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116-474: The larger island (on the left when looking from Lanikai) is referred to as Moku Nui and the smaller is Moku Iki, which translates literally to big island and small island. Some Native Hawaiian cultural practitioners note that there was likely a non-generic name given to the islands that have since been lost because neither Moku Nui nor Moku Iki are listed in Hawaiian-print newspapers or older maps of

232-579: A near threatened species due to excessive finning and fishing by humans according to International Union for Conservation of Nature . In June 2018, the New Zealand Department of Conservation classified the tiger shark as "Migrant" with the qualifier "Secure Overseas" under the New Zealand Threat Classification System . While shark fin has very few nutrients, shark liver has a high concentration of vitamin A , which

348-477: A dike swarm. These dikes are a part of the larger Ko'olau shield. Locals surf the breaks on both sides of Moku Nui and spearfish alongside tiger sharks where they are known to hang out on the ocean side drop-off. On the backside of Moku Nui, there is an eight-foot deep natural saltwater swimming hole known as "Queen's Bath". saltwater Kayak and outrigger canoe tours to the islands are very popular but laws prohibit deliveries to Kailua or Lanikai Beach. In May 2011,

464-591: A fluid that nourishes them. This allows for the young to dramatically increase in size, even though they have no placental connection to the mother. The young develop inside the mother's body up to 16 months. Litters range from 10 to 80 pups. A newborn is generally 51 to 76 cm (20 to 30 in) long. How long tiger sharks live is unknown, but they can live longer than 12 years. Tiger shark ontogeny has been little studied until recently, but studies by Hammerschlag et al. , indicated that as they grow, their tails become more symmetrical with age. Additionally, while

580-420: A kayak tourist was swept off the rocks and drowned 21°23′20″N 157°41′56″W  /  21.38889°N 157.69889°W  / 21.38889; -157.69889 Tiger sharks The tiger shark ( Galeocerdo cuvier ) is a species of ground shark , and the only extant member of the genus Galeocerdo and family Galeocerdonidae. It is a large macropredator, with females capable of attaining

696-431: 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,

812-598: A large share of fatal shark-bite incidents, and is regarded as one of the most dangerous shark species. They often visit shallow reefs, harbors, and canals, creating the potential for encounter with humans. The tiger shark also dwells in river mouths and other runoff-rich water. While it ranks second on the list of number of recorded shark attacks on humans, behind only the great white shark, such attacks are few and very seldom fatal. Typically, three to four shark bites occur per year in Hawaii; one notable survivor of such an attack

928-410: A length of over 5 m (16 ft 5 in). Populations are found in many tropical and temperate waters, especially around central Pacific islands. Its name derives from the dark stripes down its body, which resemble a tiger 's pattern, but fade as the shark matures. The tiger shark is a solitary, mostly nocturnal hunter. It is notable for having the widest food spectrum of all sharks, with

1044-626: 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 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

1160-451: A range of prey that includes crustaceans , fish , seals , birds , squid , turtles , sea snakes , dolphins , and others, even smaller sharks. It also has a reputation as a "garbage eater", consuming a variety of inedible, man-made objects that linger in its stomach. Tiger sharks have only one recorded natural predator, the orca . It is considered a near threatened species because of finning and fishing by humans. The tiger shark

1276-408: A record of an exceptional 7.4-metre (24 ft 3 in), 3,110-kilogram (6,860 lb) tiger shark, but since this is far larger than any scientifically observed specimen, verification would be needed. A 2019 study suggested that Pliocene tiger sharks could have reached 8 m (26 ft) in maximum length. There is variation in the speed of growth rates of juvenile tiger sharks depending on

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1392-503: 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

1508-585: A shark cage in a 2007 Discovery Channel special, and underwater photographer Fiona Ayerst swam with them in the Bahamas . At "Tiger Beach" off Grand Bahama, uncaged diving with – and even the handling of – female tiger sharks has become a routine occurrence. Warming Atlantic Ocean currents have caused tiger shark migration paths to move further north, according to a University of Miami study. Tiger sharks are considered to be sacred ʻaumākua (ancestor spirits) by some native Hawaiians . Tiger sharks possess

