Megalodon

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Megalodon
Artist's impression of a megalodon.  To give an impression of the size, the hunt for two whales of the genus Eobalaenoptera is illustrated in the picture.

Artist's impression of a megalodon. To give an impression of the size, the hunt for two whales of the genus Eobalaenoptera is illustrated in the picture .

Temporal occurrence
Burdigalium ( Miocene ) to Pliocene
10.3 to 3.6 or 2.6 million years
Locations
  • Worldwide
Systematics
without rank: Sharks (selachii)
Superordinate : Galeomorphii
Order : Mackerel shark (Lamniformes)
Family : Otodontidae
Genre : Otodus
Type : Megalodon
Scientific name
Otodus megalodon
( Agassiz , 1835)

The megalodon ( Otodus megalodon , syn .: Megaselachus megalodon , Carcharocles megalodon or Carcharodon megalodon ) is an extinct species of shark from the family of Otodontidae or possibly the mackerel sharks (Lamnidae), which was scientifically described by Louis Agassiz in 1835 . The fossil record of this shark ranges from the Upper Miocene to the Pliocene - Pleistocene boundary 3.6 or 2.6 million years ago and consists of worldwide tooth or (less often) vertebral finds. This species probably preferred the euphotic zone of warm seas . With an estimated maximum length of 15.9 to 20.3 meters, O. megalodon was probably the largest species of shark in Earth's history. Features include enormous body size and large, triangular teeth, which is why this species was previously assigned to the genus Carcharodon . However, more recent studies suggest that O. megalodon was less closely related to the great white shark , and assign the animal to different genera ( Carcharocles , Megaselachus or Otodus , the former the most common in scientific work, the latter the one that is valid today), all of them lie within the extinct family Otodontidae. Despite the sparse remains, numerous studies have been carried out on the physique, bite force and prey of this animal. The name is derived from the Greek μέγας (megas) large and ὀδόν (odon) tooth.

Fossil record and distribution

Tooth of a megalodon
16 meter long plastic living reconstruction of megalodons. A pine tree in the foreground.

The existence of the megalodon is documented by fossil teeth that have been dated to an age of 2 to 17 million years. They have been found in Australia , Europe , Africa , India , Japan , South and North America , suggesting a worldwide distribution. Some of these teeth are more than 18 cm long. Similar to today's great white shark , Otodus megalodon likely preferred coastal regions in warm seas. The teeth are mostly found in sediments that indicate sea depths of less than 200 m, but it is possible that O. megalodon was also found in sea depths of up to 300 m. Its huge teeth were used by Stone Age people for spearheads and the like. Usually only teeth survive in cartilaginous fish and allow conclusions to be drawn about the animal, whereas the calcified skeletal cartilage can hardly be preserved. Therefore there are only isolated vertebrae finds of Megalodon and bite marks on whale bones. The best preserved specimen (IRSNB 3121) is known for a spine from the Miocene of Belgium. Almost 150 vertebrae could be assigned to him. The diameter of the vertebrae ranges from 55 to 155 mm. The specimen is estimated to be 9.2 m tall. The largest known vortex that O. megalodon can be assigned to was found in Denmark and is approximately 230 mm in diameter. Some prismatic cartilage from late Cenozoic layers could belong to O. megalodon , but this is controversial.

features

Teeth and jaws

Jaw reconstruction of a megalodon on display at the American Museum of Natural History
Jaw reconstruction of a megalodon on display at the National Aquarium in Baltimore

O. megalodon had triangular teeth with finely serrated incisal edges and a V-shaped indented tooth root . While the front teeth are large and symmetrical , the rear teeth are more asymmetrical with a slightly sloping crown. In addition to the front and rear teeth possessed O. megalodon (engl. Yet via lateral teeth and intermediate teeth intermediate tooth ) in the maxilla. In the upper jaw , O. megalodon has four front teeth, two intermediate teeth, 14 side teeth and eight rear teeth. In the lower jaw there are six front, 16 side and eight rear teeth. Some studies only differentiate between anterior and posterior teeth. Lateral spikes on the tooth root (which are found in the relatives of O. megalodon ) are missing, but they are occasionally present in young animals. The teeth are wide but not very thick. Based on the size of the teeth and the proportions of today's great white shark, a set of teeth was reconstructed that would have been large enough to devour a person standing upright. The bit is estimated to be over 3 meters wide and over 2.5 meters high. The jaws were reconstructed by Gottfried and colleagues as larger, more robust, more massive and with stronger muscles than those of the great white shark.

