Megalodon ( ; Otodus megalodon), meaning "big tooth", is an extinct species of mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. It was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark (Carcharodon carcharias), but has been reclassified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous.

While regarded as one of the largest and most powerful predators to have ever lived, the megalodon is only known from fragmentary remains, and its appearance and maximum size are uncertain. Scientists differ on whether it would have more closely resembled a stockier version of the great white shark, the basking shark (Cetorhinus maximus) or the sand tiger shark (Carcharias taurus). The most recent estimate with the least error range suggests a maximum length estimate up to , although the modal lengths are estimated at . Extrapolation from a vertebral centra with dimensions based on the great white shark suggests that a megalodon about  long weighs up to ,  long weighs up to , and  long (the maximum length) weighs up to . Extrapolating from a vertebral column and reconstructing a 3D model with dimensions based on all extant lamnid sharks suggests that a  individual may have been much larger than previous estimates, reaching an excess of  in body mass; an individual of this size would have needed to consume 98,175 kcal per day. Their teeth were thick and robust, built for grabbing prey and breaking bone, and their large jaws could exert a bite force of up to .

Megalodon probably had a major impact on the structure of marine communities. The fossil record indicates that it had a cosmopolitan distribution. It probably targeted large prey, such as whales, seals and sea turtles. Juveniles inhabited warm coastal waters and fed on fish and small whales. Unlike the great white, which attacks prey from the soft underside, megalodon probably used its strong jaws to break through the chest cavity and puncture the heart and lungs of its prey.

The animal faced competition from whale-eating cetaceans, such as Livyatan and other macroraptorial sperm whales and possibly smaller ancestral killer whales. As the shark preferred warmer waters, it is thought that oceanic cooling associated with the onset of the ice ages, coupled with the lowering of sea levels and resulting loss of suitable nursery areas, may have also contributed to its decline. A reduction in the diversity of baleen whales and a shift in their distribution toward polar regions may have reduced megalodon's primary food source. The shark's extinction coincides with a gigantism trend in baleen whales.

Classification

Prescientific and early research history

Megalodon teeth have been excavated and used since ancient times. They were a valued artifact amongst pre-Columbian cultures in the Americas for their large sizes and serrated blades, from which they were modified into projectile points, knives, jewelry, and funeral accessories. At least some, such as the Panamanian Sitio Conte societies, seemed to have used them primarily for ceremonial purposes. Mining of megalodon teeth by the Algonquin peoples in the Chesapeake Bay and their selective trade with the Adena culture in Ohio occurred as early as 430 BC. The earliest written account of megalodon teeth was by Pliny the Elder in an AD 73 volume of Historia Naturalis, who described them as resembling petrified human tongues that Roman folklorists believed to have fallen from the sky during lunar eclipses and called them glossopetrae ("tongue stones"). The purported tongues were later thought in a 12th-century Maltese tradition to have belonged to serpents that Paul the Apostle turned to stone while shipwrecked there, and were given antivenom powers by the saint. Glossopetrae reappeared throughout Europe in late 13th to 16th century literature, ascribed with more supernatural properties that cured a wider variety of poisons. Use of megalodon teeth for this purpose became widespread among medieval and Renaissance nobility, who fashioned them into protective amulets and tableware to purportedly detoxify poisoned liquids or bodies that touched the stones. By the 16th century, teeth were directly consumed as ingredients of European-made Goa stones.

The true nature of the glossopetrae as shark's teeth was held by some since at least 1554, when cosmographer André Thevet described it as hearsay, although he did not believe it. The earliest scientific argument for this view was made by Italian naturalist Fabio Colonna, who in 1616 published an illustration of a Maltese megalodon tooth alongside a great white shark's and noted their striking similarities. He argued that the former and its likenesses were not petrified serpent's tongues but actually the teeth of similar sharks that washed up on shore. Colonna supported this thesis through an experiment of burning glossopetrae samples, from which he observed carbon residue he interpreted as proving an organic origin. However, interpretation of the stones as shark's teeth remained widely unaccepted. This was in part due the inability to explain how some of them are found far from the sea. The shark tooth argument was academically raised again during the late 17th century by English scientists Robert Hooke, John Ray, and Danish naturalist Niels Steensen (Latinized Nicholas Steno). Steensen's argument in particular is most recognized as inferred from his dissection of the head of a great white caught in 1666. His 1667 report depicted engravings of a shark's head and megalodon teeth that became especially iconic. However, the illustrated head was not actually the head that Steensen dissected, nor were the fossil teeth illustrated by him. Both engravings were originally commissioned in the 1590s by Papal physician Michele Mercati, who also had in possession the head of a great white, for his book Metallotheca. The work remained unpublished in Steensen's time due to Mercati's premature death, and the former reused the two illustrations per suggestion by Carlo Roberto Dati, who thought a depiction of the actual dissected shark was unsuitable for readers. Steensen also stood out in pioneering a stratigraphic explanation for how similar stones appeared further inland. He observed that rock layers bearing megalodon teeth contained marine sediments and hypothesized that these layers correlated to a period of flood that was later covered by terrestrial layers and uplifted by geologic activity.

Swiss naturalist Louis Agassiz gave megalodon its scientific name in his seminal 1833-1843 work Recherches sur les poissons fossiles (Research on fossil fish). He named it Carcharias megalodon in an 1835 illustration of the holotype and additional teeth, congeneric with the modern sand tiger shark. The specific name is a portmanteau of the Ancient Greek words μεγάλος (megálos, meaning "big") and ὀδών (odṓn, meaning "tooth"), combined meaning "big tooth." Agassiz referenced the name as early as 1832, but because specimens were not referenced they are not taxonomically recognized uses. Formal description of the species was published in an 1843 volume, where Agassiz revised the name to Carcharodon megalodon as its teeth were far too large for the former genus and more alike to the great white shark. He also erroneously identified several megalodon teeth as belonging to additional species eventually named Carcharodon rectidens, Carcharodon subauriculatus, Carcharodon productus, and Carcharodon polygurus. Because Carcharodon megalodon appeared first in the 1835 illustration, the remaining names are considered junior synonyms under the principle of priority.

Evolution

While the earliest megalodon remains have been reported from the Late Oligocene, around 28 million years ago (Mya), there is disagreement as to when it appeared, with dates ranging to as young as 16 mya. It has been thought that megalodon became extinct around the end of the Pliocene, about 2.6 Mya; claims of Pleistocene megalodon teeth, younger than 2.6 million years old, are considered unreliable. A 2019 assessment moves the extinction date back to earlier in the Pliocene, 3.6 Mya.

Megalodon is considered to be a member of the family Otodontidae, genus Otodus, as opposed to its previous classification into Lamnidae, genus Carcharodon. Megalodon's classification into Carcharodon was due to dental similarity with the great white shark, but most authors believe that this is due to convergent evolution. In this model, the great white shark is more closely related to the extinct broad-toothed mako (Isurus hastalis) than to megalodon, as evidenced by more similar dentition in those two sharks; megalodon teeth have much finer serrations than great white shark teeth. The great white shark is more closely related to the mako shark (Isurus spp.), with a common ancestor around 4 Mya. Proponents of the former model, wherein megalodon and the great white shark are more closely related, argue that the differences between their dentition are minute and obscure.

The genus Carcharocles contains four species: C. auriculatus, C. angustidens, C. chubutensis, and C. megalodon. The evolution of this lineage is characterized by the increase of serrations, the widening of the crown, the development of a more triangular shape, and the disappearance of the lateral cusps. The evolution in tooth morphology reflects a shift in predation tactics from a tearing-grasping bite to a cutting bite, likely reflecting a shift in prey choice from fish to cetaceans. Lateral cusplets were finally lost in a gradual process that took roughly 12 million years during the transition between C. chubutensis and C. megalodon. The genus was proposed by D. S. Jordan and H. Hannibal in 1923 to contain C. auriculatus. In the 1980s, megalodon was assigned to Carcharocles. Before this, in 1960, the genus Procarcharodon was erected by French ichthyologist Edgard Casier, which included those four sharks and was considered separate from the great white shark. It is since considered a junior synonym of Carcharocles. The genus Palaeocarcharodon was erected alongside Procarcharodon to represent the beginning of the lineage, and, in the model wherein megalodon and the great white shark are closely related, their last common ancestor. It is believed to be an evolutionary dead-end and unrelated to the Carcharocles sharks by authors who reject that model.

