


title: The Dream-Quest of Unknown Kadath

text: Carter meets Celephaïs' king, his friend Kuranes, who became a permanent resident of the Dreamlands upon his death in the waking world. Longing for home, he has dreamed parts of his kingdom to resemble his native Cornwall. Kuranes knows the pitfalls of the Dreamlands well but fails to dissuade Carter from his quest. Under the pretense of wishing to work in its quarries, Carter boards a ship bound for Inganok. As they draw near, Carter spots a nameless island from which he hears strange howls. At a breathtaking summit near a quarry, Carter is captured by a merchant he had previously encountered. Monstrous birds fly them over the Plateau of Leng, a vast tableland populated by Pan-like horned humanoid beings.


title: The Dream-Quest of Unknown Kadath

text: Carter is brought to a monastery inhabited by the dreaded High Priest Not to Be Described. There, Carter learns that the Men of Leng are the slavers who captured him, and had worn turbans to conceal their horns. He also learns that the nightgaunts do not serve Nyarlathotep, as is commonly supposed, but Nodens, and that even Earth's gods fear them. Carter recoils in horror as he realizes the masked high-priest's true identity. Carter flees through maze-like corridors, wandering through the monastery in pitch-black darkness until he chances on the exit.


title: The Dream-Quest of Unknown Kadath

text: After rescuing several ghouls from Men of Leng, Carter and ghoul reinforcements attack a moon-beast outpost on the nameless rock. In a nearby city, Carter obtains the services of a flock of nightgaunts to transport himself and the ghouls to the gods' castle on Kadath. After a long flight, Carter arrives at Kadath but finds it empty. A great procession led by a pharaoh-like man arrives. The pharaoh reveals himself as Nyarlathotep and tells Carter that the city of his dreams is the childhood memories of his home city of Boston. The gods of earth have seen the city of Carter's dreams and made it their home, abandoning Kadath and their responsibilities.


title: The Dream-Quest of Unknown Kadath

text: Impressed with Carter's resolve, Nyarlathotep grants Carter passage to the city to recall the gods of earth, but Carter realizes too late that the mocking Nyarlathotep has tricked him, and he is being taken to the court of Azathoth at the center of the universe. At first believing he is doomed, Carter suddenly remembers that he is in a dream and wakes. Nyarlathotep broods over his defeat within the halls of Kadath, mocking in anger the "mild gods of earth" whom he has snatched back from the sunset city.


title: The Dream-Quest of Unknown Kadath

text: Lovecraft included elements and characters from previous stories, many of which had been influenced by Lord Dunsany, in "Dream-Quest of Unknown Kadath", though they are not always depicted consistently.


title: The Dream-Quest of Unknown Kadath

text: Like Lovecraft's novel fragment "Azathoth" (1922, published 1938), "The Dream-Quest" appears to have been influenced by "Vathek", a 1786 novel by William Thomas Beckford that "is similarly an exotic fantasy written without chapter divisions". Critics such as Will Murray and David E. Schultz, in fact, have suggested that "The Dream-Quest" is in effect a second attempt at completing the abandoned novel "Azathoth".


title: The Dream-Quest of Unknown Kadath

text: While the influence of the fantasies of Lord Dunsany on Lovecraft's Dream Cycle is often mentioned, Robert M. Price argues that a more direct model for "The Dream-Quest" is provided by the six Mars ("Barsoom") novels of Edgar Rice Burroughs that had been published by 1927. It's been noted, however, that there is little in common between John Carter, a classic action hero, outstanding warrior and rescuer of princesses, and Randolph Carter, a melancholy figure, quiet and contemplative, who never actually fights any of his enemies, is captured several times, and needs his friends to rescue him again and again. Elsewhere, Price maintains that L. Frank Baum's "The Wonderful Wizard of Oz" (1900) was also a significant influence on "The Dream-Quest", pointing out that in both books the main character chooses in the end to return "home" as the best place to be.


title: The Dream-Quest of Unknown Kadath

text: "An H. P. Lovecraft Encyclopedia" cites Nathaniel Hawthorne's "The Marble Faun" and "The Great Stone Face" as influences.


title: The Dream-Quest of Unknown Kadath

text: "The Dream-Quest" has evoked a broad range of reactions, "some HPL enthusiasts finding it almost unreadable and others... comparing it to the "Alice" books and the fantasies of George MacDonald." Joanna Russ referred to "The Dream-Quest" as "charming... but alas, never rewritten or polished".


title: The Dream-Quest of Unknown Kadath

text: Lovecraft himself declared that "it isn't much good; but forms useful practice for later and more authentic attempts in the novel form." He expressed concern while writing it that "Randolph Carter's adventures may have reached the point of palling on the reader; or that the very plethora of weird imagery may have destroyed the power of any one image to produce the desired impression of strangeness."


title: The Dream-Quest of Unknown Kadath

text: In 1948, Arthur C. Clarke sent Lord Dunsany a copy of "The Arkham Sampler" containing part of "The Dream-Quest". Dunsany responded: "I see Lovecraft borrowed my style, & I don't grudge it to him".


title: KNVB Cup

text: The KNVB Beker (; ), branded as the TOTO KNVB Beker for sponsorship reasons, is a competition in the Netherlands organized by the Royal Dutch Football Association (KNVB) since 1898. It was based on the format of the English FA Cup. Outside the Netherlands, it is often referred to as the Dutch Cup. The tournament consists of all teams from the top four tiers of Dutch league football (Eredivisie, Eerste Divisie, Tweede Divisie and Derde Divisie), as well as the 24 semi-finalists (or replacements) of the six KNVB District Cups. The finals of the tournament traditionally takes place in De Kuip, and has been held there every season since the 1989 final. The winners of the cup compete against the winners of the Eredivisie for the Johan Cruyff Shield, which acts as the curtain raiser for the following season.


