While regarded as one of the largest and most powerfulpredators to have ever lived, megalodon is only known from fragmentary remains, and its appearance and maximum size are uncertain. Scientists have argued whether its body form was more stocky or elongated than the modernlamniform sharks. Maximum body length estimates between 14.2 and 24.3 metres (47 and 80 ft) based on various analyses have been proposed, though themodal lengths for individuals of all ontogenetic stages from juveniles to adults are estimated at 10.5 meters (34 ft). Theirteeth were thick and robust, built for grabbing prey and breaking bone, and their large jaws could exert a bite force of up to 108,500 to 182,200 newtons (24,390 to 40,960 lbf).
Megalodon probably had a major impact on the structure ofmarine communities. The fossil record indicates that it had acosmopolitan distribution. It probably targeted large prey, such aswhales,seals andsea 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-eatingcetaceans, such asLivyatan and othermacroraptorial sperm whales and possibly smaller ancestral killer whales (Orcinus). As the shark preferred warmer waters, it is thought that oceanic cooling associated with the onset of theice 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 ofbaleen whales and a shift in their distribution toward polar regions may have reduced megalodon's primary food source. The shark's extinction coincides with agigantism trend in baleen whales.
Megalodon teeth have been excavated and used since ancient times. They were a valued artifact amongstpre-Columbian cultures in theAmericas for their large sizes and serrated blades, from which they were modified intoprojectile points, knives, jewelry, and funeral accessories.[8][9] At least some, such as thePanamanianSitio Conte societies, seemed to have used them primarily for ceremonial purposes.[9] Mining[10] of megalodon teeth by theAlgonquin peoples in theChesapeake Bay and their selective trade with theAdena culture inOhio occurred as early as430 BC.[8] The earliest written account of megalodon teeth was byPliny the Elder in anAD 73 volume ofHistoria Naturalis, who described them as resembling petrified humantongues thatRoman folklorists believed to have fallen from the sky duringlunar eclipses and called themglossopetrae ("tongue stones").[11] The purported tongues were later thought in a 12th-centuryMaltese tradition to have belonged to serpents thatPaul the Apostle turned to stonewhile shipwrecked there, and were givenantivenom powers by the saint.[12]Glossopetrae reappeared throughout Europe in late 13th to 16th century literature, ascribed with moresupernatural properties that cured a wider variety ofpoisons. Use of megalodon teeth for this purpose became widespread amongmedieval andRenaissance 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-madeGoa stones.[11]
Mercati's depictions of a great white's head and teeth (left) and fossil megalodon and great white teeth (right), reused bySteensen in 1667
The true nature of theglossopetrae as shark's teeth was held by some since at least 1554, whencosmographerAndré Thevet described it as hearsay, although he did not believe it. The earliest scientific argument for this view was made by Italian naturalistFabio Colonna, who in 1616 published an illustration of a Maltese megalodon tooth alongside agreat 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 burningglossopetrae samples, from which he observedcarbon residue he interpreted as proving an organic origin.[12] 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.[13] The shark tooth argument was academically raised again during the late 17th century byEnglish scientistsRobert Hooke,John Ray, andDanish naturalistNiels Steensen (LatinizedNicholas Steno).[14] 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 byPapalphysicianMichele Mercati, who also had in possession the head of a great white, for his bookMetallotheca. The work remained unpublished in Steensen's time due to Mercati's premature death, and the former reused the two illustrations per suggestion byCarlo Roberto Dati, who thought a depiction of the actual dissected shark was unsuitable for readers.[15] Steensen also stood out in pioneering astratigraphic 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 aperiod of flood that was later covered by terrestrial layers and uplifted by geologic activity.[13]
