Megalodon may have been looked like a big lemon shark

Otodus megalodon, the biggest shark in Earth’s history, may have just gotten a new makeover. Traditionally, size and body reconstructions have relied heavily on the great white shark due to it being considered either a close relative or an ecological proxy for megalodon. Now, a new study revisits the shape, size, and biology of this iconic extinct shark through a fresh lens.

The historical image of megalodon: a history

Otodus megalodon, the “megalodon”, almost needs no introduction. As the biggest shark to ever exist, it swam across every ocean during the Miocene and Pliocene epochs until its extinction 3.6 million years ago (Pimiento et al. 2016; Boessenecker et al. 2019). With a trophic level comparable to or potentially even higher than that of the living great white shark (Carcharodon carcharias) (Martin et al. 2015; McCormack et al. 2022; 2025; Kast et al. 2022; Paredes-Aliaga & Herraiz 2024), it was almost certainly an apex predator. Incredible fossils showing evidence of healing, or even with O. megalodon teeth stuck in them, suggest that it was a whale killer (Aguilera et al. 2008; Godfrey & Beatty 2022), though a new study extracting zinc isotopes from teeth has revealed that it probably ate whatever it wanted rather than just being a whale specialist (McCormack et al. 2025). Its teeth alone are huge, the size of a human hand (Figure 1). It’s fair to say that megalodon is one of the most iconic extinct taxa in palaeontology, fuelling both scientific fascination and public awe.

Figure 1. A megalodon tooth from the collections of the University of Bristol compared against my own hand. Taken in 2018 during my master’s course.

“Many people have both a fear and fascination of sharks. I think it is only natural that people are quite interested not only in the largest shark that ever lived but also as one of the largest carnivores to ever live,” says Dr Phil Sternes, who was one of those scientists captured by megalodon. His words ring true to me, my own interest spawning from childhood astonishment that such a shark had actually existed only a few million years ago. 

Professor Kenshu Shimada, a veteran researcher of fossil sharks, also first became interested in megalodon as a child. He reckons the public interest in megalodon “stems from the fact that megalodon is mostly represented only by its large, triangular, serrated teeth, compounded by the fact that ‘sharks’ are already often feared by the general public as dangerous animals.” 

Yet, despite this, one of the most basic questions about megalodon remains enigmatic: what did it look like?

The short answer is “we don’t know”. That’s because there has never been a complete skeleton of megalodon found in the fossil record, making it difficult to determine its appearance (Sternes et al. 2022). It’s tempting to say, “Well, it probably looked like a big shark”, but the natural follow-up question is “Okay, but what kind of shark?”

Megalodon was originally thought to be a direct ancestor of the great white shark, its name for many decades being Carcharodon megalodon. At the time, this was based on their broadly similar teeth: both being large, triangular and serrated. This went so far as to influence a keynote 1990s study on megalodon in which the shark was reconstructed as essentially a giant great white (Gottfried et al. 1996). Since then, several pieces of evidence have contradicted this old hypothesis. One study found little geometric similarity between white shark and megalodon teeth, including distinctly different serrations (Nyberg et al. 2006). This study, and others, ultimately concluded that white sharks evolved from a lineage of mako-like sharks (Ehret et al. 2012). Instead, megalodon was part of the “megatooth” clade in a separate family from white sharks altogether. Under this hypothesis, it was traditionally given the name Carcharocles megalodon, and later Otodus megalodon (to make the genus Otodus a more evolutionarily meaningful taxonomic unit) following the discovery of a likely sister taxon, Megalolamna (Shimada et al. 2017; Pollerspöck & Shimada 2024). Yet, Kenshu notes, “the exact evolutionary affinity for ‘Otodus megalodon’, or its group, remains uncertain.”

