Extinct giant shark species from 23 to 3.6 million years ago

Megalodon ( Otodus megalodon ), [ 6 ] [ 7 ] [ 8 ] mean “ 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 era. [ 9 ] It was once thought to be a penis of the family Lamnidae and a close relative of the bang-up ashen shark ( Carcharodon carcharias ). however, it is nowadays classified into the extinct family Otodontidae, which diverged from the great white shark during the early Cretaceous. Its genus placement is still debated, with authors placing it in either Carcharocles, Megaselachus, Otodus, or Procarcharodon. This is because transitional fossils have been found showing that megalodon is the final chronospecies of a descent of giant sharks in the first place of the genus Otodus which evolved during the Paleocene. While regarded as one of the largest and most mighty predators to have always lived, the megalodon is only known from fragmental remains, and its appearance and maximal size are uncertain. Scientists differ on whether it would have more closely resembled a stockier version of the great white shark, the giant shark ( Rhincodon typus ), the enjoy shark ( Cetorhinus maximus ) or the sandpaper tiger shark ( Carcharias taurus ). Most estimates of the megalodon ‘s size generalize from teeth, with maximal length estimates up to 14–20.3 meters ( 46–67 foot ) [ 7 ] [ 8 ] [ 10 ] and modal distance estimates of 10.5 meters ( 34 foot ). [ 11 ] [ 12 ] Estimates suggest that a Megaldodon about 16 meters ( 52 foot ) weighs up to 48 metric function tons ( 53 short tons ), 17 meters ( 56 foot ) farseeing weighs up to 59 metric unit tons ( 65 light tons ), and 20.3 meters ( 67 foot ) long ( the maximal distance ) weighs up to 103 metric unit tons ( 114 short-change tons ). [ 13 ] [ 14 ] Their teeth were thick and robust, built for grabbing prey and breaking bone, and their large jaws could exert a bite pull of up to 108,500 to 182,200 newtons ( 24,400 to 41,000 lbf ). [ 14 ]

Megalodon credibly had a major impact on the social organization of nautical communities. The fossil criminal record indicates that it had a cosmopolitan distribution. It credibly targeted boastfully prey, such as whales, seals and sea turtles. Juveniles inhabited warm coastal waters and fed on fish and small whales. Unlike the bang-up white, which attacks raven from the balmy bottom, megalodon probably used its potent yack to break through the chest pit and puncture the heart and lungs of its prey. The animal faced contest from whale-eating cetaceans, such as Livyatan and early macroraptorial sperm whales and possibly smaller ancestral killer whales. As the shark preferred warmer waters, it is thought that oceanic cool associated with the onset of the ice ages, coupled with the heavy of sea levels and resulting passing of desirable greenhouse areas, may have besides contributed to its descent. A reduction in the diversity of whalebone whales and a shift key in their distribution toward polar regions may have reduced megalodon ‘s chief food source. The shark ‘s extinction coincides with a gigantism tendency in whalebone whales .

taxonomy

Naming

An illustration of a shark head (sideview). Visible are wrinkles and an exaggerated nose and eyes, and at the bottom are two individual drawings of shark teeth The Head of a Shark Dissected The delineation of a shark ‘s forefront by Nicolas Steno in his ferment According to Renaissance accounts, gigantic trilateral fossil teeth frequently found embedded in rocky formations were once believed to be the lapidify tongues, or glossopetrae, of dragons and snakes. This interpretation was corrected in 1667 by danish naturalist Nicolas Steno, who recognized them as shark tooth, and famously produced a depicting of a shark ‘s lead wear such teeth. He described his findings in the reserve The Head of a Shark Dissected, which besides contained an exemplification of a megalodon tooth. [ 15 ] [ 16 ] [ 17 ] swiss naturalist Louis Agassiz gave this shark its initial scientific name, Carcharodon megalodon, in his 1843 cultivate Recherches sur les poissons fossiles, based on tooth remains. [ 1 ] [ 18 ] English paleontologist Edward Charlesworth in his 1837 newspaper used the list Carcharias megalodon, while citing Agassiz as the author, indicating that Agassiz described the species anterior to 1843. english paleontologist Charles Davies Sherborn in 1928 listed an 1835 series of articles by Agassiz as the first scientific description of the shark. [ 19 ] The particular identify megalodon translates to “ boastfully tooth ”, from ancient greek : μέγας, romanized : (mégas), fall. ‘big, mighty ‘ and ὀδούς ( odoús ), “ tooth ”. [ 20 ] [ 21 ] The tooth of megalodon are morphologically alike to those of the bang-up white shark ( Carcharodon carcharias ), and on the basis of this observation, Agassiz assigned megalodon to the genus Carcharodon. [ 18 ] Though “ megalodon ” is an informal name for the shark, it is besides often colloquially dubbed the “ giant flannel shark ”, [ 22 ] the “ megatooth shark ”, the “ big tooth shark ”, or “ Meg ”. [ 23 ] : 4 There was one apparent description of the shark in 1881 classifying it as Selache manzonii. [ 24 ]

