42 Extinct Animals That Might Still Be Alive | Full Series

Some of the animals you think are extinct are still alive right now. We've explored less than 5% of our oceans, and there are jungles no human has ever walked into. We didn't watch these animals die. We just stopped looking. Forty-two animals the world gave up on that keep turning up on camera traps, in the deep, in the dark. A few were already found alive after we'd buried them, and the last one, scientists are bringing it back as we speak. Number 42, Megalodon. Some people will tell you the ocean is simply too big to be sure of anything. They're not entirely wrong.

looking. 42 animals the world gave up on that [music] keep turning up on camera traps, in the deep, in the dark. A few were already found alive after we'd buried them and the last one, scientists are bringing it back as we speak. Number

We've mapped more of Mars than our own deep sea floor. So when a fisherman swears he saw a shark the size of a boat, the honest answer is unsettling. We can't prove he didn't. The Megalodon was the largest shark that ever lived. Picture a creature up to 50 feet long, longer than a city bus, with teeth as big as your hand and a jaw wide enough to swallow a person whole.

We've mapped more of Mars than our own deep sea floor. So when a fisherman swears he saw a shark the size of a boat, the honest answer is unsettling.

It ruled the oceans for millions of years, but around 3.6 million years ago, it vanished. Scientists think the seas cooled and its prey thinned out. Therefore, the giant slowly starved. So why won't the story die? Part of it traces to a real voyage, the HMS Challenger in the 1870s, which dredged Megalodon teeth off the seabed.

It ruled the oceans for millions of years, [music] but around 3.6 million years ago, it vanished. Scientists think the seas cooled and its prey thinned [music] out. Therefore, the giant slowly starved. So why won't the story die?

Later, someone claimed those teeth were only about 10,000 years old, but that dating method was flawed, and researchers have since thrown it out. Then in 2013, a Discovery Channel special hinted the shark still swims, except it was staged fiction played by actors. Here's what's strange. Recent studies suggest Megalodon wasn't the bulky great white we imagine. It may have been longer and far more slender.

Later, someone claimed those [music] teeth were only about 10,000 years old, but that dating method was flawed and researchers have since [music] thrown it out. Then in 2013, a Discovery Channel special hinted [music] the shark still swims, except it was staged fiction

But if a hunter hiding in the ocean unsettles you, the next one never needed the sea. It ruled the swamps, and it had no legs. Number 41, Titanoboa. Deep in a Colombian coal mine, workers dug up a single backbone wider than a dinner plate. It didn't belong to a dinosaur. It belonged to a snake, and that snake was as long as a school bus. Scientists named it Titanoboa and announced it to the world in 2009. Picture a snake more than 40 feet long, as thick around as your whole body, weighing over a ton. It ruled the swamps of South America nearly 60 million years ago, long after the dinosaurs were gone. But then the planet cooled, and a snake that big couldn't survive the chill. Therefore, it vanished. Here's where it gets strange. No one has ever found a living Titanoboa, but the Amazon has never stopped whispering about giant snakes. In Brazil, people tell stories of the Sucuriju Gigante, a monster far larger than any anaconda on record. In 1907, British explorer Percy Fawcett swore he shot a snake over 60 feet long on a remote river. Scientists doubted him, yet he never took it back.

But if a hunter hiding in the ocean unsettles you, the [music] next one never needed the sea. It ruled the swamps and it had no legs. Number 41, Titanoboa. Deep in a Colombian coal mine, workers dug up a single backbone

The jungle is enormous and mostly unmapped. Therefore, people keep asking what might still be hiding in water no human has touched. But here's the part most people miss. Titanoboa could only grow that huge because the world was blisteringly hot back then, and cold-blooded animals need heat to get big. A giant snake in a river is one thing. The next creature supposedly waits in deep, cold water, and people have hunted it for almost 100 years.

than 40 ft long, as thick around as your whole body, weighing over a ton. It ruled the swamps of South America nearly 60 million years ago, long after the dinosaurs were gone. But then the planet cooled, and a snake that big couldn't

Number 40, Plesiosaur. Picture this. It's 1977, and a Japanese fishing boat off the coast of New Zealand hauls something up from the deep, a rotting carcass with a long neck, four flippers, and a small head. The crew photographed it before dumping it back into the sea. The Plesiosaur was a marine reptile that ruled the oceans alongside the dinosaurs. Some species stretched over 40 feet, longer than a school bus, with a neck that made up nearly half their body. They hunted with rows of needle teeth, gliding through cold water on four powerful flippers. The fossil record says they all died out around 66 million years ago, when the same event that killed the dinosaurs wiped them clean. But that carcass off New Zealand reopened the question. The creature became known as the Zuiyo Maru monster, named for the ship. And for a while, even Japanese scientists weren't sure what it was. Then there's Loch Ness, the most famous suspect of all. For nearly a century, people have claimed the thing in that Scottish lake looks exactly like a plesiosaur, long neck, humped back, gliding low in the water. Therefore, the comparison stuck even though nobody has ever surfaced. Here's the twist. In 1978, tissue samples from the New Zealand carcass were tested. The verdict? It was a decomposed basking shark. Their bodies rot into a shape that fakes a long neck perfectly. But if a shark fooling sailors feels unsettling, the next creature was never a fish at all. Locals deep in the African swamps swear it still walks. Number 39, Mokele-mbembe. Deep in the swamps of the Congo, the locals have a name for it, the one who stops the flow of rivers. They speak of it in low voices. They say it's still out there. The Mokele-mbembe is said to be huge. Picture a creature with the long neck and thick body of the dinosaurs you've seen in museums, something the size of an elephant or bigger. The legend says it lives in the rivers and lakes of the Congo basin. That area is thick jungle, so far from everything that parts of it have barely been mapped. Real dinosaurs like this died out about 66 million years ago, but the people who live near these waters swear this one never left. Here's where it gets strange. Westerners have chased this story for over a hundred years. The first big search trips began around 1980. That same year, a biologist named Roy Mackal traveled to Cameroon and the Congo to look for it. He collected stories from local fishermen. For a moment, the legend felt a little more real, but no search has ever found a clear photo, a bone, or a body. Every blurry story falls apart once you start asking hard questions. Now the twist. Many researchers think the descriptions actually match a rhino, an animal that isn't known to live in that region today. That could explain why people keep spotting something large they can't name. A hidden dinosaur sounds bold, but the next creature never touched the ground at all. It ruled the sky.

larger than any Anaconda on record. In 1907, British explorer Percy Fawcett [music] swore he shot a snake over 60 ft long on a remote river. Scientists doubted him, yet he never took it back.

