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131-552: Eogruidae (also spelled Eogruiidae in some publications) is a family of large, flightless birds that inhabited Asia from the Eocene to Pliocene epochs. Related to modern ostriches , it was formerly thought to be related to cranes , limpkins and trumpeters and that the similarities with ostriches were due to similar speciations to cursoriality , with both groups showing reduced numbers of toes to two in some taxa. It has been suggested that competition from true ostriches has caused

262-463: A Middle Jurassic fossil of the early mammal Didelphis , Lyell told his father that "There was everything but man even as far back as the Oolite." Lyell inaccurately portrayed Lamarckism as a response to the fossil record, and said it was falsified by a lack of progress. He said in the second volume of Principles that the occurrence of this one fossil of the higher mammalia "in these ancient strata,

393-578: A "remarkable manifestation of creative Power" as creating each species separately. He countered Lamarck's views by rejecting continued cooling of the earth in favour of "a fluctuating cycle", a long-term steady-state geohistory as proposed by James Hutton . The fragmentary fossil record already showed "a high class of fishes, close to reptiles" in the Carboniferous period which he called "the first Zoological era", and quadrupeds could also have existed then. In November 1827, after William Broderip found

524-506: A copy of Principles and praising the book as opening a way for bold speculation on "that mystery of mysteries, the replacement of extinct species by others" – by analogy with other intermediate causes , "the origination of fresh species, could it ever come under our cognizance, would be found to be a natural in contradistinction to a miraculous process". Lyell replied: "In regard to the origination of new species, I am very glad to find that you think it probable that it may be carried on through

655-431: A large body of water is also present. In an attempt to try to mitigate the cooling polar temperatures, large lakes were proposed to mitigate seasonal climate changes. To replicate this case, a lake was inserted into North America and a climate model was run using varying carbon dioxide levels. The model runs concluded that while the lake did reduce the seasonality of the region greater than just an increase in carbon dioxide,

786-540: A marine ecosystem)—one of the largest in the Cenozoic. This event happened around 55.8 Ma, and was one of the most significant periods of global change during the Cenozoic. The middle Eocene was characterized by the shift towards a cooler climate at the end of the EECO, around 47.8 Ma, which was briefly interrupted by another warming event called the middle Eocene climatic optimum (MECO). Lasting for about 400,000 years,

917-607: A profession, entering Lincoln's Inn in 1820. He completed a circuit through rural England, where he could observe geological phenomena. In 1821 he attended Robert Jameson 's lectures in Edinburgh, and visited Gideon Mantell at Lewes , in Sussex . In 1823 he was elected joint secretary of the Geological Society . As his eyesight began to deteriorate, he turned to geology as a full-time profession. His first paper, "On

1048-600: A profitable mining area, bears Lyell's name; and the Lyell Range in north-west Western Australia is named after him as well. In Southwest Nelson in the South Island of New Zealand, the Lyell Range, Lyell River and the gold mining town of Lyell (now only a camping site) were all named after Lyell. Lyall Bay in Wellington, New Zealand was possibly named after Lyell. The jawless fish Cephalaspis lyelli , from

1179-523: A recent formation of freshwater limestone in Forfarshire", was presented in 1826. By 1827, he had abandoned law and embarked on a geological career that would result in fame and the general acceptance of uniformitarianism, a working out of the ideas proposed by James Hutton a few decades earlier. In 1832, Lyell married Mary Horner in Bonn, daughter of Leonard Horner (1785–1864), also associated with

1310-474: A remarkable series of nearly three hundred manuscript notebooks and diaries. These span Lyell's long scientific career (1825–1874), and offer an unrivalled insight into personal influences, field observations, thoughts and relationships. They were acquired in 2019 by the University of Edinburgh 's Heritage Collections, thanks to a fundraising campaign, with many generous individual and institutional donors from

1441-511: A role in triggering the ETM2 and ETM3. An enhancement of the biological pump proved effective at sequestering excess carbon during the recovery phases of these hyperthermals. These hyperthermals led to increased perturbations in planktonic and benthic foraminifera , with a higher rate of fluvial sedimentation as a consequence of the warmer temperatures. Unlike the PETM, the lesser hyperthermals of

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1572-488: A separate family, Ergilornithidae , but they are now generally accepted to be a subfamily within Eogruidae. Eogruids are rather similar to Geranoididae , a clade of similar flightless gruiforms from North America and Europe , and both groups have occasionally been classified as sister taxa. Recently geranoidids have been recovered as basal to the rest of Gruoidea, however, while eogruids are sister-taxa to cranes. There

1703-533: A significant amount of water vapor is released. Another requirement for polar stratospheric clouds is cold temperatures to ensure condensation and cloud production. Polar stratospheric cloud production, since it requires the cold temperatures, is usually limited to nighttime and winter conditions. With this combination of wetter and colder conditions in the lower stratosphere, polar stratospheric clouds could have formed over wide areas in Polar Regions. To test

1834-775: A wide variety of climate conditions that includes the warmest climate in the Cenozoic Era , and arguably the warmest time interval since the Permian-Triassic mass extinction and Early Triassic, and ends in an icehouse climate. The evolution of the Eocene climate began with warming after the end of the Paleocene–Eocene Thermal Maximum (PETM) at 56 Ma to a maximum during the Eocene Optimum at around 49 Ma. During this period of time, little to no ice

1965-459: Is an important factor in the creation of the primary Type II polar stratospheric clouds that were created in the early Eocene. Since water vapor is the only supporting substance used in Type II polar stratospheric clouds, the presence of water vapor in the lower stratosphere is necessary where in most situations the presence of water vapor in the lower stratosphere is rare. When methane is oxidized,

2096-756: Is as fatal to the theory of successive development, as if several hundreds had been discovered." In the first edition of Principles , the first volume briefly set out Lyell's concept of a steady state with no real progression of fossils. The sole exception was the advent of humanity, with no great physical distinction from animals, but with absolutely unique intellectual and moral qualities. The second volume dismissed Lamarck's claims of animal forms arising from habits, continuous spontaneous generation of new life, and man having evolved from lower forms. Lyell explicitly rejected Lamarck's concept of transmutation of species, drawing on Cuvier's arguments, and concluded that species had been created with stable attributes. He discussed