whirl

O. megalodon vertebrae are rarely found, but 20 vertebrae from the Gram Formation (Upper Miocene, Denmark) allow insight into the vortex anatomy of O. megalodon . The vertebral bodies were short and tall. All vertebrae had calcified surfaces in the joint cavities . The vertebrae differ from those of the basking shark (which are often found in the same formations and are of similar size) by having thicker walls, a less elongated structure and smaller holes in the middle. It is believed that the spine of O. megalodon consisted of 190 to 200 vertebrae, which means that it would have significantly more vertebrae than that of the great white shark.

size

Megalodon (gray and red) with a whale shark (purple), great white shark (green) and a human (black)

There are different opinions about the size of O. megalodon . Earlier estimates ranged from 9 to 30 meters. The 30-meter data were later (1994) considered to be untenable, subsequent estimates were from 12 to 18 meters as the range for the size of an adult megalodon. Michael Gottfried (1996) calculated the size of the largest specimen known at the time, based on a 168 mm high tooth. The calculations are based on the assumption that the ratio between the height of the front teeth and the overall length was similar to that of a great white shark. This assumption is supported by the fact that great white sharks already have relatively large teeth and that O. megalodon had proportionally wider teeth than the great white shark. Therefore proportionally longer teeth are unlikely. Gottfried gave a conservative calculation of 15.9 meters and about 50 tons, an average figure of 17 meters and 60 tons and a generous figure of 20.2 meters and 103 tons. This method and the figures are relatively widely accepted. Using a comparable method, Kenshu Shimada achieved body lengths of 14.2 to 15.3 meters in 2019, the latter value relating to the tooth also used by Gottfried in 1996. In Shimada's opinion, sizes over 15 meters were seldom reached.

An alternative method uses the tooth width of the upper front teeth to calculate the size. With it, the owner of a tooth 12 centimeters wide can be estimated to have a total length of 16.5 meters. The method is supported by the fact that the jaw circumference (which results from the width of the largest tooth) is proportional to the size of the animal. This principle applies to most large sharks.

Specimens less than 10.5 meters tall are defined as juveniles and specimens less than 4 meters tall as newborns. Gottfried suspects that males reached heights of 10 to 14 meters, while according to his information, females reached 13 to 17 meters.

Originally, comparisons of teeth from different lithostratigraphic units suggested that the size of O. megalodon increased over time. However, a study from 2015 could not confirm this hypothesis based on 544 O. megalodon teeth of all ages. Body length was calculated here using the tooth height, based on the great white shark. The body length of the specimens ranged (according to the above calculation) from 2.2 to 17.9 meters with an average of about 10 meters. The highest average value is found in specimens from the late Miocene.

anatomy

Reconstructed O. megalodon skeleton. Exhibited at the Calvert Marine Museum .

Almost nothing is known about the physique as nothing has been found apart from a few vertebrae and teeth. However, there is a reconstructed skeleton based on that of the great white shark. There O. megalodon is represented with a proportionally wider jaw and proportionally slightly longer fins than today's great white shark; in addition, it is built much stronger in the reconstruction.

Other researchers suspect that O. megalodon was more closely related to the sand tiger shark than to the great white shark and therefore looked more like it. Bretton Kent doubts this, however, as the body of the sand tiger shark is designed for acceleration . To maintain its ability to swim, such a large sand tiger shark needed proportionally much larger fins. They would be a hindrance when swimming because a lot of strength would be required to move. Therefore, Kent suspects that the only body shape that could be considered for such a large shark is one that is designed for energy-saving cruising speed . Kent suggests whale and basking sharks as the basis for body shape. These have a sickle-shaped caudal fin and a small anal fin . This body shape reduces the pulling force when swimming. Other big float (white sharks, mako sharks , marlin and tuna ) also have such features.

