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203-548: The Paleocene ( IPA : / ˈ p æ l i . ə s iː n , - i . oʊ -, ˈ p eɪ l i -/ PAL -ee-ə-seen, -⁠ee-oh-, PAY -lee- ), or Palaeocene , is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era . The name is a combination of the Ancient Greek παλαιός palaiós meaning "old" and

406-483: A pitch trace on a musical scale . Beyond the letters themselves, there are a variety of secondary symbols which aid in transcription. Diacritic marks can be combined with the letters to add tone and phonetic detail such as secondary articulation . There are also special symbols for prosodic features such as stress and intonation. There are two principal types of brackets used to set off (delimit) IPA transcriptions: Less common conventions include: All three of

609-513: A chart; the chart displayed here is the official chart as posted at the website of the IPA. The letters chosen for the IPA are meant to harmonize with the Latin alphabet . For this reason, most letters are either Latin or Greek , or modifications thereof. Some letters are neither: for example, the letter denoting the glottal stop , ⟨ ʔ ⟩, originally had the form of a question mark with

812-732: A climate similar to the Pacific Northwest . On the Alaska North Slope , Metasequoia was the dominant conifer. Much of the diversity represented migrants from nearer the equator. Deciduousness was dominant, probably to conserve energy by retroactively shedding leaves and retaining some energy rather than having them die from frostbite. In south-central Alaska, the Chickaloon Formation preserves peat-forming swamps dominated by taxodiaceous conifers and clastic floodplains occupied by angiosperm–conifer forests. At

1015-483: A conflicting use to delimit prosodic transcription within the Voice Quality Symbols , which are an extension of IPA used in extIPA, but are not otherwise used in IPA proper. Other delimiters sometimes seen are pipes and double pipes taken from Americanist phonetic notation . However, these conflict with the pipes used in basic IPA prosodic transcription. Other delimiters are double slashes, –

1218-535: A defined deep-water thermocline (a warmer mass of water closer to the surface sitting on top of a colder mass nearer the bottom) persisting throughout the epoch. The Atlantic foraminifera indicate a general warming of sea surface temperature–with tropical taxa present in higher latitude areas–until the Late Paleocene when the thermocline became steeper and tropical foraminifera retreated back to lower latitudes. Early Paleocene atmospheric CO 2 levels at what

1421-622: A depth of about 1,000 m (3,300 ft). The Danian deposits are sequestered into the Aitzgorri Limestone Formation , and the Selandian and early Thanetian into the Itzurun Formation . The Itzurun Formation is divided into groups A and B corresponding to the two stages respectively. The two stages were ratified in 2008, and this area was chosen because of its completion, low risk of erosion, proximity to

1624-538: A floral and faunal turnover of species, with previously abundant species being replaced by previously uncommon ones. In the Paleocene, with a global average temperature of about 24–25 °C (75–77 °F), compared to 14 °C (57 °F) in more recent times, the Earth had a greenhouse climate without permanent ice sheets at the poles, like the preceding Mesozoic . As such, there were forests worldwide—including at

1827-661: A higher rate than deciduous angiosperms as deciduous plants can become dormant in harsh conditions. In the Gulf Coast, angiosperms experienced another extinction event during the PETM, which they recovered quickly from in the Eocene through immigration from the Caribbean and Europe. During this time, the climate became warmer and wetter, and it is possible that angiosperms evolved to become stenotopic by this time, able to inhabit

2030-431: 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,

2233-604: A major extinction event called the Grande Coupure (the "Great Break" in continuity) or 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"

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2436-540: 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,

2639-452: A mix of IPA with Americanist phonetic notation or Sinological phonetic notation or otherwise use nonstandard symbols for various reasons. Authors who employ such nonstandard use are encouraged to include a chart or other explanation of their choices, which is good practice in general, as linguists differ in their understanding of the exact meaning of IPA symbols and common conventions change over time. Many British dictionaries, including

2842-440: A narrow range of temperature and moisture; or, since the dominant floral ecosystem was a highly integrated and complex closed-canopy rainforest by the middle Paleocene, the plant ecosystems were more vulnerable to climate change . There is some evidence that, in the Gulf Coast, there was an extinction event in the late Paleocene preceding the PETM, which may have been due to the aforementioned vulnerability of complex rainforests, and

3045-460: 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

3248-695: A row left out to save space. In the table below, a slightly different arrangement is made: All pulmonic consonants are included in the pulmonic-consonant table, and the vibrants and laterals are separated out so that the rows reflect the common lenition pathway of stop → fricative → approximant , as well as the fact that several letters pull double duty as both fricative and approximant; affricates may then be created by joining stops and fricatives from adjacent cells. Shaded cells represent articulations that are judged to be impossible or not distinctive. Vowel letters are also grouped in pairs—of unrounded and rounded vowel sounds—with these pairs also arranged from front on

3451-419: A short time frame. The freezing temperatures probably reversed after three years and returned to normal within decades, sulfuric acid aerosols causing acid rain probably dissipated after 10 years, and dust from the impact blocking out sunlight and inhibiting photosynthesis would have lasted up to a year though potential global wildfires raging for several years would have released more particulates into

3654-533: 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

3857-718: A single formation (a stratotype ) identifying the lower boundary of the stage. In 1989, the ICS decided to split the Paleocene into three stages: the Danian, Selandian, and Thanetian. The Danian was first defined in 1847 by German-Swiss geologist Pierre Jean Édouard Desor based on the Danish chalks at Stevns Klint and Faxse , and was part of the Cretaceous, succeeded by the Tertiary Montian Stage. In 1982, after it

4060-440: A standard written representation for the sounds of speech . The IPA is used by lexicographers , foreign language students and teachers, linguists , speech–language pathologists , singers, actors, constructed language creators, and translators . The IPA is designed to represent those qualities of speech that are part of lexical (and, to a limited extent, prosodic ) sounds in oral language : phones , intonation and

4263-452: A variety of foreign languages. They are also taught by vocal coaches to perfect diction and improve tone quality and tuning. Opera librettos are authoritatively transcribed in IPA, such as Nico Castel 's volumes and Timothy Cheek's book Singing in Czech . Opera singers' ability to read IPA was used by the site Visual Thesaurus , which employed several opera singers "to make recordings for

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4466-722: 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