Swiss naturalistLouis Agassiz gave megalodon itsscientific name in his seminal 1833-1843 workRecherches sur les poissons fossiles (Research on fossil fish). He named itCarcharias megalodon in an 1835 illustration of theholotype and additional teeth,congeneric with the modernsand tiger shark.[1][2] Thespecific name is aportmanteau of theAncient Greek words μεγάλος (megálos, meaning "big") and ὀδών (odṓn, meaning "tooth"),[16][17] combined meaning "big tooth". Agassiz referenced the name as early as 1832, but because specimens were not referenced they are nottaxonomically recognized uses.[2] Formal description of the species was published in an 1843 volume, where Agassiz revised the name toCarcharodon megalodon as its teeth were far too large for the formergenus and more alike to the great white shark.[1] He also erroneously identified several megalodon teeth as belonging to additional species eventually namedCarcharodon rectidens,Carcharodon subauriculatus,Carcharodon productus, andCarcharodon polygurus.[1][18] BecauseCarcharodon megalodon appeared first in the 1835 illustration, the remaining names are consideredjunior synonyms under theprinciple of priority.[2][18]
While the earliest megalodon remains have been reported from theLate Oligocene, around 28million years ago (Mya),[19][20] there is disagreement as to when it appeared, with dates ranging to as young as 16 mya.[21] It has been thought that megalodon became extinct around the end of thePliocene, about 2.6 Mya;[21][22] claims ofPleistocene megalodon teeth, younger than 2.6 million years old, are considered unreliable.[22] A 2019 assessment moves the extinction date back to earlier in the Pliocene, 3.6 Mya.[23]
Megalodon is considered to be a member of the family Otodontidae, genusOtodus, as opposed to its previous classification into Lamnidae, genusCarcharodon.[21][24][22][7][25] Megalodon's classification intoCarcharodon was due to dental similarity with the great white shark, but most authors believe that this is due toconvergent evolution. In this model, the great white shark is more closely related to the extinctbroad-toothed mako (Cosmopolitodus 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 themako sharks (Isurus spp.), with acommon ancestor around 4 Mya.[26][27] 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.[28]: 23–25
The genusCarcharocles contains four species:C. auriculatus,C. angustidens,C. chubutensis, andC. megalodon.[29]: 30–31 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 thelateralcusps.[29]: 28–31 [30] 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.[31] Lateral cusplets were finally lost in a gradual process that took roughly 12 million years during the transition betweenC. chubutensis andC. megalodon.[31] The genus was proposed by D. S. Jordan and H. Hannibal in 1923 to containC. auriculatus. In the 1980s, megalodon was assigned toCarcharocles.[26][29]: 30 Before this, in 1960, the genusProcarcharodon was erected by Frenchichthyologist Edgard Casier, which included those four sharks and was considered separate from the great white shark. It is since considered ajunior synonym ofCarcharocles.[29]: 30 The genusPalaeocarcharodon was erected alongsideProcarcharodon 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 anevolutionary dead-end and unrelated to theCarcharocles sharks by authors who reject that model.[28]: 70
Thegreat white shark (Carcharodon carcharias) and megalodon were previously thought to be close relatives.[26][27]
Another model of the evolution of this genus, also proposed by Casier in 1960, is that the direct ancestor of theCarcharocles is the sharkOtodus obliquus, which lived from thePaleocene through theMiocene epochs, 60 to 13 Mya.[27][30] The genusOtodus is ultimately derived fromCretolamna, a shark from theCretaceous period.[7][32] In this model,O. obliquus evolved intoO. aksuaticus, which evolved intoC. auriculatus, and then intoC. angustidens, and then intoC. chubutensis, and then finally intoC. megalodon.