development

Diagram of the chronospecies development of megalodon While the earliest megalodon remains have been reported from the Late Oligocene, around 28 million years ago ( Mya ), [ 25 ] [ 26 ] there is disagreement as to when it appeared, with dates ranging to adenine young as 16 mya. [ 27 ] It has been thought that megalodon became extinct around the end of the Pliocene, about 2.6 Mya ; [ 27 ] [ 28 ] claims of Pleistocene megalodon tooth, younger than 2.6 million years old, are considered undependable. [ 28 ] A 2019 assessment moves the extinction date back to earlier in the Pliocene, 3.6 Mya. [ 29 ] Megalodon is now considered to be a member of the syndicate Otodontidae, genus Otodus, as opposed to its previous classification into Lamnidae, genus Carcharodon. [ 27 ] [ 12 ] [ 28 ] [ 6 ] [ 7 ] Megalodon ‘s classification into Carcharodon was ascribable to dental similarity with the great white shark, but most authors presently 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 like teething in those two sharks ; megalodon teeth have much finer serrations than great white shark tooth. The capital white shark is more closely related to the mako shark ( Isurus spp. ), with a common ancestor around 4 Mya. [ 18 ] [ 30 ] Proponents of the former exemplary, wherein megalodon and the great white shark are more closely related, argue that the differences between their dentition are moment and hidden. [ 31 ] : 23–25
The genus Carcharocles presently contains four species : C. auriculatus, C. angustidens, C. chubutensis, and C. megalodon. [ 23 ] : 30–31 The development of this descent is characterized by the increase of serrations, the let out of the crown, the development of a more trilateral form, and the disappearance of the lateral cusp. [ 23 ] : 28–31 [ 32 ] The development in tooth morphology reflects a shift in depredation tactics from a tearing-grasping morsel to a cutting bite, probable reflecting a lurch in prey option from pisces to cetaceans. [ 33 ] Lateral cusplets were last lost in a gradual process that took roughly 12 million years during the transition between C. chubutensis and C. megalodon. [ 33 ] 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. [ 18 ] [ 23 ] : 30 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 big white shark. It is now considered a junior synonym of Carcharocles. [ 23 ] : 30 The genus Palaeocarcharodon was erected aboard Procarcharodon to represent the begin of the descent, and, in the model wherein megalodon and the great white shark are close 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. [ 31 ] : 70
A great white shark swimming a few meters below the surface, above a school of much smaller fish. Carcharodon carcharias) and megalodon were previously thought to be close relatives.[18][30] The great white shark ) and megalodon were previously thought to be close relatives. Another model of the evolution of this genus, besides proposed by Casier in 1960, is that the lead ancestor of the Carcharocles is the shark Otodus obliquus, which lived from the Paleocene through the Miocene epoch, 60 to 13 Mya. [ 30 ] [ 32 ] The genus Otodus is ultimately derived from Cretolamna, a shark from the cretaceous period. [ 6 ] [ 34 ] 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 last into C. megalodon. Another model of the evolution of Carcharocles, proposed in 2001 by paleontologist Michael Benton, is that the three early species are actually a individual species of shark that gradually changed over time between the Paleocene and the Pliocene, making it a chronospecies. [ 23 ] : 17 [ 26 ] [ 35 ] Some authors suggest that C. auriculatus, C. angustidens, and C. chubutensis should be classified as a unmarried species in the genus Otodus, leaving C. megalodon the sole extremity of Carcharocles. [ 26 ] [ 36 ] The genus Carcharocles may be invalid, and the shark may actually belong in the genus Otodus, making it Otodus megalodon. [ 4 ] A 1974 survey on Paleogene sharks by Henri Cappetta erected the subgenus Megaselachus, classifying the shark as Otodus ( Megaselachus ) megalodon, along with O. (M.) chubutensis. A 2006 revue of Chondrichthyes elevated Megaselachus to genus, and classified the sharks as Megaselachus megalodon and M. chubutensis. [ 4 ] 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 body of the Carcharocles sharks in Otodus would make it monophyletic, with the sister clade being Megalolamna. [ 6 ] The cladogram below represents the conjectural relationships between megalodon and other sharks, including the great white shark. Modified from Shimada et alabama. ( 2016 ), [ 6 ] Ehret et aluminum, ( 2009 ), [ 30 ] and the findings of Siversson et alabama. ( 2013 ). [ 37 ] [ 38 ] [ 39 ]

biota

appearance

One rendition 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 jaw may have been blunter and wider than the great white, and the fins would have besides been alike in condition, though thick due to its size. It may have had a pig-eyed appearance, in that it had small, deep-set eyes. [ 40 ] Another interpretation is that megalodon bore a similarity to the giant shark ( Rhincodon typus ) or the enjoy shark ( Cetorhinus maximus ). The tail fin would have been crescent, the anal fin and second dorsal five would have been humble, and there would have been a caudally keel salute on either side of the tail tail fin ( on the caudal peduncle ). This construct is common in other big aquatic animals, such as whales, tuna, and other sharks, in order to reduce drag while swimming. The head human body can vary between species as most of the drag-reducing adaptations are toward the tail-end of the animal. [ 23 ] : 35–36
Sculpture of a giant shark mounted on display in a museum next to a mounted shark jawbone sculpture in the Museum of Evolution in Puebla, Mexico Since Carcharocles is derived from Otodus, and the two had teeth that bear a close similarity to those of the backbone tiger shark ( Carcharias taurus ), megalodon may have had a build more alike to the backbone tiger shark than to other sharks. This is improbable since the backbone tiger shark is a carangiform swimmer which requires faster movement of the tail for propulsion through the water than the great white shark, a thunniform swimmer. [ 23 ] : 35–36 [ 41 ]