4669-436: Is also evidence this occurred again 300,000 years later in the early Thanetian dubbed MPBE-2. Respectively, about 83 and 132 gigatons of methane-derived carbon were ejected into the atmosphere, which suggests a 2–3 °C (3.6–5.4 °F) rise in temperature, and likely caused heightened seasonality and less stable environmental conditions. It may have also caused an increase of grass in some areas. From 59.7 to 58.1 Ma, during

4872-459: 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,

5075-638: 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

5278-531: Is controversial, but most likely about 2,500 years. This carbon also interfered with the carbon cycle and caused ocean acidification, and potentially altered and slowed down ocean currents, the latter leading to the expansion of oxygen minimum zones (OMZs) in the deep sea. In surface water, OMZs could have also been caused from the formation of strong thermoclines preventing oxygen inflow, and higher temperatures equated to higher productivity leading to higher oxygen usurpation. Further, expanding OMZs could have caused

5481-594: 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

5684-603: Is derived from Ancient Greek Ἠώς ( Ēṓs ) meaning "Dawn", and καινός kainos meaning "new" or "recent", as 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

5887-495: Is elected by the membership – for further discussion and a formal vote. Many users of the alphabet, including the leadership of the Association itself, deviate from its standardized usage. The Journal of the IPA finds it acceptable to mix IPA and extIPA symbols in consonant charts in their articles. (For instance, including the extIPA letter ⟨ 𝼆 ⟩ , rather than ⟨ ʎ̝̊ ⟩, in an illustration of

6090-531: Is more abstract than either [t̠̺͡ʃʰ] or [c] and might refer to either, depending on the context and language. Occasionally, letters or diacritics are added, removed, or modified by the International Phonetic Association. As of the most recent change in 2005, there are 107 segmental letters, an indefinitely large number of suprasegmental letters, 44 diacritics (not counting composites), and four extra-lexical prosodic marks in

6293-528: Is not always accessible to sight-impaired readers who rely on screen reader technology. Double angle brackets may occasionally be useful to distinguish original orthography from transliteration, or the idiosyncratic spelling of a manuscript from the normalized orthography of the language. Pipes are sometimes used instead of double angle brackets to denote the distinct allographs of a grapheme that are known as glyphs . For example, print | g | and script | ɡ | are two glyph variants of

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6496-435: Is now Castle Rock , Colorado, were calculated to be between 352 and 1,110 parts per million (ppm), with a median of 616 ppm. Based on this and estimated plant-gas exchange rates and global surface temperatures, the climate sensitivity was calculated to be +3 °C when CO 2 levels doubled, compared to 7 °C following the formation of ice at the poles. CO 2 levels alone may have been insufficient in maintaining

6699-581: Is now the Gulf Coast , angiosperm diversity increased slowly in the early Paleocene, and more rapidly in the middle and late Paleocene. This may have been because the effects of the K–Pg extinction event were still to some extent felt in the early Paleocene, the early Paleocene may not have had as many open niches, early angiosperms may not have been able to evolve at such an accelerated rate as later angiosperms, low diversity equates to lower evolution rates, or there

6902-550: Is now the Mediterranean Sea tropical. South-central North America had a humid, monsoonal climate along its coastal plain, but conditions were drier to the west and at higher altitudes. Svalbard was temperate, having a mean temperature of 19.2 ± 2.49 °C during its warmest month and 1.7 ± 3.24 °С during its coldest. Global deep water temperatures in the Paleocene likely ranged from 8–12 °C (46–54 °F), compared to 0–3 °C (32–37 °F) in modern day. Based on

7105-720: 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

7308-535: 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

7511-547: Is why the GSSP was moved to Zumaia. Today, the beginning of the Selandian is marked by the appearances of the nannofossils Fasciculithus tympaniformis , Neochiastozygus perfectus , and Chiasmolithus edentulus , though some foraminifera are used by various authors. The Thanetian was first proposed by Swiss geologist Eugène Renevier , in 1873; he included the south England Thanet , Woolwich , and Reading formations. In 1880, French geologist Gustave Frédéric Dollfus narrowed

7714-820: The Antarctic Peninsula . In the Paleocene, the waterways between the Arctic Ocean and the North Atlantic were somewhat restricted, so North Atlantic Deep Water (NADW) and the Atlantic Meridional Overturning Circulation (AMOC)—which circulates cold water from the Arctic towards the equator—had not yet formed, and so deep water formation probably did not occur in the North Atlantic. The Arctic and Atlantic would not be connected by sufficiently deep waters until

7917-823: The Caribbean Plate ), which had formed from the Galápagos hotspot in the Pacific in the latest Cretaceous, was moving eastward as the North American and South American plates were getting pushed in the opposite direction due to the opening of the Atlantic ( strike-slip tectonics ). This motion would eventually uplift the Isthmus of Panama by 2.6 mya. The Caribbean Plate continued moving until about 50 mya when it reached its current position. The components of

8120-765: The Cretaceous Period and the Mesozoic Era , and initiated the Cenozoic Era and the Paleogene Period. It is divided into three ages : the Danian spanning 66 to 61.6 million years ago (mya), the Selandian spanning 61.6 to 59.2 mya, and the Thanetian spanning 59.2 to 56 mya. It is succeeded by the Eocene. The K–Pg boundary is clearly defined in the fossil record in numerous places around

8323-520: The Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event , brought on by an asteroid impact ( Chicxulub impact ) and possibly volcanism ( Deccan Traps ), marked the beginning of the Paleocene and killed off 75% of species, most famously the non-avian dinosaurs. The end of

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8526-466: The Handbook recommended against their use, as cursive IPA is "harder for most people to decipher". A braille representation of the IPA for blind or visually impaired professionals and students has also been developed. The International Phonetic Alphabet is occasionally modified by the Association. After each modification, the Association provides an updated simplified presentation of the alphabet in

8729-460: The Hebrew alphabet for transcription of foreign words. Bilingual dictionaries that translate from foreign languages into Russian usually employ the IPA, but monolingual Russian dictionaries occasionally use pronunciation respelling for foreign words. The IPA is more common in bilingual dictionaries, but there are exceptions here too. Mass-market bilingual Czech dictionaries, for instance, tend to use

8932-548: The Holarctic region (comprising most of the Northern Hemisphere) was mainly early members of Ginkgo , Metasequoia , Glyptostrobus , Macginitiea , Platanus , Carya , Ampelopsis , and Cercidiphyllum . Patterns in plant recovery varied significantly with latitude , climate, and altitude. For example, what is now Castle Rock, Colorado featured a rich rainforest only 1.4 million years after

