Astrum Space - We Were Wrong About Megalodon | Astrum Earth

Episode Date: December 25, 2025

Everything scientists thought about Megalodon was wrong.The Megalodon. More than just a Great White, this beast might be the most terrifying predator to ever rule the oceans. But new research suggests it was even more fearsome than scientists previously thought, and didn't look how we expected. Is this colossal beast still lurking in Earth’s deepest waters? ▀▀▀▀▀▀Want to restore the planet’s ecosystems and see your impact in monthly videos? The first 100 people to join Planet Wild with my code ASTRUM12 will get the first month for free at: https://planetwild.com/r/astrumearth/...If you want to get to know them better first, check out their mission using art to protect marine life: https://planetwild.com/r/astrumearth/...▀▀▀▀▀▀Astrum's newsletter has launched! Want to know what's happening in space? Sign up here: ⁠https://astrumspace.kit.com⁠A huge thanks to our Patreons who help make these videos possible. Sign-up here: ⁠https://bit.ly/4aiJZNF

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Leaving behind only teeth the size of your hand and questions big enough to fill an ocean. What happened to this nightmare of the deep? Could it still be out there lurking? Because more terrifying than the idea of Megalodon surviving somewhere in the abyss is the possibility that we never truly understood it at all. But new evidence is suggesting we were very, very wrong. Could Megalodon not just have been faster, but far bigger than we thought? I'm James Stewart and you're watching Astrom Earth.

Join me on this journey back to a time when Megalodon was at its peak. We'll uncover the truth about the truth about this colossal predator and find out how and why scientists got things so, so wrong. Imagining our oceans patrolled by something three times the size of a great white shark, with jaws easily big enough to swallow two people side by side, is irresistible. But is it real? To find out, we need to go back to a fateful day in 1666. when two fishermen caught a giant shark off the coast of Livorno in Italy.

The locals were so shocked by their discovery that the Duke at the time ordered that this curiosity be sent to Niels Steenson, better known as Steno, a Danish anatomist working in Florence. Curiously, it wasn't the size of the shark that most interested Steno, but rather its teeth. He was struck by how much they resembled to. tongue stones, triangular pieces of rock that since ancient times, many thought to be petrified snake or dragon tongues. Instead, Steno postulated that they were the remains of ancient sharks

entombed in rock. He argued that rock layers formed slowly over time and that an object like the teeth could give us a snapshot of a particular moment in history. The significance of this observation would change the course of paleontology forever. He had discovered what fossils really were. This was a revolutionary idea, and whilst great for the future of paleontology, what's the link to Megalodon? Well, because sharks don't have bones, their teeth are often the only part that survives, making them our best clues. And Megalodon had a lot of teeth, 276 to be exact, some of which were up to 18 centimetres long. Like modern sharks, Megalodon's teeth were being constantly replaced. They were arranged so that every time a tooth

fell out, one in the row behind would push forward. One Megalodon could get through 40,000 teeth in its lifetime. In other words, over Megalodon's 19 million year existence, the sea floor became absolutely littered with old gnashes, and each one stood a chance of becoming a fossil. And those fossilised teeth hold the key to nearly everything we know about this enormous shark. We even named it for them. The word Megalodon itself simply means big tooth. So in order to determine what Megalodon was, biologically speaking, paleontologists have long trance. tried to use these massive teeth to identify its closest living relatives. Megalodon was first formally described in 1835 by Swiss-born American naturalist, geologist

and teacher Louis Agassiz, who named the species Carcaridon Megalodon. It was placed here in the genus of sharks within the Lamnadee family, almost entirely because its large triangular serrated teeth were pretty similar to that of modern-day Great Whites, known as Carcarodon Carcarius. A skeletal reconstruction led by Mike Godfried in 1996 backed this up. He gave Megalodon the look of the stockier great white we know and fear today, extrapolating Megalodon's size from the dimensions of its teeth. Which is all pretty handy, isn't it? Case closed. Giant Great White Shark incoming, J. Sim Statham's Delighted and the Meg wreaks havoc in Hollywood. Well, not quite. In the early 2000s, distinct differences between the

teeth and a closer look at the fossil record suggested something a bit more complicated. So during the mid-2000s, Kevin Nyberg and his colleagues conducted a series of morphometric analysis between Megalodon and Great White Sharks. They found no overlap in shape variants of the teeth, nor in the shape of their roots. In simple terms, the serrations of white shark teeth were irregular and triangular, whereas those of Megalodon were finer and rounder. Essentially, it seemed very unlikely that the Great White evolved from Megalodon, as originally thought. But something else.