size

due to fragmental remains, there have been many contradictory size estimates for megalodon, as they can entirely be drawn from fossil teeth and vertebra. [ 42 ] : 87 [ 43 ] The great white shark has been the basis of reconstruction and size estimate, as it is regarded as the best analogue to megalodon. several entire length estimate methods have been produced from comparing megalodon teeth and vertebra to those of the capital white. [ 40 ] [ 44 ] [ 10 ] [ 7 ] Size comparison of the great white and whale shark to estimates for megalodon Proportions of megalodon at lengths of 3 meter ( 9.8 foot ), 8 m ( 26 foot ), and 16 megabyte ( 52 foot ), extrapolated from extant relatives, with a 1.65 molarity ( 5 foot 5 in ) diver Megalodon size estimates vary depending on the method acting used, with maximum total distance estimates ranging from 14.2–20.3 meters ( 47–67 foot ). [ 40 ] [ 10 ] [ 7 ] A 2015 study estimated the average total soundbox length at 10.5 meters ( 34 foot ), calculated from 544 megalodon teeth, found throughout geological time and geography, including adults and juveniles. [ 11 ] [ 12 ] In comparison, bombastic big white sharks are broadly around 6 meters ( 20 foot ) in distance, with a few contentious reports suggesting larger sizes. [ 45 ] [ 46 ] [ 40 ] The whale shark is the largest surviving pisces, with one big female reported with a precaudal length of 15 meters ( 49 foot ) and an estimated sum length of 18.8 meters ( 62 foot ). [ 45 ] [ 47 ] It is potential that different populations of megalodon around the ball had different torso sizes and behaviors ascribable to different ecological pressures. [ 12 ] Megalodon is thought to have been the largest macropredatory shark that always lived. [ 40 ] A 2020 study—looking at the dimensions of the modern big white, mako, and Lamna sharks—suggested a 16 meters ( 52 foot ) megalodon would have had a 4.65 m ( 15.3 foot ) long principal, 1.41 m ( 4 foot 8 in ) tall gill slits, a 1.62 molarity ( 5 foot 4 in ) tall abaxial fin, 3.08 m ( 10 foot 1 in ) long pectoral fins, and a 3.85 megabyte ( 12 foot 8 in ) grandiloquent chase fin. [ 8 ] Mature male megalodon may have had a body multitude of 12.6 to 33.9 metric tons ( 13.9 to 37.4 short-change tons ), and suppurate females may have been 27.4 to 59.4 metric function tons ( 30.2 to 65.5 light tons ), assuming that males could range in distance from 10.5 to 14.3 meters ( 34 to 47 foot ) and females 13.3 to 17 meters ( 44 to 56 foot ). [ 40 ] A 2015 study linking shark size and typical swimming speed estimated that megalodon would have typically swum at 18 kilometers per hour ( 11 miles per hour ) –assuming that its body mass was typically 48 measured tons ( 53 short-circuit tons ) –which is reproducible with other aquatic creatures of its size, such as the louver whale ( Balaenoptera physalus ) which typically cruises at speeds of 14.5 to 21.5 km/h ( 9.0 to 13.4 miles per hour ). [ 48 ] Its large size may have been due to climatic factors and the abundance of big prey items, and it may have besides been influenced by the evolution of regional endothermy ( mesothermy ) which would have increased its metabolic rate and swimming amphetamine. The otodontid sharks have been considered to have been ectotherms, then on that footing megalodon would have been poikilothermic. however, the largest contemporary poikilothermic sharks, such as the giant shark, are percolate feeders, while lamnids are now known to be regional endotherms, implying some metabolic correlations with a marauding life style. These considerations, equally well as tooth oxygen isotopic data and the need for higher burst swimming speeds in macropredators of endothermic raven than ectothermy would allow, imply that otodontids, including megalodon, were probably regional endotherms. [ 49 ] In 2020, Shimada and colleagues suggested large size was alternatively due to intrauterine cannibalism, where the larger fetus eats the smaller fetus, resulting in increasingly larger and larger fetuses, requiring the mother to attain even greater size adenine well as caloric requirements which would have promoted endothermy. Males would have needed to keep up with female size in order to placid efficaciously copulate ( which credibly involved latching onto the female with claspers, like advanced cartilaginous pisces ). [ 50 ]