9135-570: The IPA extensions . In the IPA itself, however, only lower-case letters are used. The 1949 edition of the IPA handbook indicated that an asterisk ⟨*⟩ might be prefixed to indicate that a word was a proper name, but this convention was not included in the 1999 Handbook , which notes the contrary use of the asterisk as a placeholder for a sound or feature that does not have a symbol. The IPA has widespread use among classical singers during preparation as they are frequently required to sing in

9338-566: The International Clinical Phonetics and Linguistics Association in 1994. They were substantially revised in 2015. The general principle of the IPA is to provide one letter for each distinctive sound ( speech segment ). This means that: The alphabet is designed for transcribing sounds (phones), not phonemes , though it is used for phonemic transcription as well. A few letters that did not indicate specific sounds have been retired (⟨ ˇ ⟩, once used for

9541-713: 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

9744-792: The Oxford English Dictionary and some learner's dictionaries such as the Oxford Advanced Learner's Dictionary and the Cambridge Advanced Learner's Dictionary , now use the International Phonetic Alphabet to represent the pronunciation of words. However, most American (and some British) volumes use one of a variety of pronunciation respelling systems, intended to be more comfortable for readers of English and to be more acceptable across dialects, without

9947-477: 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 –planktonic species which are used as bioindicators of the health of a marine ecosystem—one of the largest in the Cenozoic. This event happened around 55.8 mya, and

10150-761: 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

10353-627: The Quaternary from the Tertiary in 1829; and Scottish geologist Charles Lyell (ignoring the Quaternary) had divided the Tertiary Epoch into the Eocene , Miocene , Pliocene , and New Pliocene ( Holocene ) Periods in 1833. British geologist John Phillips had proposed the Cenozoic in 1840 in place of the Tertiary, and Austrian paleontologist Moritz Hörnes had introduced the Paleogene for

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10556-529: The Transantarctic Mountains . The poles probably had a cool temperate climate; northern Antarctica, Australia, the southern tip of South America, what is now the US and Canada, eastern Siberia, and Europe warm temperate; middle South America, southern and northern Africa, South India, Middle America, and China arid; and northern South America, central Africa, North India, middle Siberia, and what

10759-406: 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

10962-844: The opening of the North Atlantic Ocean and seafloor spreading , the divergence of the Greenland Plate from the North American Plate , and, climatically, the PETM by dissociating methane clathrate crystals on the seafloor resulting in the mass release of carbon. North and South America remained separated by the Central American Seaway , though an island arc (the South Central American Arc) had already formed about 73 mya. The Caribbean Large Igneous Province (now

11165-417: 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

11368-473: 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

11571-427: The water column . Though the temperature in the latest Danian varied at about the same magnitude, this event coincides with an increase of carbon. About 60.5 mya at the Danian/Selandian boundary, there is evidence of anoxia spreading out into coastal waters, and a drop in sea levels which is most likely explained as an increase in temperature and evaporation, as there was no ice at the poles to lock up water. During

11774-399: The Østerrende Clay . The beginning of this stage was defined by the end of carbonate rock deposition from an open ocean environment in the North Sea region (which had been going on for the previous 40 million years). The Selandian deposits in this area are directly overlain by the Eocene Fur Formation —the Thanetian was not represented here—and this discontinuity in the deposition record

11977-583: The "compound" tone of Swedish and Norwegian, and ⟨ ƞ ⟩, once used for the moraic nasal of Japanese), though one remains: ⟨ ɧ ⟩, used for the sj-sound of Swedish. When the IPA is used for broad phonetic or for phonemic transcription, the letter–sound correspondence can be rather loose. The IPA has recommended that more 'familiar' letters be used when that would not cause ambiguity. For example, ⟨ e ⟩ and ⟨ o ⟩ for [ɛ] and [ɔ] , ⟨ t ⟩ for [t̪] or [ʈ] , ⟨ f ⟩ for [ɸ] , etc. Indeed, in

12180-494: The 150,000 words and phrases in VT's lexical database ... for their vocal stamina, attention to the details of enunciation, and most of all, knowledge of IPA". The International Phonetic Association organizes the letters of the IPA into three categories: pulmonic consonants, non-pulmonic consonants, and vowels. Pulmonic consonant letters are arranged singly or in pairs of voiceless ( tenuis ) and voiced sounds, with these then grouped in columns from front (labial) sounds on

12383-503: The Americas had not yet joined, the Indian Plate had begun its collision with Asia, and the North Atlantic Igneous Province was forming in the third-largest magmatic event of the last 150 million years. In the oceans, the thermohaline circulation probably was much different from what it is today, with downwellings occurring in the North Pacific rather than the North Atlantic, and water density mainly being controlled by salinity rather than temperature. The K–Pg extinction event caused

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12586-479: 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

12789-442: The Cretaceous, had receded. Between about 60.5 and 54.5 mya, there was heightened volcanic activity in the North Atlantic region—the third largest magmatic event in the last 150 million years—creating the North Atlantic Igneous Province . The proto- Iceland hotspot is sometimes cited as being responsible for the initial volcanism, though rifting and resulting volcanism have also contributed. This volcanism may have contributed to

12992-431: The Cretaceous, tropical or subtropical , and the poles were temperate , with an average global temperature of roughly 24–25 °C (75–77 °F). For comparison, the average global temperature for the period between 1951 and 1980 was 14 °C (57 °F). The latitudinal temperature gradient was approximately 0.24 °C per degree of latitude. The poles also lacked ice caps, though some alpine glaciation did occur in

13195-404: 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

13398-404: 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

13601-440: 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

13804-407: 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

14007-457: 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

14210-503: 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

14413-425: The Eocene". The Eocene, in turn, is derived from Ancient Greek eo— eos ἠώς meaning "dawn", and—cene kainos καινός meaning "new" or "recent", as the epoch saw the dawn of recent, or modern, life. Paleocene did not come into broad usage until around 1920. In North America and mainland Europe, the standard spelling is "Paleocene", whereas it is "Palaeocene" in the UK. Geologist T. C. R. Pulvertaft has argued that

14616-544: 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

14819-664: 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

15022-466: 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

15225-733: The Greek alphabet, though their sound values may differ from Greek. For most Greek letters, subtly different glyph shapes have been devised for the IPA, specifically ⟨ ɑ ⟩, ⟨ ꞵ ⟩, ⟨ ɣ ⟩, ⟨ ɛ ⟩, ⟨ ɸ ⟩, ⟨ ꭓ ⟩ and ⟨ ʋ ⟩, which are encoded in Unicode separately from their parent Greek letters. One, however – ⟨ θ ⟩ – has only its Greek form, while for ⟨ ꞵ ~ β ⟩ and ⟨ ꭓ ~ χ ⟩, both Greek and Latin forms are in common use. The tone letters are not derived from an alphabet, but from