Another model of the evolution ofCarcharocles, proposed in 2001 by paleontologistMichael 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 achronospecies.[29]: 17 [20][33] Some authors suggest thatC. auriculatus,C. angustidens, andC. chubutensis should be classified as a single species in the genusOtodus, leavingC. megalodon the sole member ofCarcharocles.[20][34]
The genusCarcharocles may be invalid, and the shark may actually belong in the genusOtodus, making itOtodus megalodon. A 1974 study on Paleogene sharks byHenri Cappetta erected thesubgenusMegaselachus, classifying the shark asOtodus (Megaselachus)megalodon, along withO. (M.) chubutensis.[5] A 2006 review ofChondrichthyes elevatedMegaselachus to genus, and classified the sharks asMegaselachus megalodon andM. chubutensis. The discovery of fossils assigned to the genusMegalolamna in 2016 led to a re-evaluation ofOtodus, which concluded that it isparaphyletic, that is, it consists of alast common ancestor but it does not include all of its descendants. The inclusion of theCarcharocles sharks inOtodus would make itmonophyletic, with thesister clade beingMegalolamna.[7]
The cladogram below represents the hypothetical relationships between megalodon and other sharks, including the great white shark. Modified from Shimada et al. (2016),[7] Ehret et al., (2009),[27] and the findings of Siversson et al. (2015).[32]
Lateral view of anOtodus megalodon restoration based onCretalamna and modernlamnids
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.[35]
Another interpretation is that megalodon bore a similarity to thewhale shark (Rhincodon typus) or thebasking 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 acaudal keel present on either side of the tail fin (on thecaudal peduncle). This build is common in other large aquatic animals, such as whales, tuna, and other sharks, in order to reducedrag while swimming. The head shape can vary between species as most of the drag-reducing adaptations are toward the tail-end of the animal.[29]: 35–36
It has also been suggested in 2024 that megalodon had a more elongated body plan than previously thought.[36] Shimada et al. (2025) also supported this hypothesis based on comparing the proportions of the neurocranium and caudal fin relative to its trunk to those of other laminforms (excludinggoblin sharks andthresher sharks). They also estimated that the maximum body length of megalodon would have been significantly longer than previously published estimates.[37]
In 2023, Shimada and colleagues reported the associated set of megalodon remains found with placoid scales, which are 0.3 to 0.8 millimetres (0.012 to 0.031 in) in maximum width, and have broadly spaced keels. The quantitative relationship of the distance between each keel and the reported maximum cruising speeds of modern sharks were consistent with the hypothesis that megalodon was regionally endothermic but generally not a fast swimmer, though it may have been capable of occasional burst swimming to capture prey.[38]
Size
Size comparison of the great white and whale shark to estimates for megalodon
Proportions of megalodon at lengths of 3 m (10 ft), 8 m (26 ft), and 16 m (52 ft), extrapolated from extant relatives, with a 1.65 m (5 ft 5 in) diver
Theorized size variation of O. megalodon with individuals of 23 m (75 ft), 18.6 m (61 ft), 15 m (49 ft) adults and a 10 m (33 ft) juvenile
Due to fragmentary remains, there have been many contradictory size estimates for megalodon, as they can only be drawn from fossil teeth and vertebrae.[39]: 87 [40] 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.[35][41][42][25]
Size estimates of megalodon vary depending on the method used and the hypothesis of its body plan, with maximum total length estimates ranging from 14.2–24.3 meters (47–80 ft).[35][25][37] Gottfried (1996) suggested that mature male megalodon may have had a body mass of 12.6 to 33.9 t (13.9 to 37.4 short tons; 12.4 to 33.4 long tons), and mature females may have been 27.4 to 59.4 t (30.2 to 65.5 short tons; 27.0 to 58.5 long tons), assuming that males could range in length from 10.5 to 14.3 meters (34 to 47 ft) and females 13.3 to 17 meters (44 to 56 ft).[35] A 2015 study estimated themodal total body length at 10.5 meters (34 ft), calculated from 544 megalodon teeth, found throughout geological time and geography, including juveniles and adults ranging from 2.2 to 17.9 metres (7.2 to 58.7 ft) in total length.[43][24] In comparison, large great white sharks are generally around 6 meters (20 ft) in length, with a few contentious reports suggesting larger sizes.[44][45][35] The whale shark is the largest living fish, with one large female reported with a precaudal length of 15 meters (49 ft) and an estimated total length of 18.8 meters (62 ft).[44][46] It is possible that different populations of megalodon around the globe had different body sizes and behaviors due to different ecological pressures.[24] Megalodon is thought to have been the largest macropredatory shark that ever lived.[35]