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 30 meters ( 98 foot ) in length. Dean had overestimated the size of the cartilage on both jaws, causing it to be excessively tall. [ 51 ] [ 52 ]Black-and-white photo of a man sitting inside a megalodon jaw reconstruction. reconstruction by Bashford Dean in 1909A white megalodon tooth on the palms of a person. On the right side of the image is a ruler. The tip of the tooth starts at zero and ends at the seventeen centimeter marker on the ruler. Tooth compared to hand In 1973, John E. Randall, an ichthyologist, used the enamel stature ( the erect distance of the blade from the base of the enamel helping of the tooth to its topple ) to measure the length of the shark, yielding a utmost length of about 13 meters ( 43 foot ). [ 53 ] however, tooth enamel stature does not necessarily increase in symmetry to the animal ‘s full distance. [ 31 ] : 99 In 1994, marine biologists Patrick J. Schembri and Stephen Papson opined that O. megalodon may have approached a utmost of around 24 to 25 meters ( 79 to 82 foot ) in total length. [ 54 ] [ 55 ] In 1996, shark researchers Michael D. Gottfried, Leonard Compagno, and S. Curtis Bowman proposed a linear relationship between the great white shark ‘s total distance and the altitude of the largest upper front tooth tooth. The proposed kinship is : total length in meters = − ( 0.096 ) × [ UA utmost acme ( millimeter ) ] – ( 0.22 ). [ 56 ] [ 40 ] Using this tooth height regression equation, the authors estimated a total duration of 15.9 meters ( 52 foot ) based on a tooth 16.8 centimeters ( 6.6 in ) tall, which the authors considered a bourgeois maximal appraisal. They besides compared the ratio between the tooth acme and total length of bombastic female great whites to the largest megalodon tooth. A 6-meter ( 20 foot ) long female great flannel, which the authors considered the largest ‘reasonably trustworthy ‘ total distance, produced an estimate of 16.8 meters ( 55 foot ). however, based on the largest female big white reported, at 7.1 meters ( 23 foot ), they estimated a maximum estimate of 20.2 meters ( 66 foot ). [ 40 ] In 2002, shark research worker Clifford Jeremiah proposed that total length was proportional to the root width of an upper front tooth tooth. He claimed that for every 1 centimeter ( 0.39 in ) of root width, there are approximately 1.4 meters ( 4.6 foot ) of shark distance. Jeremiah pointed out that the jaw margin of a shark is directly proportional to its entire length, with the width of the roots of the largest tooth being a tool for estimating yack circumference. The largest tooth in Jeremiah ‘s possession had a root width of about 12 centimeters ( 4.7 in ), which yielded 16.5 meters ( 54 foot ) in sum length. [ 23 ] : 88 In 2002, paleontologist Kenshu Shimada of DePaul University proposed a linear kinship between tooth crown altitude and sum length after conducting anatomic analysis of respective specimens, allowing any size 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 emergence rate between the crown and ancestor is not isometric, which he considered in his model. Using this model, the upper anterior tooth possessed by Gottfried and colleagues corresponded to a sum duration of 15 meters ( 49 foot ). [ 57 ] Among several specimens found in the Gatún Formation of Panama, one amphetamine lateral tooth was used by other researchers to obtain a total length appraisal of 17.9 meters ( 59 foot ) using this method. [ 36 ] [ 58 ] 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 tooth is difficult to identify. Shimada provided maximum total distance estimates using the largest front tooth tooth available in museums. The tooth with the tallest peak altitude known to Shimada, NSM PV-19896, produced a sum length estimate of 14.2 meters ( 47 foot ). The tooth with the tallest total altitude, FMNH PF 11306, was reported at 16.8 centimeters ( 6.6 in ). however, Shimada remeasured the tooth and found it actually to measure 16.2 centimeters ( 6.4 in ). Using the entire height tooth arrested development equation proposed by Gottfried and colleagues produced an appraisal of 15.3 meters ( 50 foot ). [ 7 ] [ 10 ] In 2021, Victor J. Perez, Ronny M. Leder, and Teddy Badaut proposed a method of estimating total distance of megalodon from the total 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 acme equations produce wildly deviate results for different teeth belonging to the lapp shark, casting doubt on some of the conclusions of previous studies using that method acting. Using the largest tooth available to the authors, GHC 6, with a crown width of 13.3 centimeters ( 5.2 in ), they estimated a sum length between 17.4 to 24.2 meters ( 57 to 79 ft ) with a intend of 20.3 meters ( 67 foot ). [ 10 ]

“ A C. megalodon about 16 meters long would have weighed about 48 system of measurement tons ( 53 tons ). A 17-meter ( 56-foot ) C. megalodon would have weighed about 59 measured tons ( 65 tons ), and a 20.3-meter ( 67 foot ) freak would have topped off at 103 metric unit tons ( 114 tons ). ” [ 13 ]

In 2015, Donald Prothero wrote in his book, The Story of Life in 25 Fossils: Tales of Intrepid Fossil Hunters and the Wonders of Evolution, that the maximal mass that the longest Megalodon can reach is up to 103 metric function tons ( 114 light tons ). [ 13 ] This utmost mass calculate is besides supported from the 2008 cogitation. [ 14 ] There are anecdotal reports of teeth larger than those found in museum collections. [ 7 ] Gordon Hubbell from Gainesville, Florida, possesses an upper anterior megalodon tooth whose utmost acme is 18.4 centimeters ( 7.25 in ), one of the largest known tooth specimens from the shark. [ 59 ] In addition, a 2.7-by-3.4-meter ( 9 by 11 foot ) megalodon yack reconstruction developed by fossil orion Vito Bertucci contains a tooth whose utmost stature is reportedly over 18 centimeters ( 7 in ). [ 60 ]

Teeth and morsel military unit

The most coarse fossils of megalodon are its teeth. diagnostic characteristics include a trilateral shape, robust structure, large size, fine serrations, a miss of lateral denticles, and a visible v-shaped neck ( where the settle meets the crown ). [ 31 ] : 55 [ 36 ] The tooth met the jaw at a exorbitant angle, similar to the big white shark. The tooth was anchored by connection tissue fibers, and the choppiness of the basis may have added to mechanical force. [ 61 ] The linguistic side of the tooth, the separate facing the tongue, was convex ; and the labial consonant side, the other side of the tooth, was slightly convex or bland. The anterior teeth were about vertical to the call on the carpet and harmonious, whereas the back tooth teeth were slanted and asymmetrical. [ 62 ]