title: KNVB Cup

text: The competition was conceived during a board meeting of the Dutch Football Association, in The Hague, on 19 January 1898. The tournament began the following season, 1898–99. The first final was played on 9 May 1899 between RAP Amsterdam and HVV Den Haag, and ended in a 1–0 victory for the former thanks to a goal from Julius Hisgen in extra-time. In 1946, the trophy was changed to one made out of silver, which was extremely rare in the immediate aftermath of World War II. That trophy remains in use today. In 2018, a trophy colored in gold was commissioned to commemorate the 100th edition of the tournament.


title: KNVB Cup

text: Like many national cup competitions, the name of the tournament has changed with sponsorship. From 1995, the competition went from being the KNVB Beker to being known as the Amstel Cup after the then sponsor Amstel. On 16 August 2005, the name was changed to the Gatorade Cup after the drinks company Gatorade. In 2006, the name returned to being the KNVB Beker with Gatorade remaining as the principal sponsor.


title: KNVB Cup

text: On 12 January 2018, it was announced that TOTO would be the name sponsor of the KNVB Cup, until the 2021–22 season. The competition was renamed the TOTO KNVB Beker with immediate effect.


title: KNVB Cup

text: Up until 1998, the winner of the cup entered into the UEFA Cup Winners' Cup, but with the abandonment of that tournament, the winner now goes into the UEFA Europa League. If the winning team has finished in the top two of the Eredivisie and thus gained entry into the UEFA Champions League, the berth will be redistributed to that season's Eredivisie.


title: KNVB Cup

text: In 1998, both KNVB Cup finalists, Ajax and PSV, gained entry in the Champions League, so a third-place play-off was played between the beaten semi-finalists, SC Heerenveen and FC Twente, to determine who would take the Cup Winners' Cup place.


title: KNVB Cup

text: The broadcast rights are included in the KNVB broadcast rights package, which also include the Johan Cruyff Shield.


title: Frieze

text: In architecture, the frieze is the wide central section part of an entablature and may be plain in the Ionic or Doric order, or decorated with bas-reliefs. Paterae are also usually used to decorate friezes. Even when neither columns nor pilasters are expressed, on an astylar wall it lies upon the architrave ("main beam") and is capped by the moldings of the cornice. A frieze can be found on many Greek and Roman buildings, the Parthenon Frieze being the most famous, and perhaps the most elaborate. This style is typical for the Persians.


title: Frieze

text: In interiors, the frieze of a room is the section of wall above the picture rail and under the crown moldings or cornice. By extension, a frieze is a long stretch of painted, sculpted or even calligraphic decoration in such a position, normally above eye-level. Frieze decorations may depict scenes in a sequence of discrete panels. The material of which the frieze is made of may be plasterwork, carved wood or other decorative medium.


title: Frieze

text: In an example of an architectural frieze on the façade of a building, the octagonal Tower of the Winds in the Roman agora at Athens bears relief sculptures of the eight winds on its frieze.


title: Frieze

text: A pulvinated frieze (or pulvino) is in section. Such friezes were features of 17th-century Northern Mannerism, especially in subsidiary friezes, and much employed in interior architecture and in furniture.


title: Edmontosaurus

text: Edmontosaurus ( ) (meaning "lizard from Edmonton") is a genus of hadrosaurid (duck-billed) dinosaur. It contains two known species: "Edmontosaurus regalis" and "Edmontosaurus annectens". Fossils of "E. regalis" have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago, while those of "E. annectens" were found in the same geographic region but in rocks dated to the end of the Maastrichtian stage of the Cretaceous, 66 million years ago. "Edmontosaurus" was one of the last non-avian dinosaurs, and lived alongside dinosaurs like "Triceratops", "Tyrannosaurus", "Ankylosaurus", and "Pachycephalosaurus" shortly before the Cretaceous–Paleogene extinction event.


title: Edmontosaurus

text: "Edmontosaurus" included some of the largest hadrosaurid species, with "E. annectens" measuring up to in length and weighing around in average asymptotic body mass, although some individuals would have been larger. Several well-preserved specimens are known that include not only bones, but in some cases extensive skin impressions and possible gut contents. It is classified as a genus of saurolophine (or hadrosaurine) hadrosaurid, a member of the group of hadrosaurids which lacked large, hollow crests, instead having smaller solid crests or fleshy combs.


title: Edmontosaurus

text: The first fossils named "Edmontosaurus" were discovered in southern Alberta (named after Edmonton, the capital city), in the Horseshoe Canyon Formation (formerly called the lower Edmonton Formation). The type species, "E. regalis", was named by Lawrence Lambe in 1917, although several other species that are now classified in "Edmontosaurus" were named earlier. The best known of these is "E. annectens", named by Othniel Charles Marsh in 1892; originally as a species of "Claosaurus", known for many years as a species of "Trachodon", and later as "Anatosaurus annectens". Anatosaurus, Anatotitan and probably Ugrunaaluk are now generally regarded as synonyms of "Edmontosaurus".


title: Edmontosaurus

text: "Edmontosaurus" was widely distributed across western North America, ranging from Colorado to the north slopes of Alaska. The distribution of "Edmontosaurus" fossils suggests that it preferred coasts and coastal plains. It was a herbivore that could move on both two legs and four. Because it is known from several bone beds, "Edmontosaurus" is thought to have lived in groups, and may have been migratory as well. The wealth of fossils has allowed researchers to study its paleobiology in detail, including its brain, how it may have fed, and its injuries and pathologies, such as evidence for tyrannosaur attacks on a few edmontosaur specimens.


title: Edmontosaurus

text: "Edmontosaurus" has had a long and complicated history in paleontology, having spent decades with various species classified in other genera. Its taxonomic history intertwines at various points with the genera "Agathaumas", "Anatosaurus", "Anatotitan", "Claosaurus", "Hadrosaurus", "Thespesius", and "Trachodon", and references predating the 1980s typically use "Anatosaurus", "Claosaurus", "Thespesius", or "Trachodon" for edmontosaur fossils (excluding those assigned to "E. regalis"), depending on author and date. Although "Edmontosaurus" was only named in 1917, its oldest well-supported species ("E. annectens") was named in 1892 as a species of "Claosaurus".