2227-493: Is best known, however, for his role in elaborating the doctrine of uniformitarianism . He played a critical role in advancing the study of loess . From 1830 to 1833 his multi-volume Principles of Geology was published. The work's subtitle was "An attempt to explain the former changes of the earth's surface by reference to causes now in operation", and this explains Lyell's impact on science. He drew his explanations from field studies conducted directly before he went to work on

2358-638: Is considered to be primarily due to carbon dioxide increases, because carbon isotope signatures rule out major methane release during this short-term warming. A sharp increase in atmospheric carbon dioxide was observed with a maximum of 4,000 ppm: the highest amount of atmospheric carbon dioxide detected during the Eocene. Other studies suggest a more modest rise in carbon dioxide levels. The increase in atmospheric carbon dioxide has also been hypothesised to have been driven by increased seafloor spreading rates and metamorphic decarbonation reactions between Australia and Antarctica and increased amounts of volcanism in

2489-594: Is conventionally divided into early (56–47.8 Ma), middle (47.8–38 Ma), and late (38–33.9 Ma) subdivisions. The corresponding rocks are referred to as lower, middle, and upper Eocene. The Ypresian Stage constitutes the lower, the Priabonian Stage the upper; and the Lutetian and Bartonian stages are united as the middle Eocene. The Western North American floras of the Eocene were divided into four floral "stages" by Jack Wolfe ( 1968 ) based on work with

2620-720: Is short lived, as benthic oxygen isotope records indicate a return to cooling at ~40 Ma. At the end of the MECO, the MLEC resumed. Cooling and the carbon dioxide drawdown continued through the late Eocene and into the Eocene–Oligocene transition around 34 Ma. The post-MECO cooling brought with it a major aridification trend in Asia, enhanced by retreating seas. A monsoonal climate remained predominant in East Asia. The cooling during

2751-481: Is some contention in regards to ergilornithine genera, particularly Amphipelargus and Urmiornis , which have assimilated each other's species from study to study. The most recent consensus is that nearly all Neogene eogruid remains belong to Urmiornis , while a few western Eurasian taxa can be referred to as Amphipelargus . Eocene The Eocene spans the time from the end of the Paleocene Epoch to

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2882-535: Is the period of time when the Antarctic ice sheet began to rapidly expand. Greenhouse gases, in particular carbon dioxide and methane , played a significant role during the Eocene in controlling the surface temperature. The end of the PETM was met with very large sequestration of carbon dioxide into the forms of methane clathrate , coal , and crude oil at the bottom of the Arctic Ocean , that reduced

3013-452: Is to happen thereafter." Geological remains from the distant past can, and should, be explained by reference to geological processes now in operation and thus directly observable. Lyell's interpretation of geological change as the steady accumulation of minute changes over enormously long spans of time was a powerful influence on the young Charles Darwin . Lyell asked Robert FitzRoy , captain of HMS Beagle , to search for erratic boulders on

3144-653: The British Geological Survey (founded in 1835), and the US Geological Survey (founded in 1879), map and exhibit the natural resources within their countries. Over time, these surveys have been used extensively by modern extractive industries, such as nuclear, coal and oil. Before the work of Lyell, phenomena such as earthquakes were understood by the destruction that they brought. One of the contributions that Lyell made in Principles

3275-545: The Elements in 1838. The book went through six editions, eventually growing to two volumes and ceasing to be the inexpensive, portable handbook that Lyell had originally envisioned. Late in his career, therefore, Lyell produced a condensed version titled Student's Elements of Geology that fulfilled the original purpose. Geological Evidences of the Antiquity of Man brought together Lyell's views on three key themes from

3406-565: The Eocene–Oligocene extinction event , which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay . As with other geologic periods , the strata that define the start and end of the epoch are well identified, though their exact dates are slightly uncertain. The term "Eocene" is derived from Ancient Greek Ἠώς ( Ēṓs ) meaning "Dawn", and καινός kainos meaning "new" or "recent", as

3537-682: The Geological Society of London . The new couple spent their honeymoon in Switzerland and Italy on a geological tour of the area. During the 1840s, Lyell travelled to the United States and Canada, and wrote two popular travel-and-geology books: Travels in North America (1845) and A Second Visit to the United States (1849). In 1866, he was elected a foreign member of the Royal Swedish Academy of Sciences . After

3668-719: The Great Chicago Fire in 1871, Lyell was one of the first to donate books to help found the Chicago Public Library . In 1841, Lyell was elected as a member to the American Philosophical Society . Lyell's wife died in 1873, and two years later (in 1875) Lyell himself died as he was revising the twelfth edition of Principles . He is buried in Westminster Abbey where there is a bust to him by William Theed in

3799-694: The Highlands . His family's second country home was in a completely different geological and ecological area: he spent much of his childhood at Bartley Lodge in the New Forest , in Hampshire in southern England. Lyell entered Exeter College, Oxford , in 1816, and attended William Buckland 's geological lectures. He graduated with a BA Hons. second class degree in classics, in December 1819, and gained his M.A. 1821. After graduation he took up law as

3930-568: The Holocene by French paleontologist Paul Gervais in 1867 – included all deposits from the era subject to human observation. In recent years Lyell's subdivisions have been widely discussed in relation to debates about the Anthropocene . In Principles of Geology (first edition, vol. 3, ch. 2, 1833) Lyell proposed that icebergs could be the means of transport for erratics . During periods of global warming, ice breaks off

4061-713: The Middle Eocene Climatic Optimum (MECO). At around 41.5 Ma, stable isotopic analysis of samples from Southern Ocean drilling sites indicated a warming event for 600,000 years. A similar shift in carbon isotopes is known from the Northern Hemisphere in the Scaglia Limestones of Italy. Oxygen isotope analysis showed a large negative change in the proportion of heavier oxygen isotopes to lighter oxygen isotopes, which indicates an increase in global temperatures. The warming

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4192-533: The Old Red Sandstone of southern Scotland, was named by Louis Agassiz in honour of Lyell. Sir Charles Lyell was buried at Westminster Abbey on 27 February 1875. The pallbearers included T. H. Huxley , the Rev. W. S. Symonds and Mr John Carrick Moore . Lyell had private means, and earned further income as an author. He came from a prosperous family, worked briefly as a lawyer in the 1820s, and held