Nevertheless, the white shark continued to be used for size and body reconstructions of megalodon as an ecological analogue. Linear tooth-to-body size relationships in the white shark were universally extrapolated to megalodon, producing a range of “maximum” size estimates between 15 and 20 m (e.g., Shimada 2003, 2019; Pimiento & Balk 2015; Perez et al. 2021). My own master’s work took this a step further and attempted a reconstruction of other body parts based on their relationships with total length (Cooper et al. 2020). That work used all the lamnid sharks (the white, mako, salmon and porbeagle sharks) due to ecological similarities and regional endothermy, a trait of lamnids thought to also have been present in megalodon at the time (Ferrón 2017; Pimiento et al. 2019) but not yet explicitly confirmed. I was then part of a follow-up study that made a 3D reconstruction based on the most complete vertebral column specimen – IRSNB P 9893 from the Miocene of Belgium – and used those same analogue sharks to fill in the gaps (Cooper et al. 2022). One major finding of that study was that the vertebral column, originally thought to belong to a megalodon only 9.2 m long, was over 11 m: leading to the resulting model to be 15.9 m. Ultimately, these studies based on the lamnid sharks recreated a rather bulky shark (Figure 2).

Figure 2. The old “bulky” reconstruction based on my 2020 paper (Cooper et al. 2020). Artwork by Oliver E. Demuth.

An alternative to consider

However, using proxies or analogues to recreate extinct taxa is naturally fraught with assumptions – especially in species like megalodon that are known from only fragments (Gayford et al. 2024). A 2024 study led by Phil and Kenshu, in collaboration with a whole heap of other leading experts, highlighted the revelation of the vertebral column’s 11 m length. Given that this column was so much longer than simply scaling vertebral size up from a white shark, they suggested that megalodon may have instead had a slender, more elongated appearance (Sternes et al. 2024). Now, they have a new paper putting this new hypothesis to the test (Shimada et al. 2025).

The new study – and its many implications for our understanding of megalodon

The first step was to reassess the size of the shark IRSNB P 9893 came from. And the way the authors do this is a method I find particularly clever. They essentially gathered the proportions of the head (“neurocranium”), body (“trunk”) and tail (“caudal”) in over 165 species of shark, both living and extinct, where we have complete bodies. Then by treating the 11.1 m vertebral column as the “trunk proportion” of megalodon and scaling it against the median head and tail proportions from the data, the authors extrapolate the megalodon’s complete body length (Figure 3). What I like about this approach is that it doesn’t make any assumptions about any living sharks being appropriate analogues for megalodon, instead treating it more like a “typical shark”. And the results were quite eye-catching. The scaling indicated that the shark IRSNB P 9893 measured 16.4 m long. Scaling this up to the largest known megalodon vertebra in literature – a 230 mm centrum from Denmark (Bendix-Almgreen 1983; Greenfield 2022) – revealed a size of a whopping 24.3 m long (Shimada et al. 2025).

Figure 3. A schematic illustration detailing the paper’s new method of estimating megalodon body size based on NP (neurocranium proportion), TP (trunk proportion; with the length of IRSNB P 9893 used as such), and CP (caudal proportion) of 165 living and extinct sharks. A crocodile shark is used as basis. Sourced from Figure 1b and c of Shimada et al. (2025); see the paper for further details.

The head, body and tail proportions of sharks were then compared in a cluster analysis. What the authors found was that megalodon did not cluster with the white shark as earlier reconstructions might expect. Instead, it clustered with the porbeagle shark (Lamna nasus) and the lemon shark (Negaprion brevirostis). The authors then calculated fineness ratio – essentially body length divided by depth to determine how slender a shark is – for megalodon compared it against other large animals with similar hydrodynamic demands such as whales and large filter-feeding sharks.

“Any object moving through the water will incur drag,” Phil explains, “However, as size increases, we notice certain shapes are ideal for minimizing drag. We found out that Megalodon must have had a slender body form to be a an ‘efficient’ swimmer.” Their results (Figure 4) indicated that a 24 m shark with a fineness ratio of 6.01-6.15 and the body proportions of a great white or a porbeagle would essentially incur hydrodynamic disadvantages and therefore be unable to sustain energetic swimming due to drag. On the other hand, a slender body plan like that of a lemon shark was found to be better suited for a shark of such gigantic sizes to swim (Shimada et al. 2025).