1624-526: 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

1740-472: A symmetrical tail is more advantageous in long-distance traveling, and that tiger sharks consume more diverse prey items with age, which requires a greater bite force and broader head. The tiger shark is captured and killed for its fins , flesh , and liver . It is caught regularly in target and nontarget fisheries. Several populations have declined where they have been heavily fished. Continued demand for fins may result in further declines. They are considered

1856-521: A tiger shark attacked and killed a 23-year-old Russian man in the Red Sea off the coast of the Egyptian city of Hurghada . The attack was filmed by onlookers and the recording went viral . The shark was later captured by fishermen and killed. This was the third fatal tiger shark attack in the area since 2022. Between 1959 and 1976, 4,668 tiger sharks were culled in the state of Hawaii in an effort to protect

1972-483: A tiger shark can typically range from blue to light green with a white or light-yellow underbelly. The advantage of this is that when it is hunting for its prey, when prey looks at the shark from above, the shark will be camouflaged, since the water below is darker. When prey is below the shark and looks up the light underbelly will also camouflage the shark with the sunlight. This is known as countershading . Dark spots and stripes are most visible in young sharks and fade as

2088-499: A unique significance as ʻaumakua, revered as family guardians in Hawaiian culture. The tiger shark, regarded as an intelligent and highly perceptive spiritual entity, assumes the role of a messenger bridging the gap between humans and the divine. In the Hawaiian belief system, ʻaumakua take on various forms, either animals or objects, representing ancestral connections and manifestations of departed family members. This perspective underscores

2204-701: 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

2320-430: Is surfing champion Bethany Hamilton , who lost her left arm at age 13 to a tiger shark in 2003. This bite rate is very low, considering that thousands of people swim, surf, and dive in Hawaiian waters every day. Human interactions with tiger sharks in Hawaiian waters have been shown to increase between September and November, when tiger shark females are believed to migrate to the islands to give birth. On 8 June 2023,

2436-667: Is 810 kg (1,790 lb). It is sexually dimorphic , with females being the larger sex. Mature females are often over 3.7 m (12 ft 2 in) while mature males rarely get that large. Exceptionally large females reportedly can measure over 5 m (16 ft 5 in), and the largest males 4 m (13 ft 1 in). Weights of particularly large female tiger sharks can exceed 1,300 kg (2,900 lb). One pregnant female caught off Australia reportedly measured 5.5 m (18 ft 1 in) long and weighed 1,524 kg (3,360 lb). Even larger unconfirmed catches have been claimed. Some papers have accepted

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2552-796: Is an apex predator and has a reputation for eating almost anything. These predators swim close inland to eat at night, and during the day swim out into deeper waters. Young tiger sharks are found to feed largely on small fish , as well as various small jellyfish , and mollusks including cephalopods . Around the time they attain 2.3 m (7.5 ft), or near sexual maturity, their selection expands considerably, and much larger animals become regular prey. Numerous fish , mollusks (including gastropods and cephalopods), crustaceans , sea birds , sea snakes , marine mammals (e.g. bottlenose dolphins ( Tursiops ), common dolphins ( Delphinus ), spotted dolphins ( Stenella ), dugongs ( Dugong dugon ), seals and sea lions ), and sea turtles (including

2668-454: 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,

2784-543: Is around 80 to 130 kg (180 to 290 lb). Females mate once every three years. They breed by internal fertilization. The male inserts one of his claspers into the female's genital opening ( cloaca ), acting as a guide for the sperm . The male uses his teeth to hold the female still during the procedure, often causing the female considerable discomfort. Mating in the Northern Hemisphere generally takes place between March and May, with birth between April and June

2900-638: 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

3016-419: 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 the epoch saw the dawn of recent, or modern, life. Scottish geologist Charles Lyell (ignoring

3132-400: Is often colloquially called the man-eater shark. The tiger shark is a member of the order Carcharhiniformes , the most species-rich order of sharks, with more than 270 species also including the small catsharks and hammerhead sharks . Members of this order are characterized by the presence of a nictitating membrane over the eyes, two dorsal fins, an anal fin , and five gill slits. It