Another model of the evolution of this genus, also proposed by Casier in 1960, is that the direct ancestor of the Carcharocles is the shark Otodus obliquus, which lived from the Paleocene through the Miocene epochs, 60 to 13 Mya. The genus Otodus is ultimately derived from Cretolamna, a shark from the Cretaceous period. In this model, O. obliquus evolved into O. aksuaticus, which evolved into C. auriculatus, and then into C. angustidens, and then into C. chubutensis, and then finally into C. megalodon.

Another model of the evolution of Carcharocles, proposed in 2001 by paleontologist Michael Benton, is that the three other species are actually a single species of shark that gradually changed over time between the Paleocene and the Pliocene, making it a chronospecies. Some authors suggest that C. auriculatus, C. angustidens, and C. chubutensis should be classified as a single species in the genus Otodus, leaving C. megalodon the sole member of Carcharocles.

The genus Carcharocles may be invalid, and the shark may actually belong in the genus Otodus, making it Otodus megalodon. A 1974 study on Paleogene sharks by Henri Cappetta erected the subgenus Megaselachus, classifying the shark as Otodus (Megaselachus) megalodon, along with O. (M.) chubutensis. A 2006 review of Chondrichthyes elevated Megaselachus to genus, and classified the sharks as Megaselachus megalodon and M. chubutensis. The discovery of fossils assigned to the genus Megalolamna in 2016 led to a re-evaluation of Otodus, which concluded that it is paraphyletic, that is, it consists of a last common ancestor but it does not include all of its descendants. The inclusion of the Carcharocles sharks in Otodus would make it monophyletic, with the sister clade being Megalolamna.

The cladogram below represents the hypothetical relationships between megalodon and other sharks, including the great white shark. Modified from Shimada et al. (2016), Ehret et al., (2009), and the findings of Siversson et al. (2013).

Biology

Appearance

One interpretation on how megalodon appeared was that it was a robust-looking shark, and may have had a similar build to the great white shark. The jaws may have been blunter and wider than the great white, and the fins would have also been similar in shape, though thicker due to its size. It may have had a pig-eyed appearance, in that it had small, deep-set eyes.

Another interpretation is that megalodon bore a similarity to the whale shark (Rhincodon typus) or the basking shark (Cetorhinus maximus). The tail fin would have been crescent-shaped, the anal fin and second dorsal fin would have been small, and there would have been a caudal keel present on either side of the tail fin (on the caudal peduncle). This build is common in other large aquatic animals, such as whales, tuna, and other sharks, in order to reduce drag while swimming. The head shape can vary between species as most of the drag-reducing adaptations are toward the tail-end of the animal.

One associated set of megalodon remains was found with placoid scales, which are  in maximum width, and have broadly spaced keels.

Size
Due to fragmentary remains, there have been many contradictory size estimates for megalodon, as they can only be drawn from fossil teeth and vertebrae. The great white shark has been the basis of reconstruction and size estimation, as it is regarded as the best analogue to megalodon. Several total length estimation methods have been produced from comparing megalodon teeth and vertebrae to those of the great white.
Megalodon size estimates vary depending on the method used, with maximum total length estimates ranging from . A 2015 study estimated the average total body length at , calculated from 544 megalodon teeth, found throughout geological time and geography, including adults and juveniles. In comparison, large great white sharks are generally around  in length, with a few contentious reports suggesting larger sizes. The whale shark is the largest living fish, with one large female reported with a precaudal length of  and an estimated total length of . It is possible that different populations of megalodon around the globe had different body sizes and behaviors due to different ecological pressures. Megalodon is thought to have been the largest macropredatory shark that ever lived.

In his 2015 book, The Story of Life in 25 Fossils: Tales of Intrepid Fossil Hunters and the Wonders of Evolution, Donald Prothero proposed the body mass estimates for different individuals of different length by extrapolating from a vertebral centra based on the dimensions of the great white, a methodology also used for the 2008 study which supports the maximum mass estimate.

In 2020, Cooper and his colleagues reconstructed a 2D model of megalodon based on the dimensions of all the extant lamnid sharks and suggested that a  long megalodon would have had a  long head,  tall gill slits, a  tall dorsal fin,  long pectoral fins, and a  tall tail fin. In 2022, Cooper and his colleagues also reconstructed a 3D model with the same basis as the 2020 study, resulting in a body mass estimate of  for a  long megalodon (higher than the previous estimates); a vertebral column specimen named IRSNB P 9893 (formerly IRSNB 3121), belonging to a 46 year old individual from Belgium, was used for extrapolation. An individual of this size would have required 98,175 kcal per day, 20 times more than what the adult great white requires.

Mature male megalodon may have had a body mass of , and mature females may have been , assuming that males could range in length from  and females .

A 2015 study linking shark size and typical swimming speed estimated that megalodon would have typically swum at –assuming that its body mass was typically –which is consistent with other aquatic creatures of its size, such as the fin whale (Balaenoptera physalus) which typically cruises at speeds of . In 2022, Cooper and his colleagues converted this calculation into relative cruising speed (body lengths per second), resulting in an mean absolute cruising speed of  and a mean relative cruising speed of 0.09 body lengths per second for a  long megalodon; the authors found their mean absolute cruising speed to be faster than any extant lamnid sharks and their mean relative cruising speed to be slower, consistent with previous estimates.

Its large size may have been due to climatic factors and the abundance of large prey items, and it may have also been influenced by the evolution of regional endothermy (mesothermy) which would have increased its metabolic rate and swimming speed. The otodontid sharks have been considered to have been ectotherms, so on that basis megalodon would have been ectothermic. However, the largest contemporary ectothermic sharks, such as the whale shark, are filter feeders, while lamnids are regional endotherms, implying some metabolic correlations with a predatory lifestyle. These considerations, as well as tooth oxygen isotopic data and the need for higher burst swimming speeds in macropredators of endothermic prey than ectothermy would allow, imply that otodontids, including megalodon, were probably regional endotherms.

In 2020, Shimada and colleagues suggested large size was instead due to intrauterine cannibalism, where the larger fetus eats the smaller fetus, resulting in progressively larger and larger fetuses, requiring the mother to attain even greater size as well as caloric requirements which would have promoted endothermy. Males would have needed to keep up with female size in order to still effectively copulate (which probably involved latching onto the female with claspers, like modern cartilaginous fish).

Maximum estimates
The first attempt to reconstruct the jaw of megalodon was made by Bashford Dean in 1909, displayed at the American Museum of Natural History. From the dimensions of this jaw reconstruction, it was hypothesized that megalodon could have approached  in length. Dean had overestimated the size of the cartilage on both jaws, causing it to be too tall.

In 1973, John E. Randall, an ichthyologist, used the enamel height (the vertical distance of the blade from the base of the enamel portion of the tooth to its tip) to measure the length of the shark, yielding a maximum length of about . However, tooth enamel height does not necessarily increase in proportion to the animal's total length.

In 1994, marine biologists Patrick J. Schembri and Stephen Papson opined that O. megalodon may have approached a maximum of around  in total length.

In 1996, shark researchers Michael D. Gottfried, Leonard Compagno, and S. Curtis Bowman proposed a linear relationship between the great white shark's total length and the height of the largest upper anterior tooth. The proposed relationship is: total length in meters = − (0.096) × [UA maximum height (mm)]-(0.22). Using this tooth height regression equation, the authors estimated a total length of  based on a tooth  tall, which the authors considered a conservative maximum estimate. They also compared the ratio between the tooth height and total length of large female great whites to the largest megalodon tooth. A  long female great white, which the authors considered the largest 'reasonably trustworthy' total length, produced an estimate of . However, based on the largest female great white reported, at , they estimated a maximum estimate of .

In 2002, shark researcher Clifford Jeremiah proposed that total length was proportional to the root width of an upper anterior tooth. He claimed that for every  of root width, there are approximately  of shark length. Jeremiah pointed out that the jaw perimeter of a shark is directly proportional to its total length, with the width of the roots of the largest teeth being a tool for estimating jaw perimeter. The largest tooth in Jeremiah's possession had a root width of about , which yielded  in total length.

In 2002, paleontologist Kenshu Shimada of DePaul University proposed a linear relationship between tooth crown height and total length after conducting anatomical analysis of several specimens, allowing any sized tooth to be used. Shimada stated that the previously proposed methods were based on a less-reliable evaluation of the dental homology between megalodon and the great white shark, and that the growth rate between the crown and root is not isometric, which he considered in his model. Using this model, the upper anterior tooth possessed by Gottfried and colleagues corresponded to a total length of . Among several specimens found in the Gatún Formation of Panama, one upper lateral tooth was used by other researchers to obtain a total length estimate of  using this method.