15428-682: The IPA only for sounds not found in Czech . IPA letters have been incorporated into the alphabets of various languages, notably via the Africa Alphabet in many sub-Saharan languages such as Hausa , Fula , Akan , Gbe languages , Manding languages , Lingala , etc. Capital case variants have been created for use in these languages. For example, Kabiyè of northern Togo has Ɖ ɖ , Ŋ ŋ , Ɣ ɣ , Ɔ ɔ , Ɛ ɛ , Ʋ ʋ . These, and others, are supported by Unicode , but appear in Latin ranges other than

15631-685: The IPA so that the sound values of most letters would correspond to "international usage" (approximately Classical Latin ). Hence, the consonant letters ⟨ b ⟩, ⟨ d ⟩, ⟨ f ⟩, ⟨ ɡ ⟩, ⟨ h ⟩, ⟨ k ⟩, ⟨ l ⟩, ⟨ m ⟩, ⟨ n ⟩, ⟨ p ⟩, ⟨ s ⟩, ⟨ t ⟩, ⟨ v ⟩, ⟨ w ⟩, and ⟨ z ⟩ have more or less their word-initial values in English ( g as in gill , h as in hill , though p t k are unaspirated as in spill, still, skill ); and

15834-550: The IPA. These are illustrated in the current IPA chart , posted below in this article and on the International Phonetic Association's website. In 1886, a group of French and English language teachers, led by the French linguist Paul Passy , formed what would be known from 1897 onwards as the International Phonetic Association (in French, l'Association phonétique internationale ). The idea of

16037-532: The IPA.) Of more than 160 IPA symbols, relatively few will be used to transcribe speech in any one language, with various levels of precision. A precise phonetic transcription, in which sounds are specified in detail, is known as a narrow transcription . A coarser transcription with less detail is called a broad transcription. Both are relative terms, and both are generally enclosed in square brackets. Broad phonetic transcriptions may restrict themselves to easily heard details, or only to details that are relevant to

16240-439: 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

16443-671: The K–Pg boundary, the largest the Mexican Chicxulub crater whose impact was a major precipitator of the K–Pg extinction, and also the Ukrainian Boltysh crater , dated to 65.4 mya the Canadian Eagle Butte crater (though it may be younger), the Vista Alegre crater (though this may date to about 115 mya). Silicate glass spherules along the Atlantic coast of the U.S. indicate a meteor impact in

16646-414: The K–Pg extinction event, every land animal over 25 kg (55 lb) was wiped out, leaving open several niches at the beginning of the epoch. International Phonetic Alphabet The International Phonetic Alphabet ( IPA ) is an alphabetic system of phonetic notation based primarily on the Latin script . It was devised by the International Phonetic Association in the late 19th century as

16849-538: The Late Cretaceous became dominant trees in Patagonia, before going extinct. Some plant communities, such as those in eastern North America, were already experiencing an extinction event in the late Maastrichtian, particularly in the 1 million years before the K–Pg extinction event. The "disaster plants" that refilled the emptied landscape crowded out many Cretaceous plants, and resultantly, many went extinct by

17052-426: 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

17255-679: 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

17458-587: The Miocene about 24–17 mya. There is evidence that some plants and animals could migrate between India and Asia during the Paleocene, possibly via intermediary island arcs. In the modern thermohaline circulation , warm tropical water becomes colder and saltier at the poles and sinks ( downwelling or deep water formation) that occurs at the North Atlantic near the North Pole and the Southern Ocean near

17661-405: 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

17864-725: The Northern Component Waters by Greenland in the Eocene—the predecessor of the AMOC—may have caused an intense warming in the North Hemisphere and cooling in the Southern, as well as an increase in deep water temperatures. In the PETM, it is possible deep water formation occurred in saltier tropical waters and moved polewards, which would increase global surface temperatures by warming the poles. Also, Antarctica

18067-415: 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

18270-411: The Paleocene, especially at the end, in tandem with the increasing global temperature. At the North Pole, woody angiosperms had become the dominant plants, a reversal from the Cretaceous where herbs proliferated. The Iceberg Bay Formation on Ellesmere Island , Nunavut (latitude 75 – 80 ° N) shows remains of a late Paleocene dawn redwood forest, the canopy reaching around 32 m (105 ft), and

18473-529: The South Pole, due to the increasing isolation of Antarctica, many plant taxa were endemic to the continent instead of migrating down. Patagonian flora may have originated in Antarctica. The climate was much cooler than in the Late Cretaceous, though frost probably was not common in at least coastal areas. East Antarctica was likely warm and humid. Because of this, evergreen forests could proliferate as, in

18676-602: The Tertiary subdivided into the Paleogene and Neogene periods. In 1978, the Paleogene 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

18879-525: The Tertiary, and Austrian paleontologist Moritz Hörnes introduced the Paleogene for 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

19082-898: The Thanetian is best correlated with the C26r/C26n reversal. Several economically important coal deposits formed during the Paleocene, such as the sub-bituminous Fort Union Formation in the Powder River Basin of Wyoming and Montana, which produces 43% of American coal; the Wilcox Group in Texas, the richest deposits of the Gulf Coastal Plain ; and the Cerrejón mine in Colombia, the largest open-pit mine in

19285-678: The Turgai route connecting Europe with Asia (which were otherwise separated by the Turgai Strait at this time). The Laramide orogeny , which began in the Late Cretaceous, continued to uplift the Rocky Mountains ; it ended at the end of the Paleocene. Because of this and a drop in sea levels resulting from tectonic activity, the Western Interior Seaway , which had divided the continent of North America for much of

19488-485: The above are provided by the IPA Handbook . The following are not, but may be seen in IPA transcription or in associated material (especially angle brackets): Also commonly seen are the braces of set theory , especially when enclosing the set of phonemes that constitute the morphophoneme, e.g. {t d} or {t|d} or {/t/, /d/} for a conflated /t/ and /d/ . Braces have

19691-437: The absence of frost and a low probability of leaves dying, it was more energy efficient to retain leaves than to regrow them every year. One possibility is that the interior of the continent favored deciduous trees, though prevailing continental climates may have produced winters warm enough to support evergreen forests. As in the Cretaceous, podocarpaceous conifers, Nothofagus , and Proteaceae angiosperms were common. In

