Megalodon

[elosha11]

@infinity Blade, I saw your earlier comment, did it get deleted?

Shimada's research is getting some media attention. www.forbes.com/sites/melissacristinamarquez/2019/10/02/turns-out-the-megalodon-shark-aint-that-big/#27d8a90f503b.

Pretty much any research about Meg's size will probably get media coverage. Hopefully, other coming studies about associated dentition with different conclusions about Meg's size will also get media coverage.

[Infinity Blade]

Body dimensions of the extinct giant shark Otodus megalodon: a 2D reconstruction

Inferring the size of extinct animals is fraught with danger, especially when they were much larger than their modern relatives. Such extrapolations are particularly risky when allometry is present. The extinct giant shark †Otodus megalodon is known almost exclusively from fossilised teeth. Estimates of †O. megalodon body size have been made from its teeth, using the great white shark (Carcharodon carcharias) as the only modern analogue. This can be problematic as the two species likely belong to different families, and the position of the †Otodus lineage within Lamniformes is unclear. Here, we infer †O. megalodon body dimensions based on anatomical measurements of five ecologically and physiologically similar extant lamniforms: Carcharodon carcharias, Isurus oxyrinchus, Isurus paucus, Lamna ditropis and Lamna nasus. We first assessed for allometry in all analogues using linear regressions and geometric morphometric analyses. Finding no evidence of allometry, we made morphological extrapolations to infer body dimensions of †O. megalodon at different sizes. Our results suggest that a 16 m †O. megalodon likely had a head ~ 4.65 m long, a dorsal fin ~ 1.62 m tall and a tail ~ 3.85 m high. Morphometric analyses further suggest that its dorsal and caudal fins were adapted for swift predatory locomotion and long-swimming periods.

www.nature.com/articles/s41598-020-71387-y


Fig. 2. Silhouette models visualising †Otodus megalodon body dimensions based on our extrapolations at different total lengths. (a)  ~ 16 m, (b)  ~ 3 m and (c)  ~ 8 m. Abbreviations as in Table 1. Silhouettes created in Adobe Illustrator CC 2018. (d) Palaeoartistic reconstruction of a 16 m †O. megalodon scaled against a 1.65 m human (illustration by Oliver E. Demuth). Fin shapes are based on our generalised morphometric shapes in the silhouettes whereas the reconstruction aims to capture their true biological shapes, i.e. the ceratotrichia of the tail present in all five modern analogues.

[elosha11]

In light of the new study, this picture would seem to be quite plausible and useful to demonstrate the difference between an adult male and an adult female Megalodon. From the Encyclopedia Britannica.

I do hope that Leder and Perez, et al's abstract can be fully realized in a published paper. I think that would shed further light on the question of the shark's size.

[kekistani]

www.tandfonline.com/doi/full/10.1080/08912963.2020.1812598

Shimada Study finding Megalodon's size is an outlier in the predatory shark world

" The tooth of O. megalodon illustrated in Figure 1(b) has the tallest known CH in scientific literature for the species, and based on the CH-TL relationship in extant Carcharodon carcharias, that specific individual of O. megalodon is conservatively estimated to be about 14.5 m TL, although the species could have reached at least slightly over 15 m TL (Shimada 2019)."

[elosha11]

What Sealed The Fate of The Giant Megalodon? Its Ancient Teeth May Reveal The Answer
ELEONORE HUGHES, AFP26 NOVEMBER 2020


The largest sharks ever to have roamed the oceans parked their young in shallow, warm-water nurseries where food was abundant and predators scarce until they could assume their title as kings and queens of the sea.

But as sea levels declined in a cooling world, the brutal mega-predator, Otodus megalodons, may have found fewer and fewer safe-haven coastal zones where its young could safely reach adulthood, researchers reported Wednesday in The Royal Society journal Biology Letters.

Indeed, the reliance of megalodon on nurseries may have contributed to the end of their 20-million-year reign, according to the research.

Otodus megalodon – sometimes classified as a Carcharocles megalodon – took 25 years to become an adult – "an extremely delayed sexual maturity", the authors said in the research paper.


Illustration of a megalodon nursery. (Humberto Ferrón)

But once it was fully grown, the shark could reach up to 18 metres, three times the size of the largest great white shark, made famous by the 1975 hit-movie Jaws.

As an apex predator, and up until its extinction around three million years ago, the adult megalodon had no rivals among other ocean hunters and feasted on smaller sharks and even whales.