Systematics

Originally O. megalodon by Louis Agassiz , the author of the first description, due to the similar tooth shape next to the white shark as another kind in the genus Carcharodon asked. Later researchers supported this classification by stating that the second front tooth in the upper jaw in both types is symmetrical and the largest tooth in the jaw in each case. Comparative studies by Gordon Hubbel contradict this old thesis. Hubbel found that in the great white shark, the third tooth in the front part of the upper jaw is considerably smaller than the first two. With O. megalodon this is only slightly smaller than the first two. In addition, this tooth in the great white shark has a larger angle of inclination. Hubbel concludes from this that O. megalodon was probably not (as previously assumed) the ancestor of the great white shark and has no recent descendants. If one follows the different genus hypothesis, the great white shark likely descended from a group of extinct mako sharks , which is supported by comparative studies between the great white shark and the extinct mako shark Isurus hatalis . In a 2006 analysis, a family tree was published by Nyberg and colleagues:

 Lamniformes  

O. obliquus


   

I. hastalis


   

C. carcharias


   

C. megalodon



Template: Klade / Maintenance / 3

Subsequently, most scientists supported the assumption that O. megalodon belongs to the genus Carcharocles , which was established in 1923. If the Carcharocles theory is followed, megalodon did not belong to the Lamnidae family , but to the Otodontidae family . The genus Carcharocles was probably a sister taxon of the genera Otodus and Parotodus .

The following is a cladogram by Hubbel and colleagues from 2009, which lists Megalodon as the sister taxon of Otodus :

 Lamniformes  


O. obliquus


   

C. megalodon



   

I. hastalis


   

C. carcharias




In the early 2010s showed single phylogenetic analyzes that Megalodon within the otodontidae the terminal form of Otodus forming group and by spinning off into a separate genus Otodus turn poly- or paraphyletic is. Some scientists therefore saw megalodons within the genus Otodus . Ultimately, in 2017, Kenshu Shimada and fellow researchers converted megalodons into the genus Otodus , which was subsequently also supported by other scientists.

Some authors assign O. megalodon to its own genus called Megaselachus , because Megalodon lack the lateral prongs on the tooth root (as in other Carcharocles species). Others use Megaselachus , including Megalodon, as well as Carcharocles as a subgenus of Otodus .

Although not as closely related as originally thought, of the recent mackerel sharks, the great white shark has most in common with O. megalodon and is most commonly used for comparisons. This is in part because the jack sharks are seen as the closest living relatives of the Otodontidae today.

Paleobiology

Biting force

Teeth of a megalodon, in the Natural History Museum Vienna

For O. megalodon there are calculations of the biting forces based on a scaling of the great white shark. The individual used is a cub that is 2.5 m long and weighs 240 kg. In the back of the jaw, the biting force of the individual used is approximately 3.1 kN . The weight values ​​from Gottfried (1996) were used for scaling. For the lower limit (~ 50 t), a bite force of around 109 kN was determined. For the upper limit of 103 t, the result according to computer calculations was 182 kN. This would mean that the biting force of the megalodon would be up to ten times as strong as the biting force of the great white shark calculated in the same study.

The researchers point out that the forces acting on the prey when it bites were probably higher than the calculated values. This is because sharks often shake their jaws when killing their prey.

nutrition

Whale vertebrae with O. megalodon bite marks.