Number 38, Pterosaur. A British explorer in 1920s Africa once showed local villagers a picture of a long-extinct flying reptile. They panicked and fled. They called the thing Kongamato, the breaker of boats. Pterosaurs ruled the skies tens of millions of years before the first bird ever flapped. The largest Quetzalcoatlus stood as tall as a giraffe with wings stretching wider than a school bus is long. Picture a creature that could look you straight in the eye while standing on the ground, then unfold leathery wings and lift into the air. They disappeared 66 million years ago, wiped out alongside the dinosaurs.

cold-blooded animals need heat to get big. A giant snake in a river is one thing. The next creature supposedly waits in deep, cold water, and people have hunted it for almost 100 years.

That explorer's story is real, but the creature is legend. In the swamps of Zambia, people described a reddish, featherless flying thing with a long beak full of teeth. Decades later and half a world away, villagers in Papua New Guinea spoke of the ropen, a winged shape that supposedly glowed as it crossed the night sky. Expeditions went searching, therefore you'd expect proof, but every camera came back empty. Still, the descriptions kept matching an animal that shouldn't exist. Here's what most people miss. In 2018, scientists examining pterosaur fossils found something strange, fuzzy, feather-like fibers covering their bodies. So, those smooth, dragon-like creatures from your childhood books, they may have looked completely different. But a flying reptile hiding in a swamp is one thing. The next creature didn't fly. It walked, and it towered over any human who ever lived.

it before dumping it back into the [music] sea. The Plesiosaur was a marine reptile that ruled the oceans alongside the dinosaurs. [music] Some species stretched over 40 ft, longer than a school bus, with a neck that made up

Number 37, Gigantopithecus. Deep in the bamb

clean. But that carcass off New Zealand reopened the question. The creature became known as the Zuiyo Maru monster, named for the ship. [music] And for a while even Japanese scientists weren't sure what it was. Then there's Loch Ness, the most famous suspect [music]

of all. For nearly a century people have claimed the thing in that Scottish lake looks exactly like a plesiosaur, long neck, humped back, gliding low in the water. Therefore, the comparison stuck even though nobody has ever [music] surfaced. Here's the twist. In 1978,

tissue samples from the New Zealand carcass [music] were tested. The verdict? It was a decomposed basking shark. Their bodies rot into a shape that fakes a long neck perfectly. But if a shark fooling sailors [music] feels unsettling, the next creature was never

a fish at all. Locals deep in the African swamps swear it still walks. Number 39, Mokele-mbembe. Deep in the swamps of the Congo, the locals have a name for it, the one who stops the flow of rivers. They speak of it in low

voices. They say it's still out there. The Mokele-mbembe is said to be huge. Picture a creature with the long neck and thick body of the dinosaurs you've seen in museums, something the size of an elephant or bigger. The legend says

it lives in the rivers and lakes of the Congo basin. That area is thick jungle, so far from everything that parts of it have barely been mapped. Real dinosaurs like this died out about 66 million years ago, but the people who live near

these waters swear this one never left. Here's where it gets strange. Westerners have chased this story for over a hundred years. The first big search trips began around 1980. That same year, a biologist named Roy Mackal traveled to

Cameroon and the Congo to look for it. He collected stories from local fishermen. For a moment, the legend felt a little more real, but no search has ever found a clear photo, a bone, or a body. Every blurry story falls apart

once you start asking hard questions. Now the twist. Many researchers think the descriptions actually match a rhino, an animal that isn't known to live in that region today. That could explain why people keep spotting something large they can't name. A hidden dinosaur

sounds bold, but the next creature never touched the ground at all. It ruled the sky.

Number 38, Pterosaur. A British explorer in 1920s Africa once showed local villagers a picture of a long-extinct flying reptile. They panicked and fled.

[music] They called the thing Kongamato, the breaker of boats. Pterosaurs ruled the skies tens of millions of years before the first bird ever flapped. The largest Quetzalcoatlus [music] stood as tall as a giraffe with wings stretching wider than a school bus is

long. Picture a creature that could look [music] you straight in the eye while standing on the ground, then unfold leathery wings and lift [music] into the air. They disappeared 66 million years ago, wiped out alongside the dinosaurs.

That explorer's story is real, but the creature is legend. In the swamps of Zambia, people described a reddish, featherless flying thing with a long beak full of teeth. [music] Decades later and half a world away, villagers in Papua New Guinea spoke [music] of the

ropen, a winged shape that supposedly glowed as it crossed the night sky. Expeditions went searching, [music] therefore you'd expect proof, but every camera came back empty. Still, the descriptions kept matching an animal that shouldn't exist. [music] Here's what most people miss. In 2018,

scientists examining Pterosaur fossils found something [music] strange, fuzzy, feather-like fibers covering their bodies. So, those [music] smooth, dragon-like creatures from your childhood books, they may have looked completely different. But a flying reptile hiding in a swamp [music] is one

thing. The next creature didn't fly. It walked, and it towered over any human who ever lived.

Number 37, Gigantopithecus. Deep in the bamboo forests of southern China, people still tell stories about a giant covered in red hair. They say it walks upright through the fog. They call it the Yeren.

Some believe it's the last of an ape that should have died out long ago.

Picture an ape almost 10 ft tall, taller than a basketball hoop. It weighed as much as three grown men put together.

This was Gigantopithecus, the largest ape that ever lived. It once roamed across Asia. Scientists believe it disappeared around 200,000 years ago.

The forests it ate from slowly vanished, and the ape was simply too big to survive on anything else. But the stories never went away. For hundreds of years, people across China and the Himalayas have reported seeing [music] a

huge hairy figure in the far off mountains. In China, they call it the Yeren. Farther west, people call it the Yeti. In 1958, Chinese researchers took the legend seriously. They sent out real expeditions to search for the creature.

They never found proof. Here's the strange part. Gigantopithecus was real. Its giant teeth and jawbones have been dug out of caves. So, people started to wonder, what if a few of them survived somewhere no one had looked? But here's

the twist most [music] people miss. In 2024, a study finally explained why the ape died out. When the climate changed, it couldn't change its diet fast enough to keep up. A giant ape barely hanging on is a creepy thought, but the next

animal is even stranger. It was caught on film, alive, and then declared gone forever.

