Otodus megalodon (formerly Carcharocles megalodon, and before that Carcharodon megalodon) was history’s largest known carnivorous fish – an enormous mackerel shark that lived from the early Miocene to the end of the Pliocene Period (approx. 23 million to 3.6 million years ago).

According to my calculations, and based on a comparative study to established lengths of its ancestors, Megalodon reached a maximum length of approximately 56 feet (somewhat akin to Gottfried’s 1996 size estimation formula). Officially, however, the experts have recently reduced its maximum estimated size to 50 feet (Shimada 2019) with an average adult size of around 35 feet. Regardless, a mammoth predator. The shark’s weight will be discussed later.

Megalodon devours a rotting sperm whale
Carcharodon megalodon feeds on a dead sperm whale (Image credit Alberto Gennari).

Megalodon has been widely touted as a killing machine and has been what I call the “primeval protagonist” in numerous novels, starting with Robin Brown’s book of the same name, circa 1981. Brown depicted the colossal fish as surviving in the ocean abysses and rising with considerable zeal to inflict death and destruction on us, unsuspecting surface dwellers.

Since 1981, the extinct shark has appeared in a plethora of direct-to-video and TV films, including “Shark Attack 3 – Megalodon” where, at 80 feet, it was the size of a large rorqual, and such outrageous turkeys as “Mega-Shark vs Giant Octopus”, where it was the size of an ocean liner and could leap 10,000 feet in the air to snatch passing jets out of the sky.

Spiraling back down to earth: let me say up front that Megalodon was, without a doubt, an awe-inspiring flesh eater. But cinematic artistry aside, was it the fearsome apex predator that the public has been led to believe? The answer is yes . . . and no. In my recent novel, Kronos Rising: Kraken (vol. 1) I featured a Carcharodon megalodon by the name of “Ursula”, which was up-scaled to 84 feet and 200+ tons to battle a similar-sized pliosaur. KRONOS RISING: KRAKEN vol. 2 Amazon link As I disclosed in Kraken, the fossil evidence suggests that history’s largest shark was an efficient and active hunter as a juvenile and sub-adult but, as it matured, it switched over to a diet that was primarily carrion.

This may come as a surprise to some, and there will undoubtedly be a lot of die-hard Megalodon fans who, like the Spinosaurus fans when their Tyrannosaurus-killing “Jurassic Park 3” monster was downgraded to a quadrupedal piscivore, will be offended or even outraged by this, but the evidence is there, and in abundance. What is this evidence and what brought me to such a conclusion? It is found where one might expect: in the fossils I studied, combined with physics and good old fashioned common sense.

Let’s start by looking at one of Megalodon’s modern-day relatives and the fish it is so often based upon, Carcharodon carcharias, AKA the great white shark. Great whites are active predators with sharp and serrated teeth which are designed to help them catch, kill, and consume their prey. It is a widely-known fact that the white shark is an active hunter that starts off life preying on fish (including smaller sharks) and then, as it becomes larger and more cumbersome, switches to a diet of marine mammals such as sea lions and elephant seals. It also changes hunting strategies and becomes more of a mugger, creeping along the bottom camouflaged before rushing up to ambush its more agile prey. Like most hunters, it misses most of the time but, obviously, succeeds often enough to survive. And, like most predators, it supplements its diet with blubber-rich whale carcasses whenever possible.Changes in the prey of great white sharks.

Carcharodon carcharias misses its dinner.
A great white shark’s attack on a hapless seal misses its mark.

The reason the white shark loses agility as it grows and has to make this conversion is the chink in its rough-skinned armor – it has a skeleton made of cartilage. Cartilage is like tire rubber; it’s tough and flexible and is great when you’re six or ten feet long (700-pound mako sharks can reach incredible speeds, clear the water in 20 feet leaps, and maneuver like a jet fighter with thrusters at full burn) but as the animal gets larger that rubbery skeleton becomes a problem (think of a skyscraper – the “skeleton” is made of steel girders, not tire rubber. If it WAS made of rubber, it would eventually collapse under its own weight). When a shark like a great white reaches fifteen or more feet in length its skeleton can no longer support it as well, even in the water. It loses top-end speed, agility, and the ability to make tight turns. Hence, it changes into an ambush predator.