Megalodon teeth can measure over 180 millimeters ( 7.1 in ) in slant acme ( diagonal distance ) and are the largest of any known shark species, [ 23 ] : 33 implying it was the largest of all macropredatory sharks. [ 40 ] In 1989, a closely complete laid of megalodon tooth was discovered in Saitama, Japan. Another about 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 rule was put together for megalodon in 1996. [ 31 ] : 55 [ 63 ] The alveolar consonant rule of megalodon is : 2.1.7.43.0.8.4. As apparent from the formula, megalodon had four kinds of teeth in its chew the fat : 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 harmonious and does not point mesially ( side of the tooth toward the midplane of the chew where the left and right jaw meet ). Megalodon had a very robust teething, [ 31 ] : 20–21 and had over 250 teeth in its chew, spanning 5 rows. [ 23 ] : four It is possible that big megalodon individuals had jaws spanning roughly 2 meters ( 6.6 foot ) across. [ 23 ] : 129 The teeth were besides serrated, which would have improved efficiency in cutting through pulp or bone. [ 18 ] [ 23 ] : 1 The shark may have been able to open its sass to a 75° lean, though a reconstruction at the USNM approximates a 100° lean. [ 40 ] In 2008, a team of scientists led by S. Wroe conducted an experiment to determine the bite violence of the capital egg white shark, using a 2.5-meter ( 8.2 foot ) long specimen, and then isometrically scaled the results for its maximal size and the conservative minimum and utmost body multitude of megalodon. They placed the sting force of the latter between 108,514 to 182,201 newtons ( 24,395 to 40,960 lbf ) in a back tooth bite, compared to the 18,216 newtons ( 4,095 lbf ) bite force for the largest confirm bang-up white shark, and 7,400 newtons ( 1,700 lbf ) for the placoderm pisces Dunkleosteus. In addition, Wroe and colleagues pointed out that sharks shake sideways while feeding, amplifying the power generated, which would credibly have caused the sum force experienced by prey to be higher than the calculate. [ 14 ] [ 64 ] 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 refer 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 result simulations identified higher levels of tension 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 component. This suggests that megalodon teeth were of a different functional meaning than previously expected, challenging prior interpretations that megalodon ‘s dental morphology was chiefly driven by a dietary careen towards marine mammals. alternatively, the authors proposed that it was a by-product of an increase in soundbox size caused by heterochronic choice. [ 65 ]

Internal anatomy

Megalodon is represented in the dodo record by teeth, vertebral centrum, and coprolites. [ 40 ] [ 66 ] As with all sharks, the skeletal system of megalodon was formed of cartilage quite than bone ; consequently most fossil specimens are ill preserved. [ 67 ] To support its bombastic teething, the jaw of megalodon would have been more massive, hardy, and more strongly developed than those of the great white, which possesses a relatively gracile teething. Its chondrocranium, the cartilaginous skull, would have had a blockier and more robust appearance than that of the big whiten. Its fins were proportional to its larger size. [ 40 ] Some fossil vertebrae have been found. The most noteworthy exercise 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 centrum rate from 55 millimeters ( 2.2 in ) to 155 millimeters ( 6 in ) in diameter. The shark ‘s vertebra may have gotten much bigger, and examination of the specimen revealed that it had a higher vertebral consider than specimens of any known shark, possibly over 200 centra ; only the great white approached it. [ 40 ] 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 centrum range from 100 millimeters ( 4 in ) to 230 millimeters ( 9 in ) in diameter. [ 61 ] The coprolite remains of megalodon are spiral-shaped, indicating that the shark may have had a spiral valve, a corkscrew-shaped dowry of the lower intestines, exchangeable to extant lamniform sharks. Miocene coprolite remains were discovered in Beaufort County, South Carolina, with one measuring 14 curium ( 5.5 in ). [ 66 ] Gottfried and colleagues reconstructed the entire skeleton of megalodon, which was late put on display at the Calvert Marine Museum in the United States and the Iziko South African Museum. [ 40 ] [ 32 ] This reconstruction is 11.3 meters ( 37 foot ) long and represents a mature male, [ 40 ] : 61 based on the ontogenetic changes a capital white shark experiences over the naturally of its life. [ 40 ] : 65

paleobiology

Range and habitat

Megalodon had a cosmopolitan distribution ; [ 27 ] [ 58 ] its fossils have been excavated from many parts of the populace, including Europe, Africa, the Americas, and Australia. [ 31 ] : 67 [ 68 ] It most normally occurred in subtropical to temperate latitudes. [ 27 ] [ 31 ] : 78 It has been found at latitudes improving to 55° N ; its understand tolerate temperature range was 1–24 °C ( 34–75 °F ). [ note 1 ] It arguably had the capacity to endure such low temperatures due to mesothermy, the physiologic capability of big sharks to maintain a higher body temperature than the surround water by conserving metabolic inflame. [ 27 ] Megalodon inhabited a wide compass of nautical environments ( i.e., shoal coastal waters, areas of coastal upwelling, boggy coastal lagoons, flaxen littorals, and offshore deep water environments ), and exhibited a transient life style. Adult megalodon were not abundant in shallow water environments, and by and large inhabited offshore areas. Megalodon may have moved between coastal and oceanic waters, peculiarly in different stages of its life cycle. [ 23 ] : 33 [ 70 ] fossil remains show a tendency for specimens to be larger on average in the Southern Hemisphere than in the Northern, with mean lengths of 11.6 and 9.6 meters ( 38 and 31 foot ), respectively ; and besides larger in the Pacific than the Atlantic, with beggarly lengths of 10.9 and 9.5 meters ( 36 and 31 foot ) respectively. They do not suggest any course of changing body size with absolute latitude, or of change in size over fourth dimension ( although the Carcharocles descent in general is thought to display a course of increasing size over time ). The overall modal length has been estimated at 10.5 meters ( 34 foot ), with the length distribution skewed towards larger individuals, suggesting an ecological or competitive advantage for larger body size. [ 12 ]