Number 36, thylacine. In 1936, the last one died alone in a locked cage in Tasmania. Someone [music] forgot to let it inside, and it froze overnight. But people who live near the woods [music] still say they see it sliding between

the trees. There have been thousands of sightings, [music] and not one clear photo. Picture a dog about the size of a big German Shepherd, but this animal walked stiff-legged and it had dark stripes down its back like a

tiger. It could open its jaws almost flat, far wider than almost any animal alive today. Farmers said it was killing [music] their sheep, so the government paid hunters to kill them all. By 1936, [music] they were gone. 50 years later,

scientists made it official. The animal was extinct. Here's where it gets strange. [music] The hunting stopped, but the sightings didn't. People all over Tasmania keep saying they see a striped animal with a stiff tail crossing dark roads at night. In 2017,

scientists from James Cook University went looking. Two people had given [music] reports they believed, and one was a former park ranger. The team set up cameras all across the woods. They found nothing. Even so, the Tasmanian government still writes down [music] new

sightings every year. Then, in 2023, scientists found [music] something inside an old museum specimen that no one had ever pulled from an extinct animal before. They found its RNA, tiny molecules that carry the instructions a body uses to stay alive. For the first

time ever, we read the genetic code of an animal that had been dead for almost a hundred years. But this animal only disappeared about a lifetime ago. The next one vanished way back when the ice age ended, and people still say they see

its fangs in the dark. Number 35, saber-toothed tiger. Picture this. It's 1975, and [music] three farmers in Cordillera, Paraguay, swear they saw a cat the size of a small lion with teeth curving past its jaw like ivory daggers. They never

reported it officially, but the story spread anyway. The saber-toothed cat, most [music] people call it the saber-toothed tiger, though it wasn't a tiger at all, was a true monster. Stand one beside you, and its shoulders would reach your chest. Its body heavier than

a refrigerator. Its two front fangs longer than your hand. It hunted across the Americas during the last Ice Age.

Therefore, when the ice melted and its giant prey died off around 10,000 years ago, the cat was supposed to vanish [music] with them. Supposed to. In the 1970s, the explorer Juan Acavar claimed [music] local people in South America

described a fanged beast still prowling remote forests. [music] Reports of long-toothed cats trickled out of the Andes and the Amazon for decades. None were ever confirmed. No body, no clear photo, no bones fresher than the Ice Age, only [music] stories

passed mouth to mouth, growing teeth with every telling. Here's the part that unsettles scientists. Those fangs were surprisingly fragile, built to slip between [music] ribs, not crush bone. A creature that specialized that hard rarely survives a changing world. So,

the legend sadly [music] stays a legend. But, if a cat clinging to life seems unlikely, the next animal may already be coming back on purpose.

Number 34, woolly mammoth. In 2012, a video appeared online showing a huge, shaggy, dark shape wading across a river in Siberia. It moved like an elephant, but there are no elephants in Siberia.

The woolly mammoth stood up to 11 ft tall. Imagine an animal that could look down on the roof of a car. It weighed about 6 tons, [music] close to the weight of a city bus. Its curved tusks could grow longer than a grown man is

tall. Most of them vanished around 10,000 years ago when the Ice Age ended and the frozen world they were built [music] for slowly melted away. But, Siberia is vast, empty, and brutally cold, exactly the kind of place where

something might hide. For centuries, the native people there pulled strange, curved tusks out of the frozen ground.

They didn't believe in extinction. [music] Therefore, they invented an explanation, a giant beast that tunneled underground and died the instant it touched daylight. Then, that 2012 video spread and the old legend suddenly felt real. Experts studied the footage

closely. Their verdict was less thrilling. Most likely a brown bear carrying a fish across the water. Still, the ice keeps handing back mammoths so fresh they have skin, hair, and even reddish blood, and you start to wonder how sure we really are. Here's the part

most people never hear. A small group of mammoths survived on a lonely Arctic island until about [music] 4,000 years ago, which means these animals were still walking the earth while the pyramids of Egypt already stood. But a mammoth hiding in the snow is [music]

almost easy to believe. The next creature wasn't supposed to exist anywhere except [music] the deep black ocean. Yet people keep claiming they've watched it break the surface.

Number 33, Mosasaur. Picture a fishing boat off the coast of South Africa. The crew watching something long and dark slide beneath the surface. Too big to be a shark, too smooth [music] to be a whale. They never got a photo, but

stories like this are why the Mosasaur won't stay buried. This was the ocean's nightmare 70 million years ago. The largest Mosasaur stretched around 50 ft with jaws lined with cone-shaped teeth and a second set in the roof [music] of

their mouths to stop prey from escaping. They ruled the seas right up until the asteroid that killed the dinosaurs wiped them out. So by every record we have, they've been gone for 66 million years.

Here's where it gets murky. The deep ocean is barely explored. We've mapped more of Mars [music] than our own seafloor. People point to that emptiness and ask, "What if something survived down there?" It doesn't help that real animals have pulled this trick before.

The coelacanth, a fish thought dead for 65 million years, turned up alive in 1938. Therefore, some believe a Mosasaur could be hiding, too. But there's a problem. [music] Nobody, no bone, no verified footage has ever surfaced. And the twist, the closest living relatives

to Mosasaurs [music] aren't fish at all. Scientists believe they were related to modern snakes and monitor lizards. So, that sea monster was basically a giant ocean-going lizard. Number 32, dodo. Most people think they know the year the dodo died

out. They don't. [music] The last clear sighting that someone wrote down in detail was in 1662, [music] but that one date hides a messier story. For years after that, sailors kept [music] saying they saw birds that looked like dodos on

Mauritius. Mauritius is the island east of Madagascar [music] where the dodo lived. One of these later reports may have come as late as 1688. So, when did the last dodo really die? Two scientists, [music] Roberts and Solo, took all the old sightings and ran them

through a math tool called a statistical model. This kind of math uses scattered, messy reports [music] to guess the real end date. Their answer was 1693. That's more than 30 [music] years after the official goodbye date.

This matters because back then, the middle of Mauritius was full of thick, tangled forest, [music] and almost no one ever went there. The dodo also bred slowly and laid just one egg at a time. So, a few dodos [music]

could have stayed hidden in those deep woods long after people stopped looking for them. None of this means a dodo is alive today. It isn't. But, it does mean the dodo's extinction date was always just a guess. [music] And in another

way, the bird won't fully go away. In early 2025, scientists shared a complete, high-quality dodo genome. A genome is the full set [music] of instructions written in an animal's DNA.

So, the dodo left the world later [music] and in a stranger way than the textbooks say.

Number 31, Caribbean monk seal. Picture a warm, sandy beach in the Caribbean. [music] A round, gentle seal lies in the sun.

People walk toward it, but the seal isn't scared at all. That trust [music] is what got the Caribbean monk seal killed. People found it easy to hunt. In 1952, someone saw one for the last time that we know for sure. It was at

Serranilla Bank, a faraway reef in the ocean [music] between Jamaica and the Yucatan in Mexico. Here's the strange part. The United States did not call the seal [music] extinct, meaning all gone, until 2008. That's 56 years later. Why

did it take so long? Because people kept saying they saw the seals. Fishermen and divers in places like Haiti and Jamaica kept telling stories about seals in quiet, empty parts of the sea.