In 2020, Cooper and his colleagues reconstructed a 2D model of megalodon based on the dimensions of all the extantlamnid sharks and suggested that a 16 meters (52 ft) long megalodon would have had a 4.65 m (15.3 ft) long head, 1.41 m (4 ft 8 in) tall gill slits, a 1.62 m (5 ft 4 in) tall dorsal fin, 3.08 m (10 ft 1 in) long pectoral fins, and a 3.85 m (12 ft 8 in) tall tail fin.[47] 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 61.56 t (67.86 short tons; 60.59 long tons) for a 16 meters (52 ft) long megalodon, higher than the previous estimates. A 11.1 metres (36 ft) longvertebral column specimen IRSNB P 9893 (formerly IRSNB 3121) fromBelgium, likely belonging to a 46 year old individual, 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.[48] Because the total body length of IRSNB P 9893 was previously estimated around 9.2 metres (30 ft),[35] the longer body length estimate by Cooper et al. (2022) led to an alternative hypothesis that megalodon had a more elongated body form than previously thought based on comparison between IRSNB P 9893 and corresponding parts of the extant white sharks' vertebral columns.[36] Shimada et al. (2025) also supported the elongated body plan hypothesis, and this resulted in a similar body length estimate of 16.4 metres (54 ft) and a significantly lower body mass estimate between 26.9–33.7 metric tons (29.7–37.1 short tons) for IRSNB P 9893.[37]
A 2015 study linking shark size and typical swimming speed estimated that megalodon would have typically swum at 18 kilometers per hour (11 mph)–assuming that its body mass was typically 48 t (53 short tons; 47 long tons)–which is consistent with other aquatic creatures of its size, such as thefin whale (Balaenoptera physalus) which typically cruises at speeds of 14.5 to 21.5 km/h (9.0 to 13.4 mph).[49] In 2022, Cooper and his colleagues converted this calculation into relative cruising speed (body lengths per second), resulting in a mean absolute cruising speed of 5 kilometers per hour (3.1 mph) and a mean relative cruising speed of 0.09 body lengths per second for a 16 meters (52 ft) 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.[48]
Sculpture in the Museum of Evolution in Puebla, Mexico
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 itsmetabolic rate and swimming speed. The otodontid sharks have been considered to have beenectotherms, 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.[50]
In 2020, Shimada and colleagues suggested large size was instead due tointrauterine 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 withclaspers, like modern cartilaginous fish).[51]
Maximum estimates
The first attempt to reconstruct the jaw of megalodon was made byBashford Dean in 1909, displayed at theAmerican Museum of Natural History. From the dimensions of this jaw reconstruction, it was hypothesized that megalodon could have approached 30 meters (98 ft) in length. Dean had overestimated the size of the cartilage on both jaws, causing it to be too tall.[52][53]
In 1973, John E. Randall, anichthyologist, used theenamel 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 13 meters (43 ft).[54] However, tooth enamel height does not necessarily increase in proportion to the animal's total length.[28]: 99
In 1994, marine biologists Patrick J. Schembri and Stephen Papson opined thatO. megalodon may have approached a maximum of around 24 to 25 meters (79 to 82 ft) in total length.[55][56]
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).[57][35] Using this tooth height regression equation, the authors estimated a total length of 15.9 meters (52 ft) based on a tooth 16.8 centimeters (6.6 in) 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 6-meter (20 ft) long female great white, which the authors considered the largest 'reasonably trustworthy' total length, produced an estimate of 16.8 meters (55 ft). However, based on the largest female great white reported, at 7.1 meters (23 ft), they estimated a maximum estimate of 20.2 meters (66 ft).[35]
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 1 centimeter (0.39 in) of root width, there are approximately 1.4 meters (4.6 ft) 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 12 centimeters (4.7 in), which yielded 16.5 meters (54 ft) in total length.[29]: 88
In 2002, paleontologist Kenshu Shimada ofDePaul 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 dentalhomology between megalodon and the great white shark, and that the growth rate between the crown and root is notisometric, which he considered in his model. Using this model, the upper anterior tooth possessed by Gottfried and colleagues corresponded to a total length of 15 meters (49 ft).[58] Among several specimens found in theGatún Formation of Panama, one upper lateral tooth was used by other researchers to obtain a total length estimate of 17.9 meters (59 ft) using this method.[34][59]
A C. megalodon about 16 meters long would have weighed about 48 metric tons (53 tons). A 17-meter (56-foot) C. megalodon would have weighed about 59 metric tons (65 tons), and a 20.3-meter (67 foot) monster would have topped off at 103 metric tons (114 tons).[60]
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,[60] a methodology also used for the 2008 study which supports the maximum mass estimate.[61]
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 14.2 meters (47 ft). The tooth with the tallest total height, 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 total height tooth regression equation proposed by Gottfried and colleagues produced an estimate of 15.3 meters (50 ft).[25][42]
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 ± 9 metres (30 ft)), 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 13.3 centimeters (5.2 in), they estimated a maximum body length of approximately 20 meters (66 ft), with a range of error of approximately ± 3.5 metres (11 ft).[42] This maximum length estimate was also supported by Cooper and his colleagues in 2022.[48]