In 2019, Shimada revisited the size of megalodon and discouraged using non-anterior teeth for estimations, noting that the exact position of isolated non-anterior teeth is difficult to identify. Shimada provided maximum total length estimates using the largest anterior teeth available in museums. The tooth with the tallest crown height known to Shimada, NSM PV-19896, produced a total length estimate of . The tooth with the tallest total height, FMNH PF 11306, was reported at . However, Shimada remeasured the tooth and found it actually to measure . Using the total height tooth regression equation proposed by Gottfried and colleagues produced an estimate of .

In 2021, Victor J. Perez, Ronny M. Leder, and Teddy Badaut proposed a method of estimating total length of megalodon from the sum of the tooth crown widths. Using more complete megalodon dentitions, they reconstructed the dental formula and then made comparisons to living sharks. The researchers noted that the 2002 Shimada crown height equations produce wildly varying results for different teeth belonging to the same shark (range of error of ± ), casting doubt on some of the conclusions of previous studies using that method. Using the largest tooth available to the authors, GHC 6, with a crown width of , they estimated a maximum body length of approximately , with a range of error of approximately ± . This maximum length estimate was also supported by Cooper and his colleagues in 2022.

There are anecdotal reports of teeth larger than those found in museum collections. Gordon Hubbell from Gainesville, Florida, possesses an upper anterior megalodon tooth whose maximum height is , one of the largest known tooth specimens from the shark. In addition, a  megalodon jaw reconstruction developed by fossil hunter Vito Bertucci contains a tooth whose maximum height is reportedly over .

Teeth and bite force

The most common fossils of megalodon are its teeth. Diagnostic characteristics include a triangular shape, robust structure, large size, fine serrations, a lack of lateral denticles, and a visible V-shaped neck (where the root meets the crown). The tooth met the jaw at a steep angle, similar to the great white shark. The tooth was anchored by connective tissue fibers, and the roughness of the base may have added to mechanical strength. The lingual side of the tooth, the part facing the tongue, was convex; and the labial side, the other side of the tooth, was slightly convex or flat. The anterior teeth were almost perpendicular to the jaw and symmetrical, whereas the posterior teeth were slanted and asymmetrical.

Megalodon teeth can measure over  in slant height (diagonal length) and are the largest of any known shark species, implying it was the largest of all macropredatory sharks. In 1989, a nearly complete set of megalodon teeth was discovered in Saitama, Japan. Another nearly complete associated megalodon dentition was excavated from the Yorktown Formations in the United States, and served as the basis of a jaw reconstruction of megalodon at the National Museum of Natural History (USNM). Based on these discoveries, an artificial dental formula was put together for megalodon in 1996.

The dental formula of megalodon is: . As evident from the formula, megalodon had four kinds of teeth in its jaws: anterior, intermediate, lateral, and posterior. Megalodon's intermediate tooth technically appears to be an upper anterior and is termed as "A3" because it is fairly symmetrical and does not point mesially (side of the tooth toward the midline of the jaws where the left and right jaws meet). Megalodon had a very robust dentition, and had over 250 teeth in its jaws, spanning 5 rows. It is possible that large megalodon individuals had jaws spanning roughly  across. The teeth were also serrated, which would have improved efficiency in cutting through flesh or bone. The shark may have been able to open its mouth to a 75° angle, though a reconstruction at the USNM approximates a 100° angle.

In 2008, a team of scientists led by S. Wroe conducted an experiment to determine the bite force of the great white shark, using a  long specimen, and then isometrically scaled the results for its maximum size and the conservative minimum and maximum body mass of megalodon. They placed the bite force of the latter between  in a posterior bite, compared to the  bite force for the largest confirmed great white shark, and  for the placoderm fish Dunkleosteus. In addition, Wroe and colleagues pointed out that sharks shake sideways while feeding, amplifying the force generated, which would probably have caused the total force experienced by prey to be higher than the estimate.

In 2021, Antonio Ballell and Humberto Ferrón used Finite Element Analysis modeling to examine the stress distribution of three types of megalodon teeth and closely related mega-toothed species when exposed to anterior and lateral forces, the latter of which would be generated when a shark shakes its head to tear through flesh. The resulting simulations identified higher levels of stress in megalodon teeth under lateral force loads compared to its precursor species such as O. obliquus and O. angusteidens when tooth size was removed as a factor. This suggests that megalodon teeth were of a different functional significance than previously expected, challenging prior interpretations that megalodon's dental morphology was primarily driven by a dietary shift towards marine mammals. Instead, the authors proposed that it was a byproduct of an increase in body size caused by heterochronic selection.

Internal anatomy

Megalodon is represented in the fossil record by teeth, vertebral centra, and coprolites. As with all sharks, the skeleton of megalodon was formed of cartilage rather than bone; consequently most fossil specimens are poorly preserved. To support its large dentition, the jaws of megalodon would have been more massive, stouter, and more strongly developed than those of the great white, which possesses a comparatively gracile dentition. Its chondrocranium, the cartilaginous skull, would have had a blockier and more robust appearance than that of the great white. Its fins were proportional to its larger size.

Some fossil vertebrae have been found. The most notable example is a partially preserved vertebral column of a single specimen, excavated in the Antwerp Basin, Belgium, in 1926. It comprises 150 vertebral centra, with the centra ranging from  to  in diameter. The shark's vertebrae may have gotten much bigger, and scrutiny of the specimen revealed that it had a higher vertebral count than specimens of any known shark, possibly over 200 centra; only the great white approached it. Another partially preserved vertebral column of a megalodon was excavated from the Gram Formation in Denmark in 1983, which comprises 20 vertebral centra, with the centra ranging from  to  in diameter.

The coprolite remains of megalodon are spiral-shaped, indicating that the shark may have had a spiral valve, a corkscrew-shaped portion of the lower intestines, similar to extant lamniform sharks. Miocene coprolite remains were discovered in Beaufort County, South Carolina, with one measuring .

Gottfried and colleagues reconstructed the entire skeleton of megalodon, which was later put on display at the Calvert Marine Museum in the United States and the Iziko South African Museum. This reconstruction is  long and represents a mature male, based on the ontogenetic changes a great white shark experiences over the course of its life.

Paleobiology

Range and habitat
Megalodon had a cosmopolitan distribution; its fossils have been excavated from many parts of the world, including Europe, Africa, the Americas, and Australia. It most commonly occurred in subtropical to temperate latitudes. It has been found at latitudes up to 55° N; its inferred tolerated temperature range was . It arguably had the capacity to endure such low temperatures due to mesothermy, the physiological capability of large sharks to maintain a higher body temperature than the surrounding water by conserving metabolic heat.

Megalodon inhabited a wide range of marine environments (i.e., shallow coastal waters, areas of coastal upwelling, swampy coastal lagoons, sandy littorals, and offshore deep water environments), and exhibited a transient lifestyle. Adult megalodon were not abundant in shallow water environments, and mostly inhabited offshore areas. Megalodon may have moved between coastal and oceanic waters, particularly in different stages of its life cycle.

Fossil remains show a trend for specimens to be larger on average in the Southern Hemisphere than in the Northern, with mean lengths of , respectively; and also larger in the Pacific than the Atlantic, with mean lengths of  respectively. They do not suggest any trend of changing body size with absolute latitude, or of change in size over time (although the Carcharocles lineage in general is thought to display a trend of increasing size over time). The overall modal length has been estimated at , with the length distribution skewed towards larger individuals, suggesting an ecological or competitive advantage for larger body size.

Locations of fossils
Megalodon had a global distribution and fossils of the shark have been found in many places around the world, bordering all oceans of the Neogene.

Prey relationships

Though sharks are generally opportunistic feeders, megalodon's great size, high-speed swimming capability, and powerful jaws, coupled with an impressive feeding apparatus, made it an apex predator capable of consuming a broad spectrum of animals. Otodus megalodon was probably one of the most powerful predators to have existed. A study focusing on calcium isotopes of extinct and extant elasmobranch sharks and rays revealed that megalodon fed at a higher trophic level than the contemporaneous great white shark ("higher up" in the food chain.)

Fossil evidence indicates that megalodon preyed upon many cetacean species, such as dolphins, small whales, cetotheres, squalodontids (shark toothed dolphins), sperm whales, bowhead whales, and rorquals. In addition to this, they also targeted seals, sirenians, and sea turtles. The shark was an opportunist and piscivorous, and it would have also gone after smaller fish and other sharks. Many whale bones have been found with deep gashes most likely made by their teeth. Various excavations have revealed megalodon teeth lying close to the chewed remains of whales, and sometimes in direct association with them.