3248-454: Is second only to the great white in recorded fatal attacks on humans, but these events are still exceedingly rare. The shark was first described by Peron and Lesueur in 1822, and was given the name Squalus cuvier . Müller and Henle in 1837 renamed it Galeocerdo tigrinus . The genus, Galeocerdo , is derived from the Greek galeos , which means shark, and kerdo , the word for fox. It

3364-703: 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

3480-733: Is the largest member of the order, commonly referred to as ground sharks . It is the only extant member of Galeocerdo , the only member of the family Galeocerdonidae. The oldest remains of Galeocerdo extend back to the Eocene epoch, while the oldest fossils of the modern tiger shark Galeocerdo cuvier date to the Middle Miocene , around 13.8 million years ago. The tiger shark commonly attains adult length of 3.5 to 4.7 m (11 ft 6 in – 15 ft 5 in) and weighs between 300 and 900 kg (700 and 2,000 lb). The International Game Fish Association 's all-tackle record

3596-524: 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

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3712-407: Is used in the production of vitamin oils. In addition, the tiger shark is captured and killed for its distinct skin, as well as by big-game fishers. In 2010, Greenpeace International added the tiger shark to its seafood red list, which is a list of commonly sold fish likely to come from unsustainable fisheries. Although sharks rarely bite humans, the tiger shark is reported to be responsible for

3828-739: The Laramide Orogeny came to an end in 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

3944-622: 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

4060-454: 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

4176-500: 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 the Eocene–Oligocene extinction event , which may be related to the impact of one or more large bolides in Siberia and in what

4292-417: 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

4408-654: 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

4524-530: The tapetum lucidum , allows light-sensing cells a second chance to capture photons of visible light. This enhances vision in low-light conditions. The tiger shark is often found close to the coast, mainly in tropical and subtropical waters throughout the world. Its behavior is primarily nomadic , but is guided by warmer currents, and it stays closer to the equator throughout the colder months. It tends to stay in deep waters that line reefs, but it does move into channels to pursue prey in shallower waters. In

4640-477: The tourism industry. Despite damaging the shark population, these efforts were shown to be ineffective in decreasing the number of interactions between humans and tiger sharks. Feeding sharks in Hawaii (except for traditional Hawaiian cultural or religious practices) is illegal, and interaction with them, such as cage diving , is discouraged. South African shark behaviorist and shark diver Mark Addison demonstrated divers could interact and dive with them outside of

4756-559: The " garbage can of the sea ". Tiger sharks are preyed on by orcas . Orcas have been recorded hunting and killing tiger sharks by holding them upside down to induce tonic immobility in order to drown the shark. The orcas bite off the shark's fins before disemboweling and devouring it. All tiger sharks generally swim slowly, which, combined with cryptic coloration, may make them difficult for prey to detect in some habitats. They are especially well camouflaged against dark backgrounds. Despite their sluggish appearance, tiger sharks are one of

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4872-564: The Australian coast. Additionally, examination of adult dugongs has shown scars from failed shark attacks. To minimize attacks, dugong microhabitats shift similarly to those of known tiger shark prey when the sharks are abundant. The broad, heavily calcified jaws and nearly terminal mouth, combined with robust, serrated teeth, enable the tiger shark to take on these large prey. In addition, excellent eyesight and acute sense of smell enable it to react to faint traces of blood and follow them to

4988-650: 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

5104-404: 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

5220-585: 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

5336-440: 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

5452-557: 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

5568-608: 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

5684-544: 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

5800-491: 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 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

5916-458: 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

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6032-674: 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

6148-462: 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

6264-415: 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

6380-714: 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 the Eocene and Neogene for the Miocene and Pliocene in 1853. After decades of inconsistent usage,

6496-405: 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

6612-410: 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

6728-422: 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

6844-456: 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,

6960-524: 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

7076-413: 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

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7192-437: 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,