19894-405: 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

20097-410: 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

20300-473: The algae Discoaster and a diversification of Heliolithus , though the best correlation is in terms of paleomagnetism . A chron is the occurrence of a geomagnetic reversal —when the North and South poles switch polarities . Chron 1 (C1n) is defined as modern day to about 780,000 years ago, and the n denotes "normal" as in the polarity of today, and an r "reverse" for the opposite polarity. The beginning of

20503-519: The alphabet had been suggested to Passy by Otto Jespersen . It was developed by Passy along with other members of the association, principally Daniel Jones . The original IPA alphabet was based on the Romic alphabet , an English spelling reform created by Henry Sweet that in turn was based on the Palaeotype alphabet of Alexander John Ellis , but to make it usable for other languages the values of

20706-617: The alphabet or the chart is to propose the change in the Journal of the IPA . (See, for example, December 2008 on an open central unrounded vowel and August 2011 on central approximants.) Reactions to the proposal may be published in the same or subsequent issues of the Journal (as in August 2009 on the open central vowel). A formal proposal is then put to the Council of the IPA – which

20909-422: 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

21112-456: 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,

21315-528: 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

21518-502: The atmosphere. For the following half million years, the carbon isotope gradient—a difference in the C / C ratio between surface and deep ocean water, causing carbon to cycle into the deep sea—may have shut down. This, termed a "Strangelove ocean", indicates low oceanic productivity ; resultant decreased phytoplankton activity may have led to a reduction in cloud seeds and, thus, marine cloud brightening , causing global temperatures to increase by 6 °C ( CLAW hypothesis ). Following

21721-524: 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

21924-604: The boundary; for example, in the Williston Basin of North Dakota, an estimated 1/3 to 3/5 of plant species went extinct. The K–Pg extinction event ushered in a floral turnover; for example, the once commonplace Araucariaceae conifers were almost fully replaced by Podocarpaceae conifers, and the Cheirolepidiaceae , a group of conifers that had dominated during most of the Mesozoic but had become rare during

22127-403: The conceptual counterparts of spoken sounds, are usually enclosed in slashes (/ /) and tend to use simpler letters with few diacritics. The choice of IPA letters may reflect theoretical claims of how speakers conceptualize sounds as phonemes or they may be merely a convenience for typesetting. Phonemic approximations between slashes do not have absolute sound values. For instance, in English, either

22330-555: The consonant is produced. The main chart includes only consonants with a single place of articulation. Notes Non-pulmonic consonants are sounds whose airflow is not dependent on the lungs. These include clicks (found in the Khoisan languages and some neighboring Bantu languages of Africa), implosives (found in languages such as Sindhi , Hausa , Swahili and Vietnamese ), and ejectives (found in many Amerindian and Caucasian languages ). Eocene The Eocene spans

22533-745: The country. Paleocene coal has been mined extensively in Svalbard , Norway, since near the beginning of the 20th century, and late Paleocene and early Eocene coal is widely distributed across the Canadian Arctic Archipelago and northern Siberia. In the North Sea, Paleocene-derived natural gas reserves, when they were discovered, totaled approximately 2.23 trillion m (7.89 trillion ft), and oil in place 13.54 billion barrels. Important phosphate deposits—predominantly of francolite —near Métlaoui , Tunisia were formed from

22736-402: The dark forest floor, and epiphytism where a plant grows on another plant in response to less space on the forest floor. Despite increasing density—which could act as fuel—wildfires decreased in frequency from the Cretaceous to the early Eocene as the atmospheric oxygen levels decreased to modern day levels, though they may have been more intense. There was a major die-off of plant species over

22939-413: 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

23142-437: 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,

23345-410: 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

23548-487: The deep sea possibly due to a global cooling trend and increased circulation into the deep sea. The Dan–C2 event may represent a release of this carbon after deep sea temperatures rose to a certain threshold, as warmer water can dissolve less carbon. Alternatively, the cause of the Dan-C2 event may have been a pulse of Deccan Traps volcanism. Savanna may have temporarily displaced forestland in this interval. Around 62.2 mya in

23751-470: The definition to just the Thanet Formation. The Thanetian begins a little after the mid-Paleocene biotic event—a short-lived climatic event caused by an increase in methane —recorded at Itzurun as a dark 1 m (3.3 ft) interval from a reduction of calcium carbonate . At Itzurun, it begins about 29 m (95 ft) above the base of the Selandian, and is marked by the first appearance of

23954-731: The discussion at hand, and may differ little if at all from phonemic transcriptions, but they make no theoretical claim that all the distinctions transcribed are necessarily meaningful in the language. For example, the English word little may be transcribed broadly as [ˈlɪtəl] , approximately describing many pronunciations. A narrower transcription may focus on individual or dialectical details: [ˈɫɪɾɫ] in General American , [ˈlɪʔo] in Cockney , or [ˈɫɪːɫ] in Southern US English . Phonemic transcriptions, which express

24157-476: The dot removed. A few letters, such as that of the voiced pharyngeal fricative , ⟨ ʕ ⟩, were inspired by other writing systems (in this case, the Arabic letter ⟨ ﻉ ⟩, ʿayn , via the reversed apostrophe). Some letter forms derive from existing letters: The International Phonetic Alphabet is based on the Latin script , and uses as few non-Latin letters as possible. The Association created

24360-411: 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

24563-901: 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

24766-542: The early to middle Eocene. There is evidence of deep water formation in the North Pacific to at least a depth of about 2,900 m (9,500 ft). The elevated global deep water temperatures in the Paleocene may have been too warm for thermohaline circulation to be predominately heat driven. It is possible that the greenhouse climate shifted precipitation patterns, such that the Southern Hemisphere

24969-639: 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

25172-528: The ecosystem may have been disrupted by only a small change in climate. The warm Paleocene climate, much like that of the Cretaceous , allowed for diverse polar forests. Whereas precipitation is a major factor in plant diversity nearer the equator, polar plants had to adapt to varying light availability ( polar nights and midnight suns ) and temperatures. Because of this, plants from both poles independently evolved some similar characteristics, such as broad leaves. Plant diversity at both poles increased throughout