The feeding ecology of megalodon appears to have varied with age and between sites, like the modern great white shark. It is plausible that the adult megalodon population off the coast of Peru targeted primarily cetothere whales  in length and other prey smaller than itself, rather than large whales in the same size class as themselves. Meanwhile, juveniles likely had a diet that consisted more of fish.

Competition

Megalodon faced a highly competitive environment. Its position at the top of the food chain probably had a significant impact on the structuring of marine communities. Fossil evidence indicates a correlation between megalodon and the emergence and diversification of cetaceans and other marine mammals. Juvenile megalodon preferred habitats where small cetaceans were abundant, and adult megalodon preferred habitats where large cetaceans were abundant. Such preferences may have developed shortly after they appeared in the Oligocene.

Megalodon were contemporaneous with whale-eating toothed whales (particularly macroraptorial sperm whales and squalodontidae), which were also probably among the era's apex predators, and provided competition. Some attained gigantic sizes, such as Livyatan, estimated between . Fossilized teeth of an undetermined species of such physeteroids from Lee Creek Mine, North Carolina, indicate it had a maximum body length of 8–10 m and a maximum lifespan of about 25 years. This is very different from similarly sized modern killer whales that live to 65 years, suggesting that unlike the latter, which are apex predators, these physeteroids were subject to predation from larger species such as megalodon or Livyatan. By the Late Miocene, around 11 Mya, macroraptorials experienced a significant decline in abundance and diversity. Other species may have filled this niche in the Pliocene, such as the fossil killer whale Orcinus citoniensis which may have been a pack predator and targeted prey larger than itself, but this inference is disputed, and it was probably a generalist predator rather than a marine mammal specialist.

Megalodon may have subjected contemporaneous white sharks to competitive exclusion, as the fossil records indicate that other shark species avoided regions it inhabited by mainly keeping to the colder waters of the time. In areas where their ranges seemed to have overlapped, such as in Pliocene Baja California, it is possible that megalodon and the great white shark occupied the area at different times of the year while following different migratory prey. Megalodon probably also had a tendency for cannibalism, much like contemporary sharks.

Feeding strategies

Sharks often employ complex hunting strategies to engage large prey animals. Great white shark hunting strategies may be similar to how megalodon hunted its large prey. Megalodon bite marks on whale fossils suggest that it employed different hunting strategies against large prey than the great white shark.

One particular specimen–the remains of a  long undescribed Miocene baleen whale–provided the first opportunity to quantitatively analyze its attack behavior. Unlike great whites which target the underbelly of their prey, megalodon probably targeted the heart and lungs, with their thick teeth adapted for biting through tough bone, as indicated by bite marks inflicted to the rib cage and other tough bony areas on whale remains. Furthermore, attack patterns could differ for prey of different sizes. Fossil remains of some small cetaceans, for example cetotheres, suggest that they were rammed with great force from below before being killed and eaten, based on compression fractures.

There is also evidence that a possible separate hunting strategy existed for attacking raptorial sperm whales; a tooth belonging to an undetermined  physeteroid closely resembling those of Acrophyseter discovered in the Nutrien Aurora Phosphate Mine in North Carolina suggests that a megalodon or O. chubutensis may have aimed for the head of the sperm whale in order to inflict a fatal bite, the resulting attack leaving distinctive bite marks on the tooth. While scavenging behavior cannot be ruled out as a possibility, the placement of the bite marks is more consistent with predatory attacks than feeding by scavenging, as the jaw is not a particularly nutritious area to for a shark feed or focus on. The fact that the bite marks were found on the tooth's roots further suggest that the shark broke the whale's jaw during the bite, suggesting the bite was extremely powerful. The fossil is also notable as it stands as the first known instance of an antagonistic interaction between a sperm whale and an otodontid shark recorded in the fossil record.

During the Pliocene, larger cetaceans appeared. Megalodon apparently further refined its hunting strategies to cope with these large whales. Numerous fossilized flipper bones and tail vertebrae of large whales from the Pliocene have been found with megalodon bite marks, which suggests that megalodon would immobilize a large whale before killing and feeding on it.

Growth and reproduction

In 2010, Ehret estimated that megalodon had a fast growth rate nearly two times that of the extant great white shark. He also estimated that the slowing or cessation of somatic growth in megalodon occurred around 25 years of age, suggesting that this species had an extremely delayed sexual maturity. In 2021, Shimada and colleagues calculated the growth rate of an approximately  individual based on the Belgian vertebrate column specimen that presumably contains annual growth rings on three of its vertebrae. They estimated the individual died at 46 years of age, with a growth rate of  per year, and a length of  at birth. For a  individualwhich they considered to have been the maximum size attainablethis would equate to a lifespan of 88 to 100 years. However, Cooper and his colleagues in 2022 estimated the length of this 46 year old individual at nearly  based on the 3D reconstruction which resulted in the complete vertebral column to be  long; the researchers claimed that this size estimate difference occurred due to the fact that Shimada and his colleagues extrapolated its size only based on the vertebral centra.

Megalodon, like contemporaneous sharks, made use of nursery areas to birth their young in, specifically warm-water coastal environments with large amounts of food and protection from predators. Nursery sites were identified in the Gatún Formation of Panama, the Calvert Formation of Maryland, Banco de Concepción in the Canary Islands, and the Bone Valley Formation of Florida. Given that all extant lamniform sharks give birth to live young, this is believed to have been true of megalodon also. Infant megalodons were around  at their smallest, and the pups were vulnerable to predation by other shark species, such as the great hammerhead shark (Sphyrna mokarran) and the snaggletooth shark (Hemipristis serra). Their dietary preferences display an ontogenetic shift: Young megalodon commonly preyed on fish, sea turtles, dugongs, and small cetaceans; mature megalodon moved to off-shore areas and consumed large cetaceans.

An exceptional case in the fossil record suggests that juvenile megalodon may have occasionally attacked much larger balaenopterid whales. Three tooth marks apparently from a  long Pliocene shark were found on a rib from an ancestral blue or humpback whale that showed evidence of subsequent healing, which is suspected to have been inflicted by a juvenile megalodon.

Extinction

Climate change
The Earth experienced a number of changes during the time period megalodon existed which affected marine life. A cooling trend starting in the Oligocene 35 Mya ultimately led to glaciation at the poles. Geological events changed currents and precipitation; among these were the closure of the Central American Seaway and changes in the Tethys Ocean, contributing to the cooling of the oceans. The stalling of the Gulf Stream prevented nutrient-rich water from reaching major marine ecosystems, which may have negatively affected its food sources. The largest fluctuation of sea levels in the Cenozoic era occurred in the Plio-Pleistocene, between around 5 million to 12 thousand years ago, due to the expansion of glaciers at the poles, which negatively impacted coastal environments, and may have contributed to its extinction along with those of several other marine megafaunal species. These oceanographic changes, in particular the sea level drops, may have restricted many of the suitable shallow warm-water nursery sites for megalodon, hindering reproduction. Nursery areas are pivotal for the survival of many shark species, in part because they protect juveniles from predation.

As its range did not apparently extend into colder waters, megalodon may not have been able to retain a significant amount of metabolic heat, so its range was restricted to shrinking warmer waters. Fossil evidence confirms the absence of megalodon in regions around the world where water temperatures had significantly declined during the Pliocene. However, an analysis of the distribution of megalodon over time suggests that temperature change did not play a direct role in its extinction. Its distribution during the Miocene and Pliocene did not correlate with warming and cooling trends; while abundance and distribution declined during the Pliocene, megalodon did show a capacity to inhabit colder latitudes. It was found in locations with a mean temperature ranging from , with a total range of , indicating that the global extent of suitable habitat should not have been greatly affected by the temperature changes that occurred. This is consistent with evidence that it was a mesotherm.

Changing ecosystem

Marine mammals attained their greatest diversity during the Miocene, such as with baleen whales with over 20 recognized Miocene genera in comparison to only six extant genera. Such diversity presented an ideal setting to support a super-predator such as megalodon. By the end of the Miocene, many species of mysticetes had gone extinct; surviving species may have been faster swimmers and thus more elusive prey. Furthermore, after the closure of the Central American Seaway, tropical whales decreased in diversity and abundance. The extinction of megalodon correlates with the decline of many small mysticete lineages, and it is possible that it was quite dependent on them as a food source. Additionally, a marine megafauna extinction during the Pliocene was discovered to have eliminated 36% of all large marine species including 55% of marine mammals, 35% of seabirds, 9% of sharks, and 43% of sea turtles. The extinction was selective for endotherms and mesotherms relative to poikilotherms, implying causation by a decreased food supply and thus consistent with megalodon being mesothermic. Megalodon may have been too large to sustain itself on the declining marine food resources. The cooling of the oceans during the Pliocene might have restricted the access of megalodon to the polar regions, depriving it of the large whales which had migrated there.