4323-761: The Puget Group fossils of King County, Washington . The four stages, Franklinian , Fultonian , Ravenian , and Kummerian covered the Early Eocene through early Oligocene, and three of the four were given informal early/late substages. Wolfe tentatively deemed the Franklinian as Early Eocene, the Fultonian as Middle Eocene, the Ravenian as Late, and the Kummerian as Early Oligocene. The beginning of

4454-458: The amount of oxygen in the Earth's atmosphere more or less doubled. During the warming in the early Eocene between 55 and 52 Ma, there were a series of short-term changes of carbon isotope composition in the ocean. These isotope changes occurred due to the release of carbon from the ocean into the atmosphere that led to a temperature increase of 4–8 °C (7.2–14.4 °F) at the surface of

4585-417: The proxy data . Using all different ranges of greenhouse gasses that occurred during the early Eocene, models were unable to produce the warming that was found at the poles and the reduced seasonality that occurs with winters at the poles being substantially warmer. The models, while accurately predicting the tropics, tend to produce significantly cooler temperatures of up to 20 °C (36 °F) colder than

4716-603: The southeast United States . After the Paleocene–Eocene Thermal Maximum, members of the Equoidea arose in North America and Europe, giving rise to some of the earliest equids such as Sifrhippus and basal European equoids such as the palaeothere Hyracotherium . Some of the later equoids were especially species-rich; Palaeotherium , ranging from small to very large in size, is known from as many as 16 species. Established large-sized mammals of

4847-712: The survey voyage of the Beagle , and just before it set out FitzRoy gave Darwin Volume 1 of the first edition of Lyell's Principles . When the Beagle made its first stop ashore at St Jago in the Cape Verde islands, Darwin found rock formations which seen "through Lyell's eyes" gave him a revolutionary insight into the geological history of the island, an insight he applied throughout his travels. While in South America Darwin received Volume 2 which considered

4978-399: The 'Recent', is widely cited as providing the foundations for the modern discussion of the Anthropocene . Building on the innovative work of James Hutton and his follower John Playfair , Lyell favoured an indefinitely long age for the earth, despite evidence suggesting an old but finite age. He was a close friend of Charles Darwin , and contributed significantly to Darwin's thinking on

5109-620: The Azolla Event. This cooling trend at the end of the EECO has also been proposed to have been caused by increased siliceous plankton productivity and marine carbon burial, which also helped draw carbon dioxide out of the atmosphere. Cooling after this event, part of a trend known as the Middle-Late Eocene Cooling (MLEC), continued due to continual decrease in atmospheric carbon dioxide from organic productivity and weathering from mountain building . Many regions of

5240-404: The EECO. Relative to present-day values, bottom water temperatures are 10 °C (18 °F) higher according to isotope proxies. With these bottom water temperatures, temperatures in areas where deep water forms near the poles are unable to be much cooler than the bottom water temperatures. An issue arises, however, when trying to model the Eocene and reproduce the results that are found with

5371-548: The Early Eocene had negligible consequences for terrestrial mammals. These Early Eocene hyperthermals produced a sustained period of extremely hot climate known as the Early Eocene Climatic Optimum (EECO). During the early and middle EECO, the superabundance of the euryhaline dinocyst Homotryblium in New Zealand indicates elevated ocean salinity in the region. One of the unique features of

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5502-440: The Earth including the poles. Tropical forests extended across much of modern Africa, South America, Central America, India, South-east Asia and China.  Paratropical forests grew over North America, Europe and Russia, with broad-leafed evergreen and broad-leafed deciduous forests at higher latitudes. Polar forests were quite extensive. Fossils and even preserved remains of trees such as swamp cypress and dawn redwood from

5633-691: The Eocene and Neogene for the Miocene and Pliocene in 1853. After decades of inconsistent usage, the newly formed International Commission on Stratigraphy (ICS), in 1969, standardized stratigraphy based on the prevailing opinions in Europe: the Cenozoic Era subdivided into the Tertiary and Quaternary sub-eras, and the Tertiary subdivided into the Paleogene and Neogene periods. In 1978, the Paleogene

5764-566: The Eocene have been found on Ellesmere Island in the Arctic . Even at that time, Ellesmere Island was only a few degrees in latitude further south than it is today. Fossils of subtropical and even tropical trees and plants from the Eocene also have been found in Greenland and Alaska . Tropical rainforests grew as far north as northern North America and Europe . Palm trees were growing as far north as Alaska and northern Europe during

5895-619: The Eocene include the Uintatherium , Arsinoitherium , and brontotheres , in which the former two, unlike the latter, did not belong to ungulates but groups that became extinct shortly after their establishments. Large terrestrial mammalian predators had already existed since the Paleocene, but new forms now arose like Hyaenodon and Daphoenus (the earliest lineage of a once-successful predatory family known as bear dogs ). Entelodonts meanwhile established themselves as some of

6026-544: The Eocene's climate as mentioned before was the equable and homogeneous climate that existed in the early parts of the Eocene. A multitude of proxies support the presence of a warmer equable climate being present during this period of time. A few of these proxies include the presence of fossils native to warm climates, such as crocodiles , located in the higher latitudes, the presence in the high latitudes of frost-intolerant flora such as palm trees which cannot survive during sustained freezes, and fossils of snakes found in

6157-664: The Eocene, and compression was replaced with crustal extension that ultimately gave rise to the Basin and Range Province . The Kishenehn Basin, around 1.5 km in elevation during the Lutetian, was uplifted to an altitude of 2.5 km by the Priabonian. Huge lakes formed in the high flat basins among uplifts, resulting in the deposition of the Green River Formation lagerstätte . At about 35 Ma, an asteroid impact on

6288-466: The Eocene-Oligocene transition is the timing of the creation of the circulation is uncertain. For Drake Passage , sediments indicate the opening occurred ~41 Ma while tectonics indicate that this occurred ~32 Ma. Solar activity did not change significantly during the greenhouse-icehouse transition across the Eocene-Oligocene boundary. During the early-middle Eocene, forests covered most of

6419-439: The Kummerian was refined by Gregory Retallack et al (2004) as 40 Mya, with a refined end at the Eocene-Oligocene boundary where the younger Angoonian floral stage starts. During the Eocene, the continents continued to drift toward their present positions. At the beginning of the period, Australia and Antarctica remained connected, and warm equatorial currents may have mixed with colder Antarctic waters, distributing