25375-491: 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

25578-608: The end of words. the alternations /f/  – /v/ in plural formation in one class of nouns, as in knife /naɪf/  – knives /naɪvz/ , which can be represented morphophonemically as {naɪV } – {naɪV+z }. The morphophoneme {V } stands for the phoneme set {/f/, /v/ }. [ˈf\faɪnəlz ˈhɛld ɪn (.) ⸨knock on door⸩ bɑɹsə{ 𝑝 ˈloʊnə and ˈmədɹɪd 𝑝 }] — f-finals held in Barcelona and Madrid. IPA letters have cursive forms designed for use in manuscripts and when taking field notes, but

25781-508: 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

25984-411: 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

26187-569: The epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification . In the Paleocene, the continents of the Northern Hemisphere were still connected via some land bridges ; and South America, Antarctica, and Australia had not completely separated yet. The Rocky Mountains were being uplifted,

26390-484: The event, probably due to a rain shadow effect causing regular monsoon seasons. Conversely, low plant diversity and a lack of specialization in insects in the Colombian Cerrejón Formation , dated to 58 mya, indicates the ecosystem was still recovering from the K–Pg extinction event 7 million years later. Flowering plants ( angiosperms ), which had become dominant among forest taxa by

26593-494: 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

26796-610: The extreme disruptions in the aftermath of the K-Pg extinction event, the relatively cool, though still greenhouse, conditions of the Late Cretaceous–Early Palaeogene Cool Interval (LKEPCI) that began in the Late Cretaceous continued. The Dan –C2 Event 65.2 mya in the early Danian spanned about 100,000 years, and was characterized by an increase in carbon, particularly in the deep sea. Since the mid- Maastrichtian , more and more carbon had been sequestered in

26999-403: The form of a chart. (See History of the IPA .) Not all aspects of the alphabet can be accommodated in a chart of the size published by the IPA. The alveolo-palatal and epiglottal consonants, for example, are not included in the consonant chart for reasons of space rather than of theory (two additional columns would be required, one between the retroflex and palatal columns and the other between

27202-533: The former southern supercontinent Gondwanaland in the Southern Hemisphere continued to drift apart, but Antarctica was still connected to South America and Australia. Africa was heading north towards Europe, and the Indian subcontinent towards Asia, which would eventually close the Tethys Ocean . The Indian and Eurasian Plates began colliding in the Paleocene, with uplift (and a land connection) beginning in

27405-412: The grapheme ⟨ g ⟩ of Latin script. Some examples of contrasting brackets in the literature: In some English accents, the phoneme /l/ , which is usually spelled as ⟨l⟩ or ⟨ll⟩ , is articulated as two distinct allophones: the clear [l] occurs before vowels and the consonant /j/ , whereas the dark [ɫ] / [lˠ] occurs before consonants, except /j/ , and at

27608-451: The greenhouse climate, and some positive feedbacks must have been active, such as some combination of cloud, aerosol, or vegetation related processes. A 2019 study identified changes in orbital eccentricity as the dominant drivers of climate between the late Cretaceous and the early Eocene. The effects of the meteor impact and volcanism 66 mya and the climate across the K–Pg boundary were likely fleeting, and climate reverted to normal in

27811-399: 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

28014-402: 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

28217-401: The illustration of Hindi in the IPA Handbook , the letters ⟨ c ⟩ and ⟨ ɟ ⟩ are used for /t͡ʃ/ and /d͡ʒ/ . Among the symbols of the IPA, 107 letters represent consonants and vowels , 31 diacritics are used to modify these, and 17 additional signs indicate suprasegmental qualities such as length , tone , stress , and intonation . These are organized into

28420-438: The implication of a preferred pronunciation that the IPA might convey. For example, the respelling systems in many American dictionaries (such as Merriam-Webster ) use ⟨y⟩ for IPA [ j] and ⟨sh⟩ for IPA [ ʃ ] , reflecting the usual spelling of those sounds in English. (In IPA, [y] represents the sound of the French ⟨u⟩ , as in tu , and [sh] represents

28623-524: 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

28826-516: 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

29029-481: The late Danian, there was a warming event and evidence of ocean acidification associated with an increase in carbon; at this time, there was major seafloor spreading in the Atlantic and volcanic activity along the southeast margin of Greenland. The Latest Danian Event, also known as the Top Chron C27n Event, lasted about 200,000 years and resulted in a 1.6–2.8 °C increase in temperatures throughout

29232-865: The late Paleocene to the early Eocene. Impact craters formed in the Paleocene include: the Connolly Basin crater in Western Australia less than 60 mya, the Texan Marquez crater 58 mya, the Greenlandic Hiawatha Glacier crater 58 mya, and possibly the Jordan Jabel Waqf as Suwwan crater which dates to between 56 and 37 mya. Vanadium -rich osbornite from the Isle of Skye , Scotland, dating to 60 mya may be impact ejecta . Craters were also formed near

29435-487: The late Selandian and early Thanetian, organic carbon burial resulted in a period of climatic cooling, sea level fall and transient ice growth. This interval saw the highest δO values of the epoch. The Paleocene–Eocene Thermal Maximum was an approximately 200,000-year-long event where the global average temperature rose by some 5 to 8 °C (9 to 14 °F), and mid-latitude and polar areas may have exceeded modern tropical temperatures of 24–29 °C (75–84 °F). This

29638-477: The latter spelling is incorrect because this would imply either a translation of "old recent" or a derivation from "pala" and "Eocene", which would be incorrect because the prefix palæo- uses the ligature æ instead of "a" and "e" individually, so only both characters or neither should be dropped, not just one. The Paleocene Epoch is the 10 million year time interval directly after the K–Pg extinction event , which ended

29841-454: The left to back (glottal) sounds on the right. In official publications by the IPA, two columns are omitted to save space, with the letters listed among "other symbols" even though theoretically they belong in the main chart. They are arranged in rows from full closure (occlusives: stops and nasals) at top, to brief closure (vibrants: trills and taps), to partial closure (fricatives), and finally minimal closure (approximants) at bottom, again with

30044-428: The left to back on the right, and from maximal closure at top to minimal closure at bottom. No vowel letters are omitted from the chart, though in the past some of the mid central vowels were listed among the "other symbols". A pulmonic consonant is a consonant made by obstructing the glottis (the space between the vocal folds) or oral cavity (the mouth) and either simultaneously or subsequently letting out air from

30247-556: 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

30450-408: The lungs. Pulmonic consonants make up the majority of consonants in the IPA, as well as in human language. All consonants in English fall into this category. The pulmonic consonant table, which includes most consonants, is arranged in rows that designate manner of articulation , meaning how the consonant is produced, and columns that designate place of articulation , meaning where in the vocal tract