7308-410: 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

7424-411: 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

7540-888: 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

7656-617: 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

7772-535: 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

7888-502: 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

8004-466: 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

8120-534: 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

8236-545: The following year. In the Southern Hemisphere, mating takes place in November, December, or early January. The tiger shark is the only species in its family that is ovoviviparous ; its eggs hatch internally and the young are born live when fully developed. Tiger Sharks are unique among all sharks in the fact that they employ embrytrophy to nourish their young inside the womb. The young gestate in sacks which are filled with

8352-615: 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 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

8468-700: The heads on juvenile tiger sharks are more conical and similar to other requiem sharks , adult tiger sharks have a head which is relatively broader. The reason for the larger caudal fin on juvenile tiger sharks is theorized to be an adaptation to escape predation by larger predators and to catch quicker-moving prey. As tiger sharks mature, their head also becomes much wider and their tails no longer become as large in proportion to their body size as when they are juveniles because they do not face elevated levels of predation risk upon maturity. The results of this study were interpreted as reflecting two ecological transitions: as tiger sharks mature they become more migratory and having

8584-569: 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

8700-465: The intricate web of interdependence among plants, animals, elements, and humans, underscoring the imperative to honor and coexist harmoniously with nature. Eocene The Eocene ( IPA : / ˈ iː ə s iː n , ˈ iː oʊ -/ EE -ə-seen, EE -oh- ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in

8816-516: 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

8932-415: The length of their sides. The primary role of this structure is to detect minute vibrations in the water. These adaptations allow the tiger shark to hunt in darkness and detect hidden prey. Sharks do not have moveable upper or lower eyelids, but the tiger shark—among other sharks—has a nictitating membrane , a clear eyelid that can cover the eye. A reflective layer behind the tiger shark's retina , called

9048-556: 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

9164-607: 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 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

9280-610: 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

9396-530: 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

9512-474: 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)

9628-557: 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

9744-581: The modern Cenozoic Era . The name Eocene comes from the Ancient Greek Ἠώς ( Ēṓs , " Dawn ") and καινός ( kainós , "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans 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

9860-399: 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

9976-689: 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 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

10092-644: 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

10208-416: 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

10324-416: 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

10440-438: 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

10556-458: 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

10672-628: The region they inhabit, with some growing close to twice as fast as others. Among the largest extant sharks, the tiger shark ranks in average size only behind the whale shark ( Rhincodon typus ), the basking shark ( Cetorhinus maximus ), and the great white shark ( Carcharodon carcharias ). This makes it the second-largest predatory shark, after the great white. Some other species such as megamouth sharks ( Megachasma pelagios ), Pacific sleeper sharks ( Somniosus pacificus ), Greenland sharks ( Somniosus microcephalus ), and bluntnose sixgill sharks ( Hexanchus griseus ) broadly overlap in size with

10788-454: 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

10904-481: The region. They are part of the Hawaii State Seabird Sanctuary and activities on them as well as off-limit areas on them are regulated by law. Specifically, the smaller islet, Moku Iki, is off-limits to visitors, as is the interior of Moku Nui. Also, no pets are allowed. Many birds nest in ground burrows on the islands. The two islands are composed of many basaltic intrusive igneous dikes, often called

11020-461: 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 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

11136-445: 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

11252-438: The shark matures. Its head is somewhat wedge-shaped, which makes it easy to turn quickly to one side. They have small pits on the snout which hold electroreceptors called the ampullae of Lorenzini , which enable them to detect electric fields, including the weak electrical impulses generated by prey, which helps them to hunt. Tiger sharks also have a sensory organ called a lateral line which extends on their flanks down most of

11368-485: The shark's life. Relative to the shark's size, tiger shark teeth are considerably shorter than those of a great white shark, but they are nearly as broad as the root as the great white's teeth and are arguably better suited to slicing through hard-surfaced prey. A tiger shark generally has long fins to provide lift as the shark maneuvers through water, while the long upper tail provides bursts of speed. The tiger shark normally swims using small body movements. The skin of