6550-489: The MECO was responsible for a globally uniform 4° to 6°C warming of both the surface and deep oceans, as inferred from foraminiferal stable oxygen isotope records. The resumption of a long-term gradual cooling trend resulted in a glacial maximum at the late Eocene/early Oligocene boundary. The end of the Eocene was also marked by the Eocene–Oligocene extinction event , also known as the Grande Coupure . The Eocene

6681-679: The MECO. Both groups of modern ungulates (hoofed animals) became prevalent because of a major radiation between Europe and North America, along with carnivorous ungulates like Mesonyx . Early forms of many other modern mammalian orders appeared, including horses (most notably the Eohippus ), bats , proboscidians (elephants), primates, and rodents . Older primitive forms of mammals declined in variety and importance. Important Eocene land fauna fossil remains have been found in western North America, Europe, Patagonia , Egypt , and southeast Asia . Marine fauna are best known from South Asia and

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6812-469: The North American continent, and it reduced the seasonal variation of temperature by up to 75%. While orbital parameters did not produce the warming at the poles, the parameters did show a great effect on seasonality and needed to be considered. Another method considered for producing the warm polar temperatures were polar stratospheric clouds . Polar stratospheric clouds are clouds that occur in

6943-503: The Origin of Species , Lyell finally offered a tepid endorsement of evolution in the tenth edition of Principles . Elements of Geology began as the fourth volume of the third edition of Principles : Lyell intended the book to act as a suitable field guide for students of geology. The systematic, factual description of geological formations of different ages contained in Principles grew so unwieldy, however, that Lyell split it off as

7074-415: The PETM event in the sea floor or wetland environments. For contrast, today the carbon dioxide levels are at 400 ppm or 0.04%. During the early Eocene, methane was another greenhouse gas that had a drastic effect on the climate. Methane has 30 times more of a warming effect than carbon dioxide on a 100-year scale (i.e., methane has a global warming potential of 29.8±11). Most of the methane released to

7205-572: The UK and overseas. Highlights include his travels throughout Europe and the United States of America, the drafts of his correspondence with the likes of Charles Darwin, his geological and landscape sketches and his constant gathering of evidence and refinement of his theories. Principles of Geology , Lyell's first book, was also his most famous, most influential, and most important. First published in three volumes in 1830–33, it established Lyell's credentials as an important geological theorist and propounded

7336-405: The actual determined temperature at the poles. This error has been classified as the "equable climate problem". To solve this problem, the solution would involve finding a process to warm the poles without warming the tropics. Some hypotheses and tests which attempt to find the process are listed below. Due to the nature of water as opposed to land, less temperature variability would be present if

7467-410: The addition of a large lake was unable to reduce the seasonality to the levels shown by the floral and faunal data. The transport of heat from the tropics to the poles, much like how ocean heat transport functions in modern times, was considered a possibility for the increased temperature and reduced seasonality for the poles. With the increased sea surface temperatures and the increased temperature of

7598-422: The amount of polar stratospheric clouds. While the polar stratospheric clouds could explain the reduction of the equator to pole temperature gradient and the increased temperatures at the poles during the early Eocene, there are a few drawbacks to maintaining polar stratospheric clouds for an extended period of time. Separate model runs were used to determine the sustainability of the polar stratospheric clouds. It

7729-530: The ancient spirit of speculation revived, and a desire manifestly shown to cut, rather than patiently untie, the Gordian Knot. -Sir Charles Lyell, Principles of Geology , 1854 edition, p. 196; quoted by Stephen Jay Gould . Lyell saw himself as "the spiritual saviour of geology, freeing the science from the old dispensation of Moses." The two terms, uniformitarianism and catastrophism , were both coined by William Whewell ; in 1866 R. Grove suggested

7860-456: The atmosphere during this period of time would have been from wetlands, swamps, and forests. The atmospheric methane concentration today is 0.000179% or 1.79 ppmv . As a result of the warmer climate and the sea level rise associated with the early Eocene, more wetlands, more forests, and more coal deposits would have been available for methane release. If we compare the early Eocene production of methane to current levels of atmospheric methane,

7991-528: The atmosphere may have been more important. Once the Antarctic region began to cool down, the ocean surrounding Antarctica began to freeze, sending cold water and icefloes north and reinforcing the cooling. The northern supercontinent of Laurasia began to fragment, as Europe , Greenland and North America drifted apart. In western North America, the Laramide Orogeny came to an end in

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8122-524: The atmospheric carbon dioxide. This event was similar in magnitude to the massive release of greenhouse gasses at the beginning of the PETM, and it is hypothesized that the sequestration was mainly due to organic carbon burial and weathering of silicates. For the early Eocene there is much discussion on how much carbon dioxide was in the atmosphere. This is due to numerous proxies representing different atmospheric carbon dioxide content. For example, diverse geochemical and paleontological proxies indicate that at

8253-505: The beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope C in the atmosphere was exceptionally low in comparison with the more common isotope C . The average temperature of Earth at the beginning of the Eocene was about 27 degrees Celsius. The end is set at a major extinction event called the Grande Coupure (the "Great Break" in continuity) or

8384-413: The decline into an icehouse climate and the rapid expansion of the Antarctic ice sheet . The transition from a warming climate into a cooling climate began at around 49 Ma. Isotopes of carbon and oxygen indicate a shift to a global cooling climate. The cause of the cooling has been attributed to a significant decrease of >2,000 ppm in atmospheric carbon dioxide concentrations. One proposed cause of

8515-437: The deep ocean water during the early Eocene, one common hypothesis was that due to these increases there would be a greater transport of heat from the tropics to the poles. Simulating these differences, the models produced lower heat transport due to the lower temperature gradients and were unsuccessful in producing an equable climate from only ocean heat transport. While typically seen as a control on ice growth and seasonality,

8646-410: The deep ocean. On top of that, MECO warming caused an increase in the respiration rates of pelagic heterotrophs , leading to a decreased proportion of primary productivity making its way down to the seafloor and causing a corresponding decline in populations of benthic foraminifera. An abrupt decrease in lakewater salinity in western North America occurred during this warming interval. This warming