A perfect example of this is a recent video of the well-known white shark “Deep Blue”. Seen here accompanied by Ocean Ramsey and a pair of dolphins, the bloated (and possibly pregnant) shark is only interested in a nearby whale carcass. She appears too slow to chase the dolphins that frolic around her, and even ignores one when it rudely flaps its flukes right in her face (around the 1 minute mark). One would think an apex predator like that would seize on the chance the sink its teeth into a fresh dolphin flesh, but she doesn’t. Is it because the carcass is there, the proverbial “bird in the hand”? Or is it because both the shark and dolphins know she is so cumbersome that, even at point blank range, they can dance away from her without effort?


If anyone doubts the limitations a cartilaginous skeleton imposes on large sharks, one has only to compare it to its rival Orcinus orca, the killer whale. The world’s largest dolphins, Orcas are designed to drag down and kill baleen whales many times their size and have a well-earned reputation for killing and feeding on similar-sized great whites as well. Pound-for-pound, a killer whale is far more powerful than a white shark. True, it reaches a larger maximum size, yet despite this additional mass it remains faster and more maneuverable. This is due to steely muscles attached and anchored to dense bones. We’ve all seen videos of an Orca beaching itself to take a seal and then working its way back into the water.

Can you picture a 5,000-pound shark doing that? No, because it’s impossible. Even a 6-foot juvenile is often incapable of returning to the surf without human intervention.

I shot these photos of captive killer whales at SeaWorld. In the first shot, the cetaceans are “tail-walking”, holding themselves vertically up out of the water using thrusts from their flukes to keep their multi-ton bodies upright. And in the second, an Orca of greater mass than any known white shark is able to hoist both its tail and head up off the deck and, while staying suspended in that pose, wriggle itself around so that it spins in full circles – an astonishing display of strength. What would happen to a shark of any species that size if it was pulled up out of the water? It would flap its tail in protest a few times and then lay there, exhausted until it had breathed its last.

Seaworld Orcas pack a punch.
Captive Orcas demonstrate astonishing, gravity defying strength and agility.

I say this not to defame sharks in general, but to illustrate the reason why Megalodon graduated from an active hunter to a carrion consumer. As it got bigger and heavier and gravity and water resistance exerted more and more influence on its enormous body, the shark inevitably became slower and clumsier. Let’s consider Cetorhinus maximus, AKA the basking shark. Basking sharks grow quite large, up to 40 feet, and like their extant relative the great white, and their extinct cousin Megalodon, they are mackerel sharks. Despite occasionally falling prey to Orcas, they are surprisingly slow and lumber along with a maximum swimming speed of around 4 mph. They are also far from agile.

Basking shark and great white. The bigger they get the slower they get.
A basking shark and a great white – two mackerel sharks. With greater mass comes reduced agility.

Granted, basking sharks are filter feeders and smaller great whites are far faster (maximum speed of 30 mph versus the larger Orca at 35-40 mph), but the principal still holds. When you see footage of the largest known great white, “Deep Blue”, you can see right away that, gravid or no, the fish is both clumsy and lethargic. It doesn’t have to move as fast because it has few predators at that size. But more importantly, it can’t. It’s a matter of anatomy, and it’s the same reason why National Geographic, in their recent special, “Sea Monsters: The Definitive Guide” explained why whale sharks don’t grow as large as a blue whale. It’s the limitations of a cartilaginous skeleton.

My research, and a preponderance of evidence, suggests that Megalodon went through a transitional period as it grew. As a pup, commonly estimated at 7-10 feet at birth, it was a fast and agile hunter, much like a great white of similar size. It fed on fish, whale calves, sea turtles, and sirenids (sea cows). As it grew larger, reaching fifteen to twenty feet in length, it was still an active predator and would have hunted small cetaceans without a doubt. But as it got bigger and clumsier (approx. thirty+ feet) its own mass became its enemy and, at a certain point, it became easier for it to look for alternative sources of food, i.e. carrion.