In 2019, Dana J. Urt used this new evidence to officially allocate Megalodon within the extinct otodontaday family, aka the megatoothed sharks. Other sharks in this family include Otodos Obliquus, Megalodon's earliest ancestor, that lived during the Eocene times, about 60 to 37 and a half million years ago. So today we arrive at the middle ground of Otodos Megalodon.

The scientific name Megalodon now generally goes by, although it should be noted not everyone agrees with this and some still prefer to use caracaryclays. There's a bit more dental drama in amongst all of that, to be honest, but I think that gives us a good overview of Megalodon's lineage. But that's not the only thing scientists were mistaken about, though, and something even more sinister was about to come to light. Every depiction of this prehistoric shark you've seen in theatres,

online and in your nightmares is very likely wrong. Because the largest shark to have ever lived was actually bigger than we first thought, much bigger. For a long time, the estimates for how long Megalodon was were based purely on lots of fossilised teeth and the occasional very rare fossilised vertebrae. No complete skeleton has ever been found. Now, from that evidence we had, we thought its body was between about 15 and 18 metres in length, most until now, because this year in 2025, a group of 28 international scientists led by paleobiologist Dr Kenchu Shimada reshaped how the world thinks about this prehistoric giant.

Central to this reimagining is one particularly rare set of vertebrae. Discovered in Belgium and now safely catalogued in the Royal Belgian Institute of Natural Sciences, conservatories in Brussels. It measures a whopping 11 metres in length, but that only represents the trunk of the shark, its head and tail are still missing. So to try and fill in the gaps, Shimada's team compared it to the bodies of 165 other living and extinct shark species.

This enabled them to extrapolate the animal's true size, and they found that Megalodon's head likely made up about 16.6%. of it, while its tail accounted for around 32.6%. Applying this to the Belgian vertebrae specimen, the shark's total length would have been roughly 16.4 metres, with a 1.8 metre head and a 3.6 metre tail, which was pretty much in line with what the current estimates were. But here's where things get really interesting. because there's another even larger fossilised vertebrae from Denmark, 23 centimetres wide. Now that suggests that some individuals may have been even larger than that 16.4 meters.

Perhaps even reaching an astonishing 24.3 meters, nearly 10 metres larger than we previously thought, rivaling the size of a blue whale and weighing in at a mind-blood. 904 tons. But the revelations don't stop there. Not only were Megalodons bigger than we previously thought, they also looked vastly different too. Whilst reviewing a paper from August 2022, in which scientists built a digital 3D model of Megalodon, Shimada and his team realised that some of the maths behind the shark's proportions didn't seem to add up. Using the same 145 species of living sharks and 20 extinct species, they built a database logging the proportions of their heads, bodies and tails. The researchers then compared them to the parts of Megalodon's body that have been

found, and what they found changed everything. Megalodon was not a stout, tank-like great white shark at all, but rather a more streamlined fish with a much shorter nose when compared with the Great White. It had a flatter, almost squashed jaw, equipped with extra long pectoral fins to support its weight and size. It was more like a lemon shark. The same study also revealed something deeply disturbing. Fossilised vertebrae suggested that baby megalodons were born huge, measuring between 3.6 and 3.9 metres long. But that's not the gross parts, because like modern-day Great Whites, they also likely practice. a form of in-utero cannibalism, where embryos ate unfertilized eggs to fuel their early development.