8777-522: The doctrine of uniformitarianism . It was a work of synthesis, backed by his own personal observations on his travels. The central argument in Principles was that the present is the key to the past  – a concept of the Scottish Enlightenment which David Hume had stated as "all inferences from experience suppose ... that the future will resemble the past", and James Hutton had described when he wrote in 1788 that "from what has actually been, we have data for concluding with regard to that which

8908-411: The early Eocene would have produced triple the amount of methane. The warm temperatures during the early Eocene could have increased methane production rates, and methane that is released into the atmosphere would in turn warm the troposphere, cool the stratosphere, and produce water vapor and carbon dioxide through oxidation. Biogenic production of methane produces carbon dioxide and water vapor along with

9039-740: The early Eocene, although they became less abundant as the climate cooled. Dawn redwoods were far more extensive as well. The earliest definitive Eucalyptus fossils were dated from 51.9 Ma, and were found in the Laguna del Hunco deposit in Chubut province in Argentina . Cooling began mid-period, and by the end of the Eocene continental interiors had begun to dry, with forests thinning considerably in some areas. The newly evolved grasses were still confined to river banks and lake shores, and had not yet expanded into plains and savannas . The cooling also brought seasonal changes. Deciduous trees, better able to cope with large temperature changes, began to overtake evergreen tropical species. By

9170-411: The eastern coast of North America formed the Chesapeake Bay impact crater . The Tethys Ocean finally closed with the collision of Africa and Eurasia, while the uplift of the Alps isolated its final remnant, the Mediterranean , and created another shallow sea with island archipelagos to the north. Planktonic foraminifera in the northwestern Peri-Tethys are very similar to those of the Tethys in

9301-435: The end of the period, deciduous forests covered large parts of the northern continents, including North America, Eurasia and the Arctic, and rainforests held on only in equatorial South America , Africa , India and Australia . Antarctica began the Eocene fringed with a warm temperate to sub-tropical rainforest . Pollen found in Prydz Bay from the Eocene suggest taiga forest existed there. It became much colder as

9432-508: The enhanced burial of azolla could have had a significant effect on the world atmospheric carbon content and may have been the event to begin the transition into an ice house climate. The azolla event could have led to a draw down of atmospheric carbon dioxide of up to 470 ppm. Assuming the carbon dioxide concentrations were at 900 ppmv prior to the Azolla Event they would have dropped to 430 ppmv, or 30 ppmv more than they are today, after

9563-472: The enhanced carbon dioxide levels found in the early Eocene. The isolation of the Arctic Ocean, evidenced by euxinia that occurred at this time, led to stagnant waters and as the azolla sank to the sea floor, they became part of the sediments on the seabed and effectively sequestered the carbon by locking it out of the atmosphere for good. The ability for the azolla to sequester carbon is exceptional, and

9694-633: The epoch saw the dawn of recent, or modern, life. Scottish geologist Charles Lyell (ignoring the Quaternary) divided the Tertiary Epoch into the Eocene, Miocene , Pliocene , and New Pliocene ( Holocene ) Periods in 1833. British geologist John Phillips proposed the Cenozoic in 1840 in place of the Tertiary, and Austrian paleontologist Moritz Hörnes introduced the Paleogene for

9825-494: The expansion of the ice sheet was the creation of the Antarctic Circumpolar Current . The creation of the Antarctic circumpolar current would isolate the cold water around the Antarctic, which would reduce heat transport to the Antarctic along with creating ocean gyres that result in the upwelling of colder bottom waters. The issue with this hypothesis of the consideration of this being a factor for

9956-494: The extant manatees and dugongs . It is thought that millions of years after the Cretaceous-Paleogene extinction event , brain sizes of mammals now started to increase , "likely driven by a need for greater cognition in increasingly complex environments". Charles Lyell Sir Charles Lyell, 1st Baronet , FRS (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated

10087-431: The extinction of these birds, though this has never been formally tested and several ostrich taxa do occur in the late Cenozoic of Asia and some species do occur in areas where ostrich fossils have also been found. It has been suggested that the family is paraphyletic , with Ergilornithidae more closely related to modern ostriches than to Eogrus or Sonogrus . Most eogruids are known from rather sparse remains, mostly

10218-422: The formation of atolls , which supported Lyell's uniformitarianism. On the return of the Beagle (October 1836) Lyell invited Darwin to dinner and from then on they were close friends. Although Darwin discussed evolutionary ideas with him from 1842, Lyell continued to reject evolution in each of the first nine editions of the Principles . He encouraged Darwin to publish, and following the 1859 publication of On

10349-583: The fossil record indicated a directional geohistory in which species went extinct. Around 1826, when he was on circuit, he read Lamarck 's Zoological Philosophy and on 2 March 1827 wrote to Mantell , expressing admiration, but cautioning that he read it "rather as I hear an advocate on the wrong side, to know what can be made of the case in good hands".: He struggled with the implications for human dignity, and later in 1827 wrote private notes on Lamarck's ideas. Lyell reconciled transmutation of species with natural theology by suggesting that it would be as much

10480-603: The founding geology text. He was, along with the earlier John Playfair , the major advocate of James Hutton 's idea of uniformitarianism , that the earth was shaped entirely by slow-moving forces still in operation today, acting over a very long period of time. This was in contrast to catastrophism , an idea of abrupt geological changes, which had been adapted in England to explain landscape features—such as rivers much smaller than their associated valleys—that seemed impossible to explain other than through violent action. Criticizing

10611-588: The geographical distribution of plants and animals, and proposed that every species of plant or animal was descended from a pair or individual, originated in response to differing external conditions. Species would regularly go extinct, in a "struggle for existence" between hybrids, or a "war one with another" due to population pressure. He was vague about how replacement species formed, portraying this as an infrequent occurrence which could rarely be observed. The leading man of science Sir John Herschel wrote from Cape Town on 20 February 1836, thanking Lyell for sending

10742-793: The geology of the Quaternary Period of earth history: glaciers, evolution, and the age of the human race . First published in 1863, it went through three editions that year, with a fourth and final edition appearing in 1873. The book was widely regarded as a disappointment because of Lyell's equivocal treatment of evolution . Lyell, a highly religious man with a strong belief in the special status of human reason, had great difficulty reconciling his beliefs with natural selection . Lyell's geological interests ranged from volcanoes and geological dynamics through stratigraphy , palaeontology , and glaciology to topics that would now be classified as prehistoric archaeology and paleoanthropology . He