Competition from large odontocetes, such as macropredatory sperm whales which appeared in the Miocene, and a member of genus Orcinus (i.e., Orcinus citoniensis) in the Pliocene, is assumed to have contributed to the decline and extinction of megalodon. But this assumption is disputed: The Orcininae emerged in Mid-Pliocene with O. citoniensis reported from the
Pliocene of Italy, and similar forms reported from the Pliocene of England and South Africa, indicating the capacity of these dolphins to cope with increasingly prevalent cold water temperatures in high latitudes. These dolphins were assumed to have been macrophagous in some studies, but on closer inspection, these dolphins are not found to be macrophagous and fed on small fishes instead. On the other hand, gigantic macropredatory sperm whales such as Livyatan-like forms are last reported from Australia and South Africa circa 5 million years ago. Others, such as Hoplocetus and Scaldicetus also occupied a niche similar to that of modern killer whales but the last of these forms disappeared during the Pliocene. Members of genus Orcinus became large and macrophagous in the Pleistocene.

Paleontologist Robert Boessenecker and his colleagues rechecked the fossil record of megalodon for carbon dating errors and concluded that it disappeared circa 3.5 million years ago. Boessenecker and his colleagues further suggest that megalodon suffered range fragmentation due to climatic shifts, and competition with white sharks might have contributed to its decline and extinction. Competition with white sharks is assumed to be a factor in other studies as well, but this hypothesis warrants further testing. Multiple compounding environmental and ecological factors including climate change and thermal limitations, collapse of prey populations and resource competition with white sharks are believed to have contributed to decline and extinction of megalodon.

The extinction of megalodon set the stage for further changes in marine communities. The average body size of baleen whales increased significantly after its disappearance, although possibly due to other, climate-related, causes. Conversely the increase in baleen whale size may have contributed to the extinction of megalodon, as they may have preferred to go after smaller whales; bite marks on large whale species may have come from scavenging sharks. Megalodon may have simply become coextinct with smaller whale species, such as Piscobalaena nana. The extinction of megalodon had a positive impact on other apex predators of the time, such as the great white shark, in some cases spreading to regions where megalodon became absent.

In popular culture

Megalodon has been portrayed in many works of fiction, including films and novels, and continues to be a popular subject for fiction involving sea monsters. Reports of supposedly fresh megalodon teeth, such as those found by  in 1873 which were dated in 1959 by the zoologist Wladimir Tschernezky to be around 11,000 to 24,000 years old, helped popularise claims of recent megalodon survival amongst cryptozoologists. These claims have been discredited, and are probably teeth that were well-preserved by a thick mineral-crust precipitate of manganese dioxide, and so had a lower decomposition rate and retained a white color during fossilization. Fossil megalodon teeth can vary in color from off-white to dark browns, greys, and blues, and some fossil teeth may have been redeposited into a younger stratum. The claims that megalodon could remain elusive in the depths, similar to the megamouth shark which was discovered in 1976, are unlikely as the shark lived in warm coastal waters and probably could not survive in the cold and nutrient-poor deep sea environment.

Contemporary fiction about megalodon surviving into modern times was pioneered by the 1997 novel Meg: A Novel of Deep Terror by Steve Alten and its subsequent sequels. Megalodon subsequently began to feature in films, such as the 2003 direct to video Shark Attack 3: Megalodon, and later The Meg, a 2018 film based on the 1997 book which grossed over $500 million at the box office.

Animal Planet's pseudo-documentary Mermaids: The Body Found included an encounter 1.6 mya between a pod of mermaids and a megalodon. Later, in August 2013, the Discovery Channel opened its annual Shark Week series with another film for television, Megalodon: The Monster Shark Lives, a controversial docufiction about the creature that presented alleged evidence in order to suggest that megalodons still lived. This program received criticism for being completely fictional and for inadequately disclosing its fictional nature; for example, all of the supposed scientists depicted were paid actors, and there was no disclosure in the documentary itself that it was fictional. In a poll by Discovery, 73% of the viewers of the documentary thought that megalodon was not extinct. In 2014, Discovery re-aired The Monster Shark Lives, along with a new one-hour program, Megalodon: The New Evidence, and an additional fictionalized program entitled Shark of Darkness: Wrath of Submarine, resulting in further backlash from media sources and the scientific community. Despite the criticism from scientists, Megalodon: The Monster Shark Lives was a huge ratings success, gaining 4.8 million viewers, the most for any Shark Week episode up to that point.

Megalodon teeth are the state fossil of North Carolina.

See also

 List of prehistoric cartilaginous fish
 Prehistoric fish
 Largest prehistoric organisms

Notes

References

Further reading

External links

 The rise of super predatory sharks
 Carcharocles: Extinct Megatoothed shark

Paleontological videos

  with comments on its extinction.

  (featuring expert Dana Ehret)
  (featuring expert Mikael Siverson)
  (featuring expert Bretton Kent)

Carcharocles
Miocene sharks
Pliocene sharks
Miocene first appearances
Piacenzian extinctions
Pisco Formation
Fossil taxa described in 1835
Taxa named by Louis Agassiz
Symbols of North Carolina
Apex predators

Megalodon


Celtic Swing, né le  en Angleterre et mort le  en Italie, est un cheval de course pur-sang anglais. Il fut l'un des 2 ans les plus impressionnants de l'histoire des courses britanniques, sans pouvoir se montrer à la hauteur des espérances à 3 ans.

Carrière de courses

2 ans (1995)
Élevé par la Duchesse de Norfolk et confié à l'entraînement à la fille de celle-ci, Lady Herries, Celtic Swing est acquis à 2 ans par Peter Savill, président du British Horseracing Board, l'institution des courses hippiques anglaises. Savill avait envoyé son premier jockey, Kevin Darley, essayer un poulain prometteur le temps d'un galop du matin, mais en descendant de cheval, le jockey signale se déclare impressionné non par sa monture, mais par le grand poulain noir qui l'accompagnait lors de ce galop d'essai et conseille au propriétaire de l'acheter. Ce grand poulain noir se nomme Celtic Swing, au vu de ses aplombs un peu tordus, il est estimé à un prix très modeste,  livres. Peter Savill propose à Lady Herries de l'acheter, et l'affaire est conclue à condition qu'un autre poulain, valant beaucoup plus cher, soit inclus dans la transaction. C'est ainsi que Celtic Swing rejoint l'écurie de Peter Savill, tout en restant à l'entraînement chez Lady Herries. L'autre poulain mourra de coliques le lendemain de ses débuts victorieux à Sandown.

Quant à Celtic Swing, il n'est pas forcément très attendu pour ses débuts, qu'il effectue en juillet 1994 sur le petit hippodrome de Ayr, mais son impressionnante victoire, par quatre longueurs, attire tous les regards. On se presse pour revoir, en octobre, au départ d'une course à conditions où il pulvérise une opposition menée par un poulain appelé aux plus grandes destinées, Singspiel, lequel suit comme il peut et finit deuxième à huit longueurs. Cette fois, c'est sûr, on tient le meilleur 2 ans d'Angleterre. Reste à le confirmer dans le Racing Post Trophy, et Celtic Swing fait mieux que cela, il se balade, ils s'envole, il écrabouille : douze longueurs sanctionnent sa supériorité. L'enthousiasme est immense : on n'a pas vu un 2 ans pareil depuis... depuis peu de temps certes, depuis Arazi deux ans plus tôt. Mais Arazi était l'un des plus éblouissants 2 ans de l'histoire des courses et Celtic Swing semble fait du même métal. Il reçoit le titre de meilleur 2 ans européen de l'année, certes, mais c'est surtout au niveau des ratings que l'effet Celtic Swing se fait sentir. Les handicapeurs internationaux de la FIAH dégainent un 130, comme pour Arazi, soit le meilleur rating de l'histoire pour un 2 ans (à titre de comparaison, le crackissime Frankel n'obtiendra "que" 126 à 2 ans, avant de faire exploser tous les compteurs l'année suivante, et il faudra attendre 25 ans pour qu'un autre juvenile s'approche d'un tel score, en l'occurrence Pinatubo). Chez Timeform, la fièvre monte encore d'un cran : 138, un score inouï qu'aucun poulain n'avait même approché, pas même Arazi, qui avait décroché un 135 déjà formidable.