But its young were vulnerable to attacks by other predators, often other razor-toothed sharks.

Nurseries on shallow continental shelves with extensive smaller fish for food and few competing predators gave them the ideal space to reach their awesome size.

"Our results reveal, for the first time, that nursery areas were commonly used by the O. megalodon over large temporal and spatial scales," said the authors.

Perfect place to grow
The research team discovered a nursery zone off the eastern coast of Spain in Tarragona Province after visiting a museum and observing a collection of megalodon teeth.

"Many of them were quite small for such a large animal," the authors from British University of Bristol, Carlos Martinez-Perez and Humberto Ferron, told AFP.

Judging by the size of the teeth, they surmised the area had once been home to young megalodons.


Megalodon jaws at the National Aquarium in Baltimore. (Serge Illaryonov/Wikimedia Commons/CC BY 3.0)

The Spanish nursery could be described as "a perfect place to grow", the authors said.

It would have been a "shallow bay area of warm waters, connected to the sea and with extensive coral reefs and plenty of invertebrates, fish species, marine mammals and other sharks and rays".

The researchers analysed eight other sets of shark teeth which had previously been gathered, spread across the United States, Peru, Panama and Chile.

They came to the conclusion in four of them – two in the United States and two in Panama – had belonged to younger sharks.

As a result, the authors suggest these four areas where the teeth were found might also have been nurseries.

"The remaining four formations ... demonstrate size-class structures typical of populations dominated by adults, suggesting these regions might correspond to feeding or mating areas," the study said.

Sharks continuously shed their teeth throughout their lifetime, and nurseries are zones with a high abundance of sharks.

"As a consequence, huge numbers of teeth can be shed, increasing the chances of subsequent fossil discoveries," the authors said.

Megalodons enjoyed the warm and temperate waters of the Miocene period which extended from about five million to 23 million years ago.

But the cooler Pliocene period suited them far less.

As their prey adapted and headed towards colder waters, the megalodon stayed where the oceans remained warm.

The remaining food was also favoured by great white sharks, increasing competition with the smaller, but more agile, predator.

The vast reduction of shallow water nurseries due to sea-level losses – caused by a cooler climate – may also have contributed to the megalodon's eventual extinction. ​ ​

[Infinity Blade]

A 3D reconstruction of the extinct giant shark Otodus megalodon
Jack Cooper, John Hutchinson, Matt Dicken, Jan Menzel, Catalina Pimiento

Combining exceptionally preserved fossil specimens with computational modelling has given palaeontologists the unprecedented ability to digitally reconstruct entire bodies of extinct animals. However, cartilaginous skeletons of extinct sharks have particularly poor preservation, often only leaving behind hard teeth and occasional vertebrae. Palaeontologists therefore typically use dental and ecological similarities with extant relatives to infer morphology of extinct sharks. Using exceptional fossils, the morphology of an ecological analogue, and an “octagonal hooping” method previously used in reconstructions of dinosaurs, we create a 3D computational model of the extinct giant shark Otodus megalodon. The base model is created from CT scans of a reconstructed jaw and the longest vertebral column of O. megalodon known to the fossil record. Vertebrae and teeth are scaled to real size based on direct measurements of the fossils, with tooth crown height being used to calculate total length (TL) of our model based on previously published equations. The rest of the body is constructed using a digitally reconstructed head and a CT scanned full body specimen of the great white shark (Carcharodon carcharias), the most commonly used ecological analogue to O. megalodon, scaled up to our model TL, in conjunction with our base model. Our final model is of an O. megalodon at ~15.93 m TL and a body mass of ~50 metric tons. This study marks the first ever digital reconstruction of an extinct giant shark; a model now being used to calculate a variety of inertial properties.

www.palass.org/sites/default/files/media/progressive_palaeontology/2020/ProgPal_2020_Abstract_Booklet_v2.pdf

[Life]

Body length estimation of Neogene macrophagous lamniform sharks (Carcharodon and Otodus) derived from associated fossil dentitions.