Scientists looked into it, but most of the time the animal people saw was a different kind of seal, the hooded seal.

Hooded seals live in the cold Arctic up north. Sometimes they swim way too far south and end up far from home. From 1996 to 2008, [music] scientists confirmed more than 20 of these lost Arctic seals in warm tropical

water. That [music] probably explains why people kept thinking they saw monk seals. Still, scientists say there's a small chance monk seals could live 20 to 30 years, so a few grown seals might have stayed alive, hidden in quiet, into

the 1960s or even the 1970s, long after that last sighting in 1952. The Caribbean monk seal is almost surely gone for good, but for 50 years, the Caribbean kept whispering that maybe, just maybe, it wasn't.

Number 30, quagga. Right now, on wild animal parks in South Africa, some animals are out in the open eating grass. They look almost exactly like an animal that died out back in 1883.

People call them Rau quaggas, and they are the strangest comeback [music] on this whole list. The first quaggas were a kind of zebra. They had stripes only on the front half of their body, and the back half [music] was plain brown. They

lived in South Africa. The very last one died in a zoo in Amsterdam in 1883. For a long time, that looked like the end.

The quagga was gone for good. But a nature scientist named Reinhold Rau spotted something important.

[music] The quagga wasn't its own separate kind of animal after all. It was really just one type of the plains zebra, [music] and that zebra is still alive today. So, Rau had an idea. If the quagga was just

a kind of plains zebra, then the quagga's faded stripe look might still be hidden inside normal zebras. It could be tucked away in their DNA, the instructions [music] inside every animal that decide how it looks. Maybe that look could be brought back out. So,

starting in the 1980s, a team called the Quagga Project went to work. They picked out zebras that had the fewest [music] stripes. Then they let those zebras have babies together. They did this again and again, year after year, with each new

group of babies. Today, there are about 160 animals in the program. A few of them, around six, now have that special [music] light-striped look so clearly that they are hard to tell apart from a real quagga. But here's the catch. These

animals are not exact copies [music] of the lost quagga. Their DNA is not the same. They only look like it on the outside. So, is the quagga really back, or is this just a really good copy? Walk past one, and you'd swear you just saw a

ghost. Number 29, Japanese wolf. In 1905, a team of explorers from Britain came to a village called Higashiyoshino [music] in central Japan. There they bought the body of a small dead wolf. No one knew it then, but that wolf was special.

[music] It was the last Japanese wolf anyone would ever prove was real. The Japanese wolf was very small for a wolf.

It was only about the size of a border collie, which [music] is a medium-sized dog. Long ago, it lived in the forests on the Japanese islands of Honshu, Shikoku, and Kyushu. But disease spread among the wolves. At the same time, the

government [music] tried to kill them all off. By the early 1900s, the Japanese wolf was gone. [music] So, why talk about it here? Because people kept saying they saw it. For more than 100 years, hikers in Honshu's mountains have

reported seeing animals that look and sound just like the lost wolf. But experts have never proven that [music] even one of these sightings was real.

Most of the animals people saw were probably just stray dogs, or maybe people only saw what they hoped to see.

Still, there's a reason people can't [music] give up on this wolf. In 2021, scientists tested the DNA from nine of these wolves kept in museums. They learned something amazing. Out of all wild animals, [music] the Japanese wolf is the closest

relative to every pet dog on Earth. That makes [music] it very important to science. It also makes it really hard to say goodbye to. So, if even a few of these wolves were still alive in the [music] deep forests, it would be one of

the greatest animal comebacks ever. Most likely, [music] the wolf is truly gone, but every blurry mountain photo makes people wonder again. That's [music] because Japan has never stopped hoping its lost wolf is still out there.

Number 28, Eastern Cougar. On June 11th, 2011, a car on a Connecticut road hit and killed a mountain lion. The big cat weighed 140 lb. This should have been impossible. No wild cougar had been seen for sure in Connecticut in over 100

years. So, where did it come from? A DNA test [music] gave a shocking answer. DNA is the code inside an animal's body that shows where it came from. This [music] one male cougar had walked all the way from the Black Hills of South Dakota.

Along the way, it left clues behind: droppings, hair, and photos snapped by cameras in the woods. Those clues showed up in Minnesota, Wisconsin, and New York. In a straight line, that trip is about 1,500 mi. But the cat didn't walk in a

straight line. It had to follow the land, going around hills, rivers, and towns. [music] So, scientists think it really walked closer to 1,700 mi, [music] and it did this over 2 years. It is the longest trip ever recorded for any cougar. The whole time

it was searching [music] for a mate. It never found one. Now, here's the part that surprises people. For a long time, scientists [music] treated the Eastern Cougar as its own special kind of cougar, but it may not have been special

[music] at all. It may have been the same as the cougars out west the whole time. In 2018, US [music] officials said the Eastern cougar was extinct, and they took it off the list of animals that need protecting. Around that time, some

scientists who sort animals into groups said something surprising. Maybe the Eastern cougar was never really a separate kind in the first place. So, the Eastern cougar isn't coming back exactly, but something even better is happening. Real cougars, the Western

kind, are walking east all on their own. They are taking back land that cougars lost 100 years [music] ago. The cats showing up in Eastern forests are not ghosts of a lost animal. They are explorers moving into new land.

Number 27, ivory-billed woodpecker. Here's something strange. The US government tried to say this bird was gone forever and then couldn't. The ivory-billed woodpecker was the biggest woodpecker in North America. It was black and white, and it lived in the

swampy forests of the south. The last time most people agreed they saw one was way back in 1944. In 2021, a US wildlife agency wanted to make it official. The bird would be called extinct, which means all of them had died and none were

left. They planned to take it off the list of animals to protect, but they ran into a problem. In 2023, a group of scientists led by Steven Latta shared a new study. Before it came out, other scientists [music] checked their work to

make sure it was solid. The study showed 10 years of clues from a forest in Louisiana. There were photos from cameras [music] left in the woods, video from a flying drone, sound recordings, and people who said they saw the bird

with their own eyes. The clues hinted that maybe more than one was still alive, but the clues were fuzzy, and scientists argued hard about them.

Nobody had the one clear photo that would prove it for sure. Still, [music] it was enough to make the government stop and think. Later in 2023, officials called 21 other animals extinct all at once, but they left the ivory bill off

the list. They said they needed more time to look at the new clues. So, the bird is stuck in the middle. It's not proven alive. It's not proven gone.

Somewhere in a Louisiana forest, a question mark the size of a crow keeps America's most famous extinct woodpecker from being buried for good.