L'Angleterre en est certaine : Celtic Swing est le nouveau cheval du siècle, et les cotes qu'ont lui attribue pour les classiques du printemps suivants (les 2000 Guinées et le Derby d'Epsom) sont les plus basses jamais enregistrées. On se dit même que le poulain fera aussi bien que le grand Nijinsky et remportera la triple couronne britannique (2000 Guinées, Derby et St. Leger), un exploit que l'on s'accorde à juger impossible à l'ère moderne, dominée par un élevage orienté vers la vitesse. Pendant ce temps, Celtic Swing passe un hiver tranquille et prépare son retour en lisant peut-être les éditos du Times, qui s'est laissé gagner par la fièvre à son propos - après tout, on dit des chevaux intelligents qu'ils savent lire le journal.

3 ans (1996)
Mais des "cheval du siècle", il y en eut d'autres avant Celtic Swing et il y en aura d'autres ensuite. Et la déception sera à la hauteur des espoirs placés en lui. Sans doute le poulain était-il bien l'un des plus talentueux de l'histoire des courses, mais il ne l'a pas vraiment démontré, la faute, peut-être, à des jambes fragiles. Fébrilement attendu pour son retour dans les Greenham Stakes, une préparatoire aux Guinées, Celtic Swing s'impose devant le très bon Bahri, futur vainqueur des St. James's Palaces Stakes et des Queen Elizabeth II Stakes. Victoire il y a, mais point d'envolée. Y en avait-il besoin, à part pour satisfaire les yeux ? Le poulain a fait ce qu'on lui demandait, s'imposant facilement, restant invaincu. Il est donc confirmé dans son statut de grandissime favori des Guinées. Dix poulains osent l'affronter, dont Bahri et un "french raider" entraîné à Chantilly par André Fabre, Pennekamp, qui avait osé à l'automne dernier ravir les Dewhurst Stakes en terre ennemie. Et c'est ce dernier, monté par Thierry Jarnet, qui va faire chuter l'idole naissante : Celtic Swing court plutôt bien, laisse sur place Bahri, se démène, lutte, mais concède une tête au poulain français sur le poteau, il est battu sans excuses, coup de tonnerre.

Et nouveau coup de tonnerre lorsque Lady Herries annonce que le poulain ne courra pas le Derby, et sera orienté vers le Prix du Jockey Club à Chantilly, sacrilège. Dans le Racing Post, la bible des courses anglaises, le journaliste vedette juge cette décision "sad, mad, bad" (triste, folle, nulle). Après coup, Peter Savill expliquera que son protégé s'est fait mal dans la descente des 2000 Guinées, et qu'il a choisi Chantilly plutôt qu'Epsom car il n'y aime pas le profil de la piste et qu'il craignait le terrain léger pour les jambes fragiles de son poulain. Pennekamp, d'ailleurs, alla sur le Derby en grand favori (il est alors invaincu), y sombra, s'y blessa et on ne le revit plus jamais. Tandis que le Derby révèle une étoile filante nommée Lammtarra, Celtic Swing prend donc la direction de la France et s'impose dans le Jockey Club, sans être plus impressionnant que ça. Un mois plus tard, Peter Savill croise le maître-entraîneur irlandais Vincent O'Brien, qui lui assure que, pour avoir regardé le poulain après la course, il est certain qu'il a un problème à l'antérieur gauche. Les radios ne révèle rien d'anormal.

Derby winner malgré tout, Celtic Swing tente le doublé Prix du Jockey-Club / Irish Derby. Mais plus dure est la chute au Curragh : le poulain n'est que l'ombre de lui-même, finissant huitième du Français Winged Love, troisième à Chantilly. Cette fois, un examen aux ultrasons est réalisé et montre une lésion au tendon de l'antérieur gauche. O'Brien avait raison. La saison du poulain est terminée. On le soigne, on l'espère guéri pour l'année prochaine et il est bien question d'un come back en 1996. Mais le 20 juillet, l'entourage jette l'éponge : le "wonderhorse" n'a jamais recouvré tous ses moyens et on ne le reverra plus. Et l'on ne saura jamais si, sans ce tendon douloureux, Celtic Swing était autre chose que l'un des plus enthousiasmants 2 ans de l'histoire des courses.

Résumé de carrière

Au haras

Celtic Swing, avec son pedigree à contre-courant des modes, suscitait moins d'espoir au haras qu'il n'en avait fait naître sur les pistes. Installé au Irish National Stud, il fut proposé d'emblée à un tarif modeste, £  la saillie, fut exporté en France après deux saisons, puis quatre ans plus tard rapatrié au Irish National Stud (où son tarif culmina à ) avant de terminer sa carrière en Italie à . De fait, il ne réussit guère dans ses nouvelles fonctions d'étalons, et pourtant on lui doit deux véritables champions : le sprinter Australien Takeover Target, qui remporta huit groupe 1 aux quatre coins du monde, de l'Australie à Singapour, du Japon à l'Angleterre ; et la championne français Six Perfections, lauréate du Prix Marcel Boussac, du Jacques Le Marois et de la Breeders' Cup Mile.

Celtic Swing est mort d'une colite dans son haras italien quelques mois après son arrivée.

Origines

À l'époque où Celtic Swing se prépare à faire sa rentrée à 3 ans, Damister, son père, prend ses fonctions au Japon où vient d'être vendu. Celtic Swing sera bien sûr le plus grand fait d'armes de ce vainqueur de deux groupe 2 anglais, troisième du Derby en 1985, modeste reproducteur bien que fils du grand Mr. Prospector. La famille maternelle, un peu old school, n'est notable que par la deuxième mère du champion, Pencuik Jewel, qui se trouve être la sœur du vainqueur de Gold Cup, Ragstone, et de Castle Moon, grande poulinière qui a donné Moon Madness (St. Leger), Sheriff's Star (Coronation Cup, Grand Prix de Saint-Cloud) et Lucky Moon (Goodwood Cup).

Pedigree

Notes et références

Cheval de course
Animal né en 1992
Cheval de course né en 1992
Animal mort en 2010
Étalon pur-sang anglais
Lauréat d'un Cartier Racing Award
Famille 8-c

Celtic Swing


Karbonpapir er særligt præpareret papir, der bruges til at fremstillet kopier, når der skrives. Der kan enten bruges kuglepen, skrivemaskine eller printer med anslag (matrixprinter og typehjulsprinter). Karbonpapir benyttes ofte hæftet sammen med blanketter i en 'sandwich', således at der fremstilles et antal kopier under brugen. På den måde kan en person, der har kvitteret for et eller andet, med det samme få en kopi. Blanketter med karbonpapir og flere kopier fås i 'endeløse' baner til visse printere. Karbonpapir findes også som et løst ark, der kan lægges ind mellem to ark på en dags dato-blanket eller lignende. Endelig findes karbonpapir som løse ark i formatet A4, der kan lægges mellem to ark papir, som derefter benyttes i en skrivemaskine. Denne type karbonpapir mangler ofte to af hjørnerne, hvilket gør det nemmere at holde sammen på lagene af papir. Kopierne kan eventuelt skrives på særligt tyndt gennemslagspapir.

Karbonpapir består af et papirlag, kaldet råpapiret, der på den ene side er behandlet med voks for at modvirke arkets tilbøjelighed til at glide. Under voksen findes ofte et påtryk, der viser fabrikantens navn. På den anden side af råpapiret er der et lag plastik kaldet mellemplasten. Dette lag skal forhindre det yderste lag, der består af en fedtet, ikke-tørrende farve i at opsuges i råpapiret. Det er dette farvelag, der smitter af på det bagvedliggende papirark, når der skrives på det forreste ark.

Karbonpapir kan ofte benyttes op til 50 gange, før farven er brugt op. Karbonpapir findes i kvaliteter, der tillader 5, 8 og 12 gennemslag. Karbonpapir tåler dårligt varme og direkte sollys. Sort karbonpapir giver lysægte gennemslag.

Karbonpapir erstattes i nogle tilfælde med selvkopierende papir.

Kilder og henvisninger
 Bogladens papirvarer. Odder, 1976. Af Poul Rishede og Per Salbøg.

Se også
 Carbon copy

Tegne- og skriveudstyr

Karbonpapir


102 هـ هي سنة في التقويم الهجري امتدت مقابلةً في التقويم الميلادي بين سنتي 720 و721.

أحداث
 معركة تولوز بين الجيش الأموي بقيادة السمح بن مالك الخولاني والغالي بمنطقة أكيتانيا جنوب فرنسا بتاريخ 9 ذو الحجة، وقد قتل السمح بن مالك وانهزم المسلمون.
 معركة قندابيل للقائد هلال بن أحوز التميمي على أنصار الوالي المتمرد المفضل بن المهلب في مدينة قندابيل من أعمال إقليم السند.