Abstract

The megatooth shark, Otodus megalodon, is widely accepted as the largest macrophagous shark that ever lived; and yet, despite over a century of research, its size is still debated. The great white shark, Carcharodon carcharias, is regarded as the best living ecological analog to the extinct megatooth shark and has been the basis for all body length estimates to date. The most widely accepted and applied method for estimating body size of O. megalodon was based upon a linear relationship between tooth crown height and total body length in C. carcharias. However, when applying this method to an associated dentition of O. megalodon (UF-VP-311000), the estimates for this single individual ranged from 11.4 to 41.1 m. These widely variable estimates showed a distinct pattern, in which anterior teeth resulted in lower estimates than posterior teeth. Consequently, previous paleoecological analyses based on body size estimates of O. megalodon may be subject to misinterpretation. Herein, we describe a novel method based on the summed crown width of associated fossil dentitions, which mitigates the variability associated with different tooth positions. The method assumes direct proportionality between the ratio of summed crown width to body length in ecologically and taxonomically related fossil and modern species. Total body lengths were estimated from 11 individuals, representing five lamniform species: Otodus megalodon, Otodus chubutensis, Carcharodon carcharias, Carcharodon hubbelli, and Carcharodon hastalis. The method was extrapolated for the largest known isolated upper tooth of O. megalodon, resulting in a maximum body length estimate of 20 m.

Citation: Perez, V. J., Leder, R. M., and Badaut, T. (2021). Body length estimation of Neogene macrophagous lamniform sharks (Carcharodon and Otodus) derived from associated fossil dentitions. Palaeontologia Electronica, 24(1):a09. doi.org/10.26879/1140

Full read: palaeo-electronica.org/content/2021/3284-estimating-lamniform-body-size

NOTE: One of the co-authors is a member of this Forum.

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[elosha11]

Great article, and lo and behold already some other well-known Megalodon researchers are backing it up. See this March 10, 2021 article by Mikael Silversson (who's published a number of Megalodon related papers) and John Long. it's a fascinating article for many reasons, but this particular section lines up exactly with the new Perez, Leder and Badaut paper.

theconversation.com/making-a-megalodon-the-evolving-science-behind-estimating-the-size-of-the-largest-ever-killer-shark-155475

Calculating maximum size
The meghead model in Perth was based on several specific tooth specimens found locally and from overseas, painting a picture of a 14m-long predator.

However, to calculate the species’s maximum size, we first estimated the maximum jaw size possible for Meg and then scaled this up, using the same jaw size-to-body length ratio of living white sharks.

The maximum jaw size of meg can be calculated by scaling up the few known “associated dentitions” (multiple tooth specimens that were found together and came from a single shark) with the widest meg tooth ever found.

Once we did this, the size estimate we reached was between 19–20m. And this is much larger than most other recent estimates.

[Infinity Blade]

This is an interesting paper from 2018. Physeteroids from Lee Creek were found to have had a raptorial orca-like feeding ecology, and seem to have been similar in size to modern orcas as well. Despite this, their life histories were very different, with the Lee Creek raptorial sperm whales having much shorter lifespans and rapid growth (compare this to modern orcas that grow slowly and have long lifespans). Predation pressure by giant sharks (like O. megalodon) and potentially colossal raptorial sperm whales (like L. melvillei) was likely responsible for these differences.

EDIT: I checked and it was posted by Life in his megalodon review thread. I was beaten to it. I'll keep it here anyway for anyone interested in this particular paper. Also, I think it will be personally easier for me to remember one post dedicated to it here than the paper in with various others in the other thread.

Living fast and dying young: life history and ecology of a Neogene sperm whale
Gilbert, K. N., Ivany, L. C., and Uhen, M. D.

Physeteroidea (sperm whales) attained great diversity during the Miocene and early Pliocene, and the phosphatic sands of the U.S. Atlantic Coastal Plain have produced thousands of specimens. Although postcranial and cranial materials are rare, teeth are remarkably common and have the potential to provide valuable insight into the lives of these animals. We examine a suite of Physeteroidea indet. teeth from the Lee Creek Mine to better constrain the life history and ecology of this extinct group. Wear facets indicate that these animals, unlike modern sperm whales, had both maxillary and mandibular teeth, suggesting a raptorial feeding ecology more akin to killer whales. A relationship between tooth diameter and body size established for modern odontocetes suggests that these animals as adults were also about the size of modern killer whales. Because physeteroid teeth grow continuously over ontogeny and are not replaced, counts of accretionary growth layer groups can be used to ascertain the age of an animal at death. Tallies of growth increments from 10 teeth, including some of the largest available, reveal that life spans only rarely exceeded 20 years, significantly shorter than the 65+ years typical of modern sperm whales or orcas. Despite their large size, these odontocetes experienced a ‘fast’ life history, more like beluga whales today. We suggest that the rapid growth and short life span exhibited by the Lee Creek physeteroids are, like the modern beluga, evolutionary responses to high predation pressure imposed by large co-occurring predatory taxa, particularly including Carcharocles megalodon or other large macroraptorial physeteorids.