title: Edmontosaurus

text: The first well-supported species of "Edmontosaurus" was named in 1892 as "Claosaurus annectens" by Othniel Charles Marsh. This species is based on USNM 2414, a partial skull-roof and skeleton, with a second skull and skeleton, YPM 2182, designated the paratype. Both were collected in 1891 by John Bell Hatcher from the late Maastrichtian-age Upper Cretaceous Lance Formation of Niobrara County (then part of Converse County), Wyoming. This species has some historical footnotes attached: it is among the first dinosaurs to receive a skeletal restoration, and is the first hadrosaurid so restored; and YPM 2182 and UNSM 2414 are, respectively, the first and second essentially complete mounted dinosaur skeletons in the United States. YPM 2182 was put on display in 1901, and USNM 2414 in 1904.


title: Edmontosaurus

text: Because of the incomplete understanding of hadrosaurids at the time, following Marsh's death in 1897 "Claosaurus annectens" was variously classified as a species of "Claosaurus", "Thespesius" or "Trachodon". Opinions varied greatly; textbooks and encyclopedias drew a distinction between the ""Iguanodon"-like" "Claosaurus annectens" and the "duck-billed" "Hadrosaurus" (based on remains now known as adult "Edmontosaurus annectens"), while Hatcher explicitly identified "C. annectens" as synonymous with the hadrosaurid represented by those same duck-billed skulls. Hatcher's revision, published in 1902, was sweeping: he considered almost all hadrosaurid genera then known as synonyms of "Trachodon". This included "Cionodon", "Diclonius", "Hadrosaurus", "Ornithotarsus", "Pteropelyx", and "Thespesius", as well as "Claorhynchus" and "Polyonax", fragmentary genera now thought to be horned dinosaurs. Hatcher's work led to a brief consensus, until after 1910 new material from Canada and Montana showed a greater diversity of hadrosaurids than previously suspected. Charles W. Gilmore in 1915 reassessed hadrosaurids and recommended that "Thespesius" be reintroduced for hadrosaurids from the Lance Formation and rock units of equivalent age, and that "Trachodon", based on inadequate material, should be restricted to a hadrosaurid from the older Judith River Formation and its equivalents. In regards to "Claosaurus annectens", he recommended that it be considered the same as "Thespesius occidentalis". His reinstatement of "Thespesius" for Lance-age hadrosaurids would have other consequences for the taxonomy of "Edmontosaurus" in the following decades.


title: Edmontosaurus

text: During this time frame (1902–1915), two additional important specimens of "C. annectens" were recovered. The first, the "mummy" specimen AMNH 5060, was discovered in 1908 by Charles Hazelius Sternberg and his sons in Lance Formation rocks near Lusk, Wyoming. Sternberg was working for the British Museum of Natural History, but Henry Fairfield Osborn of the American Museum of Natural History was able to purchase the specimen for $2,000. The Sternbergs recovered a second similar specimen from the same area in 1910, not as well preserved but also found with skin impressions. They sold this specimen (SM 4036) to the Senckenberg Museum in Germany.


title: Edmontosaurus

text: As a side note, "Trachodon selwyni", described by Lawrence Lambe in 1902 for a lower jaw from what is now known as the Dinosaur Park Formation of Alberta, was erroneously described by Glut (1997) as having been assigned to "Edmontosaurus regalis" by Lull and Wright. It was not, instead being designated "of very doubtful validity." More recent reviews of hadrosaurids have concurred.


title: Edmontosaurus

text: "Edmontosaurus" itself was coined in 1917 by Lawrence Lambe for two partial skeletons found in the Horseshoe Canyon Formation (formerly the lower Edmonton Formation) along the Red Deer River of southern Alberta, Canada. These rocks are older than the rocks in which "Claosaurus annectens" was found. The Edmonton Formation lends "Edmontosaurus" its name. The type species, "E. regalis" ("regal", or, more loosely, "king-sized"), is based on NMC 2288, consisting of a skull, articulated vertebrae up to the sixth tail vertebra, ribs, partial hips, an upper arm bone, and most of a hind limb. It was discovered in 1912 by Levi Sternberg. The second specimen, paratype NMC 2289, consists of a skull and skeleton lacking the beak, most of the tail, and part of the feet. It was discovered in 1916 by George F. Sternberg. Lambe found that his new dinosaur compared best to "Diclonius mirabilis" (specimens now assigned to "Edmontosaurus annectens"), and drew attention to the size and robustness of "Edmontosaurus". Initially, Lambe only described the skulls of the two skeletons, but returned to the genus in 1920 to describe the skeleton of NMC 2289. The postcrania of the type specimen remains undescribed, still in its plaster jackets.


title: Edmontosaurus

text: Two more species that would come to be included with "Edmontosaurus" were named from Canadian remains in the 1920s, but both would initially be assigned to "Thespesius". Gilmore named the first, "Thespesius edmontoni", in 1924. "T. edmontoni" also came from the Horseshoe Canyon Formation. It was based on NMC 8399, another nearly complete skeleton lacking most of the tail. NMC 8399 was discovered on the Red Deer River in 1912 by a Sternberg party. Its forelimbs, ossified tendons, and skin impressions were briefly described in 1913 and 1914 by Lambe, who at first thought it was an example of a species he had named "Trachodon marginatus", but then changed his mind. The specimen became the first dinosaur skeleton to be mounted for exhibition in a Canadian museum. Gilmore found that his new species compared closely to what he called "Thespesius annectens", but left the two apart because of details of the arms and hands. He also noted that his species had more vertebrae than Marsh's in the back and neck, but proposed that Marsh was mistaken in assuming that the "annectens" specimens were complete in those regions.