Number 26, Haast's eagle. Long ago, the skies over New Zealand held a killer as big as a small child [music] with wings.

Haast's eagle was the largest eagle that ever lived. It weighed up to 30 lb, and its claws [music] were strong enough to break bone. Its favorite meal was the moa, a giant bird that couldn't fly. The eagle would dive down from the sky and

hit it like a falling spear. The Maori, the native people of New Zealand, [music] told stories about a huge bird called the pouakai. They said it could grab and kill people. Many scientists think this story is a real memory of

Haast's eagle. So, could one still be flying out there? Let's be honest first. When people [music] came to New Zealand, they hunted every moa until there were none left around the year [music] 1400.

A bird as big as Haast's eagle needed big animals to eat. Once its food was gone, [music] the eagle almost surely starved soon after. Still, there's one tempting clue. In the 1870s, an explorer [music] named Charles Douglas said he

shot two giant hunting birds in a faraway valley. But that was long ago, and no one can prove it now. New Zealand still has wild land where almost no one walks, and the country has surprised the world before. In 1948, [music]

people found the takahe, a bird everyone thought was extinct, alive and well. But a giant eagle [music] is a tougher case.

Without the moa to hunt, the pouakai had nothing left to eat. So, the legend [music] probably lived on longer than the real bird did.

Number 25, Steller's sea cow. 27 years, that's all it took [music] for people to wipe out one of the biggest animals of modern times. Steller's sea cow was a giant relative of the manatee. It grew up to 30 ft long and could weigh as much

as 10 [music] tons. It ate kelp, a kind of seaweed, in the cold Bering Sea between [music] Russia and Alaska. A scientist named Georg Steller first wrote about it in 1741. By 1768, only about one lifetime later, [music] hungry

sailors had hunted the slow, trusting animal until it was gone. Or was it? In July 1962, the crew of [music] a Soviet whaling ship called the Baran saw something amazing near Russia's far [music] eastern coast. About six huge,

dark animals were feeding in a shallow bay. The water was full of the sea cabbage that sea cows love to eat. The crew [music] said the animals were slow, 20 ft long or more, with small heads and split tails. The report [music] reached

Soviet scientists, who took it seriously enough to write it down and share it. Another report [music] like it came in 1976.

So, is a group of sea cows hiding up there? [music] Almost surely not. Most scientists think the people saw narwhals instead. Narwhals are Arctic whales, [music] and in rough water they can look like something much stranger. Still, the

sea off Russia's [music] Far East is cold, huge, and barely explored even today. In the parts [music] of the ocean almost no one watches, an animal the size of a bus is hard to completely rule out.

Number 24, Javan tiger. A single hair caught on a fence in Indonesia in 2019 started a science fight that still isn't over. The Javan tiger once lived on the island of Java in Indonesia, but farming took over its home and hunters killed it

off. The last clear sign of one was back in the 1970s. So, officially, [music] it's extinct. Then, in 2024, scientists in Indonesia shared a study. They said the hair from the fence came from a living Javan tiger. Its DNA matched old

tigers kept in museums. The news hit like a thunderclap. Indonesia's government started a real search. They set up cameras in the woods and sent out teams to collect DNA, hoping to find proof. But other DNA experts pushed back. And here's where it gets tricky.

They said the signal in the hair might not be true tiger DNA at all. Instead, it might be old, broken copies of DNA that hide inside a cell and can trick a test. In 2025, another team looked again

and had even [music] more doubts. So, the tiger's fate now rests on an argument in a lab, not a clear photo. No camera has caught a living Javan tiger.

No body has been found. All anyone has is one hair that people can't agree [music] on. A government out searching and scientists still arguing in print.

For now, the word extinct wears a question mark in the hills of Java. Number 23, moa. In January 1993, three hikers in New Zealand said they saw a bird that had been dead for hundreds of years. One of them was Paddy Freney. He

ran a hotel, [music] and he used to be a soldier in a tough British special unit.

He wasn't the kind of person people expected to make up a story. The hikers said [music] the bird stood about 6 ft tall with a long neck and a small head.

Freney took a quick, blurry photo before it ran off. The bird they said they saw was a moa, a giant bird that couldn't fly. Moas once ruled New Zealand. Here's the problem. Scientists are sure the moa died out around the year 1400. People

hunted them all within a couple hundred years of arriving. Most experts said Freney's photo was just a deer or a trick of the eyes from far away. And the footprints washed away before [music] anyone could study them. So, was it

real? Almost surely not. But the chance isn't quite zero, either. There's no solid proof of a moa after about the year 1550. Still, the South Island [music] has huge stretches of wild land with no roads, where almost no one goes.

If any animal could slip through unseen, a few moa hiding deep in that wild land is the kind of long shot people just can't shake. [music] The bird is gone, but somehow the doubt keeps walking.

Number 22, giant ground sloth. Deep in the Amazon rainforest, hunters tell of a tall, smelly beast that walks on two legs and leaves a trail of flattened trees behind it. They call it the mapinguari. To most people from the

outside, that's just a scary campfire story. But one scientist took it seriously. David Oren was an expert on birds. Born in America and living in Brazil, he spent years in the rainforest collecting more than 100 stories from people who said they'd seen the beast.

He even talked to seven hunters who swore they had shot one. Oren had a bold idea about what they were describing. He thought it might be a giant ground sloth, a shaggy plant-eating animal with big claws about the size of a car. The

idea fit in a creepy way. Ground sloths walked on the sides of their feet. That would leave [music] tracks pointing backward, just like the legend says. And here's the part that gives the story some weight. Giant ground sloths were

absolutely real. They died out only about 10,000 years ago, which [music] is like yesterday in the long story of Earth. So is one still out there?

Honestly, probably not. Every real clue Oren found fell apart when it was tested. Hair samples turned out to be from regular anteaters or normal sloths that are alive today. No body, no bone, and no clear photo has ever shown up. So

the mapinguari stays unproven. Still, [music] the Amazon hides a lot of secrets, and it lost its real giant sloths so recently that the legend feels less like make-believe and more like a memory that won't fade away. Number 21,

coelacanth. In October 2024, divers near the Maluku Islands of Indonesia swam almost 500 ft down into dark water.

There, they came face to face with a fish that scientists once thought had been dead for 70 million years. They took photos. They were the first [music] pictures ever taken by divers of the Indonesian Coelacanth in its own home,

and they shared them in 2025. That's the amazing [music] thing about the Coelacanth. It keeps showing up where we don't expect it. This big deep-water fish was famously found again in 1938, long after people thought it was extinct, but it didn't stop there. A

whole different kind of Coelacanth was found near Indonesia in the late 1990s, thousands of miles away from the first one, and it gets even stranger. A study [music] in 2021 found that Coelacanths can live to be about 100 years old. The

mothers stay pregnant for about 5 years. That's [music] the longest pregnancy of any animal we know about. Every now and then, one shows up somewhere new in water nobody had checked before.