Locations of fossils

Megalodon had a global distribution and fossils of the shark have been found in many places around the worldly concern, bordering all oceans of the Neogene. [ 71 ] Megalodon is located in EarthMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonMegalodonclass=notpageimage| [27][71] Locations of megalodon fossil discoveries, jaundiced from the Pliocene and blue from the Miocene

Prey relationships

A square piece of fossil bone with some roughly parallel grooves across it. Vertebra of a whale bitten in half by a megalodon with visible gashes from teeth Though sharks are broadly opportunist feeders, megalodon ‘s great size, high-speed swimming capability, and brawny jaws, coupled with an impressive feed apparatus, made it an vertex predator capable of consuming a across-the-board spectrum of animals. It was credibly one of the most mighty predators to have existed. [ 31 ] : 71–75 [ 14 ] 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 coetaneous great egg white shark ( “ higher up ” in the food chain. ) [ 73 ] 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. [ 51 ] [ 74 ] [ 75 ] In addition to this, they besides targeted seals, sirenians, and sea turtles. [ 70 ] The shark was an opportunist and piscivorous, and it would have besides gone after smaller fish and other sharks. [ 51 ] Many whale bones have been found with bass gashes most likely made by their teeth. [ 31 ] : 75 versatile excavations have revealed megalodon teeth lying close up to the chew remains of whales, [ 31 ] : 75 [ 32 ] and sometimes in direct affiliation with them. [ 22 ] The feeding ecology of megalodon appears to have varied with old age and between sites, like the modern great whiten. It is plausible that the adult megalodon population off the slide of Peru targeted primarily cetothere whales 2.5 to 7 meters ( 8.2 to 23 foot ) in distance and early prey smaller than itself, quite than big whales in the lapp size class as themselves. [ 74 ] interim, juveniles likely had a diet that consisted more of pisces. [ 36 ] [ 76 ]

competition

Megalodon faced a highly competitive environment. [ 77 ] Its position at the circus tent of the food chain [ 78 ] credibly had a significant impact on the structure of nautical communities. [ 77 ] [ 79 ] Fossil evidence indicates a correlation coefficient between megalodon and the emergence and diversification of cetaceans and other marine mammals. [ 31 ] : 78 [ 77 ] 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. [ 31 ] : 74–75 Megalodon were coetaneous with whale-eating serrate whales ( particularly macroraptorial sperm whales and squalodontids ), which were besides probably among the era ‘s vertex predators, and provided competition. [ 77 ] Some reach gigantic sizes, such as Livyatan, estimated between 13.5 to 17.5 meters ( 44 to 57 foot ). Fossilized tooth 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 life of about 25 years. This is very unlike from similarly sized modern killer whale 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. [ 80 ] 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, [ 77 ] [ 81 ] such as the fossil killer whale Orcinus citoniensis which may have been a pack predator and targeted prey larger than itself, [ 32 ] [ 82 ] [ 83 ] [ 84 ] but this inference is disputed, [ 29 ] and it was probably a renaissance man marauder rather than a marine mammal specialist. [ 85 ] Megalodon may have subjected coetaneous white sharks to competitive ejection, as the fossil records indicate that other shark species avoided regions it inhabited by chiefly keeping to the cold waters of the time. [ 86 ] [ 31 ] : 77 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. [ 31 ] : 77 [ 87 ] Megalodon credibly besides had a leaning for cannibalism, much like contemporary sharks. [ 88 ]

Feeding strategies

A painting of a megalodon about to eat two small whales. The mouth is open, and two rows of teeth are visible only on the bottom jaw. There are two other sharks in the background. Eobalaenoptera whales artistic impression of a megalodon quest for twowhales Sharks often employ complex hunt strategies to engage large prey animals. Great white shark hunting strategies may be like to how megalodon hunted its large prey. [ 89 ] Megalodon sting marks on whale fossils suggests that it employed unlike hunting strategies against big raven than the capital flannel shark. [ 51 ] One particular specimen–the remains of a 9-meter ( 30 foot ) long undescribed Miocene whalebone whale–provided the first opportunity to quantitatively analyze its attack behavior. Unlike big whites which target the underbelly of their prey, megalodon credibly targeted the heart and lungs, with their dense teeth adapted for biting through street fighter bone, as indicated by pungency marks inflicted to the rib cage and other bully osseous areas on whale remains. [ 51 ] Furthermore, attack patterns could differ for raven of different sizes. Fossil remains of some little cetaceans, for example cetotheres, suggest that they were rammed with great coerce from below before being killed and eaten, based on compression fractures. [ 89 ] There is besides testify that a possible separate hunt strategy existed for attacking raptorial sperm whales ; a tooth belonging to an undetermined 4 thousand ( 13 foot ) physeteroid close 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 giant in order to inflict a fateful sting, the resulting attack leaving distinctive bite marks on the tooth. While scavenging behavior can not be ruled out as a possibility, the placement of the bite marks is more consistent with predatory attacks than feeding by scavenging, as the call on the carpet is not a peculiarly alimentary area to for a shark feed or focus on. The fact that the sting marks were found on the tooth ‘s roots further suggest that the shark broke the whale ‘s jaw during the bite, suggesting the pungency was extremely brawny. The fossil is besides celebrated as it stands as the first known case of an antagonistic interaction between a sperm whale and an otodontid shark recorded in the fossil record. [ 90 ] During the Pliocene, larger cetaceans appeared. [ 91 ] Megalodon apparently foster refined its search strategies to cope with these big whales. numerous fossilize flipper bones and fag end vertebra 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. [ 14 ] [ 51 ]