As also illustrated by the phocoenids (Van Utrecht, 1978) and kogiids (Plon, 2004), small body size is often a correlate of rapid maturation associated with high predation pressure (Reznick et al., 1997; Huang et al., 2008), especially where resources are limited and competition is strong (Arendt and Reznick, 2005). However, with estimated maximum body lengths >8 m, size reduction seems not to be a hallmark of evolution of the animal producing the teeth in our sample, although its direct ancestor is unknown. Two factors likely countered the tendency toward small size. First, resources were evidently not in short supply on the Neogene mid-Atlantic Coast given the upwelling indicated by rich phosphate deposits (Riggs, 1984) in the units that produce physeteroid teeth, the remarkable fossil assemblage that accompanies them (Ray, 1983, 1987; Whitmore, 1994; Ray and Bohaska, 2001; Ray et al., 2008), and the high metabolic demands of the many odontocetes and other marine mammals in the assemblage (Benoit-Bird, 2004; Williams et al., 2004). In addition, vulnerability to predation, especially in larger animals, tends to inversely relate to body size, and faster-growing animals suffer lower predation mortality than slow growers (Abrams et al., 1996; Craig et al., 2006). Although even very large animals are subject to attack by predators (Pitman et al., 2001; Fitzpatrick et al., 2006), the likelihood of a successful kill declines with increasing body size of the prey (Lundvall et al., 1999; Fitzpatrick et al., 2006). Because these Lee Creek physeteroids were already quite large animals, fast growth to reach a size refuge from predation is a likely evolutionary response.

What could have been the source of high extrinsic mortality on these whales? Clearly formidable marine predators themselves, few organisms would have been capable of inflicting the requisite high mortality on these populations to force a shift in life history strategy toward fast growth and early maturation. Interestingly, several species of large sharks, including Carcharocles megalodon and Carcharodon carcharias, also occur in the ACP and at Lee Creek Mine (Purdy et al., 2001). Ecologically, sharks are apex predators, and these species probably played a critical role in structuring the biological community on the ACP. Carcharocles megalodon is the largest known shark, with adult body length estimates that range from 15 to 20 m (Gottfried et al., 1996; Pimiento and Balk, 2015), and the species is thought to have preyed on medium- to large-sized baleen whales (Purdy, 1996; Govender and Turan, 2011; Govender, 2015; but see Collareta et al., 2017). At least five different modern shark taxa, including white sharks, are known to routinely prey on smaller odontocetes (Long and Jones, 1996; Heithaus, 2001), and the larger the shark, the more likely it is to include the high-food-value odontocetes among their prey items (Heithaus, 2001). It is feasible and even likely that C. megalodon exploited moderately sized physeteroids and other Lee Creek cetaceans for food. The smaller juveniles would have been more susceptible to predation, so fast growth and early reproduction would have been selectively advantageous.

Accretionary growth banding in the teeth of Lee Creek physeteroids indicates a maximum life span of ~25 years, similar to that of small extant odontocetes. This life span is coupled with maximum body length estimates of 8–10 m, smaller than the modern sperm whale and comparable to killer whales. Although body size estimates based on tooth diameter alone are tenuous for all the reasons discussed above, by any measure these were not small whales. The von Bertalanffy growth function suggests a markedly high rate of attainment of adult body size and associated early onset of sexual maturity. These life history traits may be indicative of an evolutionary response to high predation pressure. These animals coexisted with one of the most accomplished predators known to have existed, Carcharocles megalodon. It is likely that C. megalodon, and potentially other large macroraptorial physeteroids, preyed on them and that this ecological interaction acted as a selective mechanism favoring rapid growth and maturation.