In 2025, Shimada and colleagues proposed a significantly higher maximum length estimate of 24.3 metres (80 ft) based on the hypothesis that megalodon had a much more elongated body plan than previously thought. An individual of such length was estimated to have weighed between 83.6 and 104.7 metric tons (92.2 and 115.4 short tons), with an estimated cruising speed of 2.1–3.5 kilometers per hour (1.3–2.2 mph).[37]
There are anecdotal reports of teeth larger than those found in museum collections.[25] Gordon Hubbell fromGainesville, Florida, possesses an upper anterior megalodon tooth whose maximum height is 18.4 centimeters (7.25 in), one of the largest known tooth specimens from the shark.[62] In addition, a 2.7-by-3.4-meter (9 by 11 ft) megalodon jaw reconstruction developed by fossil hunter Vito Bertucci contains a tooth whose maximum height is reportedly over 18 centimeters (7 in).[63]
The most common fossils of megalodon are its teeth. Diagnostic characteristics include a triangular shape, robust structure, large size, fine serrations, a lack oflateral denticles, and a visible V-shaped neck (where theroot meets thecrown).[28]: 55 [34] The tooth met the jaw at a steep angle, similar to the great white shark. The tooth was anchored byconnective tissue fibers, and the roughness of the base may have added tomechanical strength.[64] 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.[65]
Megalodon teeth can measure over 180 millimeters (7.1 in) in slant height (diagonal length) and are the largest of any known shark species,[29]: 33 implying it was the largest of all macropredatory sharks.[35] In 1989, a nearly complete set of megalodon teeth was discovered inSaitama, Japan. Another nearly complete associated megalodon dentition was excavated from theYorktown Formations in the United States, and served as the basis of a jaw reconstruction of megalodon at theNational Museum of Natural History (USNM). Based on these discoveries, an artificialdental formula was put together for megalodon in 1996.[28]: 55 [66]
The dental formula of megalodon is:2.1.7.43.0.8.4. 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 themidline of the jaws where the left and right jaws meet). Megalodon had a very robust dentition,[28]: 20–21 and had over 250 teeth in its jaws, spanning 5 rows.[29]: iv It is possible that large megalodon individuals had jaws spanning roughly 2 meters (6.6 ft) across.[29]: 129 The teeth were alsoserrated, which would have improved efficiency in cutting through flesh or bone.[26][29]: 1 The shark may have been able to open its mouth to a 75° angle, though a reconstruction at the USNM approximates a 100° angle.[35]
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 2.5-meter (8.2 ft) long specimen, and thenisometrically 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 108,514 to 182,201 newtons (24,395 to 40,960 lbf) in a posterior bite, compared to the 18,216 newtons (4,095 lbf) bite force for the largest confirmed great white shark, and 7,495 newtons (1,685 lbf) for theplacoderm fishDunkleosteus. 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.[61][67]
In 2021, Antonio Ballell and Humberto Ferrón usedFinite 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 asO. obliquus andO. 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 byheterochronic selection.[68]
Internal anatomy
Restoration of the skeleton ofO. megalodon based on modern lamniforms, with known elements highlighted
Megalodon is represented in the fossil record by teeth,vertebral centra, andcoprolites.[35][69] As with all sharks, theskeleton of megalodon was formed ofcartilage rather thanbone; consequently most fossil specimens are poorly preserved.[70] 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. Itschondrocranium, 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.[35]
Some fossilvertebrae have been found. The most notable example is a partially preserved vertebral column of a single specimen, excavated in theAntwerp Basin, Belgium, in 1926. It comprises 150 vertebralcentra, with the centra ranging from 55 millimeters (2.2 in) to 155 millimeters (6 in) 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.[35] Another partially preserved vertebral column of a megalodon was excavated from theGram Formation in Denmark in 1983, which comprises 20 vertebral centra, with the centra ranging from 100 millimeters (4 in) to 230 millimeters (9 in) in diameter.[64]
The coprolite remains of megalodon are spiral-shaped, indicating that the shark may have had aspiral valve, a corkscrew-shaped portion of thelower intestines, similar to extant lamniform sharks. Miocene coprolite remains were discovered inBeaufort County, South Carolina, with one measuring 14 cm (5.5 in).[69]
Gottfried and colleagues reconstructed the entire skeleton of megalodon, which was later put on display at theCalvert Marine Museum in the United States and theIziko South African Museum.[35][30] This reconstruction is 11.3 meters (37 ft) long and represents a mature male,[35]: 61 based on theontogenetic changes a great white shark experiences over the course of its life.[35]: 65
Paleobiology
Prey relationships
Vertebra of awhale bitten in half by a megalodon with visible gashes from teeth.