Number 20, dire wolf. The dire wolf sounds made up, like something from a fantasy show, but it was terrifyingly real. It [music] hunted across the Americas during the Ice Age, bigger and stronger than any wolf alive today with

bone-crushing jaws. Thousands of them got trapped in the tar pits of Los Angeles, which is how we know them.

Here's the strange part. Despite the name, the dire wolf was not a close cousin of the gray wolf. Their lines split millions of years ago, well before it died out at the end of the Ice Age.

Therefore, building a real one back should be nearly impossible, but in 2025, a company announced it had done exactly that. They [music] made three white pups named Romulus, Remus, and Khaleesi. They called them dire wolves.

The world went wild. So, is the dire wolf truly back? Not so fast. The company's own scientist later admitted the truth. These are gray wolves with just 20 small genetic tweaks, not the real ancient predator. Yet right now, on

a secret 2,000-acre preserve, three animals wearing that famous name are alive and growing. [music] Is that a dire wolf reborn, or just a gray wolf in a costume?

Number 19, frilled shark. A A off the coast of Japan [music] radios a marine park with something strange tangled in his net. The year is 2007. What he's hauled up looks like an eel that grew wrong. Long, pale with a

mouth that shouldn't be possible. They get it into a tank alive. It's a frilled shark. A creature most people only ever meet as a fossil. And for a few hours, it swims in front of rolling cameras.

Within [music] hours, it's dead. That footage is one of the only times a living one has ever been filmed. Picture an eel stretched to 5 ft, it a flat snake's [music] head and 300 needle-sharp teeth packed into 25

curving rows. Those teeth all point backward. [music] Therefore, once prey slides into that mouth, it cannot slide back out. This shark's family has haunted the deep for roughly 80 million years since the days real dinosaurs walked above the waves. But here's what

almost every retelling skips. The shark they filmed was not healthy. It rose out of the black because it was sick or dying, which is the only reason a human ever saw it. Healthy frilled sharks live half a mile down, far below sunlight,

far below where divers go. So the one we caught was the broken one. The strong ones never come up, never counted, never filmed at home. We only know they exist because now and then, a dying one drifts toward the light.

Number 18, Doedicurus. Scientists have found ancient battle scars and they don't make sense unless this creature is real. Doedicurus was a living tank, a relative of the armadillo blown up to the size of a small car. It wore a dome

of bone over a thousand armor plates thick [music] and its head had its own bony helmet. But the armor wasn't even the scary part. Its tail ended in a spiked club that weighed as much as a grown man, up to 143 lbs of bone and

spikes. Studies found a sweet spot near the tip, the exact [music] place that delivers the hardest hit, the same physics a baseball bat uses.

[music] Therefore, this was a precision weapon, not just a lump. We know it swung hard because some fossil shells carry [music] cracked dents that match a club strike perfectly. These giants died out around 10,000 years ago, but then something

strange surfaced. In 2016, DNA proved Glyptodon wasn't just armadillo-like. It was a true giant armadillo, and its closest [music] living cousins still walk the Amazon right now. So rare and so shy that most locals [music] never see one in a lifetime. They dig, they

hide, they move at night. So, if the small ones vanished that easily, could a bigger armored ghost still be down there, hidden in plain sight? Number 17, Bili Ape. Deep in the forests of the Congo, people spoke of a huge ape that

did not act like any animal scientists knew. Locals described a creature taller and stronger-looking than a [music] normal chimp. It sometimes walked on two legs. It built nests on the ground like a gorilla, and adult males were said to

stand more than 1.8 [music] m tall. For years, outsiders treated the stories like jungle folklore, but in the early 2000s [music] researchers found signs they could not ignore. Nests, droppings, bones, and finally photographs. [music] The mystery ape was real. Genetic tests showed that

the Bili ape was a chimpanzee, not a new species. Yet, its behavior [music] was so unusual that it seemed caught between a chimp and a gorilla. That is what makes this animal so important. A large ape lived in the modern world, but

science did not properly recognize it until [music] the 21st century. Therefore, when people say a remote forest is too well-known to hide something big, the Bili ape gives us a reason to pause. How many other animals are still behind those green walls?

Number 16, short-faced bear. Now for a monster that would make a grizzly look small, the giant short-faced bear was one of the largest meat-eating land animals North America has ever seen. On all fours, it could look a grown man

straight in the eyes, but But it reared up, it towered over 11 ft tall. It had long, [music] straight legs built for one purpose, speed. Some scientists believe it could sprint over 30 miles an hour, fast enough to run down a horse.

Its wide snout hid a powerful nose that could smell a fresh carcass from miles away. Around 12,000 years ago, it [music] vanished with the rest of the Ice Age giants. But is it truly gone?

Far across the ocean, [music] in the frozen wilds of Kamchatka in eastern Russia, local hunters speak of a giant bear they call the Irkuiem. They say it stands and moves in a way no normal bear does. A few researchers wondered if it

could be a short-faced bear that never died out. Sadly, no [music] bones back that up, since this bear only ever lived in the Americas. Still, in that endless frozen land, the legend refuses [music] to die.

Number 15, Megapiranha. Here's the strange part. This monster wasn't found in a river. It was found in a dusty drawer. [music] A jawbone sat forgotten in an Argentine museum for almost 80 years, until a scientist opened it [music] in the 1980s and realized he was

holding the missing link between two of the world's weirdest fish. They named it Megapiranha. It lived 8 to 10 million years ago, and it was no normal piranha.

Picture [music] a piranha grown to 3 ft long, the size of a child, but with a bite that punched far above its weight.

Pound for pound, [music] its jaws crushed harder than a T-Rex. Its teeth sat in a creepy zigzag row, [music] halfway between the flesh-slicing fangs of today's piranhas and the nut-crushing molars of their plant-eating cousins.

[music] So it could shear and crush, which means almost nothing in the water was safe from it. But here's the part that should make you pause. We only have its jaw. We have never found the rest [music] of its body. Therefore, we don't

truly know how big this thing got, or what its final form looked like. And its direct [music] descendants? They still swim the Amazon today, in murky water no diver can see through. So if a bigger cousin were down there in the black

depths, how would anyone ever know? Number 14, Japanese serow. Now comes the proof. The Japanese [music] serow is a shaggy goat antelope from the mountains of Honshu. For centuries, people thought it had vanished while old stories [music] kept it alive as a

spirit of the forest. But reports continued. Farmers, hikers, and forest workers described a stocky animal with curved horns [music] moving through steep wooded land. The story sounded ancient, yet the details matched.