10873-399: The heat around the planet and keeping global temperatures high. When Australia split from the southern continent around 45 Ma, the warm equatorial currents were routed away from Antarctica. An isolated cold water channel developed between the two continents. However, modeling results call into question the thermal isolation model for late Eocene cooling, and decreasing carbon dioxide levels in

11004-402: The hot house to the cold house. The beginning of the Eocene is marked by the Paleocene–Eocene Thermal Maximum , a short period of intense warming and ocean acidification brought about by the release of carbon en masse into the atmosphere and ocean systems, which led to a mass extinction of 30–50% of benthic foraminifera (single-celled species which are used as bioindicators of the health of

11135-430: The ideas of Jean-Baptiste Lamarck in some detail. Lyell rejected Lamarck's idea of organic evolution , proposing instead "Centres of Creation" to explain diversity and territory of species. However, as discussed below , many of his letters show he was fairly open to the idea of evolution. In geology Darwin was very much Lyell's disciple, and brought back observations and his own original theorising, including ideas about

11266-588: The initial stages of the opening of the Drake Passage ~38.5 Ma was not global, as evidenced by an absence of cooling in the North Atlantic. During the cooling period, benthic oxygen isotopes show the possibility of ice creation and ice increase during this later cooling. The end of the Eocene and beginning of the Oligocene is marked with the massive expansion of area of the Antarctic ice sheet that

11397-453: The intervention of intermediate causes. I left this rather to be inferred, not thinking it worth while to offend a certain class of persons by embodying in words what would only be a speculation." Whewell subsequently questioned this topic, and in March 1837 Lyell told him: As a result of his letters and, no doubt, personal conversations, Huxley and Ernst Haeckel were convinced that, at

11528-516: The largest omnivores. The first nimravids , including Dinictis , established themselves as amongst the first feliforms to appear. Their groups became highly successful and continued to live past the Eocene. Basilosaurus is a very well-known Eocene whale , but whales as a group had become very diverse during the Eocene, which is when the major transitions from being terrestrial to fully aquatic in cetaceans occurred. The first sirenians were evolving at this time, and would eventually evolve into

11659-556: The lower stratosphere at very low temperatures. Polar stratospheric clouds have a great impact on radiative forcing. Due to their minimal albedo properties and their optical thickness, polar stratospheric clouds act similar to a greenhouse gas and trap outgoing longwave radiation. Different types of polar stratospheric clouds occur in the atmosphere: polar stratospheric clouds that are created due to interactions with nitric or sulfuric acid and water (Type I) or polar stratospheric clouds that are created with only water ice (Type II). Methane

11790-610: The maximum of global warmth the atmospheric carbon dioxide values were at 700–900 ppm , while model simulations suggest a concentration of 1,680 ppm fits best with deep sea, sea surface, and near-surface air temperatures of the time. Other proxies such as pedogenic (soil building) carbonate and marine boron isotopes indicate large changes of carbon dioxide of over 2,000 ppm over periods of time of less than 1 million years. This large influx of carbon dioxide could be attributed to volcanic out-gassing due to North Atlantic rifting or oxidation of methane stored in large reservoirs deposited from

11921-530: The members of the new mammal orders were small, under 10 kg; based on comparisons of tooth size, Eocene mammals were only 60% of the size of the primitive Palaeocene mammals that preceded them. They were also smaller than the mammals that followed them. It is assumed that the hot Eocene temperatures favored smaller animals that were better able to manage the heat. Rodents were widespread. East Asian rodent faunas declined in diversity when they shifted from ctenodactyloid-dominant to cricetid–dipodid-dominant after

12052-480: The methane, as well as yielding infrared radiation. The breakdown of methane in an atmosphere containing oxygen produces carbon monoxide, water vapor and infrared radiation. The carbon monoxide is not stable, so it eventually becomes carbon dioxide and in doing so releases yet more infrared radiation. Water vapor traps more infrared than does carbon dioxide. At about the beginning of the Eocene Epoch (55.8–33.9 Ma)

12183-569: The middle Lutetian but become completely disparate in the Bartonian, indicating biogeographic separation. Though the North Atlantic was opening, a land connection appears to have remained between North America and Europe since the faunas of the two regions are very similar. Eurasia was separated in three different landmasses 50 Ma; Western Europe, Balkanatolia and Asia. About 40 Ma, Balkanatolia and Asia were connected, while Europe

12314-399: The modern mammal orders appear within a brief period during the early Eocene . At the beginning of the Eocene, several new mammal groups arrived in North America. These modern mammals, like artiodactyls , perissodactyls , and primates , had features like long, thin legs , feet, and hands capable of grasping, as well as differentiated teeth adapted for chewing. Dwarf forms reigned. All

12445-790: The north aisle. Lyell was knighted ( Kt ) in 1848, and later, in 1864, made a baronet ( Bt ), which is an hereditary honour. He was awarded the Copley Medal of the Royal Society in 1858 and the Wollaston Medal of the Geological Society in 1866. Mount Lyell , the highest peak in Yosemite National Park , is named after him; the crater Lyell on the Moon and a crater on Mars were named in his honour; Mount Lyell in western Tasmania, Australia, located in

12576-585: The number and proportion of marine shells encased within. Based on this the third volume of his Principles of Geology , published in 1833, proposed dividing the Tertiary period into four parts, which he named the Eocene , Miocene , Pliocene , and Recent. In 1839, Lyell termed the Pleistocene epoch, distinguishing a more recent fossil layer from the Pliocene. The Recent epoch – renamed

12707-664: The ocean. Recent analysis of and research into these hyperthermals in the early Eocene has led to hypotheses that the hyperthermals are based on orbital parameters, in particular eccentricity and obliquity. The hyperthermals in the early Eocene, notably the Palaeocene–Eocene Thermal Maximum (PETM), the Eocene Thermal Maximum 2 (ETM2), and the Eocene Thermal Maximum 3 (ETM3), were analyzed and found that orbital control may have had

12838-416: The orbital parameters were theorized as a possible control on continental temperatures and seasonality. Simulating the Eocene by using an ice free planet, eccentricity , obliquity , and precession were modified in different model runs to determine all the possible different scenarios that could occur and their effects on temperature. One particular case led to warmer winters and cooler summer by up to 30% in