Figure 4. A summary of the hydrodynamic results of the paper (Shimada et al. 2025). (A) depicts effects of allometry on bodies of lemon shark, white shark and porbeagle shark under gigantism and the calculated fineness of megalodon. (B) exhibits relationship between fineness ratio and body size in large marine taxa. (C) shows mean growth trajectories projected of the lemon, white and porbeagle shark bodies when extrapolated to megalodon size. Sourced from Figure 4 of Shimada et al. (2025); see the paper for full details.

Three other parameters were investigated. Body mass was re-assessed with 3D volumetric modelling and the Paleomass R package (Motani 2023), indicating that IRSNB P 9893 would’ve weighed ~30 tonnes, with a 24.3 m shark possibly weighing ~94 tonnes (Shimada et al. 2025). At the same time, cruising speed calculations from this reconstruction came to 2.1-3.5 km/hr, lower than previous studies like my own. This may point to a shark swimming at steady speeds, using burst ambush predations to snatch prey, with a slender body offsetting the energetic demands of such a large body. Finally, the von Bertalanffy growth function was re-used on IRSNB P 9893, likely to have been 46 years old at death based on the number of vertebra growth bands (Shimada et al. 2021), to estimate growth rate, birth size and longevity. This revealed that at birth, this specific megalodon was likely 3.6-3.9 m long. This huge birth size is as big as a subadult white shark and strongly supports a reproductive strategy in which megalodon offspring would have eaten each other in the womb, with only a small number of large individuals being born (Shimada et al. 2021, 2025). That may well have been big enough to avoid most predators from the get-go. The average growth rate of 26-37 cm/yr and the extrapolated longevity of around 88 years for a 24 m individual further indicate a slow-growing, K-selected species that took its time to get big and with little to fear at its very largest sizes.

So, in short, megalodon was not only bigger than we originally envisioned, but probably slenderer too. This new depiction has already produced some wonderful palaeo-art (Figure 5). Based on the cluster and hydodynamic results, one could reasonably conclude that megalodon may well have resembled a giant lemon shark.

Figure 5. Two different palaeo-artistic interpretations of the “slender megalodon”. The top artwork is by Julius Csotonyi and is sourced from Long (2024). The bottom artwork is by Rhys Meyerkort.

A reflection on megalodon science and what’s next

The authors stress that their conclusions should be treated as working hypotheses. Nevertheless, a lot of data have gone into this work and that should be commended. Ultimately, confirming megalodon’s appearance will come down to finding a complete skeleton.  

Will we ever find one? I have no idea. If I were a betting man, my money would be on the Pisco formation in Peru. This is a region known for some truly exceptional fossils, such as the holotype of the raptorial sperm whale Livyatan melvelli (Lambert et al. 2010), the jaw specimen holotype of Carcharodon hubbelli (Ehret et al. 2009, 2012), and a complete skeleton of Carcharodon hastalis that even had its last meal preserved (Collareta et al. 2017).

Kenshu remains “hopeful” of the prospect of finding a megalodon skeleton one day, though points out a very interesting bit of history. “The first associated tooth set of megalodon described from Japan in 1989 came from a rock formation that is very scarce in vertebrate fossils,” he explains, “The discovery was very unexpected to palaeontologists and fossil hunters in the region (me included), so you never know where a complete skeleton may pop up.”

Like me, Phil believes that “South America is a good place to go”. Wherever such a skeleton may be found, it would be a groundbreaking piece of palaeontological research. “I encourage any fossil hunters out there to keep their eyes open as you never know what you may find out there!” Phil says.    

To wrap up, I want to talk about how this paper is the culmination of a whole series of papers all asking similar questions of “how big was megalodon?” and “what did megalodon look like?” to shape their narratives. These questions, in my experience, continue to dominate online discussions about megalodon. Other corners of the internet “fandoms” for megalodon spend a lot of time debating whether megalodon or other large predators such as Livyatan would “win in a fight” and tend to bring these questions to the professional researchers. The same is often true for other iconic extinct species such as T. rex (Mallon & Hone 2024). Personally, I do not find these questions to be all that productive given their inherently speculative nature.