This is supported by the design of the fish’s teeth. If we compare the tooth of a young Megalodon (perhaps 10 feet in length) to that of a great white we see a striking similarity in their respective dentition. The teeth are both very sharp and highly serrated – designed to impale and rend flesh and inflict horrific wounds. A twenty or even thirty-foot Megalodon would have been a voracious predator, and a deadly one, to be sure.

Baby Meg and adult great white. Almost identical at this point.
A comparison between a juvenile Megalodon tooth and that of an adult (est. 15′) great white shark.

But as that same Megalodon matured into an adult and attained a size of perhaps thirty-five feet or more, the serrations on its teeth steadily decreased in size until, eventually, they were barely visible. This is, again, opposed to the great white, whose serrations remain relatively unchanged in number and grow with the shark. Megalodon’s tooth crowns and roots also begin to change in structure, converting from serrated blades to blunter, wedge-shaped devices with wide roots and lined with tiny serrations. In terms of tools, they were like chisels with hacksaw-like edges. They were no longer designed primarily for slicing flesh. In fact, that became their secondary objection. Their main purpose was to shear through bones.

Now, some will claim that this was a hunting strategy and that Megalodon used its chisel teeth to crush the spines of whales or sever their flukes. That could be a tall order, as some prehistoric whales were as large as the whales of today. Moreover, attacking a heavily-reinforced bony region is a difficult and dangerous way to make a living. It implies a need to get a firm grip on something that is actively struggling and fighting back. A bleeding fluke or abdominal wound would be a much safer and more efficient strike. The great white’s triangular teeth certainly work well for crippling the tails of similar-sized elephant seals and whale flukes are also vulnerable to those types of bites. So why have thick, chisel-like teeth?

6.5" Megalodon tooth.
An adult C. megalodon tooth measuring 6.5″ in slant height. Note the tiny serrations and overall mass. (from the author’s private collection)

The answer is based on the need to get at a vast mound of rotting flesh. As whales grew steadily larger, smarter, and developed things like echolocation and a protective herd dynamic, they became harder for adult Megalodons to kill. At forty feet or more, a whale is far more agile than a shark of similar size, and faster, too. Hence, the larger Megalodons found it far easier to switch from active hunting to scavenging, and their teeth adapted to this role as well. One can easily picture a fifty-foot female shark, lord of all she surveys, tracking the scent of a rotting whale carcass – a vast, calorie-rich bounty upon which to satiate herself. The carcass would be days old, most likely, and may have been the victim of injury, old age, or the more svelte and agile 30-foot versions of herself. As she approached, other scavengers (including smaller Megalodons) would wisely scatter. But by the time she got there most of the whale’s blubber and outer musculature was already gone – stripped away and consumed. So what was left? The nutritious internal organs: the heart, lungs, liver: all waiting to be devoured. The smaller sharks couldn’t get to them because of the giant, bony ribs that shielded them, but the huge adult Megalodon, with her gaping nutcracker jaws, could systematically crunch through the dead whale’s rib cage, revealing the vast bounty of putrescent flesh within.

Whale becomes snack for hungry sharks
Extant sharks make short work of a drifting whale carcass. Back in the Miocene, hungry-but-ponderous adult Megalodons would often find such carcasses stripped by the time they got there.

This is why the teeth of the larger Megalodons became stouter and blunter over time. The fish had evolved to clean up whale carcasses that littered the pristine oceans of the world like sprinkles swirling on a giant cupcake. With no humans to slaughter them and millions of whales swimming around at any given time (e.g. in modern times there were 400,000 blue whales and 1.5 million humpback whales alone before we killed them), over the course of each year there would have been tens of thousands of whale carcasses to devour. And you can rest assured that the giant sharks did the job. In my novel Kronos Rising: Kraken, an elasmobranchologist by the name of Judas Cambridge seethes at the memory of his former employer rejecting the Megalodon as a candidate for their bio-weapons program, calling them the “garbage trucks of the seas”. I wouldn’t go that far – the shark would still kill anything it could physically catch – but from a “cleanup crew” perspective, he had a point.