Survival of the fittest personified. We've seen what happens when we lose large predators. The damage to ocean ecosystems is catastrophic. And sadly, human activity today doesn't help that, with things like overfishing and bottom trawling. But that's where our friends at Planet Wild come in. They're a community-based nature protection organisation fighting back. Think of them like crowdfunding but for nature. Each month, their community funds a project to restore nature around the world

and then documents it with a YouTube video report so you can see the impact of your contribution. It's actually their transparency that inspired us to become members in the first place. They had this amazing project recently where an underwater sculpture museum had been created to help combat bottom trawling in the Mediterranean than of course restore the surrounding ocean. And there's loads more projects just like that. Actually, I'm so passionate about what they do.

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than 30 days, as we have back to the video. All of those revelations about Megalodon's shape also led to Shemada's team stumbling upon a larger pattern in marine biology. This new, more streamlined, more menacing shape makes sense as to why Megalodon was able to grow to the whopping 24.3 meters his team had estimated. Stocky bodies like that of the previous iterations of Megalodon, great far more drag, make it much harder to move efficiently through the water. These constraints are why our current modern-day great white sharks tend to cap out at around

seven metres, any bigger and they would lose the speed that makes them such dominant predators. The same logic applies to other animals such as blue whales. They can grow up to 30 metres long, owing to their sleeker, more hydrodynamic shape, allowing them to traverse hundreds of thousands of miles of ocean. Megalodon's new lightweight frame may also go some way to explain why it was able to pop up all around the globe too. The species was so widespread that Megalodon teeth have been found on every continent except Antarctica. Based on what we've just discussed, it seems very much like Megalodon was superior to the Great White Shark in every single way. not only unrelated but more refined, fitter, bigger, better.

It makes the fearsome great whites we have today feel pretty feeble. But don't write off the Great White Shark just yet, because it has one last card up its sleeve, one that's about to deal a fatal blow. So now we finally know what this creature was. How did something so dominant, so powerful, just disappear? What went wrong for Megalodon? How did the ocean's most fearsome predator just vanish from history?

We know when Megalodon went extinct because we've only ever found teeth that are roughly between 20 million and 3.6 million years old. But why Megalodon went extinct is not as straightforward. It has spent millions of years flourishing in the nutrient-rich waters of the Miocene epoch, and it certainly had a good run, but all good things come to an end. One theory that has popped up time and time again is that as the planet got closer to the ice age, it brought about colder water temperatures and it simply became too cold for the giant shark to cope. However, data from scientists Catalina Pimiento and Humberto G. Ferron seem to suggest otherwise. When analysing Megalodon's global distribution through time, Pimiento found,

that Megalodon was capable of inhabiting colder latitudes, and its distribution through time did not correlate with any warming or cooling temperature trends we know of. These findings fit nicely into the work of Ferens, who has theorised that Megalodon was likely a mesothurn, a type of warm, blooded animal that keeps its body temperature somewhat warmer than the surrounding water,

and therefore able to cope quite well with a wide range of temperatures. So if the planet itself couldn't see Meglodon off, then what did? Pimiento's research showed that Megadon's global abundance and distribution peaked in the middle Miocene, roughly 11.6 to 16 million years ago, before going into decline. Now, interestingly, this correlates with a huge loss of whales, dolphins and porpoises, i.e. Megadon's favourite foods. Extinction rates of marine megafauna, the low. largest genus or species of a particular group of animals were incredibly high in the

Pliocese. Among those lost included 55% of large marine mammals, 43% of sea turtles and 9% of sharks, with a total of 36% of large marine species going extinct. Changes in sea level may have also impacted Megalodon indirectly. Flutuations were common during the Pliocene and could have spelt bad news for a giant shark if coastal habitats where there's a lot of food available were impacted. As all of that occurred, Megalodon was likely forced to compete harder for what remained, with, guess who? Jaws himself, the Great White shark.