Killer whales are top predators in today’s oceans. They experience very little threat from predation. As a consequence perhaps, they enjoy a long life span including a long postreproductive phase for females and comparatively slow growth and maturation (Foote, 2008). Earlier in the Neogene, much larger predators existed that would have shaped the life history trajectories of similar-sized odontocetes through the influence of predation. The inferred fast growth and short life span of this large carnivorous Pliocene physeteroid is atypical for animals of this size today but may have been the norm in oceans with superpredators such as Carcharocles and Livyatan. Their extinction may have enabled the trend toward slower life histories seen in many of today’s large cetaceans.

www.tandfonline.com/doi/abs/10.1080/02724634.2018.1439038?journalCode=ujvp20

(Full article available on Google Scholar)

[Infinity Blade]

Biomechanical insights into the dentition of megatooth sharks (Lamniformes: Otodontidae)

The evolution of gigantism in extinct otodontid sharks was paralleled by a series of drastic modifications in their dentition including widening of the crowns, loss of lateral cusplets, and acquisition of serrated cutting edges. These traits have generally been interpreted as key functional features that enabled the transition from piscivory to more energetic diets based on marine mammals, ultimately leading to the evolution of titanic body sizes in the most recent forms (including the emblematic Otodus megalodon). To investigate this hypothesis, we evaluate the biomechanics of the anterior, lateral, and posterior teeth of five otodontid species under different loading conditions by using two-dimensional finite element analysis. Stress distribution patterns are remarkably similar among all models under puncture and draw (i.e., when subjected to vertical and lateral forces, respectively). Contrary to expectation, higher average stress values are detected under both loading scenarios in more recent species. Altogether, this suggests little correlation between tooth morphology and key aspects of biomechanical behaviour in otodontids, making it difficult to frame the morphological trend of their dentitions within an adaptive scenario. We propose that this pattern most likely emerged as a non-functional by-product of heterochronic processes driven by selection towards larger body sizes.

www.nature.com/articles/s41598-020-80323-z

[elosha11]

Props to kekistani for bringing this to my attention. It seems Megalodon may have been even heavier than previous estimates.

3D model of the extinct giant shark Otodus megalodon suggests ability to
undertake long migrations and a preference for large prey
Jack Cooper1
, John Hutchinson2
, Rory Wilson1
, Jeanette Pirlo3
, Matt Dicken4,5, Jan Menzel6, Stephen Wroe7,
David Bernvi4, Geremy Cliff 4,8, Catalina Pimiento1,9,10
1
Swansea University, Swansea, United Kingdom
2
Royal Veterinary College, London, United Kingdom
3
University of Florida, Florida, United States of America
4KwaZulu-Natal Sharks Board, Umhlanga Rocks, South Africa
5
Nelson Mandela University, Port Elizabeth, South Africa
6Vikela.Earth, Stellenbosch, South Africa
7
University of New England, Armidale, Australia
8University of KwaZulu-Natal, Durban, South Africa
9Paleontological Institute and Museum, University of Zurich, Zurich, Switzerland
20
10Smithsonian Tropical Research Institution, Balboa, Panama
Computer modelling combined with exceptional fossil specimens has given
palaeontologists the unprecedented ability to reconstruct entire bodies of extinct animals.
Given its low preservation potential, no complete skeleton exists for the extinct giant shark
Otodus megalodon; however, the existence of an exceptional 141-centra vertebral column
from Belgium (IRSNB P 9893) allowed us to reconstruct a 3D model of this individual’s
entire body using a previously established “hoop-based” methodology in Blender. From the
completed model, we estimated body length (15.93 m) and mass (61,500 kg), revealing that
IRSNB P 9893 was larger than hitherto proposed. We then used body mass-related
equations from literature to make novel ecological calculations for this O. megalodon
individual, including cruising speed (1.39 m/s), stomach volume (9,600 L), gape size (1.81 m
in height) and daily energy requirement (98,100 kcal/day). Our measurements, compared
against living sharks, indicate that while this large O. megalodon individual was slower
than some smaller sharks, it was an adept swimmer able to move across oceans. Although
small cetaceans of 2-5 m would have provided calories beyond its daily requirement, prey
as large as 9 m could have been entirely eaten. Thus, a preference for large prey could have
been a strategy for the largest O. megalodon individuals to avoid competition with more
agile sharks. Excess calories consumed from such large prey may have been used to fuel
and sustain prolonged migrations, as seen in extant sharks. The extinction of this highly
mobile super-predator likely impacted global nutrient transfer and trophic food webs.

[Infinity Blade]

Are you still talking with kekistani somewhere else?