O. megalodon was believed to be a top predator that fed on whales . Tooth marks in the fins and vertebrae of large whales are evidence of this . There are also healed bite marks in a baleen whale vertebra, caused by a rather younger O. megalodon specimen (tooth width of almost 6 cm, calculated length of 4 to 7 m, calculated tooth height of 7 to 8 cm). However, it cannot be determined whether the dental impression came from an O. megalodon , a great white shark, a Parotodus or another animal (e.g. a toothed whale). However, due to the suspected shape of the jaw, a shark is the most likely cause. It is believed that O. megalodon preferred to hunt large whales, juveniles are seen as hunters of smaller whales. Evidence of this is provided by the fact that larger baleen whales were absent from the young animals' preferred hunting grounds. Very young specimens probably ate fish or maybe even dugongs .

In the Pliocene, baleen whales, toothed whales and seals were very numerous. They are seen as suitable prey animals and were probably included in the prey spectrum of O. megalodon . One suspects a connection between the great biodiversity of whales at the beginning of the Miocene and the appearance of O. megalodon .

In shallow, tropical seas, fish, turtles , manatees, and small whales may have been the preferred prey.

Out of 70 examined bites in whale bones, in two-thirds of the cases the fins, shoulders or thoracic vertebrae were the target of the attack. Based on the placement of the bites, it is assumed that O. megalodon first tore off the fins of its victims, rendering them immobile. Since many bites occur in the shoulder or chest region, it is also assumed that O. megalodon attacked the victim's bones, which great white sharks usually avoid. O. megalodon likely attacked important organs such as the lungs or the heart, initiating instant death, unlike the great white shark's bite, which is more likely to bleed the victim to death.

The reasons for the extinction of the O. megalodon are believed to be the disappearance of some whale species and the appearance of new, faster whale species, as well as a cooling of the seas, which led to the extinction of many prey animals.

Nurseries

Teeth of O. megalodon specimens in the Gatun Formation.
Size classes of the O. megalodon specimens from the Gatun Formation.

In 2010, teeth were found in the Gatun Formation ( Panama ) that were assigned to 32 O. megalodon specimens. Of these specimens, 21 were young (height of 4 to 10 meters) and four were newborns (height of 2 to 4 meters). Due to the fact that most of the specimens were not fully grown, it is assumed that the Gatun formation was a nursery where young O. megalodon specimens found shelter from predators and plenty of food. Larger teeth, which probably belonged to adults, were found in the Gatun Formation . They were probably predators of the young animals.

In 2013, 22 more specimens were found in this formation. Most of these were juveniles, which supports the nursery hypothesis. Since teeth of young animals were also found there from other shark species, it is assumed that this region was used as a nursery by various shark species.

Other nurseries have been found near the Peace River in Canada and in the Bone Valley region in Florida . Both regions also have bones from dugongs, dolphins, and small whales. In the latter, bones of named animals with bite marks are known, which probably originate from O. megalodon young animals.

Another possible nursery is in South Carolina . However, it is uncertain whether it is a nursery, as teeth from newborn O. megalodon specimens are missing.

Since nurseries are only known in warm regions, it is assumed that young O. megalodon specimens were more sensitive to cold than adults.

die out

There are various hypotheses about the extinction of O. megalodon . One says that the formation of the Isthmus of Panama blocked the route to the warm waters in the western Atlantic that O. megalodon needed as a nursery.

Other hypotheses suggest that there is too much competition from other predators such as killer whales or great white sharks. Killer whales are (similar to O. megalodon ) hunters of large whales and therefore represented competition for adult animals, while great white sharks were possibly rivals (or hunters) of juveniles. It is also possible that large groups of killer whales hunted O. megalodon .

One final hypothesis is that the prey of O. megalodon also played a role. During the Pliocene, whales developed more advanced caudal fins and swimming muscles. It is therefore possible that O. megalodon could no longer hunt them because it made them too fast. In addition, many whales migrated to the polar regions during this time , where O. megalodon could not follow them.

It is very likely that the cause of O. megalodon's extinction was a combination of several of these factors.

It is also possible that the (presumed) increasing size of O. megalodon played a role, because large animals are usually more sensitive to changes in their environment than smaller ones.