In an effort to appease the inevitable skeptics, let me touch on the ancestry of Megalodon to reinforce my (toothy) point. The chart below demonstrates what many paleontologists believe to be the lineage of C. megalodon. As you can see, the adult sharks’ teeth changed over time as the animals grew ever larger and their diets change. Whereas the earliest “mega-tooth” sharks like C. auriculatus were primarily fish eaters and probably remained active predators from birth to death (note: maximum length for Auriculatus is around 32 feet), later specimens like C. chubutensis and Megalodon itself fed mainly on marine mammals and gradually evolved those familiar bone-gnashing chompers.

Megalodon's ancestors
Probable mega-tooth shark lineage, leading up to C. megalodon.

Actually, let’s take a brief look at Chubutensis and do a quick comparison with Megalodon. C. chubutensis was a large mackerel shark with teeth up to 5” long and a body size of up to 40 feet. (Note: C. chubutensis and C. megalodon had an overlap of some 2.4 million years where the two fish existed at the same time. It is believed that a population of Chubutensis split off, evolving into Megalodon, while the remainder of the species remained unchanged until their eventual extinction). Chubutensis was large and powerful, a formidable hunter, but as it, too, passed the 30-foot mark it encountered the same skeletal-based speed and maneuverability limitations its larger relative did. We can state with confidence that, as an adult, Chubutensis also led a (primary) scavenger’s life, with the two sharks often sharing the same carcasses, as great white and tiger sharks do today.

Now, some might question this statement and ask, “Do we have any evidence that Chubutensis was also a scavenger as an adult?” We do, and once again it is the animal’s teeth that hold the answer. When we look at this sub-adult C. chubutensis tooth (3” slant height, indicating an approx. 24-foot shark) we see that the teeth were still sharp and had comparatively large serrations – more like a great white’s than an adult Megalodon’s. This was an active predator that made regular kills. Now, when we look at a large adult Chubutensis tooth (nearly 5” and indicating a 40-foot specimen) the tooth is surprisingly Megalodon-like. The serrations have shrunk and the tooth is thicker and blunter – heavily reinforced for biting through rib cages and vertebrae. This animal would have been a scavenger for the most part, feeding on dead whales and sirenids and appropriating kills from smaller sharks whenever it could.

Chubutensis teeth, juvenile and adult.
Comparison between a 3″ and a 4.95″ C. chubutensis tooth, showing tooth adaptations over time (image credits and Megatooth Collector)

Note: at no point am I saying that either C. chubutensis or C. megalodon were not carnivores. They were flesh-eaters of the highest order, and woe to any wounded cetacean or foundering sea turtle that could not get out of their way. But when it came to tackling big, agile prey, the very anatomy of these behemoths hamstrung them and forced them to behave more like giant hyenas – making kills if they got lucky, but primarily chowing down on the rotting carcasses their amazing senses of smell led them to. (An unfair comparison, I suppose; the much maligned hyena is actually an active predator, but you get the point)

Last but not least, if my theory still needs any “reinforcing”, let me point out the damage that is often present on fossil Megalodon teeth. Below, you will see a tooth I had in my private collection; it measured nearly 6.5” in slant height, over 5” in width, and weighed 20 ounces – a decent specimen. It is what is commonly described as a maxillary (upper jaw) “impact tooth”, meaning it is among the first to come into play when striking prey. The tip of my tooth exhibited what paleontologists describe as “feeding damage”. Before it was lost, the shark’s tooth tip was crushed down as it fed.

6.5" Megalodon tooth showing feeding damage to tip (compression)
6.5″ Megalodon tooth showing feeding damage to tip (compression)
Broken Meg tooth.
6″+ Megalodon tooth showing feeding damage (shearing). Note the fine serrations.
Broken tipped Meg tooth
Close-up of one of the author’s Megalodon teeth showing fine serrations and compression damage to the crown tip.