Gape size seems...woefully inadequate. I remember someone calculating gape height in T. rex, and based on jaw length and maximum gape angle, it could open its mouth up to 1.849 meters (link). A megalodon is way bigger with far bigger jaws, so shouldn't gape height be much greater? Or is this not at maximum jaw gape?

[elosha11]

Nov 30, 2021 4:56:29 GMT 5 Infinity Blade said:

Are you still talking with kekistani somewhere else?

Gape size seems...woefully inadequate. I remember someone calculating gape height in T. rex, and based on jaw length and maximum gape angle, it could open its mouth up to 1.849 meters (link). A megalodon is way bigger with far bigger jaws, so shouldn't gape height be much greater? Or is this not at maximum jaw gape?

I believe kekistani posted this under another name in another forum. But it was the first I had heard of it.

I agree the gape height seems undersized. In fact, the whole analogy is a bit puzzling to me. The Belgium vertebrates are an incomplete sample. They were originally thought to come from a juvenile 9m Megalodon, but the authors' earlier papers about the skeleton opined that 9m was undersized and it may have been around 11m. But those earlier papers seem to suggest that by using the skeleton along with larger associated dentition from adult sharks, they could make an accurate prediction as to the size of a close to 16m adult Megalodon. But -- a 1.8 gape height certainly does not seem adequate for a 50 ton shark ( the earlier weight predictions), much less a 67 ton shark.

I wonder if the 1.8m gape is referring to the original fossil holotype estimated from the Belgium centra, a shark that is indicated to be around 11m. But if so, the paper abstract is quite sloppy in mixing size estimates from the subadult holotype and the predicted adult sized shark.

[elosha11]

wjla.com/news/local/reality-bites-calvert-museum-megalodon-to-have-teeth-altered-based-on-new-dental-evidence

After 25 years, the Calvert Marine Museum’s life-sized skeletal model of the extinct shark, Otodus megalodon, will receive new teeth.

Over many years, paleontologists have made new discoveries that improve understanding of this extinct shark’s anatomy, including dental evidence that supports this historic transformation.

The new fossils are referred to as associated dentitions, which are sets of teeth that came from a single shark. These exceptionally rare discoveries allow paleontologists to more confidently reconstruct the tooth patterns exhibited by megalodon. With this new information available, the exhibit is being updated to reflect the most current fossil evidence to make the representation as scientifically accurate as possible.

When megalodon was first described, it was named Carcharodon megalodon and was suggested to be the immediate ancestor of the great white shark (Carcharodon carcharias). Consequently, the Calvert Marine Museum’s skeletal model was created by scaling up the size of a great white shark. However, paleontologists now recognize that the two sharks are more distantly related, and likely last shared a common ancestor more than 65 million years ago.


Paleontologists have made new discoveries that improve understanding of this extinct shark’s anatomy, including dental evidence that supports this historic transformation. (Credit: Calvert Marine Museum)

The most complete set of megalodon teeth was found in the Four Corners phosphate mine in Polk County, Florida. A total of 95 teeth were recovered that all originated from one shark. This shark was estimated to be 40.7 feet long, which matches quite closely with the museum’s 37.5 foot skeletal model. To improve the accuracy of the model, CMM staff are replacing the teeth with exact replicas of the associated teeth found in Polk County.

To make these changes to the exhibit, Calvert Marine Museum staff will remove the jaws from the megalodon skeletal model. The jaws will be brought into the Paleontology prep lab for the remodeling. Museum visitors will be able to watch this historic update to this iconic exhibit through the glass window that peers into the prep lab. New information panels will be placed in the exhibit hall, explaining how scientific evidence is utilized to guide the exhibit design.

[Infinity Blade]

New study by Shimada et al. came out basically saying...we can't know for sure what O. megalodon looked like. Which is kind of obvious, really.

www.tandfonline.com/doi/full/10.1080/08912963.2021.2025228

Interestingly, it actually acknowledges that it was indeed at least 15 meters long.

Multiple studies based on teeth have indicated that Otodus megalodon reached at least 15 m in total length (Pimiento and Balk 2015; Shimada 2019; Perez et al. 2021). Besides its gigantic teeth, O. megalodon is known from some isolated and associated vertebral specimens that are also indicative of its large body size (e.g. Uyeno and Sakamoto 1984; Gottfried et al. 1996; Kent 2018).

Otodus megalodon most certainly reached at least 15 m in total length based on its gigantic teeth (Shimada 2019; Perez et al. 2021).