Phil tells me he often declines to comment on such hypothetical scenarios when asked about them. Kenshu expands on this even further, “While I welcome people’s imagination and curiosity because it helps make the study of megalodon biology even more worthwhile, the problem in answering such questions is that, as a scientist, I am constrained to what I can say by the available fossil record and data, or the so-called empirical evidence,” he says, “Based on the simple fact that megalodon existed and went extinct, I believe the more critical issue people should think about is what might be the impact on the present-day marine ecosystem if large sharks were to go extinct, and why conservation biology of modern-day sharks matters.”

From my end, I strongly agree with their sentiment. What I consider among the most important aspects of megalodon is understanding the ecological effects of its extinction, which may provide insights into the disruption we could see in the future if we were to lose today’s sharks, of which over one-third are at risk of extinction, primarily from overfishing (Dulvy et al. 2024). “If we can understand the factors that drove megalodon to extinction, we can improve our understanding of current ecosystems,” Phil says.

Furthermore, we have learned an enormous amount of exciting information in the last two decades and that data-driven science deserves more attention. Just to list a few examples, we now have the first fossil placoid scales from megalodon (Shimada et al. 2023); several clever isotope studies have examined megalodon’s trophic level (McCormack et al. 2022, 2025; Kast et al. 2022) and confirmed that megalodon was indeed regionally endothermic as we’ve long suspected (Griffiths et al. 2023); and multiple studies have used teeth to estimate approximate extinction dates (Pimiento & Clements 2014; Boessenecker et al. 2019). Indeed, my own recent work on Cenozoic shark teeth implied that megalodon was functionally specialised (i.e., ecologically extreme), and therefore shark diversity as a whole likely dropped when it went extinct (Cooper & Pimiento 2024). Like Kenshu and Phil, I encourage online enthusiasts to focus on the data-based science and not on un-informed head-canons, which branches into speculation at best, and outright misinformation at worst.

What more is to come from megalodon research? We shall see.  

Some of you reading this may wonder if I have any plans to do any more megalodon work. In my case, I’ve mostly moved on from academia since finishing my PhD, but I still have a couple of non-megalodon related papers being written up for publication this year. And I would “never say never” to any future megalodon work on my end; I’m very open to future collaborations on this species and I’ve long accepted that it will be the species that dominates my science communication. Until then, I await all future work by the other wonderful scientists working on this species, which I’ll be sure to write about here. Studies like Shimada et al. (2025) ultimately highlight the need to understand even the basics of our iconic sharks when new evidence comes to light. I feel confident in saying that it’s never been a more exciting time to study this iconic extinct shark.

Acknowledgements and further reading

I deeply thank coauthors of the study, Professor Kenshu Shimada and Dr Phil Sternes for taking the time to answer questions I had for this blog, and for fact checking an earlier version. Kenshu’s 35+ year career and dedication towards palaeontology, particularly of sharks, as well as his work at the Society of Vertebrate Palaeontology (SVP) highlighting the challenges facing the field (e.g., Shimada et al. 2014; Carr 2025), is to be commended. Phil’s sheer passion for sharks is infectious and often reminds me of myself. I eagerly anticipate his ongoing and future research in what will no doubt be a highly fruitful career.    

You can read the full paper at Palaeontologia Electronica under the following reference:

• Shimada K, Motani R, Wood JJ, Sternes PC, Tomita T, Bazzi M, Collareta A, Gayford JH, Türtscher J, Jambura PL, Kriwet J, Vullo R, Long DJ, Summers AP, Maisey JG, Underwood C, Ward DJ, Maisch HM, Perez VJ, Feichtinger I, Naylor GJP, Moyer JK, Higham TE, da Silva JPCB, Bornatowski H, González-Barba G, Griffiths ML, Becker MA & Siversson M, 2025. Reassessment of the possible size, form, weight, cruising speed, and growth parameters of the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), and new evolutionary insights into its gigantism, life history strategies, ecology, and extinction. Palaeontologia Electronica, 28, a12.

You can also watch an excellent interview with Phil on the Elasmocast YouTube channel here: https://www.youtube.com/watch?v=1CgdKWEueqc.

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