مواليد
 عبد الله بن علي بن عبد الله

وفيات
 عدي بن أرطأة الفزاري
 يزيد بن المهلب
 السمح بن مالك الخولاني
 أبو الطفيل عامر بن واثلة الكناني
 بسطام اليشكري المعروف بشوذب من زعماء الخوارج الحرورية.
 المفضل بن المهلب
 مدرك بن المهلب

انظر أيضًا
 أحداث ومواليد ووفيات وقعت في الفترة الأولى من سنة 102 هـ
 أحداث ومواليد ووفيات وقعت في الفترة الثانية من سنة 102 هـ

مراجع

تقويم هجري

102 هـ


සභානායක යනු ශ්‍රී ලංකා පාර්ලිමේන්තුවේ තනතුරක් වන අතර සාමාන්‍යයෙන් පාර්ලිමේන්තුවේ රජයේ කටයුතු සංවිධානය කිරීමේ වගකීම දරන ශ්‍රී ලංකා කැබිනට් මණ්ඩලයේ සාමාජිකයෙකි.

සභානායකවරුන්ගේ ලැයිස්තුව

පක්ෂ

මේවාද බලන්න
ශ්‍රී ලංකාවේ පාර්ලිමේන්තුව
ශ්‍රී ලංකාවේ කැබිනට් මණ්ඩලය

මූලාශ්‍ර

බාහිර සබැඳි
ශ්‍රී ලංකා පාර්ලිමේන්තුව - පාර්ලිමේන්තු අත්පොත, Leaders of the House

සභානායක (ශ්‍රී ලංකාව)


Kürtaj ya da kazıma, hamilelikte rahim içerisindeki ceninin tıbbi müdahale ile alınması. Bunun yanı sıra rahim iç duvarından kazınarak örnek alınıp incelenmesi de kürtaj olarak adlandırılır. Türkçeye 1930'larda Fransızca curetage (küret denilen cerrahi aletler ile kazıyarak temizleme şeklinde cerrahi müdahale) sözcüğünden geçmiştir.

Tarihçe
Kürtajı resmî olarak serbest bırakan ilk ülke 1920 yılında tıbbi bir neden olmasa dahi kürtajı serbest bırakan Sovyetler Birliği'dir. Bunun ardından resmî verilere göre 1934 yılına dek 700.000 kürtaj yapıldı, 1930'lara dek artan kürtaj sayısını azaltmak için bir takım önlemler alındı. 1936-1955 yılları arasında ülkede tıbbi olmayan nedenlerle kürtaj yasaklandı. Türkiye'de de uzun yıllar yasak olan kürtaj, 12 Eylül Darbesi sonrası Askerî İdare'nin 27 Mayıs 1983'te çıkardığı yasayla serbest bırakıldı.

Uygulandığı durumlar
İstenmeyen gebelikler (hamilelik) sonlandırılmak istendiğinde kürtajın son adet tarihi itibarıyla yasal olduğu ülkelerde farklı sınırlar vardır. Bu duruma yasal tahliye ya da kürtaj denilmektedir. Türkiye' de 2827 sayılı yasanın 5. maddesine göre gebeliğin 10. haftası bir liimit şeklinde kullanılarak kürtaj işlemi yasal olarak yapılmaktadır. Yasalar ile ilgili bu işlem sadece kadın doğum uzmanlarının yetkisi altındadır. İşlem hekim ve hasta arasında gizli kalmaktadır. Gebede ciddi bir hastalık mevcut ise ve gebe kalma durumu kişi için risk oluşturuyor ise ya da gebelik süresince zararlı olan yalnız kendisinin kullanmakta zorunlu kılındığı ilaçlar var ise kişiye terapotik kürtaj (tedavi amaçlı kürtaj) uygulanır.

Uygulama şekilleri
İşlemin gerçekleşmesi için bir tane değil birden fazla hekimin onayı gerekir ve sağlık kurulu raporuna gerek duyulur. Gebelik süresince takibi yapılan bebeğin sakatlık ya da kalp ritimlerinin olmadığı kesinleştiği gibi durumlarda terapotik kürtaj (tedavi amaçlı) uygulanır. İşleme geçilmeden önce USG ile gebelik durumunun ve rahim (uterus) dışındaki yerleşim durumu gözlenir. Kürtaj işlemi sırasında Genel anestezi ya da Lokal anestezi uygulanır. Kişi genel anesteziye alınacak ise işlem öncesi 4 saat kadar oral alımı durdurulur.

Hastanın uygulanan ilk kürtajı ise ya da önceden yapılmış sezaryen ile doğumu varsa Genel anestezi ile kürtaj yapılır. Yalnız kişinin geçmişte yaptırmış olduğu kürtajları varsa ya da normal doğum eylemi gerçekleştirilmiş ise Lokal anestezi yapılabilir. Lokal anestezi Anestezi uzmanları tarafından serviks bölgesi özel ilaçlar ile uyuşturulur. Genel anestezi ise İntra Venöz (ıv) yol ile ilaç uygulanarak Anestezi uzamanı tarafından yapılır. İşlem öncesinde Jinekolojik Muayene ve rahim (uterus) yapısı değerlendirilmelidir. İşlem 5 ila 15 dakika kadar sürer. Lokal anestezi ile 15 dakika kadar, Genel anestezi ile 30 dakika kadar sonra kişi ev ortamına gönderilebilir. Analjezik (ağrı kesici), antibiyotik, Kanamayı azaltmak amaçlı Hekim tarafından ilaçlar önerilir. Önerilere uyulması istenir. Bir hafta sonra kişi Kontrol amaçlı tekrar gelmelidir.

Riskler
Kürtajın riski prosedürün ne kadar güvenli olarak yürütüldüğüne bağlıdır. Dünya Sağlık Örgütü güvenli olmayan kürtajı yetkin olmayan şahıslarca, tehlike yaratan ekipmanla veya hijyenik olmayan şartlar altında yapılan kürtaj olarak tanımlar. Gelişmiş ülkelerde yapılan yasal kürtaj tıptaki en güvenli prosedürlerdendir. Örneğin ABD'de kürtajdan ölüm oranı 100.000 vakada 0,7'dir; bu kürtajın doğum yapmaya göre 13 kat daha güvenli olduğu anlamına gelmektedir. Kürtajla alakalı ölüm oranı hamileliğin ilerlemesiyle artsa da, 21. haftaya kadar doğumdan daha azdır.

Hamileliğin ilk üç aylık döneminde vakum aspirasyonu en güvenli yöntemdir. Bu prosedürüm komplikasyonları nadirdir ve rahim delinmesi, iltihaplanma ve ikinci bir prosedür gerektirecek şekilde parça kalmasından oluşur.

 Asherman sendromu (rahim içerisinde yapışıklık oluşması)
 İşlem sonrası enfeksiyon (endometrit)
 Uzamış vajinal kanama (içeride bir miktar gebelik ürünü kalması nedeniyle oluşabilir)
 Kullanılan her türlü anestezik maddeye bağlı ilaç alerjisi
 Kürtaj işlemine rağmen gebeliğin devam etmesi
 Stress, kaygı bozukluğu, panik atak
 Sontaki regl döneminin değişmesi sayılabilecek riskler arasındadır.

İyileşme süresi
İşlem sonrası Genel anestezi etkisi 1 saat kadar sürer. Bu süre içerisinde kişi gözlem altında tutulur. Bir saat kadar sonra hasta kendine gelmesiyle normal aktivitelerine dönmesi beklenir.
Ağrı çoğu zaman olmaz, olması durumunda analjeziklere yanıt verir. Çok az derecede bir hemoraji (kanama), mensturuasyondan çok daha az vajinal hemoraji olur. Kanama en fazla on gün kadar sürer. Kişi bir buçuk ay kadar sonra mensturuasyon kanaması geçirir. Kürtaj sonrası vajinal hemoraji olacağından cinsel ilişkiye ara verilmelidir.

Kürtaj işleminden sonra tampon sakıncalı değildir kullanılabilir. Tampon kullanılacak ise sık aralıklarla değiştirilmesi gerekir. Gerekli hijyen kurallarına uyulduğu takdirde kullanımında sakınca olmaz. Kürtaj işlemi yapılan bayanlar %99,9 oranında hamile kalabilirler. Çok az olan oran Tüplerdeki tıkanıklık, kürtaj esnasında meydana gelen rahim (uterus) delinmesi, İşlem sonrası enfeksiyon (iltihaplanma), uterusun yapışması gibi olumsuz durumlarda gebelik kalımında zorluklar yaşanabilir. Tedavisi sonrası gebe kalınımı mümkün olur.