title: Edmontosaurus

text: In 1926, Charles Mortram Sternberg named "Thespesius saskatchewanensis" for NMC 8509, a skull and partial skeleton from the Wood Mountain plateau of southern Saskatchewan. He had collected this specimen in 1921, from rocks that were assigned to the Lance Formation, now the Frenchman Formation. NMC 8509 included an almost complete skull, numerous vertebrae, partial shoulder and hip girdles, and partial hind limbs, representing the first substantial dinosaur specimen recovered from Saskatchewan. Sternberg opted to assign it to "Thespesius" because that was the only hadrosaurid genus known from the Lance Formation at the time. At the time, "T. saskatchewanensis" was unusual because of its small size, estimated at in length.


title: Edmontosaurus

text: In 1942, Lull and Wright attempted to resolve the complicated taxonomy of crestless hadrosaurids by naming a new genus, "Anatosaurus", to take in several species that did not fit well under their previous genera. "Anatosaurus", meaning "duck lizard", because of its wide, duck-like beak (Latin "anas" = duck + Greek "sauros" = lizard), had as its type species Marsh's old "Claosaurus annectens". Also assigned to this genus were "Thespesius edmontoni", "T. saskatchewanensis", a large lower jaw that Marsh had named "Trachodon longiceps" in 1890, and a new species, "Anatosaurus copei", for two skeletons on display at the American Museum of Natural History that had long been known as "Diclonius mirabilis" (or variations thereof). Thus, the various species became "Anatosaurus annectens", "A. copei", "A. edmontoni", "A. longiceps", and "A. saskatchewanensis". "Anatosaurus" would come to be called the "classic duck-billed dinosaur."


title: Edmontosaurus

text: This state of affairs persisted for several decades, until Michael K. Brett-Surman reexamined the pertinent material for his graduate studies in the 1970s and 1980s. He concluded that the type species of "Anatosaurus", "A. annectens", was actually a species of "Edmontosaurus" and that "A. copei" was different enough to warrant its own genus. Although theses and dissertations are not regarded as official publications by the International Commission on Zoological Nomenclature, which regulates the naming of organisms, his conclusions were known to other paleontologists, and were adopted by several popular works of the time. Brett-Surman and Ralph Chapman designated a new genus for "A. copei" ("Anatotitan") in 1990. Of the remaining species, "A. saskatchewanensis" and "A. edmontoni" were assigned to "Edmontosaurus" as well, and "A. longiceps" went to "Anatotitan", as either a second species or as a synonym of "A. copei". Because the type species of "Anatosaurus" ("A. annectens") was sunk into "Edmontosaurus", the name "Anatosaurus" is abandoned as a junior synonym of "Edmontosaurus".


title: Edmontosaurus

text: The conception of "Edmontosaurus" that emerged included three valid species: the type "E. regalis", "E. annectens" (including "Anatosaurus edmontoni", amended to "edmontonensis"), and "E. saskatchewanensis". The debate about the proper taxonomy of the "A. copei" specimens continues to the present: returning to Hatcher's argument of 1902, Jack Horner, David B. Weishampel, and Catherine Forster regarded "Anatotitan copei" as representing specimens of "Edmontosaurus annectens" with crushed skulls. In 2007 another "mummy" was announced; nicknamed "Dakota", it was discovered in 1999 by Tyler Lyson, and came from the Hell Creek Formation of North Dakota.


title: Edmontosaurus

text: In a 2011 study by Nicolás Campione and David Evans, the authors conducted the first ever morphometric analysis to compare the various specimens assigned to "Edmontosaurus". They concluded that only two species are valid: "E. regalis", from the late Campanian, and "E. annectens", from the late Maastrichtian. Their study provided further evidence that "Anatotitan copei" is a synonym of "E. annectens"; specifically, that the long, low skull of "A. copei" is the result of ontogenetic change and represents mature "E. annectens" individuals.


title: Edmontosaurus

text: "Edmontosaurus" is currently regarded as having two valid species: type species "E. regalis", and "E. annectens". "E. regalis" is known only from the Horseshoe Canyon Formation of Alberta, dating from the late Campanian stage of the late Cretaceous period. At least a dozen individuals are known, including seven skulls with associated postcrania, and five to seven other skulls. The species formerly known as "Thespesius edmontoni" or "Anatosaurus edmontoni" represents immature individuals.


title: Edmontosaurus

text: "E. annectens" is known from the Frenchman Formation of Saskatchewan, the Hell Creek Formation of Montana, and the Lance Formation of South Dakota and Wyoming. It is limited to late Maastrichtian rocks, and is represented by at least twenty skulls, some with postcranial remains. One author, Kraig Derstler, has described "E. annectens" as "perhaps the most perfectly-known dinosaur to date [1994]." "Anatosaurus copei" and "E. saskatchewanensis" are now thought to be growth stages of "E. annectens": "A. copei" as adults, and "E. saskatchewanensis" as juveniles. "Trachodon longiceps" may be a synonym of "E. annectens" as well. "Anatosaurus edmontoni" was mistakenly listed as a synonym of "E. annectens" in both reviews of the Dinosauria, but this does not appear to be the case.


title: Edmontosaurus

text: "E. annectens" differed from "E. regalis" by having a longer, lower, less robust skull. Although Brett-Surman regarded "E. regalis" and "E. annectens" as potentially representing males and females of the same species, all "E. regalis" specimens come from older formations than "E. annectens" specimens. Edmontosaurine specimens from the Prince Creek Formation of Alaska formerly assigned to "Edmontosaurus" sp. were given their own genus and species name, "Ugrunaaluk kuukpikensis", in 2015. However, the identification of "Ugrunaaluk" as a separate genus was questioned by a 2017 study from Hai Xing and colleagues, who regarded it as a "nomen dubium" indistinguishable from other "Edmontosaurus". In 2020, Ryuji Takasaki and colleagues agreed that the Prince Creek remains should be classified as "Edmontosaurus", though species designation is unclear as the specimens are juveniles. "Edmontosaurus" was also reported from the Javelina Formation of Big Bend National Park, western Texas based on TMM 41442-1, but was later referred to "Kritosaurus cf. navajovius" by Wagner (2001), before being assigned to "Kritosaurus" sp. by Lehman "et al." (2016).