12969-416: The period progressed; the heat-loving tropical flora was wiped out, and by the beginning of the Oligocene, the continent hosted deciduous forests and vast stretches of tundra . During the Eocene, plants and marine faunas became quite modern. Many modern bird orders first appeared in the Eocene. The Eocene oceans were warm and teeming with fish and other sea life. The oldest known fossils of most of

13100-438: The polar stratospheric clouds effects on the Eocene climate, models were run comparing the effects of polar stratospheric clouds at the poles to an increase in atmospheric carbon dioxide. The polar stratospheric clouds had a warming effect on the poles, increasing temperatures by up to 20 °C in the winter months. A multitude of feedbacks also occurred in the models due to the polar stratospheric clouds' presence. Any ice growth

13231-408: The poles and floats across submerged continents, carrying debris with it, he conjectured. When the iceberg melts, it rains down sediments upon the land. Because this theory could account for the presence of diluvium, the word drift became the preferred term for the loose, unsorted material, today called till . Furthermore, Lyell believed that the accumulation of fine angular particles covering much of

13362-552: The post of Professor of Geology at King's College London in the 1830s. From 1830 onward his books provided both income and fame. Each of his three major books was a work continually in progress. All three went through multiple editions during his lifetime, although many of his friends (such as Darwin) thought the first edition of the Principles was the best written. Lyell used each edition to incorporate additional material, rearrange existing material, and revisit old conclusions in light of new evidence. Throughout his life, Lyell kept

13493-536: The power of known natural causes in explaining the earth's history. He is best known today for his association with Charles Darwin and as the author of Principles of Geology (1830–33), which presented to a wide public audience the idea that the earth was shaped by the same natural processes still in operation today, operating at similar intensities. The philosopher William Whewell dubbed this gradualistic view " uniformitarianism " and contrasted it with catastrophism , which had been championed by Georges Cuvier and

13624-653: The processes involved in evolution. As Darwin wrote in On the Origin of Species , "He who can read Sir Charles Lyell's grand work on the Principles of Geology, which the future historian will recognise as having produced a revolution in natural science, yet does not admit how incomprehensibly vast have been the past periods of time, may at once close this volume." Lyell helped to arrange the simultaneous publication in 1858 of papers by Darwin and Alfred Russel Wallace on natural selection , despite his personal religious qualms about

13755-458: The reduction in carbon dioxide during the warming to cooling transition was the azolla event . With the equable climate during the early Eocene, warm temperatures in the arctic allowed for the growth of azolla , which is a floating aquatic fern, on the Arctic Ocean . The significantly high amounts of carbon dioxide also acted to facilitate azolla blooms across the Arctic Ocean. Compared to current carbon dioxide levels, these azolla grew rapidly in

13886-459: The region. One possible cause of atmospheric carbon dioxide increase could have been a sudden increase due to metamorphic release due to continental drift and collision of India with Asia and the resulting formation of the Himalayas ; however, data on the exact timing of metamorphic release of atmospheric carbon dioxide is not well resolved in the data. Recent studies have mentioned, however, that

14017-453: The reliance of his contemporaries on what he argued were ad hoc explanations, Lyell wrote, Never was there a doctrine more calculated to foster indolence, and to blunt the keen edge of curiosity, than this assumption of the discordance between the former and the existing causes of change... The student was taught to despond from the first. Geology, it was affirmed, could never arise to the rank of an exact science... [With catastrophism] we see

14148-445: The removal of the ocean between Asia and India could have released significant amounts of carbon dioxide. Another hypothesis still implicates a diminished negative feedback of silicate weathering as a result of continental rocks having become less weatherable during the warm Early and Middle Eocene, allowing volcanically released carbon dioxide to persist in the atmosphere for longer. Yet another explanation hypothesises that MECO warming

14279-494: The rest of the postcranial skeleton is already specialised for cursoriality. Eogruids were formerly considered to be Gruiformes within the crane - limpkin - trumpeter line, Gruoidea, the exception being Olson 1985 which declared them to be stem-ostriches. A study in 2021 based on newly described remains found that eogruids and the related Ergilornithidae are indeed members of Struthoniformes. More derived taxa such as Ergilornis and Amphipelargus were sometimes classified as

14410-443: The simpler term continuity for Lyell's view, but the old terms persisted. In various revised editions (12 in all, through 1872), Principles of Geology was the most influential geological work in the middle of the 19th century, and did much to put geology on a modern footing. Lyell noted the "economic advantages" that geological surveys could provide, citing their felicity in mineral-rich countries and provinces. Modern surveys, like

14541-673: The study of nature. Lyell's grandfather, also Charles Lyell, had made the family fortune supplying the Royal Navy at Montrose , enabling him to buy Kinnordy House. The family seat is located in Strathmore , near the Highland Boundary Fault . Round the house, in the strath , is good farmland, but within a short distance to the north-west, on the other side of the fault, are the Grampian Mountains in

14672-621: The tarso-metatarsals and toes. The former are generally slender with a distinct crest along the lateral side of the plantar surface. The trochlea for the second toe shows a progressive reduction along the various taxa, culminating in its utter absence in Amphipelargus . Other skeletal remains are rare. Wing elements are known in a few taxa; these are generally highly reduced, suggesting that these birds were flightless. The exception appears to be Eogrus itself, which does not show much phalange reduction and hypothetically could still fly, though

14803-474: The theory of gradual "backed up-building" of volcanoes . In stratigraphy his division of the Tertiary period into the Pliocene , Miocene , and Eocene was highly influential. He incorrectly conjectured that icebergs were the impetus behind the transport of glacial erratics , and that silty loess deposits might have settled out of flood waters. His creation of a separate period for human history, entitled

14934-664: The theory of natural selection by Darwin and Alfred Russel Wallace in 1858: each had arrived at the theory independently. Lyell's views on gradual change and the power of a long time scale were important because Darwin thought that populations of an organism changed very slowly. Although Lyell rejected evolution at the time of writing the Principles , after the Darwin–Wallace papers and the Origin Lyell wrote in one of his notebooks on 3 May 1860: Lyell's acceptance of natural selection, Darwin's proposed mechanism for evolution,