There are suspicions that O. megalodon survived in the deep sea to this day . However, this is unlikely, as life in the deep sea requires adaptations to the extreme conditions there and O. megalodon should have completely changed behavior and anatomy in a very short time.

exhibition

The Upper Austrian State Museum in Linz has been showing a model of the megalodon in its permanent exhibition Nature Upper Austria since 2010. It was created by the Aachen taxidermist Werner Kraus , taking into account recent scientific publications on fossils, including those from the Pisco Formation in Peru . In the Calvert Marine Museum (CVM) in Solomons ( Maryland ) in the US is a reconstructed O. megalodon issued skeleton are. There is also a spine on display in the Musée Royal d'Histoire Naturelle in Brussels .

literature

  • MD Gottfried, LJV Compagno, SC Bowman: Size and Skeletal Anatomy of the Giant “Megatooth” shark Carcharocles megalodon . In: Great White Sharks: The Biology of Carcharodon Carcharias . Academic Press, 1996, ISBN 0-12-415031-4 , pp. 55-66 .
  • Purdy, Robert W .: Paleoecology of Fossil White Sharks . In: Great White Sharks: The Biology of Carcharodon Carcharias . Academic Press, 1996, ISBN 0-12-415031-4 , pp. 67-78 .
  • Pimiento C, Ehret DJ, MacFadden BJ, Hubbell G: Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama . In: PLoS ONE . tape 5 , no. 5 , 2010, p. 1-5 , doi : 10.1371 / journal.pone.0010552 .
  • Catalina Pimiento, Gerardo González-Barba, Dana J. Ehret, Austin JW Hendy, Bruce J. MacFadden and Carlos Jaramillo: Sharks and Rays (Chondrichthyes, Elasmobranchii) from the Late Miocene Gatun Formation of Panama . In: Journal of Paleontology . tape 87 , no. 5 , 2013, ISSN  0022-3360 , p. 755-774 , doi : 10.1666 / 12-117 ( stri.si.edu [PDF]).
  • Catalina Pimiento, Meghan A. Balk: Body-size trends of the extinct giant shark Carcharocles megalodon: a deep-time perspective on marine apex predators . In: Paleobiology . tape 41 , no. 3 , 2015, p. 479–490 , doi : 10.1017 / pab.2015.16 ( journals.cambridge.org [PDF]).
  • Bendix-Almgreen: SE: Carcharodon megalodon from the Upper Miocene of Denmark, with comments on elasmobranch tooth enameloid: coronoi'n . In: Bull. Geol. Soc. Denmark . tape 32 . Copenhagen 1983, p. 1–32 ( 2dgf.dk [PDF]).
  • Orangel Aguilera and Dione Rodrigues de Aguilera: Giant-toothed White Sharks and Wide-toothed Mako (Lamnidae) from the Venezuela Neogene: Their Role in the Caribbean, Shallow-water Fish Assemblage . In: Caribbean Journal of Science . tape 40 , no. 3 , 2004, p. 368-382 ( caribjsci.org [PDF]).
  • Mark Renz: Megalodon: Hunting the Hunter . In: PaleoPress . 2002, ISBN 0-9719477-0-8 , pp. 1-159 ( books.google.com ).
  • Wroe, S., Huber, DR, Lowry, M., McHenry, C., Moreno, K., Clausen, P., Ferrara, TL, Cunningham, E., Dean, MN, and Summers, A. P: Three -dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite? In: Journal of Zoology . tape 276 , no. 4 , 2008, ISSN  0952-8369 , p. 336–342 , doi : 10.1111 / j.1469-7998.2008.00494.x ( bio-nica.info [PDF; 91 kB ]).
  • Nyberg KG, Ciampaglio CN, Wray GA: Tracing the ancestry of the Great White Shark . In: Journal of Vertebrate Paleontology . tape 26 , no. 4 , 2006, p. 806-814 , doi : 10.1671 / 0272-4634 (2006) 26 [806: TTAOTG] 2.0.CO; 2 ( biology.duke.edu [PDF]).