30653-610: 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

30856-530: 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

31059-480: 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)

31262-570: The mid-Palaeocene biotic event (MPBE), also known as the Early Late Palaeocene Event (ELPE), around 59 Ma (roughly 50,000 years before the Selandian/Thanetian boundary), the temperature spiked probably due to a mass release of the deep sea methane hydrate into the atmosphere and ocean systems. Carbon was probably output for 10–11,000 years, and the aftereffects likely subsided around 52–53,000 years later. There

31465-465: The middle Cretaceous 110–90 mya, continued to develop and proliferate, more so to take advantage of the recently emptied niches and an increase in rainfall. Along with them coevolved the insects that fed on these plants and pollinated them. Predation by insects was especially high during the PETM. Many fruit-bearing plants appeared in the Paleocene in particular, probably to take advantage of the newly evolving birds and mammals for seed dispersal . In what

31668-448: 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

31871-429: The middle Paleocene. The strata immediately overlaying the K–Pg extinction event are especially rich in fern fossils. Ferns are often the first species to colonize areas damaged by forest fires , so this " fern spike " may mark the recovery of the biosphere following the impact (which caused blazing fires worldwide). The diversifying herb flora of the early Paleocene either represent pioneer species which re-colonized

32074-399: 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

32277-440: 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

32480-416: 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

32683-433: The original areas the stages were defined, accessibility, and the protected status of the area due to its geological significance. The Selandian was first proposed by Danish geologist Alfred Rosenkrantz in 1924 based on a section of fossil-rich glauconitic marls overlain by gray clay which unconformably overlies Danian chalk and limestone . The area is now subdivided into the Æbelø Formation , Holmehus Formation , and

32886-416: 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

33089-469: The pharyngeal and glottal columns), and the lateral flap would require an additional row for that single consonant, so they are listed instead under the catchall block of "other symbols". The indefinitely large number of tone letters would make a full accounting impractical even on a larger page, and only a few examples are shown, and even the tone diacritics are not complete; the reversed tone letters are not illustrated at all. The procedure for modifying

33292-438: 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

33495-515: The poles—but they had low species richness in regards to plant life, and were populated by mainly small creatures that were rapidly evolving to take advantage of the recently emptied Earth. Though some animals attained great size, most remained rather small. The forests grew quite dense in the general absence of large herbivores. Mammals proliferated in the Paleocene, and the earliest placental and marsupial mammals are recorded from this time, but most Paleocene taxa have ambiguous affinities . In

33698-443: The proliferation of sulfate-reducing microorganisms which create highly toxic hydrogen sulfide H 2 S as a waste product. During the event, the volume of sulfidic water may have been 10–20% of total ocean volume, in comparison to today's 1%. This may have also caused chemocline upwellings along continents and the dispersal of H 2 S into the atmosphere. During the PETM there was a temporary dwarfing of mammals apparently caused by

33901-502: The proposal was officially published in 2006. The Selandian and Thanetian are both defined in Itzurun beach by the Basque town of Zumaia , 43°18′02″N 2°15′34″W  /  43.3006°N 2.2594°W  / 43.3006; -2.2594 , as the area is a continuous early Santonian to early Eocene sea cliff outcrop . The Paleocene section is an essentially complete, exposed record 165 m (541 ft) thick, mainly composed of alternating hemipelagic sediments deposited at

34104-400: The recently emptied landscape, or a response to the increased amount of shade provided in a forested landscape. Lycopods , ferns, and angiosperm shrubs may have been important components of the Paleocene understory . In general, the forests of the Paleocene were species-poor, and diversity did not fully recover until the end of the Paleocene. For example, the floral diversity of what is now

34307-458: 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

34510-492: The region at the PETM. During the Paleocene, the continents continued to drift toward their present positions. In the Northern Hemisphere, the former components of Laurasia (North America and Eurasia) were, at times, connected via land bridges: Beringia (at 65.5 and 58 mya) between North America and East Asia, the De Geer route (from 71 to 63 mya) between Greenland and Scandinavia , the Thulean route (at 57 and 55.8 mya) between North America and Western Europe via Greenland, and

34713-403: 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

34916-445: 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

35119-505: The resurrection of letters for mid central vowels and the retirement of letters for voiceless implosives . The alphabet was last revised in May 2005 with the addition of a letter for a labiodental flap . Apart from the addition and removal of symbols, changes to the IPA have consisted largely of renaming symbols and categories and in modifying typefaces . Extensions to the International Phonetic Alphabet for speech pathology (extIPA) were created in 1990 and were officially adopted by

35322-647: The same is true in the North Dakotan Almont/Beicegel Creek —such as Ochnaceae , Cyclocarya , and Ginkgo cranei —indicating the same floral families have characterized South American rainforests and the American Western Interior since the Paleocene. The extinction of large herbivorous dinosaurs may have allowed the forests to grow quite dense, and there is little evidence of wide open plains. Plants evolved several techniques to cope with high plant density, such as buttressing to better absorb nutrients and compete with other plants, increased height to reach sunlight, larger diaspore in seeds to provide added nutrition on

35525-427: The same notation as for morphophonology, – exclamation marks, and pipes. For example, ⟨ cot ⟩ would be used for the orthography of the English word cot , as opposed to its pronunciation /ˈkɒt/ . Italics are usual when words are written as themselves (as with cot in the previous sentence) rather than to specifically note their orthography. However, italics are sometimes ambiguous, and italic markup

35728-517: The seas, ray-finned fish rose to dominate open ocean and recovering reef ecosystems. The word "Paleocene" was first used by French paleobotanist and geologist Wilhelm Philipp Schimper in 1874 while describing deposits near Paris (spelled "Paléocène" in his treatise). By this time, Italian geologist Giovanni Arduino had divided the history of life on Earth into the Primary ( Paleozoic ), Secondary ( Mesozoic ), and Tertiary in 1759; French geologist Jules Desnoyers had proposed splitting off

35931-588: The separation of syllables . To represent additional qualities of speech—such as tooth gnashing , lisping , and sounds made with a cleft palate —an extended set of symbols may be used. Segments are transcribed by one or more IPA symbols of two basic types: letters and diacritics . For example, the sound of the English digraph ⟨ch⟩ may be transcribed in IPA with a single letter: [c] , or with multiple letters plus diacritics: [t̠̺͡ʃʰ] , depending on how precise one wishes to be. Slashes are used to signal phonemic transcription ; therefore, /tʃ/

