In 2008, the skull of a large ocean-dweller  was found high in a Peruvian desert.

Embedded in the massive skull  – which measured about 3 meters   long – were teeth that seemed to belong  to a relative of the modern sperm whale.

But there was something… different about them.

For starters, they were larger – much larger.

Some were up to 36 centimeters long, so  they clearly came from a gigantic predator,   bigger than any whale so far discovered.

The creature was so evocative of monstrous  mythical whales that scientists eventually   named it Livyatan melvillei after the biblical  sea monster and the author of Moby Dick.

English major, yo.

I got  that reference right away.

But unlike in fiction, giant whales don't  emerge fully-formed from the ocean deep.

So, where did Livyatan come from?

How did such a   large predator live?

And what  caused the titan to die out?

Tracing the rise and fall of Livyatan reveals   a sea monster so hungry…it might  have eaten itself to extinction.

About 25 million years ago,  in the late Oligocene Epoch,   a group of whales originated  known as Physeteroidea.

At first glance, they were indistinguishable  from other toothed whales at the time – meaning   those with teeth rather than the long fibrous  baleen found in filter feeders like blue whales.

One of the earliest members of the  physeteroids was Ferecetotherium which   lived in an epicontinental sea between  what’s now the Black and Caspian seas.

But one way that Ferecetotherium and its  descendants were unique was the large,   strange organ atop their heads.

Filled with -literal tons- of a  waxy substance called spermaceti,   this organ’s exact function is  still debated by scientists.

Two common hypotheses are that it assists  with vocalization and echolocation,   or it may help these whales dive deeper.

See, spermaceti has a low melting point, so  when the whale is resting, it’s a liquid,   but with just a few degrees drop in temperature,  it turns to a solid and helps whales sink.

These sperm whales were part of a larger family  of toothed whales called the odontocetes,   which was diversifying widely since  appearing around 38 million years ago.

Also getting more diverse were the baleen whales.

Both groups were generally  modestly sized by, I don't know,   whale standards, with Ferecetotherium  measuring about 5 meters long.

But by about 13 million years ago in  the early Miocene Epoch, sperm whales   appeared around the world, with genera like  Brygmophyseter and later with Zygophyseter.

And while these new whales  had the spermaceti organ too,   they differed from earlier ancestors like  Ferecetotherium in that they had huge teeth.

And yes, all whale teeth are…pretty massive.

But these teeth were also proportionally huge,   measuring up to 20 centimeters long and  over 5 centimeters wide for Zygophyseter.

Thanks to their giant teeth,   scientists refer to this group of  sperm whales as macroraptorial whales.

That is great branding.

And researchers think that they fed using the   grip-and-shear method-- grabbing onto  prey and ripping off a chunk of flesh.

Which allowed them to consume large  prey relative to their body size.

One group of scientists have suggested  that these giant bites were so intense   that they produced bony outgrowths  on the inside of the whales’ mouths   to help buttress against the intense bite forces.

Now, these macroraptorial feeders weren’t  alone in the waters.

Other sperm whales   evolved at the same time, who, curiously,  completely lacked an upper set of teeth.

Rather than shearing flesh, these whales  used their lack of upper teeth to trap   prey like squid, before suctioning them  up whole – known as suction-feeding.

But it was the macroraptorial grip-and-shear   feeding strategy that seemed to  be most successful at the time,   because over the next few million years, the  macroraptorial group started getting larger… And around 10 million years ago, the  almost 18-meter long Livyatan emerged.

Lording over the world’s oceans – which  were filled with everything from miniature   baleen whales to aquatic giant sloths –  Livyatan was truly a master of its domain.

With a skull longer than an average human,  evolution had produced the biggest-toothed,   most hypercarnivorous whale ever known.

But with all of that bulk to support,  what did such a giant whale eat?

[laughs] Say it with me!

Whatever it wanted, of course!

And here’s where the diversity  of whales at this time comes in.

During this period, there were tons of  different filter-feeding baleen whales as well.

These were not the massive whales we know  today.

Instead of 30-meter-long giants,   these smaller ancient filter-feeders  – like Pelocetus – often measured   just a fraction of that, around 12 meters long.