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 anapex predator capable of consuming a broad spectrum of animals. Otodus megalodon was probably one of the most powerful predators to have existed.[48] A study focusing oncalcium isotopes of extinct and extantelasmobranch sharks and rays revealed that megalodon fed at a highertrophic level than the contemporaneous great white shark ("higher up" in thefood chain).[71]
Fossil evidence indicates that megalodon preyed upon many cetacean species, such as dolphins, small whales,cetotheres,squalodontids (shark toothed dolphins),sperm whales,bowhead whales, androrquals.[52][72][73] In addition to this, they also targeted seals, sirenians, and sea turtles.[74] The shark was an opportunist andpiscivorous, and it would have also gone after smaller fish and other sharks.[52] Many whale bones have been found with deep gashes most likely made by their teeth.[28]: 75 Various excavations have revealed megalodon teeth lying close to the chewed remains of whales,[28]: 75 [30] and sometimes in direct association with them.[75]
The feeding ecology of megalodon appears to have varied with age and between sites, like the moderngreat white shark. It is plausible that the adult megalodon population off the coast ofPeru targeted primarilycetothere whales 2.5 to 7 meters (8.2 to 23 ft) in length and other prey smaller than itself, rather than large whales in the same size class as themselves.[72] Meanwhile, juveniles likely had a diet that consisted more of fish.[34][76]
Feeding strategies
Artistic impression of a megalodon pursuing twoEobalaenoptera whales
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.[77] Megalodon bite marks on whale fossils suggest that it employed different hunting strategies against large prey than the great white shark.[52]
One particular specimen–the remains of a 9-meter (30 ft) 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.[52] 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 oncompression fractures.[77]
There is also evidence that a possible separate hunting strategy existed for attacking raptorial sperm whales; a tooth belonging to an undetermined 4 m (13 ft) physeteroid closely resembling those ofAcrophyseter discovered in the Nutrien Aurora Phosphate Mine in North Carolina suggests that a megalodon orO. 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.[78]
During the Pliocene, larger cetaceans appeared.[79] Megalodon apparently further refined its hunting strategies to cope with these large whales. Numerous fossilizedflipper bones andtail 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.[61][52]
Growth and reproduction
Collection of teeth of juvenile megalodon andO. chubutensis from a probable nursery area in theGatún Formation of Panama
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.[80] In 2021, Shimada and colleagues calculated the growth rate of an approximately 9.2 m (30 ft) 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 16 cm (6.3 in) per year, and a length of 2 m (6 ft 7 in) at birth. For a 15 m (49 ft) individual – which they considered to have been the maximum size attainable – this would equate to a lifespan of 88 to 100 years.[81] However, Cooper and his colleagues in 2022 estimated the length of this 46 year old individual at nearly 16 m (52 ft) based on the 3D reconstruction which resulted in the complete vertebral column to be 11.1 m (36 ft) 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.[48]
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.[34] Nursery sites were identified in the Gatún Formation of Panama, theCalvert Formation of Maryland, Banco de Concepción in theCanary Islands,[82] and theBone Valley Formation of Florida. Given that all extantlamniform sharks give birth to live young, this is believed to have been true of megalodon also.[83] Infant megalodons were around 3.5 meters (11 ft) at their smallest,[35]: 61 and the pups were vulnerable to predation by other shark species, such as thegreat hammerhead shark (Sphyrna mokarran) and thesnaggletooth shark (Hemipristis serra).[34] Their dietary preferences display anontogenetic shift:[35]: 65 Young megalodon commonly preyed on fish,[34] sea turtles,[74]dugongs,[29]: 129 and small cetaceans; mature megalodon moved to off-shore areas and consumed large cetaceans.[28]: 74–75
An exceptional case in the fossil record suggests that juvenile megalodon may have occasionally attacked much largerbalaenopterid 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 or humpback whale that showed evidence of subsequent healing, which is suspected to have been inflicted by a juvenile megalodon.[84][85]
Paleoecology
Range and habitat