11484-617: The source. The ability to pick up low-frequency pressure waves enables the shark to advance towards an animal with confidence, even in murky water. The shark circles its prey and studies it by prodding it with its snout. When attacking, the shark often eats its prey whole, although larger prey are often eaten in gradual large bites and finished over time. Notably, terrestrial mammals, including horses ( Equus ferus caballus ), goats ( Capra aegagrus hircus ), sheep ( Ovis aries ), dogs ( Canis lupus familiaris ), cats ( Felis catus ), and brown rats ( Rattus norvegicus ), are fairly common in

11600-564: The stomach contents of tiger sharks around the coasts of Hawaii. In one case, remains of two flying foxes were found in the stomach of this shark, and in another, an echidna ( Tachyglossus aculeatus ) was regurgitated by a tiger shark being tagged off Orpheus Island , Queensland . Because of its aggressive and indiscriminate feeding style, it often mistakenly eats inedible objects, such as automobile license plates , oil cans, tires , and baseballs . Due to their habits of eating essentially anything, Tiger sharks are often referred to as

11716-457: The strongest swimmers of the carcharhinid sharks. Once the shark has come close, a speed burst allows it to reach the intended prey before it can escape. Males reach sexual maturity at 2.3 to 2.9 m (7.5 to 9.5 ft) and females at 2.5 to 3.5 m (8.2 to 11.5 ft). Typical weight of relatively young sexually mature specimens, which often locally comprise the majority of tiger sharks encountered per game-fishing and scientific studies,

11832-701: The three largest species: the leatherback ( Dermochelys coriacea ), the loggerhead ( Caretta caretta ) and the green sea turtles ( Chelonia mydas ) ), are regularly eaten by adult tiger sharks. In fact, adult sea turtles have been found in up to 20.8% of studied tiger shark stomachs, indicating somewhat of a dietary preference for sea turtles where they are commonly encountered. They also eat other sharks (including adult sandbar sharks ( Carcharhinus plumbeus )), as well as rays , and sometimes even other tiger sharks . Due to high risk of predation, dolphins often avoid regions inhabited by tiger sharks. Injured or ailing whales may also be attacked and eaten. A group

11948-775: The tiger shark, but as these species are comparatively poorly studied, whether their typical mature size matches that of the tiger shark is unclear. The great hammerhead ( Sphyrna mokarran ), a member of the same taxonomic order as the tiger shark, has a similar or even greater average body length, but is lighter and less bulky, with a maximum known weight coming from a heavily pregnant 4.4 m (14 ft) long individual at 580 kg (1,280 lb). Tiger shark teeth are unique with very sharp, pronounced serrations and an unmistakable sideways-pointing tip. Such dentition has developed to slice through flesh, bone, and other tough substances such as turtle shells. Like most sharks, its teeth are continually replaced by rows of new teeth throughout

12064-418: 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 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

12180-399: 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

12296-524: The two continents. However, modeling results call into question the thermal isolation model for late Eocene cooling, and decreasing carbon dioxide levels in 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,

12412-763: The western Pacific Ocean , the shark has been found as far north as Japan and as far south as New Zealand . It has also been recorded in the Mediterranean Sea , but rarely, off Malaga (Spain), Sicily (Italy) and Libya. Tiger sharks can be seen in the Gulf of Mexico , North American beaches, and parts of South America. It is also commonly observed in the Caribbean Sea . Other locations where tiger sharks are seen include off Africa, China, India , Australia , and Indonesia . Certain tiger sharks have been recorded at depths just shy of 900 m (3,000 ft). The tiger shark

12528-457: 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

12644-528: 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

12760-470: 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

12876-417: 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, 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

12992-465: 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

13108-402: 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

13224-497: Was documented killing an ailing humpback whale ( Megaptera novaeangliae ) in 2006 near Hawaii. A scavenger, the tiger shark will feed on dead whales, and has been documented doing so alongside great white sharks. Tiger sharks have also been observed to feed on dead manta rays in the German Channel of Palau. Evidence of dugong predation was identified in one study that found dugong tissue in 15 of 85 tiger sharks caught off

13340-401: 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

13456-437: 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

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