[music] In the 1980s, the serow was confirmed alive in remote forests. A large mammal had hidden in a crowded modern country. It was not on an unknown continent. It was in Japan, beyond roads and towns, protected [music] by rough

mountains and thick trees. That matters for everything still to come. The serow shows that people can be wrong about an animal's disappearance. [music] It also shows that folklore can hold a real memory after science stops looking.

Therefore, the next [music] three creatures should not be accepted without proof, but they should not be laughed away too quickly, either.

Number 13, terror bird. A cattle rancher in Colombia spent 20 years not knowing he owned a monster. He'd pulled a single leg bone from his land while fixing a fence, and it sat ignored until 2023 when scientists scanned it and froze. It

belonged to the largest terror bird ever found. These were 9-ft killers that ran down prey on two legs, finishing it with a hooked beak built to shatter bone.

Most stood waist-high to head-high on a person, but this Colombian giant towered over 8 ft and weighed more than two grown men. Therefore, it sat at the very top of its world, but even it wasn't untouchable. That same leg bone carried

bite marks from a 30-ft crocodile relative, proof these titans still had enemies. For 60 million years, terror birds ruled South America, then slowly faded as the land bridge to the [music] north let new hunters flood in. Or so

the textbooks say. Because here's what unsettles me. This new species hid in plain sight for two decades inside one bone, and it was found at the northern edge of the continent, the doorway to the Amazon. Most of that rainforest has

never felt a human footstep. A bird built to sprint through open ground and ambush from cover would vanish in there.

So could one still be running? Number 12, Purussaurus. 10 million years ago, the Amazon flowed the wrong way.

Most of western [music] South America wasn't rainforest back then. It was a single swamp the size of a small sea, [music] and it belonged to a monster.

Meet Purussaurus, the largest caiman that ever lived. The caiman is a stocky cousin of the alligator, but this one grew as long as a city bus and weighed more than a bull [music] elephant. Its jaws snapped shut with roughly four

times the force of the strongest crocodile alive today. Nothing in that water was safe. [music] It ate giant turtles, car-sized rodents, even ground sloths. So what kills a creature like that? Not a bigger hunter, the landscape. As the Andes mountains rose

to the west, they slowly drained that endless swamp and carved out the Amazon river we know now. [music] The wetland that fed an eight-ton predator dried up, so Purussaurus starved into extinction.

Yet the deep black water lakes it left behind are barely explored. The Amazon's top predator [music] today is the black caiman, and the largest one ever measured stretched almost 19 ft. [music] Local fishermen swear they've seen bigger out in the flooded forest. Much

bigger. The kind of shadow that makes you cut the motor and drift very quietly the other way.

Number 11, Irish elk. Now meet the Irish elk, the [music] largest deer that ever lived. But forget the name for a second, because it wasn't really Irish. It wasn't even an elk. It was a giant deer that roamed from Ireland all the way to

Siberia. It stood 7 ft tall at the shoulder, taller than a doorway. Its antlers were the real shock. They stretched [music] 12 ft from tip to tip, wider than a car is long, yet the male grew a brand new pair every single year.

Growing bone that big took a massive amount of food. Therefore, when the ice age ended and its favorite plants faded away, the giant deer slowly starved. But here's the twist. It didn't die out with the other ice age monsters. [music] The

last ones were still alive around 7,700 years ago, long after people had started farming. Back in the 1600s, scientists refused to believe it was gone. They were certain a herd still survived somewhere on Earth. So, could it?

Probably not, but its DNA still sits inside its bones. Therefore, some researchers now believe the largest deer of all time could one day walk the Earth again.

Number 10, giant sea scorpion. It's longer than the couch in your living room. Now, imagine it alive, armored, many-legged, swimming straight at you with two clawed arms outstretched. This is the giant sea scorpion, and it was absolutely real.

Scientists dug up a single fossil claw measuring a foot and a half, about the length of your arm [music] from elbow to fingertips. From that one claw, they rebuilt the whole animal, roughly 8 [music] feet long, bigger than a grown

man is tall, the largest bug ever to live on this planet. It hunted the water around 400 million years ago, long before the dinosaurs. [music] Its claws were studded with spikes that trapped fish and crushed them. Therefore, very

little its own size could share the water [music] and survive. Here's the part most retellings get wrong. We call it a sea scorpion, [music] but the rocks suggest the biggest ones didn't live in the sea at all. They may have ruled the

rivers and lakes [music] instead, in fresh water. The giants are long gone, yet their distant cousins, the horseshoe crabs, still crawl the seafloor right now, barely changed in hundreds of millions of years. The ocean has a habit of keeping ancient things alive in

places we rarely look. We just don't always know they're there until one washes up on the sand.

Number nine, Cape lion. The Cape lion once roamed Southern Africa. Old reports described a massive cat with a thick mane that looked almost black. Colonial hunters killed lions across the region and by the 1860s the Cape lion was declared extinct. But

extinction is not always a clean break. Sometimes an animal disappears while part of its bloodline remains in living relatives. In 2016 a genetics project [music] raised that exact possibility.

The Cape lion's genes may have survived in isolated lion lines that had little contact with lions from other parts of Africa. That would not mean a perfect Cape lion [music] still walks the grass.

It could mean pieces of the lost animal remain such as [music] its dark mane or heavy build. There have also been reports of unusually large black maned lions in remote parts [music] of Southern Africa. None of this proves the

Cape lion survived unchanged. Maybe extinction took the animal's name, but not every trace of it.

Number eight, Helicoprion. Picture a circular saw blade, round, [music] coiled, its edge lined with dozens of sharp teeth. Now picture that blade growing straight out of the lower jaw of a living fish. That's not [music] a prop from a horror film. That's a real mouth

on a real animal and for more than a hundred years nobody could work out how it fit together. Its name is Helicoprion. It swam the oceans around 270 million [music] years ago, long before the very first dinosaur existed.

[music] three great white sharks lined up nose to tail. But the size isn't the strange part, the teeth are. [music] Helicoprion never lost a single one. Every tooth it ever grew stayed locked into that spiral curling deeper as new teeth pushed

[music] in behind it like a slow conveyor belt of blades. A full-grown adult carried its whole life's [music] worth of teeth coiled into one weapon.

For decades people drew that spiral in the wrong spot, on the snout, the tail, even down the throat. It took a CT scan in 2013, the same scan doctors use to see inside you, to finally prove the saw

sat deep inside the jaw. But we only solved where it went. We still haven't solved how it killed. A spinning coil of teeth built like nothing alive today. So what exactly was it cutting through down in those ancient seas? And why has

nothing ever grown that mouth again? Number seven, Iriomote Cat. On one small Japanese island lives a wild cat so rare that even local people may never see it.