title: Edmontosaurus

text: "Edmontosaurus" has been described in detail from numerous specimens. Traditionally, "E. regalis" has been regarded as the largest species, though this was challenged by the hypothesis that the larger hadrosaurid "Anatotitan copei" is a synonym of "Edmontosaurus annectens", as put forward by Jack Horner and colleagues in 2004, and supported in studies by Campione and Evans in 2011.


title: Edmontosaurus

text: "Edmontosaurus" was among the largest hadrosaurids. Like other hadrosaurids, it was a bulky animal with a long, laterally flattened tail and a head with an expanded, duck-like beak. The fore legs were not as heavily built as the hind legs, but were long enough to be used in standing or movement. depending on the species, previous estimates suggested that a fully grown adult could have been long, and some of the larger specimens reached the range of with a body mass on the order of .


title: Edmontosaurus

text: "E. annectens" is often seen as smaller. Two mounted skeletons, USNM 2414 and YPM 2182, measure long and long, respectively. However, these are probably subadult individuals, and there is at least one report of a much larger potential "E. annectens" specimen, almost long. Two specimens still under study in the collection of the Museum of the Rockies - a tail labelled as MOR 1142 and another labelled as MOR 1609 - indicate that "Edmontosaurus annectens" could have grown to larger sizes, possibly rivaling "Shantungosaurus" in size. The individuals to which these specimens belong may have reached nearly in length and weighed , but such large individuals were likely very rare.


title: Edmontosaurus

text: A 2022 study on the osteohistology and growth of "E. annectens" suggested that previous estimates might have underestimated or overestimated the size of this dinosaur and proposed that a fully grown adult "E. annectens" would have measured up to in length and approximately in average asymptotic body mass, while the largest individuals measured more than , even up to , based on the comparison between various specimens of different sizes from the Ruth Mason Dinosaur Quarry and other specimens from different localities; according to this analysis, "E. regalis" may have been heavier, but not enough samples exist to provide a valid estimate and examination on its osteohistology and growth, so the results for "E. regalis" aren't statistically significant.


title: Edmontosaurus

text: The skull of a fully grown "Edmontosaurus" could be over a metre long. One skull of "E. annectens" (formerly "Anatotitan") measures long. The skull was roughly triangular in profile, with no bony cranial crest. Viewed from above, the front and rear of the skull were expanded, with the broad front forming a duck-bill or spoon-bill shape. The beak was toothless, and both the upper and lower beaks were extended by keratinous material. Substantial remains of the keratinous upper beak are known from the "mummy" kept at the Senckenberg Museum. In this specimen, the preserved nonbony part of the beak extended for at least beyond the bone, projecting down vertically. The nasal openings of "Edmontosaurus" were elongate and housed in deep depressions surrounded by distinct bony rims above, behind, and below.


title: Edmontosaurus

text: In at least one case (the Senckenberg specimen), rarely preserved sclerotic rings were preserved in the eye sockets. Another rarely seen bone, the stapes (the reptilian ear bone), has also been seen in a specimen of "Edmontosaurus".


title: Edmontosaurus

text: Teeth were present only in the maxillae (upper cheeks) and dentaries (main bone of the lower jaw). The teeth were continually replaced, taking about half a year to form. They were composed of six types of tissues, rivaling the complexity of mammal teeth. They grew in columns, with an observed maximum of six in each, and the number of columns varied based on the animal's size. Known column counts for the two species are: 51 to 53 columns per maxilla and 48 to 49 per dentary (teeth of the upper jaw being slightly narrower than those in the lower jaw) for "E. regalis"; and 52 columns per maxilla and 44 per dentary for "E. annectens" (an "E. saskatchewanensis" specimen).


title: Edmontosaurus

text: The number of vertebrae differs between specimens. "E. regalis" had thirteen neck vertebrae, eighteen back vertebrae, nine hip vertebrae, and an unknown number of tail vertebrae. A specimen once identified as belonging to "Anatosaurus edmontoni" (now considered to be the same as "E. regalis") is reported as having an additional back vertebra and 85 tail vertebrae, with an undisclosed amount of restoration. Other hadrosaurids are only reported as having 50 to 70 tail vertebrae, so this appears to have been an overestimate. The anterior back was curved toward the ground, with the neck flexed upward and the rest of the back and tail held horizontally. Most of the back and tail were lined by ossified tendons arranged in a latticework along the neural spines of the vertebrae. This condition has been described as making the back and at least part of the tail "ramrod" straight. The ossified tendons are interpreted as having strengthened the vertebral column against gravitational stress, incurred through being a large animal with a horizontal vertebral column otherwise supported mostly by the hind legs and hips.


title: Edmontosaurus

text: The shoulder blades were long flat blade-like bones, held roughly parallel to the vertebral column. The hips were composed of three elements each: an elongate ilium above the articulation with the leg, an ischium below and behind with a long thin rod, and a pubis in front that flared into a plate-like structure. The structure of the hip hindered the animal from standing with its back erect, because in such a position the thigh bone would have pushed against the joint of the ilium and pubis, instead of pushing only against the solid ilium. The nine fused hip vertebrae provided support for the hip.