Megalodon had acosmopolitan distribution;[21][59] its fossils have been excavated from many parts of the world, including Europe, Africa, the Americas, and Australia.[28]: 67 [86] It most commonly occurred insubtropical totemperate latitudes.[21][28]: 78 It has been found at latitudes up to55° N; its inferred tolerated 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 physiological capability of large sharks to maintain a higher body temperature than the surrounding water by conservingmetabolic heat.[21]
Megalodon inhabited a wide range of marine environments (i.e., shallow coastal waters, areas of coastalupwelling, swampy coastallagoons, sandylittorals, 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.[29]: 33 [74]
Fossil remains show a trend 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 ft), respectively; and also larger in the Pacific than the Atlantic, with mean lengths of 10.9 and 9.5 meters (36 and 31 ft) respectively. They do not suggest any trend of changing body size with absolute latitude, or of change in size over time (although theCarcharocles lineage in general is thought to display a trend of increasing size over time). The overallmodal length has been estimated at 10.5 meters (34 ft), with the length distribution skewed towards larger individuals, suggesting an ecological or competitive advantage for larger body size.[24]
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 theNeogene.[88]
Megalodon faced a highlycompetitive environment.[93] Its position at the top of the food chain[94] probably had a significant impact on the structuring of marine communities.[93][95] Fossil evidence indicates a correlation between megalodon and theemergence and diversification of cetaceans and other marine mammals.[28]: 78 [93] 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.[28]: 74–75
Megalodon were contemporaneous with whale-eatingtoothed whales (particularlymacroraptorial sperm whales andsqualodontidae), which were also probably among the era's apex predators, and provided competition.[93] Some attained gigantic sizes, such asLivyatan, estimated between 13.5 to 17.5 meters (44 to 57 ft). Fossilized teeth of an undetermined species of suchphyseteroids from Lee Creek Mine, North Carolina, indicate it had a maximum body length of 8 to 10 m (26 to 33 ft) 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 orLivyatan.[96] By theLate Miocene, around 11 Mya, macroraptorials experienced a significant decline in abundance and diversity. Other species may have filled this niche in the Pliocene,[93][97] such as the fossil killer whaleOrcinus citoniensis which may have been apack predator and targeted prey larger than itself,[30][98][99][100] but this inference is disputed,[23] and it was probably a generalist predator rather than a marine mammal specialist.[101]
Megalodon may have subjected contemporaneous white sharks tocompetitive exclusion, as the fossil records indicate that other shark species avoided regions it inhabited by mainly keeping to the colder waters of the time.[102][28]: 77 In areas where their ranges seemed to have overlapped, such as in PlioceneBaja 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.[28]: 77 [103] Megalodon probably also had a tendency forcannibalism, much like contemporary sharks.[104]
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 theCentral American Seaway and changes in theTethys Ocean, contributing to the cooling of the oceans. The stalling of theGulf 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 theCenozoic era occurred in thePlio-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.[105] 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.[106] Nursery areas are pivotal for the survival of many shark species, in part because they protect juveniles from predation.[107][34]
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.[106][73][108] Fossil evidence confirms the absence of megalodon in regions around the world where water temperatures had significantly declined during the Pliocene.[28]: 77 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 12 to 27 °C (54 to 81 °F), with a total range of 1 to 33 °C (34 to 91 °F), indicating that the global extent of suitable habitat should not have been greatly affected by the temperature changes that occurred.[21] This is consistent with evidence that it was amesotherm.[50]