Growth and reproduction

Several triangular fossil shark teeth on a white background. C. chubutensis from a probable nursery area in the collection of teeth of juvenile megalodon andfrom a probable nursery area in the Gatún Formation of Panama In 2021, Shimada and colleagues calculated the increase rate of an approximately 9.2 m ( 30 foot ) individual based on presumably annual growth rings on three of its vertebra. They estimated the person died at 46 years of senesce, with a growth rate of 16 centimeter ( 6.3 in ) per class, and a duration of 2 megabyte ( 6 foot 7 in ) at parturition. For a 15 megabyte ( 49 foot ) individual—which they considered to have been the maximum size attainable—this would equate to a life of 88 to 100 years. [ 92 ] Megalodon, like contemporaneous sharks, made habit of greenhouse areas to birth their young in, specifically warm-water coastal environments with big amounts of food and protection from predators. [ 36 ] Nursery sites were identified in the Gatún Formation of Panama, the Calvert Formation of Maryland, Banco de Concepción in the Canary Islands, [ 93 ] and the Bone Valley Formation of Florida. Given that all extant lamniform sharks give parentage to live young, this is believed to have been genuine of megalodon besides. [ 94 ] Infant megalodons were around 3.5 meters ( 11 foot ) at their smallest, [ 40 ] : 61 and the pups were vulnerable to depredation by other shark species, such as the great hammerhead shark ( Sphyrna mokarran ) and the snaggletooth shark ( Hemipristis serra ). [ 36 ] Their dietary preferences display an ontogenetic fault : [ 40 ] : 65 Young megalodon normally preyed on fish, [ 36 ] sea turtles, [ 70 ] dugongs, [ 23 ] : 129 and minor cetaceans ; mature megalodon moved to off-shore areas and consumed large cetaceans. [ 31 ] : 74–75 An exceeding case in the fossil record suggests that juvenile megalodon may have occasionally attacked a lot larger balaenopterid whales. Three tooth marks apparently from a 4-to-7-meter ( 13 to 23 ft ) long Pliocene shark were found on a rib from an ancestral blue sky or humpback whale that showed attest of subsequent heal, which is suspected to have been inflicted by a juvenile megalodon. [ 95 ] [ 96 ]

extinction

Climate change

The Earth experienced a number of changes during the time period megalodon existed which affected marine life. A cooling course starting in the Oligocene 35 Mya ultimately led to glaciation at the poles. geological events changed currents and precipitation ; among these were the settlement of the central american Seaway and changes in the Tethys Ocean, contributing to the cooling system of the oceans. The stall of the Gulf Stream prevented nutrient-rich urine from reaching major marine ecosystems, which may have negatively affected its food sources. The largest fluctuation of ocean levels in the Cenozoic earned run average 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 early marine megafaunal species. [ 97 ] These oceanographic changes, in finical the sea level drops, may have restricted many of the suitable shallow warm-water nursery sites for megalodon, hindering reproduction. [ 98 ] Nursery areas are pivotal for the survival of many shark species, in separate because they protect juveniles from depredation. [ 99 ] [ 36 ] As its rate did not apparently extend into cold waters, megalodon may not have been able to retain a significant total of metabolic inflame, so its range was restricted to shrinking warm waters. [ 98 ] [ 75 ] [ 100 ] Fossil testify confirms the absence of megalodon in regions around the worldly concern where water temperatures had significantly declined during the Pliocene. [ 31 ] : 77 however, an analysis of the distribution of megalodon over prison term suggests that temperature change did not play a send character 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 capacitance to inhabit colder latitudes. It was found in locations with a beggarly temperature ranging from 12 to 27 °C ( 54 to 81 °F ), with a total crop of 1 to 33 °C ( 34 to 91 °F ), indicating that the ball-shaped extent of desirable habitat should not have been greatly affected by the temperature changes that occurred. [ 27 ] This is coherent with evidence that it was a mesotherm. [ 49 ]