title: Edmontosaurus

text: The fore legs were shorter and less heavily built than the hind legs. The upper arm had a large deltopectoral crest for muscle attachment, while the ulna and radius were slim. The upper arm and forearm were similar in length. The wrist was simple, with only two small bones. Each hand had four fingers, with no thumb (first finger). The index (second), third, and fourth fingers were approximately the same length and were united in life within a fleshy covering. Although the second and third finger had hoof-like unguals, these bones were also within the skin and not apparent from the outside. The little finger diverged from the other three and was much shorter. The thigh bone was robust and straight, with a prominent flange about halfway down the posterior side. This ridge was for the attachment of powerful muscles attached to the hips and tail that pulled the thighs (and thus the hind legs) backward and helped maintain the use of the tail as a balancing organ. Each foot had three toes, with no big toe or little toe. The toes had hoof-like tips.


title: Edmontosaurus

text: Multiple specimens of "Edmontosaurus annectens" have been found with preserved skin impressions. Several have been well-publicized, such as the "Trachodon mummy" of the early 20th century, and the specimen nicknamed "Dakota", the latter apparently including remnant organic compounds from the skin. Because of these finds, the scalation of "Edmontosaurus annectens" is known for most areas of the body. Skin impressions are less well known for "E. regalis", but some well-preserved examples have been studied, including one which preserves a soft tissue crest or wattle on the head. It is unknown whether such a crest was present on "E. annectens", and whether it was an indicator of sexual dimorphism.


title: Edmontosaurus

text: A preserved rhamphotheca present in the "E. annectens" specimen LACM 23502, housed in the Los Angeles County Museum, indicates the beak of "Edmontosaurus" was more hook-shaped and extensive than many illustrations in scientific and public media have previously depicted. Whether or not the specimen in question preserved the true rhamphotheca or just a cast of the inner structure attached to the bone is not known at present.


title: Edmontosaurus

text: "Edmontosaurus" was a hadrosaurid (a duck-billed dinosaur), a member of a family of dinosaurs which to date are known only from the Late Cretaceous. It is classified within the Saurolophinae (alternately Hadrosaurinae), a clade of hadrosaurids which lacked hollow crests. Other members of the group include "Brachylophosaurus", "Gryposaurus", "Lophorhothon", "Maiasaura", "Naashoibitosaurus", "Prosaurolophus", and "Saurolophus". It was either closely related to or includes the species "Anatosaurus annectens" (alternately "Edmontosaurus annectens"), a large hadrosaurid from various latest Cretaceous formations of western North America. The giant Chinese hadrosaurine "Shantungosaurus giganteus" is also anatomically similar to "Edmontosaurus"; M. K. Brett-Surman found the two to differ only in details related to the greater size of "Shantungosaurus", based on what had been described of the latter genus.


title: Edmontosaurus

text: While the status of "Edmontosaurus" as a saurolophine has not been challenged, its exact placement within the clade is uncertain. Early phylogenies, such as that presented in R. S. Lull and Nelda Wright's influential 1942 monograph, had "Edmontosaurus" and various species of "Anatosaurus" (most of which would be later considered as additional species or specimens of "Edmontosaurus") as one lineage among several lineages of "flat-headed" hadrosaurs. One of the first analyses using cladistic methods found it to be linked with "Anatosaurus" (="Anatotitan") and "Shantungosaurus" in an informal "edmontosaur" clade, which was paired with the spike-crested "saurolophs" and more distantly related to the "brachylophosaurs" and arch-snouted "gryposaurs". A 2007 study by Terry Gates and Scott Sampson found broadly similar results, in that "Edmontosaurus" remained close to "Saurolophus" and "Prosaurolophus" and distant from "Gryposaurus", "Brachylophosaurus", and "Maiasaura". However, the most recent review of Hadrosauridae, by Jack Horner and colleagues (2004), came to a noticeably different result: "Edmontosaurus" was nested between "Gryposaurus" and the "brachylophosaurs", and distant from "Saurolophus".


title: Edmontosaurus

text: As a hadrosaurid, "Edmontosaurus" was a large terrestrial herbivore. Its teeth were continually replaced and packed into dental batteries that contained hundreds of teeth, only a relative handful of which were in use at any time. It used its broad beak to cut loose food, perhaps by cropping, or by closing the jaws in a clamshell-like manner over twigs and branches and then stripping off the more nutritious leaves and shoots. Because the tooth rows are deeply indented from the outside of the jaws, and because of other anatomical details, it is inferred that "Edmontosaurus" and most other ornithischians had cheek-like structures, muscular or non-muscular. The function of the cheeks was to retain food in the mouth. The animal's feeding range would have been from ground level to around above.


title: Edmontosaurus

text: Before the 1960s and 1970s, the prevailing interpretation of hadrosaurids like "Edmontosaurus" was that they were aquatic and fed on aquatic plants. An example of this is William Morris's 1970 interpretation of an edmontosaur skull with nonbony beak remnants. He proposed that the animal had a diet much like that of some modern ducks, filtering plants and aquatic invertebrates like mollusks and crustaceans from the water and discharging water via V-shaped furrows along the inner face of the upper beak. This interpretation of the beak has been rejected, as the furrows and ridges are more like those of herbivorous turtle beaks than the flexible structures seen in filter-feeding birds.


title: Edmontosaurus

text: Because scratches dominate the microwear texture of the teeth, Williams "et al." suggested "Edmontosaurus" was a grazer instead of a browser, which would be predicted to have fewer scratches due to eating less abrasive materials. Candidates for ingested abrasives include silica-rich plants like horsetails and soil that was accidentally ingested due to feeding at ground level. The tooth structure indicates combined slicing and grinding capabilities.


title: Edmontosaurus

text: Reports of gastroliths, or stomach stones, in the hadrosaurid "Claosaurus" is actually based on a probable double misidentification. First, the specimen is actually of "Edmontosaurus annectens". Barnum Brown, who discovered the specimen in 1900, referred to it as "Claosaurus" because "E. annectens" was thought to be a species of "Claosaurus" at the time. Additionally, it is more likely that the supposed gastroliths represent gravel washed in during burial.