Web links

Commons : Category “Carcharodon megalodon”  - collection of images, videos and audio files

Individual evidence

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  2. Catalina Pimiento, Christopher F. Clements: When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record . In: PLOS ONE . tape 9 , no. 10 , October 22, 2014, p. e111086 , doi : 10.1371 / journal.pone.0111086 .
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  7. Aguilera and Rodrigues de Aguilera 2004, p. 368.
  8. a b c d John Clay Bruner: The Megatooth shark, Carcharodon megalodon Rough toothed, huge toothed . In: Dept. of Biological Sciences and Laboratory for Vertebrate Paleontology . University of Alberta, Edmonton, Alberta, T6G 2E9 Canada 1997 ( academia.edu ).
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  14. a b Bendix-Almgreen 1983, p. 7.
  15. Gottfried et al. 1996, p. 58.
  16. Pimiento et al. 2010, Fig. S1
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  19. Gottfried et al. 1996, pp. 59-61.
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  25. Gottfried et al. 1996, p. 61.
  26. a b Pimiento, C., Balk, M., Catalina: Chronoclinal body size increase of the extinct giant shark Megalodon (Carcharocles megalodon) . In: Society of Vertebrate Paleontology . 2013.
  27. Pimiento et al. 2015, p. 481.
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  32. Purdy 1996, p. 69.
  33. Renz 2002, pp. 23-24.
  34. Nyberg et al. 2006, p. 806.
  35. Nyberg et al. 2006, p. 807.
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  38. Ehret DJ, Hubbell G., Macfadden BJ: Exceptional preservation of the white shark Carcharodon from the early Pliocene of Peru . In: Journal of Vertebrate Paleontology . tape 29 , no. 1 , 2009, p. 3 , doi : 10.1671 / 039.029.0113 ( forummf.free.fr [PDF]). forummf.free.fr ( Memento of the original from October 20, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / forummf.free.fr
  39. Mikael Siverson, Johan Lindgren, Michael G. Newbrey, Peter Cederström and Todd D. Cook: Late Cretaceous (Cenomanian-Campanian) mid-palaeolatitude sharks of Cretalamna appendiculata type . In: Acta Palaeontologica Polonica . 2013, p. 2 , doi : 10.4202 / app.2012.0137 .
  40. Kenshu Shimada, Richard E. Chandler, Otto Lok Tao Lam, Takeshi Tanaka and David J. Ward: A new elusive otodontid shark (Lamniformes: Otodontidae) from the lower Miocene, and comments on the taxonomy of otodontid genera, including the 'megatoothed 'clade. In: Historical Biology. Volume 29 (5), 2017, pp. 704-714, doi: 10.1080 / 08912963.2016.1236795
  41. a b Nicolae Trif, Rodica Ciobanu and Vlad Codrea: The first record of the giant shark Otodus megalodon (Agassiz, 1835) from Romania. In: Brukenthal. Acta Musei. Volume 11 (3), 2016, pp. 507-526.
  42. Zhelezko V Kozlov V: Elasmobranchii and Paleogene biostratigraphy of Transurals and Central Asia. Materials on stratigraphy palaeontology of the Urals . In: Ekkaterinburg: Russian Academy of Sciences Urals Branch Uralian Regional Interdepartment Stratigraphical Commission . tape 3 , 1999, p. 324 .
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  44. Wroe et al. 2008, p. 339.
  45. a b Olivier Lambert, Giovanni Bianucci, Klaas Post, Christian de Muizon, Rodolfo Salas-Gismondi, Mario Urbina, Jelle Reumer: The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru. In: Nature . Volume 466, pp. 105-108, July 1, 2010. ateneo.unmsm.edu.pe (PDF; 527 kB).
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  48. a b Renz 2002, pp. 32–33.
  49. Aguilera and Rodrigues de Aguilera 2004, p. 370.
  50. Wroe et al. 2008, p. 340.
  51. Pimiento et al. 2013, p. 770.
  52. Purdy 1996, pp. 76-77.
  53. a b c Renz 2002, p. 41.
  54. Gottfried et al. 1996, p. 65.
  55. Renz 2002, p. 40.
  56. ^ Austrian State Museum Linz