Changing ecosystem

Marine mammals attained their greatest diverseness during the Miocene, [ 31 ] : 71 such as with whalebone whales with over 20 recognized Miocene genus in comparison to alone six extant genus. [ 102 ] such diverseness presented an ideal set to support a super-predator such as megalodon. [ 31 ] : 75 By the end of the Miocene, many species of mysticetes had gone extinct ; [ 77 ] surviving species may have been faster swimmers and therefore more elusive prey. [ 23 ] : 46 Furthermore, after the closing of the central american Seaway, tropical whales decreased in diversity and abundance. [ 100 ] The extinction of megalodon correlates with the refuse of many minor mysticete lineages, and it is possible that it was quite dependent on them as a food source. [ 74 ] Additionally, a marine megafauna extinction during the Pliocene was discovered to have eliminated 36 % of all big 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 causing by a decreased food provide [ 97 ] and thus consistent with megalodon being mesothermic. [ 49 ] Megalodon may have been besides large to sustain itself on the declining marine food resources. [ 98 ] The cool of the oceans during the Pliocene might have restricted the entree of megalodon to the polar regions, depriving it of the large whales which had migrated there. [ 100 ] competition from other predators of marine mammals, such as macropredatory sperm whales which appeared in the Miocene, and killer whales and bang-up ashen sharks in the Pliocene, [ 77 ] [ 81 ] [ 103 ] may have besides contributed to the descent and extinction of megalodon. [ 27 ] [ 23 ] : 46–47 [ 98 ] Fossil records indicate that the new whale-eating cetaceans normally occurred at high gear latitudes during the Pliocene, indicating that they could cope with the increasingly prevailing cold water temperatures ; but they besides occurred in the tropics ( for example, Orcinus sp. in South Africa ). [ 81 ] The largest macropredatory sperm whales such as Livyatan are well known from the Miocene, but persisted into the Pliocene, [ 104 ] while others, such as Hoplocetus and Scaldicetus, survived until the early Pleistocene. These may have occupied a niche like to that of killer whale before finally being replaced by them. [ 105 ] The extinction of megalodon set the stage for foster changes in marine communities. The average body size of whalebone whales increased significantly after its disappearance, although possibly due to other, climate-related, causes. [ 106 ] Conversely the increase in whalebone whale size may have contributed to the extinction of megalodon, as they may have preferred to go after smaller whales ; bite marks on big giant species may have come from scavenging sharks. Megalodon may have simply become coextinct with smaller giant species, such as Piscobalaena nana. [ 101 ] The extinction of megalodon had a positive shock on other apex predators of the time, such as the capital white shark, in some cases spreading to regions where megalodon became lacking. [ 27 ] [ 103 ] [ 107 ] A 2019 sketch looking at megalodon teeth from the North Pacific suggested that it died out much earlier about 4–3.6 million years ago, before typical prey items went extinct, due to both climate change and attendant compass fragmentation, equally well as competition from the big white. [ 29 ]

In popular culture

Megalodon has been portrayed in several works of fabrication, including films and novels, and continues to be a popular national for fabrication involving sea monsters. [ 108 ] Three individual megalodon, two adults and one juvenile, were portrayed in BBC ‘s 2003 television documentary series Sea Monsters, where it is defined as a “ venture ” of the earned run average. [ 109 ] The History Channel ‘s Jurassic Fight Club portrays a megalodon attacking a Brygmophyseter sperm giant in Japan. [ 110 ] several films depict megalodon, such as Shark Attack 3: Megalodon and the Mega Shark series ( for case Mega Shark Versus Giant Octopus and Mega Shark Versus Crocosaurus ). [ 108 ] The shark appears in the 2017 videogame Ark: Survival Evolved. [ 111 ] Some stories, such as Jim Shepard ‘s Tedford and the Megalodon, portray a rediscovery of the shark. [ 112 ] Steve Alten ‘s Meg: A Novel of Deep Terror portrays the shark having preyed on dinosaurs with its prologue and cover artwork depicting megalodon killing a Tyrannosaurus in the sea. [ 113 ] The sequels to the book besides ace megalodon : The Trench, Meg: Primal Waters, Meg: Hell’s Aquarium, Meg: Nightstalkers, Meg: Generations, and Meg: Origins, [ 108 ] and there is a film adaptation entitled The Meg released on 10 August 2018. [ 114 ] Animal Planet ‘s pseudo-documentary Mermaids: The Body Found included an brush 1.6 mya between a pod of mermaids and a megalodon. [ 115 ] Later, in August 2013, the Discovery Channel opened its annual Shark Week series with another film for television, Megalodon: The Monster Shark Lives, [ 116 ] a controversial docufiction about the creature that presented allege testify in order to suggest that megalodon was still alive. This plan received criticism for being wholly fabricated ; for exercise, all of the presuppose scientists depicted were paid actors. In 2014, Discovery re-aired The Monster Shark Lives, along with a fresh one-hour program, Megalodon: The New Evidence, and an extra novelize program entitled Shark of Darkness: Wrath of Submarine, resulting in far recoil from media sources and the scientific community. [ 51 ] [ 117 ] [ 118 ] Reports of purportedly fresh megalodon teeth, such as those made by HMS Challenger in 1873 which were mistakenly dated to be around 11,000 to 24,000 years erstwhile, are credibly teeth that were well-preserved by a thick mineral-crust precipitate of manganese dioxide, and so had a lower decay rate and retained a white color during fossilization. Fossil megalodon teeth can vary in color from bone to dark browns and greys, and some fossil teeth may have been redeposited into a younger stratum. The claims that megalodon could remain baffling in the depths, exchangeable to the megamouth shark which was discovered in 1976, are unlikely as the shark lived in affectionate coastal waters and probably could not survive in the cold and nutrient-poor deep sea environment. [ 119 ] [ 120 ] Megalodon teeth are the state dodo of North Carolina. [ 121 ]

See besides

For a topical guide to this national, see Outline of sharks

Notes

  1. ^18O/16O) and carbon (13C/12C), using a [69] Carbonated bio apatite from a megalodon tooth ( of strange reference placement ) dated to 5.75 ± 0.9 Ma in age has been analyzed for isotope ratios of oxygen ( O/O ) and carbon ( C/C ), using a carbonate clumped-isotope thermometer methodology to yield an estimate of the ambient temperature in that individual ‘s environment of 19 ± 4 °C .

References

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