This type of damage is, unfortunately, common in Megalodon teeth, most especially the largest and most commercially desirable teeth, and tends to take away from the value of found specimens. But why do broken or mashed down tips primarily plague the largest of teeth (usually 5”+) and not the smaller ones? Once again, we are back to the scavenging issue. The type of tip damage we’re talking about is not the result of a sudden impact, i.e. smashing into the body of a whale, jaws agape, to crush its spine. If that was the case, with tooth enamel being innately harder and stronger than whale ribs, the tooth would not suffer damage like that. Rather, the weak link would be the tooth’s insertion point at the gum line where it is anchored into comparatively soft cartilage. Instead of breaking, the tooth would most likely have shorn away, as sometimes happens when white sharks strike a surf board or kayak. The tip damage we see in large Megalodon teeth is caused by what any engineer will tell you is compression damage. The shark is biting into (oft times repeatedly) a hard substance, i.e. rib bone, and the repeated stress, all focused on the point of that chisel-shaped tooth, causes the tiny tooth tip to collapse. This happens when steady pressure is applied, and typically against a stationary target. This explains why it is mainly the biggest teeth that suffer this type of damage. The animal is too large to easily hunt the more agile whales it preys upon and is forced to fall back on scavenging to survive: biting through bone repeatedly to get the portions of the whale that smaller predators and scavengers have missed.

This combined evidence leaves little to the imagination. A white shark (or a sub-adult Megalodon) is/would-have-been an active hunter whose serrated and dagger-like teeth evolved to inflict massive wounds that caused rapid hemorrhaging and death. Those are the jaws of a predator. Whereas the chisel-shaped, hacksaw-edged teeth of an adult Megalodon (shown beside them) are more like a nutcracker – breaking open a hard shell to get at the juicy prizes others have left behind. That is the hallmark of a scavenger, and a hellaciously large one at that.

great white teeth vs meg teeth
Comparison between the jaws of C. carcharias and C. megalodon: one for slicing through flesh and blubber, the other for breaking through ribs to get to the internal organs.

Note: in terms of size, and although there are those who have created images of Megalodon as what looks like a giant sausage with teeth, it is far more likely that the shark’s physique was more like a basking shark’s or sand tiger’s, otherwise it would have even been unable to move, let alone maneuver. Scaling up from the largest accurately measured basking shark (a 40.3-footer that weighed 21 tons) we can safely conclude that a 50-foot Megalodon weighed around 40 tons, a fearsome carnivore by anyone’s definition. Using a great white as a model yields an even heavier shark somewhere in the 50-ton range, whereas scaling up from a 10.5, 350 lb sand tiger results in a more slender Megalodon weighing only 26.5 tons (personally, I’m inclined to believe the shark was bulkier than that).

One additional point: My theory that adult Megalodons were most likely primary scavengers may also shed light on what caused their decline. Toxic algae blooms, loss of plankton, and other harsh and sudden changes in the ecology of the seas that drastically affected populations of baleen whales would have had a tremendous impact on this giant hunter/scavenger. The shark’s target prey would not necessarily have had to go completely extinct to decimate its numbers; a reduction in whale populations by 80%-90% would have, similarly, reduced the number of available carcasses by the same amount. No carcasses, no food. No food, no brood stock Megalodons. No brood stock, no future generations.

In summary, based on available fossil evidence, as well as drawing parallels from related/similar extant species, we can safely conclude that C. megalodon, the 50-foot, 50-ton super-shark, was an active predator as a pup and sub-adult and, as it approached sexual maturity (approx. 30+ feet) it began to change. Its teeth grew steadily stouter and more finely serrated and it gradually converted from a hunter into a scavenger until, as a 40+foot adult, the majority of its food came from drifting cetacean remains (and an occasional pregnant or wounded whale or terror-stricken sea turtle).

We can also conclude that it is very likely that reduced whale populations, and the subsequent lack of whale carcasses, had a substantial impact on the shark’s survival, as it would have directly affected the number of breeding adults and drastically reduced its numbers. This was, in all likelihood, a contributing factor to Megalodon’s demise; it simply got so huge that the inherent limits of its cartilaginous skeleton forced it into a vulture-like role. And, with no carcasses to feed on, the colossal shark eventually disappeared.

Thanks for stopping by and I hope you enjoyed the article. If you’re a fan of Megalodon and sea monsters in general, make sure you check out my recently released novel, Kronos Rising: Kraken (volume 2). I think you’ll enjoy it. Kronos Rising Series on Amazon


Max Hawthorne, Author

PS: a little freestyle rap I did for a certain paleontologist whose knowledge is only exceeded by his arrogance. You know who you are. “You think ‘cause you can name a few bones and stones that only you know wrong from right. But you can stroke them bones ‘till the cows come home, ’cause you don’t know coprolite!”

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