15065-433: The theory. He later published evidence from geology of the time man had existed on the earth. Lyell was born into a wealthy family, on 14 November 1797, at the family's estate house , Kinnordy House , near Kirriemuir in Forfarshire. He was the eldest of ten children. Lyell's father, also named Charles Lyell , was noted as a translator and scholar of Dante . An accomplished botanist, it was he who first exposed his son to

15196-525: The time he wrote Principles , he believed new species had arisen by natural methods. Adam Sedgwick wrote worried letters to him about this. By the time Darwin returned from the Beagle survey expedition in 1836, he had begun to doubt Lyell's ideas about the permanence of species. He continued to be a close personal friend, and Lyell was one of the first scientists to support On the Origin of Species , though he did not subscribe to all its contents. Lyell

15327-399: The tropics that would require much higher average temperatures to sustain them. TEX 86 BAYSPAR measurements indicate extremely high sea surface temperatures of 40 °C (104 °F) to 45 °C (113 °F) at low latitudes, although clumped isotope analyses point to a maximum low latitude sea surface temperature of 36.3 °C (97.3 °F) ± 1.9 °C (35.4 °F) during

15458-446: The upheaval argument supported by other geologists. Lyell was a key figure in establishing the classification of more recent geological deposits, long known as the Tertiary period. From May 1828, until February 1829, he travelled with Roderick Impey Murchison (1792–1871) to the south of France (Auvergne volcanic district) and to Italy. In these areas he concluded that the recent strata (rock layers) could be categorised according to

15589-401: The world (today called loess ) was a deposit settled from mountain flood water. Today some of Lyell's mechanisms for geological processes have been disproven, though many have stood the test of time. His observational methods and general analytical framework remain in use today as foundational principles in geology. Lyell initially accepted the conventional view of other men of science, that

15720-463: The world became more arid and cold over the course of the stage, such as the Fushun Basin. In East Asia, lake level changes were in sync with global sea level changes over the course of the MLEC. Global cooling continued until there was a major reversal from cooling to warming in the Bartonian. This warming event, signifying a sudden and temporary reversal of the cooling conditions, is known as

15851-528: Was a major step into the icehouse climate. Multiple proxies, such as oxygen isotopes and alkenones , indicate that at the Eocene–Oligocene transition, the atmospheric carbon dioxide concentration had decreased to around 750–800 ppm, approximately twice that of present levels . Along with the decrease of atmospheric carbon dioxide reducing the global temperature, orbital factors in ice creation can be seen with 100,000-year and 400,000-year fluctuations in benthic oxygen isotope records. Another major contribution to

15982-399: Was also a friend of Darwin's closest colleagues, Joseph Dalton Hooker and Huxley , but unlike them he struggled to square his religious beliefs with evolution. This inner struggle has been much commented on. He had particular difficulty in believing in natural selection as the main motive force in evolution. Lyell and Hooker were instrumental in arranging the peaceful co-publication of

16113-551: Was better accepted in Europe. The combination of evidence and eloquence in Principles convinced a wide range of readers of the significance of " deep time " for understanding the earth and environment. Lyell's scientific contributions included a pioneering explanation of climate change, in which shifting boundaries between oceans and continents could be used to explain long-term variations in temperature and rainfall. Lyell also gave influential explanations of earthquakes and developed

16244-476: Was caused by the simultaneous occurrence of minima in both the 400 kyr and 2.4 Myr eccentricity cycles. During the MECO, sea surface temperatures in the Tethys Ocean jumped to 32–36 °C, and Tethyan seawater became more dysoxic. A decline in carbonate accumulation at ocean depths of greater than three kilometres took place synchronously with the peak of the MECO, signifying ocean acidification took place in

16375-465: Was connected 34 Ma. The Fushun Basin contained large, suboxic lakes known as the paleo-Jijuntun Lakes. India collided with Asia , folding to initiate formation of the Himalayas . The incipient subcontinent collided with the Kohistan–Ladakh Arc around 50.2 Ma and with Karakoram around 40.4 Ma, with the final collision between Asia and India occurring ~40 Ma. The Eocene Epoch contained

16506-402: Was determined that in order to maintain the lower stratospheric water vapor, methane would need to be continually released and sustained. In addition, the amounts of ice and condensation nuclei would need to be high in order for the polar stratospheric cloud to sustain itself and eventually expand. The Eocene is not only known for containing the warmest period during the Cenozoic; it also marked

16637-571: Was equivocal, and came in the tenth edition of Principles . The Antiquity of Man (published in early February 1863, just before Huxley's Man's place in nature ) drew these comments from Darwin to Huxley: "I am fearfully disappointed at Lyell's excessive caution" and "The book is a mere 'digest'". Quite strong remarks: no doubt Darwin resented Lyell's repeated suggestion that he owed a lot to Lamarck , whom he (Darwin) had always specifically rejected. Darwin's daughter Henrietta (Etty) wrote to her father: "Is it fair that Lyell always calls your theory

16768-457: Was officially defined as the Paleocene, Eocene, and Oligocene epochs; and the Neogene as the Miocene and Pliocene epochs. In 1989, Tertiary and Quaternary were removed from the time scale due to the arbitrary nature of their boundary, but Quaternary was reinstated in 2009. The Eocene is a dynamic epoch that represents global climatic transitions between two climatic extremes, transitioning from

16899-401: Was present on Earth with a smaller difference in temperature from the equator to the poles . Because of this the maximum sea level was 150 meters higher than current levels. Following the maximum was a descent into an icehouse climate from the Eocene Optimum to the Eocene–Oligocene transition at 34 Ma. During this decrease, ice began to reappear at the poles, and the Eocene–Oligocene transition

17030-437: Was slowed immensely and would lead to any present ice melting. Only the poles were affected with the change in temperature and the tropics were unaffected, which with an increase in atmospheric carbon dioxide would also cause the tropics to increase in temperature. Due to the warming of the troposphere from the increased greenhouse effect of the polar stratospheric clouds, the stratosphere would cool and would potentially increase

17161-421: Was to explain the cause of earthquakes. Lyell, in contrast focused on recent earthquakes (150 yrs), evidenced by surface irregularities such as faults, fissures, stratigraphic displacements and depressions. Lyell's work on volcanoes focused largely on Vesuvius and Etna , both of which he had earlier studied. His conclusions supported gradual building of volcanoes, so-called "backed up-building", as opposed to

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