A size that would have made them excellent  prey for Livyatan, which almost certainly   ate both baleen filter-feeding whales  and their own toothed-whale relatives.

Also included in Livyatans’ diet was, um,   pretty much everything.

Sharks,  seals, fishes… you name it.

Although paleontologists have yet to find  direct evidence of predation by Livyatan on   other animals – like bite marks – they see  evidence that Livyatans’ jaws experienced   especially intense bite forces through that  additional bone growth around the teeth.

So, given this impressive  size and feeding strategy,   Livyatan must have been the dominant predator  of the water 10 million years ago, right?

Well, not quite.

During the late Miocene there existed not  only the giant predatory Livyatan but also,   the most famous of sharks: Otodus megalodon.

Estimated to be around 20 meters long  and with teeth the size of your hands,   megalodon was more than equal to  Livyatan as far as biting went.

The existence of both giants demonstrates  that there was such an abundance of prey,   both predators could be supported.

And while there is no direct evidence of  interactions between Megalodon and Livyatan,   their comparable size and likely  similar prey selection means the   two titans certainly encountered each other.

Yet, this enormous mash of monsters wouldn’t last.

When we look around the world today,  we might notice a conspicuous lack of   giant sharks and sperm whales.

So what happened to them all?

The exact details about how Livyatan  went extinct are still unclear.

What is known is that, beginning around 5 million  years ago and lasting until just 10,000 years ago,   the world experienced a substantial uptick  in the extinction rate of marine megafauna,   one that peaked between 3.8  and 2.4 million years ago.

Some scientists suggest that this die-off  might be related to dramatically changing   sea levels at the end of the Pliocene, due to  growing glaciers in the Northern Hemisphere.

With so much more of the Earth’s  water frozen in polar ice caps,   what had formerly been productive  shallow coastal habitats became dry land.

And the drying out of coastal habitats  not only eliminated physical habitat space   for marine life, it also deprived marine  ecosystems of a great deal of nutrients.

It’s possible that, given the high caloric  requirements of a superpredator like Livyatan,   any change in ecosystem productivity  could be especially devastating.

Given the cost of fueling its massive body,   any disruption to even the smaller whales’  population could have caused it to die out.

Some researchers, however, advise caution  in interpreting this die-off event.

Because marine fossils from coastal areas  are preserved and collected at higher rates,   so it might make evolutionary patterns  observed in coastal areas overrepresented   in our interpretation of the marine fossil record.

But if a lot of their prey  was becoming less abundant,   such big, hungry hypercarnivores  would have been extra vulnerable.

And while there is a range of hypotheses  surrounding the giants’ extinction,   some research has suggested that Livyatan’s own  success may have contributed to its downfall.

Livyatan, together with Megalodon and other  super-predators that swam the Miocene oceans,   put enormous pressure on their main prey  animals, the medium-sized baleen whales.

Some scientists suggest that this could  have spurred the evolution of increasingly   large baleen whales – potentially  leading to the giants we know today.

As baleen whales increased in size  and smaller coastal forms died out,   there were likely fewer and fewer  snack-sized whales for Livyatan.

And while the fossil record is a fickle thing   and it’s hard to tell when the  last of a species disappeared,   Livyatan and its kin definitely vanished by  the Pliocene epoch, about 5 million years ago.

Megs held on just a little longer,  until roughly 3.6 million years ago.

The extinction of the macroraptorial  sperm whales was followed by the rapid   diversification of modern dolphins and orcas,   who seemingly evolved to take over at  least part of their evolutionary niche.

So the extinction of Livyatan (and Megalodon)  left a permanent mark on ocean food chains.

And all that’s left of a once vastly diverse group   are the three modern sperm  whale species around today.

These whales, like the most  common species alive today,   Physeter macrocephalus, do share the  spermaceti organ with their ancestors.

But their feeding habits are different from   the massive macroraptorial sperm  whales that once ruled the ocean.

In a twist of fate, this group once differed  the most from the rest – the suction-feeders.

As Livyatan and the rest of the macroraptorial  sperm whales passed into the fossil record,   it was the suction feeders that went on to  become the stuff of myth and literature.

Reminding us that being a massively-sized  predator can be an advantage until… it