title: Edmontosaurus

text: Both of the "mummy" specimens collected by the Sternbergs were reported to have had possible gut contents. Charles H. Sternberg reported the presence of carbonized gut contents in the American Museum of Natural History specimen, but this material has not been described. The plant remains in the Senckenberg Museum specimen have been described, but have proven difficult to interpret. The plants found in the carcass included needles of the conifer "Cunninghamites elegans", twigs from conifer and broadleaf trees, and numerous small seeds or fruits. Upon their description in 1922, they were the subject of a debate in the German-language journal "Paläontologische Zeitschrift". Kräusel, who described the material, interpreted it as the gut contents of the animal, while Abel could not rule out that the plants had been washed into the carcass after death.


title: Edmontosaurus

text: At the time, hadrosaurids were thought to have been aquatic animals, and Kräusel made a point of stating that the specimen did not rule out hadrosaurids eating water plants. The discovery of possible gut contents made little impact in English-speaking circles, except for another brief mention of the aquatic-terrestrial dichotomy, until it was brought up by John Ostrom in the course of an article reassessing the old interpretation of hadrosaurids as water-bound. Instead of trying to adapt the discovery to the aquatic model, he used it as a line of evidence that hadrosaurids were terrestrial herbivores. While his interpretation of hadrosaurids as terrestrial animals has been generally accepted, the Senckenberg plant fossils remain equivocal. Kenneth Carpenter has suggested that they may actually represent the gut contents of a starving animal, instead of a typical diet. Other authors have noted that because the plant fossils were removed from their original context in the specimen and were heavily prepared, it is no longer possible to follow up on the original work, leaving open the possibility that the plants were washed-in debris.


title: Edmontosaurus

text: The diet and physiology of "Edmontosaurus" have been probed by using stable isotopes of carbon and oxygen as recorded in tooth enamel. When feeding, drinking, and breathing, animals take in carbon and oxygen, which become incorporated into bone. The isotopes of these two elements are determined by various internal and external factors, such as the type of plants being eaten, the physiology of the animal, salinity, and climate. If isotope ratios in fossils are not altered by fossilization and later changes, they can be studied for information about the original factors; warmblooded animals will have certain isotopic compositions compared to their surroundings, animals that eat certain types of plants or use certain digestive processes will have distinct isotopic compositions, and so on. Enamel is typically used because the structure of the mineral that forms enamel makes it the most resistant material to chemical change in the skeleton.


title: Edmontosaurus

text: A 2004 study by Kathryn Thomas and Sandra Carlson used teeth from the upper jaw of three individuals interpreted as a juvenile, a subadult, and an adult, recovered from a bone bed in the Hell Creek Formation of Corson County, South Dakota. In this study, successive teeth in columns in the edmontosaurs' dental batteries were sampled from multiple locations along each tooth using a microdrilling system. This sampling method takes advantage of the organization of hadrosaurid dental batteries to find variation in tooth isotopes over a period of time. From their work, it appears that edmontosaur teeth took less than about 0.65 years to form, slightly faster in younger edmontosaurs. The teeth of all three individuals appeared to show variation in oxygen isotope ratios that could correspond to warm/dry and cool/wet periods; Thomas and Carlson considered the possibility that the animals were migrating instead, but favored local seasonal variations because migration would have more likely led to ratio homogenization, as many animals migrate to stay within specific temperature ranges or near particular food sources.


title: Edmontosaurus

text: The edmontosaurs also showed enriched carbon isotope values, which for modern mammals would be interpreted as a mixed diet of C3 plants (most plants) and C4 plants (grasses); however, C4 plants were extremely rare in the Late Cretaceous if present at all. Thomas and Carlson put forward several factors that may have been operating, and found the most likely to include a diet heavy in gymnosperms, consuming salt-stressed plants from coastal areas adjacent to the Western Interior Seaway, and a physiological difference between dinosaurs and mammals that caused dinosaurs to form tissue with different carbon ratios than would be expected for mammals. A combination of factors is also possible.


title: Edmontosaurus

text: Between the mid-1980s and the 2000s, the prevailing interpretation of how hadrosaurids processed their food followed the model put forward in 1984 by David B. Weishampel. He proposed that the structure of the skull permitted motion between bones that resulted in backward and forward motion of the lower jaw, and outward bowing of the tooth-bearing bones of the upper jaw when the mouth was closed. The teeth of the upper jaw would grind against the teeth of the lower jaw like rasps, processing plant material trapped between them. Such a motion would parallel the effects of mastication in mammals, although accomplishing the effects in a completely different way. Work in the early 2000s has challenged the Weishampel model. A study published in 2008 by Casey Holliday and Lawrence Witmer found that ornithopods like "Edmontosaurus" lacked the types of skull joints seen in those modern animals that are known to have kinetic skulls (skulls that permit motion between their constituent bones), such as squamates and birds. They proposed that joints that had been interpreted as permitting movement in dinosaur skulls were actually cartilaginous growth zones. An important piece of evidence for Weishampel's model is the orientation of scratches on the teeth, showing the direction of jaw action. Other movements could produce similar scratches though, such as movement of the bones of the two halves of the lower jaw. Not all models have been scrutinized under present techniques. Vincent Williams and colleagues (2009) published additional work on hadrosaurid tooth microwear. They found four classes of scratches on "Edmontosaurus" teeth. The most common class was interpreted as resulting from an oblique motion, not a simple up-down or front-back motion, which is consistent with the Weishampel model. This motion is thought to have been the primary motion for grinding food. Two scratch classes were interpreted as resulting from forward or backward movement of the jaws. The other class was variable and probably resulted from opening the jaws. The combination of movements is more complex than had been previously predicted.