After all that, Megalodon's size could well have been its undoing. The evolution of the Great White, a smaller creature that needed less to eat, meant Megalodon never really stood a chance, a deep sea version of David versus Goliath. So how is it that 3.6 million years after it went extinct? There are numerous eyewitness accounts and documentaries suggesting it's still out there. Could Megalodon really be seeking refuge in the dark depths of the ocean? Is it possible even that it's hiding in the Mariana trench, waiting for the perfect time to reveal itself to the world again?

Well, for a brief moment, they almost had us. One of the best-known fuelers of the Megadon Alive Fire was a 2013 documentary, which revolved around an investigation into the huge sharts continued existence. Watched by millions, it was, I must admit, quite compelling. It showed a blue whale carcass beached off the coast of Hawaii that looked to have been brutally attacked. A scientist in the programme explained that the culprit had to be. to be the size of a megalodon. And other scenes claim to show six foot tall fins poking out of the

ocean near similar blue whale attacks. Unfortunately, or fortunately, depending on your view, many people missed the disclaimer at the start of the show, which stated the potential return of the species was not based on fact. As it transpired, the entire documentary was full of faked photos, footage and even actors hired to portray scientists. There have, of course, been other unconfirmed sightings of living megalodons. In 1918, a fisherman off the eastern coast of Australia claimed to have seen a shark 31 to 95 metres long, making off with some lobster pots. And as recently as 2022, NBC Boston led with the headline,

two Megalodon sightings off New England. Spoiler alert, it was a basking shark. Another common argument for Megalodon being out there somewhere points to the fact that some large animals, such as the giant squid, took a while to be discovered by scientists. However, their remains have been washing up on shore and caught by fishermen for decades, if not longer, giving us real, hard evidence that they existed before

we had ever seen or recorded a full specimen. By far and away, the most common arguments you'll see for Megalodon's survival is we've only explored 5% of the oceans. Whilst that may be true, thanks to science, we don't really need to explore all that much to know that a giant whale-killing shark isn't in there. Megalodon was an apex predator, and if they were still out there, orcas and great white sharks would never have taken up their mantle. It's also no coincidence that from around the same time Megalodon went extinct, the size of whales is. exploded. In the absence of large predators like Megalodon, whales in the Pleistocene were twice

the size of those in the Pliocene, hence the appearance of the Blue Whale. But I've saved the best theory for last, don't you worry, I hadn't forgotten? What if the Meglodon is just hiding in the Mariana trench? Love this. A theory popularised, of course, by Jason Statham's film, The Meg. That story was actually based on the fact that Meglodon teeth were discovered near the trench by the HMS Challenger in 1873, and were considered new because they were unusually white, dated to between 24,000 and 11,000 years old. The reality, though, is much different. Instead, it's likely the fresh, pearly whites were just uniquely well preserved by a thick mineral crust of manganese dioxide that significantly reduced the decomposition rate. Megalodon teeth? Absolutely recent. No,

There are other issues too. If we've learned nothing else from this video, it's that Meglodon likes to eat and eat a lot. We made a video on the Mariana Trench, please you check it out on the channel. And we showed exactly what is there, and the reality is there's not loads. Certainly not enough food to sufficiently feed a 24-meter megashark. Incidentally, snail fishes are the deepest dwelling fishes, but we don't find them until much deeper than 8,000 meters. quite possibly for the same reason.

There just isn't enough to eat, and they're only 20 centimetres long. So there we have it. Our journey back in time, to the true land of the giants, and one of the most gloriously monstrous beings ever to exist, comes to an almost anticlimactic end. Something so mysterious and so powerful feels

like it deserves to bow out amongst fireworks and explosions. But instead, the reality is, rather meek. Despite that, it doesn't make the Meglodon any less intriguing. It seems fitting that something so elusive was able to keep a 19 million-year-old secret, and that leaves me feeling very satisfied indeed, actually. Yes, Megalodon is most definitely extinct, but its mystery still lives on. There's just one way to know for certain what Megalodon was, and like any good murder mystery cliffhanger, they've still never found a body. So, until then, giant lemon shark it is.

Let me know you've got this far in the video by leaving a lemon emoji in the comments as a tribute to Megalodon's Lemon Shark makeover. And I'll see you in the next one.