The Iriomote Cat moves mostly at night. It slips through thick forest, hunts near rivers, and avoids open ground.

Camera traps sometimes catch it, but clear footage is rare. The cat exists only on Iriomote Island. There is no second wild population waiting somewhere else. Roads cut through its habitat, cars can strike it, and new building pushes deeper into the places where it

hunts. Some experts fear it may already be extinct in the wild, or so close that finding the last cats could be almost impossible. Others believe a few still move through the mountain forests, unseen and uncounted. Imagine searching for one dark cat in miles of wet jungle

at night, while it is trying not to find you. The Iriomote Cat may be disappearing in front of us while staying almost invisible. If the cameras go silent, would that mean it is gone, or only hidden?

Number six, Elasmotherium. They called it the Siberian Unicorn, but it was no gentle horse from a fairy tale.

Elasmotherium was a giant rhino the size of an elephant, weighing around 4 [music] tons, with shaggy hair covering its whole body. On its forehead sat a single massive horn. Some scientists think [music] it grew several feet long.

For a long time, everyone believed this beast died out hundreds of thousands [music] of years ago, far too early to ever meet a human. But then better testing of its bones shattered that idea. It turned out the Siberian unicorn

was still alive as recently as 39,000 years [music] ago. Therefore, it walked the same land as early humans. Here's where it gets strange. Russian folklore tells of a huge one-horned beast called the Indrik, the king [music] of all

animals. Siberian legends even describe a giant creature whose single horn was so heavy [music] it had to be hauled away on a sled. Those stories survived for thousands of years. So, were they just myth [music] or was someone long

ago describing a real horned giant they had seen with their own eyes? Number five, Thylacoleo. Australia once had its own lion, but it was stranger than any lion on Earth. Meet Thylacoleo, the marsupial lion. Like a kangaroo, it

carried its babies in a pouch. Yet, [music] it was a pure meat-eater about the size of a modern jaguar. Here's what made it deadly. Pound for pound, it had the strongest [music] bite of any mammal ever measured. A single one could bite

down as hard as an African lion far heavier than itself. It didn't have long fangs like other big cats. Instead, it had huge slicing [music] teeth like bolt cutters, plus a giant hooked claw on each thumb for pinning prey. It probably

waited in the trees before dropping onto whatever walked below. [music] Around 40,000 years ago, it disappeared right as the first people reached Australia.

But, in the rainforests of Queensland, something odd keeps happening. For over 100 years, people have reported a striped cat-like predator the locals [music] call the Yari. It climbs trees.

It bears strange front teeth exactly like the marsupial lion. Most experts say these are just big feral cats.

Still, deep in that jungle, the sightings never stop. Number four, Arctotherium. South America once had the largest bear known to science. Arctotherium was enormous. On its back legs, it could stand more than 3 m tall. Its fossils have been found

across South America, including Argentina. The giant bear is supposed to be long gone, but in the Andes and Patagonia, stories continue about a creature called the demon bear.

Shepherds, miners, [music] and people far from cities have described huge reddish-brown bears. Some reports mention attacks [music] on livestock.

Others tell of tracks larger than those of any known bear. There are no clear photographs. No body has been found.

That is a serious problem because an animal this large would need food, space, and a breeding population. Still, the land is vast. Parts [music] of the Andes are hard to reach, and Patagonia holds forests, caves, and valleys where

few people walk. A small group might avoid roads for years, especially if it feared humans. Is it really Arctotherium? Probably not, but a large unknown bear in those mountains is harder to rule out. Somewhere [music] past the last farm, something may still

be leaving giant tracks in the snow. Number three, Livyatan. The whales weren't the hunters here. The whales were the food. Around 10 million years ago, [music] one predator was big enough to hunt other whales for a living, but

we didn't even learn its name until 2010, when a researcher split open a fossil skull in [music] the desert of Peru. We call it Livyatan. It was a sperm whale built completely wrong.

Today's sperm whale is gentle, with a soft mouth made for sucking down squid. Livyatan was its nightmare opposite. It reached up to 57 ft, half again as long as a city bus, with a jaw full of teeth longer than your forearm. Those are the

largest biting teeth ever found on any animal, living or extinct. Nothing we know of has bitten down with bigger. It killed other whales by ramming [music] and tearing them to pieces. Therefore, in its world, being a whale didn't keep

you [music] safe. It put you on the menu. Almost all its fossils come from one ancient coastline, but a single giant tooth, the spitting image of Livyatan's own, turned up in Australia in much younger rock, hinting that something like it was still swimming

long after the textbook say it should have vanished. Number two, Megalania. Forget the Komodo dragon, Australia once had a lizard that dwarfed it. [music] Megalania was the biggest land lizard that ever lived, a giant cousin of today's monitor lizards.

It stretched [music] up to 18 ft long, maybe more, with a heavy body and a long muscular tail. Its mouth was full of curved serrated teeth made for slicing flesh. Worse still, scientists think its bite may have been venomous, which would

make it the largest [music] venomous animal we know of. It ruled ancient Australia, hunting giant kangaroos and rhino-sized marsupials. Its youngest bones date to about 50,000 years ago, right around the time the first people arrived, but some believe it never fully

left. For decades, people across the Australian Outback have reported enormous lizards, some claimed to be 20 or 30 ft long. One researcher even made plaster [music] casts of huge clawed tracks. Most scientists doubt these stories because a predator [music] that

size would need a whole hidden population to survive. Yet the Outback [music] is one of the emptiest places on the planet. If a giant lizard were still hiding anywhere on Earth, this is exactly where it would be.

Number one, Deinosuchus. 80 million years ago, North America was home to a crocodile relative called Deinosuchus.

It could grow up to 12 m long. Its skull was larger than a T-Rex skull, [music] and it was powerful enough to attack dinosaurs near the water. That is almost the length of a city bus. So why do

people still whisper about it? Across the swamps of Louisiana, Florida, and Texas, witnesses have reported alligators far larger than any normal adult. Some come from hunters and workers who know the local animals well.

The strangest claims involve the Mississippi River. Sonar, which uses sound to reveal objects underwater, has reportedly shown shapes more than 10 m long. A real Deinosuchus surviving from the age of dinosaurs is extremely unlikely. It would have survived

millions of years without leaving fresh bones, clear video, or solid proof. But deep swamps may hide an undiscovered large relative of modern crocodiles or alligators. Not a true Deinosuchus, but something big enough to create the stories. Dark water hides size very

well. You may see two eyes, a rough back, and a wake moving toward the reeds. The rest stays below.