title: Edmontosaurus

text: Weishampel developed his model with the aid of a computer simulation. Natalia Rybczynski and colleagues have updated this work with a much more sophisticated three-dimensional animation model, scanning a skull of "E. regalis" with lasers. They were able to replicate the proposed motion with their model, although they found that additional secondary movements between other bones were required, with maximum separations of between some bones during the chewing cycle. Rybczynski and colleagues were not convinced that the Weishampel model is viable, but noted that they have several improvements to implement to their animation. Planned improvements include incorporating soft tissue and tooth wear marks and scratches, which should better constrain movements. They note that there are several other hypotheses to test as well. Further research published in 2012 by Robin Cuthbertson and colleagues found the motions required for Weishampel's model to be unlikely, and favored a model in which movements of the lower jaw produced grinding action. The lower jaw's joint with the upper jaw would permit anterior–posterior motion along with the usual rotation, and the anterior joint of the two halves of the lower jaw would also permit motion; in combination, the two halves of the lower jaw could move slightly back and forth as well as rotating slightly along their long axes. These motions would account for the observed tooth wear and a more solidly constructed skull than modeled by Weishampel.


title: Edmontosaurus

text: In a 2011 study, Campione and Evans recorded data from all known "edmontosaur" skulls from the Campanian and Maastrichtian and used it to plot a "morphometric" graph, comparing variable features of the skull with skull size. Their results showed that within both recognized "Edmontosaurus" species, many features previously used to classify additional species or genera were directly correlated with skull size. Campione and Evans interpreted these results as strongly suggesting that the shape of "Edmontosaurus" skulls changed dramatically as they grew. This has led to several apparent mistakes in classification in the past. The Campanian species "Thespesius edmontoni", previously considered a synonym of "E. annectens" due to its small size and skull shape, is more likely a subadult specimen of the contemporary "E. regalis". Similarly, the three previously recognized Maastrichtian edmontosaur species likely represent growth stages of a single species, with "E. saskatchewanensis" representing juveniles, "E. annectens" subadults, and "Anatotitan copei" fully mature adults. The skulls became longer and flatter as the animals grew.


title: Edmontosaurus

text: In a 2014 study, researchers proposed that "E. regalis" reached maturity in 10-15 years of age. In a 2022 study, Wosik and Evans proposed that "E. annectens" reached maturity in 9 years of age based on their analysis for various specimens from different loaclities. They found the result to be similar to that of other hadrosaurs.


title: Edmontosaurus

text: The brain of "Edmontosaurus" has been described in several papers and abstracts through the use of endocasts of the cavity where the brain had been. "E. annectens" and "E. regalis", as well as specimens not identified to species, have been studied in this way. The brain was not particularly large for an animal the size of "Edmontosaurus". The space holding it was only about a quarter of the length of the skull, and various endocasts have been measured as displacing to , which does not take into account that the brain may have occupied as little as 50% of the space of the endocast, the rest of the space being taken up by the dura mater surrounding the brain. For example, the brain of the specimen with the 374 millilitre endocast is estimated to have had a volume of . The brain was an elongate structure, and as with other non-mammals, there would have been no neocortex. Like "Stegosaurus", the neural canal was expanded in the hips, but not to the same degree: the endosacral space of "Stegosaurus" had 20 times the volume of its endocranial cast, whereas the endosacral space of "Edmontosaurus" was only 2.59 times larger in volume.


title: Edmontosaurus

text: In 2003, evidence of tumors, including hemangiomas, desmoplastic fibroma, metastatic cancer, and osteoblastoma, was described in "Edmontosaurus" bones. Rothschild "et al." tested dinosaur vertebrae for tumors using computerized tomography and fluoroscope screening. Several other hadrosaurids, including "Brachylophosaurus", "Gilmoreosaurus", and "Bactrosaurus", also tested positive. Although more than 10,000 fossils were examined in this manner, the tumors were limited to "Edmontosaurus" and closely related genera. The tumors may have been caused by environmental factors or genetic propensity.


title: Edmontosaurus

text: Osteochondrosis, or surficial pits in bone at places where bones articulate, is also known in "Edmontosaurus". This condition, resulting from cartilage failing to be replaced by bone during growth, was found to be present in 2.2% of 224 edmontosaur toe bones. The underlying cause of the condition is unknown. Genetic predisposition, trauma, feeding intensity, alterations in blood supply, excess thyroid hormones, and deficiencies in various growth factors have been suggested. Among dinosaurs, osteochondrosis (like tumors) is most commonly found in hadrosaurids.


title: Edmontosaurus

text: Like other hadrosaurids, "Edmontosaurus" is thought to have been a facultative biped, meaning that it mostly moved on four legs, but could adopt a bipedal stance when needed. It probably went on all fours when standing still or moving slowly, and switched to using the hind legs alone when moving more rapidly. Research conducted by computer modeling in 2007 suggests that "Edmontosaurus" could run at high speeds, perhaps up to . Further simulations using a subadult specimen estimated as weighing when alive produced a model that could run or hop bipedally, use a trot, pace, or single foot symmetric quadrupedal gait, or move at a gallop. The researchers found to their surprise that the fastest gait was kangaroo-like hopping (maximum simulated speed of ), which they regarded as unlikely based on the size of the animal and lack of hopping footprints in the fossil record, and instead interpreted the result as indicative of an inaccuracy in their simulation. The fastest non-hopping gaits were galloping (maximum simulated speed of ) and running bipedally (maximum simulated speed of ). They found weak support for bipedal running as the most likely option for high-speed movement, but did not rule out high-speed quadrupedal movement.


title: Edmontosaurus

text: While long thought to have been aquatic or semiaquatic, hadrosaurids were not as well-suited for swimming as other dinosaurs (particularly theropods, who were once thought to have been unable to pursue hadrosaurids into water). Hadrosaurids had slim hands with short fingers, making their forelimbs ineffective for propulsion, and the tail was also not useful for propulsion because of the ossified tendons that increased its rigidity, and the poorly developed attachment points for muscles that would have moved the tail from side to side.