Marine mammals attained their greatest diversity during the Miocene,[28]: 71 such as with baleen whales with over 20 recognized Miocene genera in comparison to only six extant genera.[110] Such diversity presented an ideal setting to support a super-predator such as megalodon.[28]: 75 By the end of the Miocene, many species ofmysticetes had gone extinct;[93] surviving species may have been faster swimmers and thus more elusive prey.[29]: 46 Furthermore, after the closure of theCentral American Seaway, tropical whales decreased in diversity and abundance.[108] 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.[72] 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 forendotherms and mesotherms relative topoikilotherms, implying causation by a decreased food supply[105] and thus consistent with megalodon being mesothermic.[50] Megalodon may have been too large to sustain itself on the declining marine food resources.[106] 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.[108]
Competition from large odontocetes, such as macropredatory sperm whales which appeared in the Miocene, and a member ofgenusOrcinus (i.e.,Orcinus citoniensis) in the Pliocene,[93][97] is assumed to have contributed to the decline and extinction of megalodon.[21][29]: 46–47 [106][111] But this assumption is disputed:[23] The Orcininae emerged in Mid-Pliocene withO. citoniensis reported from thePliocene of Italy,[97][112] and similar forms reported from the Pliocene of England and South Africa,[97] indicating the capacity of these dolphins to cope with increasingly prevalent cold water temperatures in high latitudes.[97] These dolphins were assumed to have been macrophagous in some studies,[21] but on closer inspection, these dolphins are not found to be macrophagous and fed on small fishes instead.[112] On the other hand, gigantic macropredatory sperm whales such asLivyatan-like forms are last reported from Australia and South Africa circa 5 million years ago.[113][114][115] Others, such asHoplocetus andScaldicetus also occupied a niche similar to that of modernkiller whales but the last of these forms disappeared during the Pliocene.[116][112] Members ofgenusOrcinus became large and macrophagous in thePleistocene.[112]
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.[23] Boessenecker and his colleagues further suggest that megalodon suffered range fragmentation due to climatic shifts,[23] and competition with white sharks might have contributed to its decline and extinction.[23] Competition with white sharks is assumed to be a factor in other studies as well,[117][21][111] but this hypothesis warrants further testing.[118] 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.[111]
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.[119] 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 becomecoextinct with smaller whale species, such asPiscobalaena nana.[109] 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.[21][117][120]
In popular culture
HMS Challenger discovered megalodon teeth which were erroneouslydated to be around 11,000 to 24,000 years old.
Megalodon has been portrayed in many works of fiction, including films and novels, and continues to be a popular subject for fiction involvingsea monsters.[121] Reports of supposedly fresh megalodon teeth, such as those found byHMS Challenger 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 amongstcryptozoologists.[122] These claims have been discredited, and are probably teeth that were well-preserved by a thick mineral-crustprecipitate ofmanganese dioxide, and so had a lowerdecomposition rate and retained a white color duringfossilization. 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 youngerstratum. The claims that megalodon could remain elusive in the depths, similar to themegamouth 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-poordeep sea environment.[123][124] Alleged sightings of the megalodon have been noted to be likely hoaxes or misidentifications of the whale shark, which shared many visual characteristics with megalodon sightings.[125]
Contemporary fiction about megalodon surviving into modern times was pioneered by the 1997 novelMeg: A Novel of Deep Terror bySteve Alten and its subsequent sequels. Megalodon subsequently began to feature in films, such as the 2002 direct to videoShark Attack 3: Megalodon, and laterThe Meg, a 2018 film based on the 1997 book which grossed over $500 million at the box office.[122][126]
Animal Planet'spseudo-documentaryMermaids: The Body Found included an encounter 1.6 mya between a pod ofmermaids and a megalodon.[127] Later, in August 2013, theDiscovery Channel opened its annualShark Week series with another film for television,Megalodon: The Monster Shark Lives,[128] a controversialdocufiction 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-airedThe Monster Shark Lives, along with a new one-hour program,Megalodon: The New Evidence, and an additional fictionalized program entitledShark of Darkness: Wrath of Submarine, resulting in further backlash from media sources and the scientific community.[52][129][130][131] 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.[132]
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