36134-420: The sequence of consonants in gra ssh opper .) The IPA is also not universal among dictionaries in languages other than English. Monolingual dictionaries of languages with phonemic orthographies generally do not bother with indicating the pronunciation of most words, and tend to use respelling systems for words with unexpected pronunciations. Dictionaries produced in Israel use the IPA rarely and sometimes use

36337-417: The symbols were allowed to vary from language to language. For example, the sound [ ʃ ] (the sh in shoe ) was originally represented with the letter ⟨c⟩ for English but with ⟨x⟩ for French and German; with German, ⟨c⟩ was used for the [ x ] sound of Bach . With a growing number of transcribed languages this proved impractical, and in 1888

36540-399: The time from the end of the Paleocene Epoch to 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

36743-399: 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

36946-401: The upper limit, average sea surface temperatures (SSTs) at 60° N and S would have been the same as deep sea temperatures, at 30° N and S about 23 °C (73 °F), and at the equator about 28 °C (82 °F). In the Danish Palaeocene sea, SSTs were cooler than those of the preceding Late Cretaceous and the succeeding Eocene. The Paleocene foraminifera assemblage globally indicates

37149-493: The upward excursion in temperature. The warm, wet climate supported tropical and subtropical forests worldwide, mainly populated by conifers and broad-leafed trees. In Patagonia, the landscape supported tropical rainforests , cloud rainforests , mangrove forests , swamp forests , savannas , and sclerophyllous forests. In the Colombian Cerrejón Formation , fossil flora belong to the same families as modern day flora—such as palm trees , legumes , aroids , and malvales —and

37352-419: The values of the letters were made uniform across languages. This would provide the base for all future revisions. Since its creation, the IPA has undergone a number of revisions. After relatively frequent revisions and expansions from the 1890s to the 1940s, the IPA remained nearly static until the Kiel Convention in 1989, which substantially revamped the alphabet. A smaller revision took place in 1993 with

37555-457: The vowel letters ⟨ a ⟩, ⟨ e ⟩, ⟨ i ⟩, ⟨ o ⟩, ⟨ u ⟩ correspond to the (long) sound values of Latin: [i] is like the vowel in mach i ne , [u] is as in r u le , etc. Other Latin letters, particularly ⟨ j ⟩, ⟨ r ⟩ and ⟨ y ⟩, differ from English, but have their IPA values in Latin or other European languages. This basic Latin inventory

37758-463: The vowel of pick or the vowel of peak may be transcribed as /i/ , so that pick , peak would be transcribed as /ˈpik, ˈpiːk/ or as /ˈpɪk, ˈpik/ ; and neither is identical to the vowel of the French pique , which would also be transcribed /pik/ . By contrast, a narrow phonetic transcription of pick , peak , pique could be: [pʰɪk] , [pʰiːk] , [pikʲ] . IPA is popular for transcription by linguists. Some American linguists, however, use

37961-402: 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

38164-412: The world by a high- iridium band, as well as discontinuities with fossil flora and fauna. It is generally thought that a 10 to 15 km (6 to 9 mi) wide asteroid impact, forming the Chicxulub Crater in the Yucatán Peninsula in the Gulf of Mexico , and Deccan Trap volcanism caused a cataclysmic event at the boundary resulting in the extinction of 75% of all species. The Paleocene ended with

38367-528: 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

38570-415: 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

38773-403: 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

38976-402: 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

39179-451: Was due to an ejection of 2,500–4,500 gigatons of carbon into the atmosphere, most commonly explained as the perturbation and release of methane clathrate deposits in the North Atlantic from tectonic activity and resultant increase in bottom water temperatures. Other proposed hypotheses include methane release from the heating of organic matter at the seafloor rather than methane clathrates, or melting permafrost . The duration of carbon output

39382-446: Was extended by adding small-capital and cursive forms, diacritics and rotation. The sound values of these letters are related to those of the original letters, and their derivation may be iconic. For example, letters with a rightward-facing hook at the bottom represent retroflex equivalents of the source letters, and small capital letters usually represent uvular equivalents of their source letters. There are also several letters from

39585-527: Was not a major contributor to the greenhouse climate, and deep water temperatures more likely change as a response to global temperature change rather than affecting it. In the Arctic, coastal upwelling may have been largely temperature and wind-driven. In summer, the land surface temperature was probably higher than oceanic temperature, and the opposite was true in the winter, which is consistent with monsoon seasons in Asia. Open-ocean upwelling may have also been possible. The Paleocene climate was, much like in

39788-428: Was not much angiosperm migration into the region in the early Paleocene. Over the K–Pg extinction event, angiosperms had a higher extinction rate than gymnosperms (which include conifers, cycads , and relatives) and pteridophytes (ferns, horsetails , and relatives); zoophilous angiosperms (those that relied on animals for pollination) had a higher rate than anemophilous angiosperms; and evergreen angiosperms had

39991-438: 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 term "Paleocene" is a portmanteau combination of the Ancient Greek palaios παλαιός meaning "old", and the word "Eocene", and so means "the old part of

40194-436: Was one of the most significant periods of global change during the Cenozoic. Geologists divide the rocks of the Paleocene into a stratigraphic set of smaller rock units called stages , each formed during corresponding time intervals called ages. Stages can be defined globally or regionally. For global stratigraphic correlation, the ICS ratify global stages based on a Global Boundary Stratotype Section and Point (GSSP) from

40397-401: 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

40600-417: Was shown that the Danian and the Montian are the same, the ICS decided to define the Danian as starting with the K–Pg boundary, thus ending the practice of including the Danian in the Cretaceous. In 1991, the GSSP was defined as a well-preserved section in the El Haria Formation near El Kef , Tunisia, 36°09′13″N 8°38′55″E  /  36.1537°N 8.6486°E  / 36.1537; 8.6486 , and

40803-437: 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

41006-423: Was still connected to South America and Australia, and, because of this, the Antarctic Circumpolar Current —which traps cold water around the continent and prevents warm equatorial water from entering—had not yet formed. Its formation may have been related in the freezing of the continent. Warm coastal upwellings at the poles would have inhibited permanent ice cover. Conversely, it is possible deep water circulation

41209-434: Was wetter than the Northern, or the Southern experienced less evaporation than the Northern. In either case, this would have made the Northern more saline than the Southern, creating a density difference and a downwelling in the North Pacific traveling southward. Deep water formation may have also occurred in the South Atlantic. It is largely unknown how global currents could have affected global temperature. The formation of

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