Kürtaj işleminin yapıldığı gün, yeni regl döngüsünün ilk günü olarak kabül edilir. Genellikle bu klasik aylık peryodik regl döneminde olan kanamalara göre daha az şekilde olması beklenir.

Hukuki boyut

Ayrıca bakınız
 Cinsiyet tercihli kürtaj

Kaynakça

Tıp terimleri
Temel ahlaki konular
Bereket
Fransızcadan Türkçeye geçen sözcükler

Kürtaj


Antonio Acero de la Cruz (Bogotá, c. 1600 - 1000) fue un pintor bogotano del Reino de la Nueva Granada.

Biografía

Antonio Acero de la Cruz era hijo del artesano español Alonso Acero, quien se instaló en el barrio Las Nieves de la Santa fe colonial, y hermano de los también artesanos Bernardo, Jerónimo y Juan de Dios. Enseñó su oficio de pintor en una casa vecina. Realizó obras pictóricas para los conventos de Las Nieves, San Diego y Las Aguas, así como en edificios de otros poblados, como Tunja, Mongui, Fúquene y Pamplona. Fundió como arquitecto de la primera ermita de Monserrate, para la cual realizó asimismo retratos y otras pinturas. Es uno de los personajes de la novela El desierto prodigioso y el prodigio de desierto, de su amigo Pedro de Solís y Valenzuela, la cual define el inicio del género en el continente, siendo a su vez la primera novela que se escribió en el área hispanoamericana.

Obras

1661
  Virgen de la inmaculada concepción, Iglesia Divino Salvador de Sopó

Véase también
Historia de Bogotá
Literatura de Colombia

Bibliografía
Hernández Molina, Rubén y Fernando Carrasco Zaldúa. . Bogotá: Gobierno de la ciudad: Alcaldía Mayor de Bogotá, 2010.

Pintores de Bogotá
Nacidos en Bogotá
Pintores de Colombia del siglo XVII

Antonio Acero de la Cruz


Carlos Mastronardi (1901 – June 5, 1976) was an Argentine journalist, poet, and translator.  His works included Luz de provincia, Tierra amanecida (1926), Conocimiento de la noche (1937), and Tratado de la pena. His non-fiction Valéry o la infinitud del método (Valéry, or the infinitude of method) won the Buenos Aires Municipal Prize for Literature (1955). Other important works of non-fiction included Formas de la realidad nacional (Forms of the National Reality, 1961) and  Memorias de un Provinciano (Memoirs of a Man from the Provinces, 1967). Some of his journalism was published posthumously as Cuadernos de vivir y pensar (Notebooks of Living and Thinking, 1984).

As a translator, Mastronardi was mainly known for translating the French Symbolist poets into Spanish. As a poet, although identified personally with the avant-garde of his time, he wrote largely in traditional forms rather than free verse, and rejected what he viewed as his contemporaries' excessive use of metaphor.

Born in Gualeguay, Entre Ríos Province, Mastronardi came to Buenos Aires at the age of 19. There he became a member of the Martín Fierro group (also known as the Florida group) and an intimate of Jorge Luis Borges, although they disagreed strongly about questions about aesthetics and poetry. Mastronardi figures as a minor character in Borges's short story Tlön, Uqbar, Orbis Tertius.

Mastronardi led a notoriously nocturnal existence. Writing of Mastronardi in 1986 in the newspaper El País (Madrid), Borges said of Mastronardi that "Like Auguste Dupin ... [the detective character created by Edgar Allan Poe] ... at night he went about the streets of Buenos Aires looking for that intellectual stimulus that only can be given by nighttime in a great city."

After a long period in which his work fell into obscurity, Mastronardi's works are () being re-published by Argentina's Universidad Nacional del Litoral.

Quotation
"Lyric poetry, for many of its ... [Argentine] ... practitioners, lacks all plan and requires no sacrifice. It allows the writer to follow the path of least resistance: everything consists of letting things be. In contrast, narrative, criticism, and essays (almost uncultivated among us), demand preparatory work and organic development."

Notes

References
 Jorge Luis Borges, Tlön, Uqbar, Orbis Tertius.
 Martín Prieto, Memorias de un provinciano, Clarin.com, 15 February 2003, accessed 25 December 2005.
 Efemérides (official Argentine government site) page on Algunos amigos e influencias importantes ("Some important friends and influences [of Jorge Luis Borges]").

1901 births
1976 deaths
20th-century Argentine historians
Place of birth missing
20th-century Argentine male writers
Male non-fiction writers

Carlos Mastronardi


Dublin City Ramblers er et irsk folkemusikband, der oprindeligt blev dannet under navnet The Quare Fellas i 1970. Gruppen har haft en lang række medlemmer siden grundlæggelsen, og Sean McGuinness er det eneste oprindelige medlem af gruppen, som også har talt Patsy Watchorn der senere blev medlem af The Dubliners.

Diskografi

Som The Quare Fellas

 At Home (1969 CBS)
 A Fond Tale (1970 CBS)

Som The Dublin City Ramblers

 A Nation Once Again (1972)
 Boys of the old Brigade (1973)
 End of it Someday (1974)
 Irish Republican Jail Songs (1978)
 The Rare Oul' Times (Original - 1980)
 The Ferryman (1983)
 DCR's Live in Dublin (1985)
 The Flight of Earls (1987)
 Home and Away (1990)
 The Craic & the Porter Black (1991)
 Live at Johnny Fox's Pub (1992)
 Raise the Roof (Lynwood Records, 1997)
 On Holy Ground (2000)
 Ireland My Ireland (Lynnwood Records, 2003)
 Saint Patricks Day (2008)
 Sing along with The DCR's''

Musikgrupper fra Irland
Folkemusik fra Irland
Musikgrupper fra 1970

Dublin City Ramblers


La tour de la Poudrière est une ancienne tour qui faisait partie de l'enceinte de Landrecies.

Histoire

La tour est probablement construite au début du  lors de la création du mur d'enceinte. Elle est construite en grès, certaines parties détruites lors de sièges ont par la suite été reconstruites en brique.

Avec l'évolution de la technique et les travaux de modernisation de l'enceinte dont le remparement des courtines vers le milieu du , la tour perd son utilité en se retrouvant à l'arrière de la courtine, elle est par la suite transformée en poudrière.

Notes et références

Références

Voir aussi

Articles connexes
 Enceinte de Landrecies
 Château de Landrecies

Enceinte de Landrecies

Tour de la Poudrière (Landrecies)


Vincenzo de' Rossi (* 1525 in Fiesole, Italien; † 1587 in Florenz, Italien) war ein italienischer Bildhauer des 16. Jahrhunderts.

Leben
De' Rossi begann um 1534 seinen beruflichen Weg als Lehrling bei dem Bildhauer Baccio Bandinelli. 1546 ging er nach Rom, wo er 1547 seinen ersten selbständig ausgeführten Auftrag erhielt. Mit dieser in einer Kapelle im Pantheon aufgestellten Statue Der junge Christus mit dem Heiligen Josef bewarb er sich gleichzeitig bei der Accademia dei Virtuosi, einer Künstlervereinigung mit ähnlichen Zielen wie die römische Accademia di San Luca oder wie die niederländischen Lukasgilden.

Weitere Werke

 1553: Büste des Uberto Strozzi in der Basilika Santa Maria sopra Minerva in Rom.
 Herakles/Herkules und Diomede aus der Serie der 12 Arbeiten des Herakles im Palazzo Vecchio in Florenz, ebenso wie eine dort aufgestellte Naiade.
 Paris beim Raub der Helena in der Grotta del Buontalenti im Giardino di Boboli in Florenz.
 Im Bargello das Relief Der sterbende Amor und Weg zum Calvario, Die Verspottung Christi und Christus vor Pilatus.
 In der Villa Medici Poggio Imperiale die Statue Herkules herrscht über den Himmel.
 1584: Laokoon-Gruppe, Nachbildung der 1506 gefundenen antiken Gruppe in weißem Marmor.

Literatur
 Regine Schallert: Studie zu Vicenzo de' Rossi. Die frühen und mittleren Werke (1536–1861). Olms, Hildesheim/Zürich/New York 1998, ISBN 3-487-10757-0.

Weblinks

Bildhauer (Italien)
Historische Person (Italien)
Geboren 1525
Gestorben 1587
Mann

Vincenzo de’ Rossi