Inside Natures Prehistoric Giants: “Livyatan”, the Killer Sperm Whale

The jagged southern coastline of Australia, 5.5 million years ago...  

Modern Sperm whales are the largest toothed animals that have ever existed. At 20 metres in length and over 50 metric tonnes, "Physeter" and its distant relatives have dominated the marine landscape since the Pliocene... Image via Caters News Agency

The Miocene climate in Australia is significantly warmer. The vegetation is slowly transitioning on the mainland; where once lush rainforests adorned the isolated continent throughout the Oligocene and mid Miocene, dry schlerophyll forests and open woodland are dominating the landscape with stringy barked eucalypts. Bizarre creatures traverse these coastlines; Zygomaturines (cow sized animals that superficially resemble wombats) stomp over small shrubby vegetation, the so-called “Demon Ducks of Doom” (2 metre tall flightless birds) race each other, kicking up the dust behind them and giant flying sea-birds (the Pelagornithids, with a 6 metre long wingspan) soar above the immensity of the Southern Ocean.  

... and like that, the band was ready for their first performance of "Miocene Night Terrors". Image of "Dromornis" (bottom left) / "Pelagornis" (right) via Peter Trussler. Image of "Zygomaturus" (top left) via the Australian Museum. 

But in these turbulent seas, life has never seen such extremes. Some baleen whales are beginning to reach massive sizes (>20 metres), but most are only between 5-8 metres in length. Baleen whales will one day go on to be the biggest creatures that have ever lived, but in this ancient ocean they would be prey to one of the largest predators of all time...

An ancient variety of baleen whale, distantly related to modern Pygmy Right Whale (“Cetotherium”) comes to the edge of a 40-metre drop-off. At 5 metres in length and 2.5 metric tonnes, this gentle filter feeder is alone as it comes up to the turbid surface to exhale its breath. It stays there for a few minutes before it starts its dive into the energy rich waters below.

Notice the four fingers in the flipper? Most modern baleen whales have five... Mounted skeleton of the cetotheriid baleen whale "Cetotherium riabinini" via Pavel Gol'din

As it begins its descent, high-pitched clicks emanate from the gloom. Unbeknownst to the “Cetotherium”, the predator makes her way closer to its prey. Like a bat finding a moth in the dark, the intensity of clicks get louder and quicker. Agitated and distressed from the noise, the “Cetotherium” dives deeper. At the edge of the photic zone, with limited light and with the clicks getting quicker, “Livyatan” makes her move. She locks onto her target, now within view and opens her mouth before impact. Using her 40 teeth shaped like artillery shells, she crunches down on the Cetotheriums tail fluke and rips it in half. The baleen whale starts thrashing around wildly, blood gushing.

'Die Hard with a vengeance," circa 5,000,000 BC ... Image via C. Letenneur

The huge predator hangs back, acutely aware that the struggling and injured whale is still an imposing hazard. Due to its 17 metre long size, “Livyatan” can hold her breath for more than an hour…

With the prey succumbing to shock and losing litres of blood every minute, it would not be long until the predator would start feasting on its prey…  

These turbulent and blood-filled seas would be home to the deadliest oceans in prehistory. Killer sperm whales and macro-raptorial sharks (the size of a school bus) would frequent these Miocene and Pliocene epochs. So how do we know anything about them? In order to answer this, we have to travel to modern day Peru, in the middle of the flat and barren desert of the Ica Province. In November 2008, palaeontologists made a shocking discovery…

The Deadliest Ocean of all time, under their feet... Image via Olivier Lambert of their discovery in 2008.

On the last day of a field trip led by Belgian palaeontologist Olivier Lambert, an immense skull was found eroding at the dust-ridden surface. Large baleen whales skulls are common in this province, but it was immediately obvious that this was no baleen whale. This skull was the size of a small car and it was studded with teeth. The largest of these teeth measured 36.2 centimetres in length, the largest of any known animal (not including tusks). They had stumbled across a predator of immense proportion, comparable to the Megalodon.

Large teeth attributable to ancient sperm whales had been found before, but they were always isolated. They were relatively different to the modern varieties of sperm whale; some were four inches thick and coated with thick enamel at the tip of the tooth. They were not teeth adapted for eating slippery prey, such as squid. Throughout the previous decade, smaller physeteroids (such as “Aulophyseter” and “Zygophyseter”) had been found in Peru and Italy (respectively). These animals were raptorial hunters, most likely occupying a similar niche to the modern Orca. But remnants of these giant teeth hinted at a super-predator. In July 2010, the world was formally introduced to “Livyatan melvillei”.

... and the award for "Most Terrifying Skull" goes to: "Zygophyseter". Image via User Hectonichus on Wikipedia

“Livyatan” was a gigantic, 13.5 -17.5 metre long macro-raptorial sperm whale that lived 9.9-8.9 million years ago off the South American coastline. Although only a partial skull was recovered, there was no doubt that this was a predator with a monstrous bite; on the side of its skull were curved indentations where jaw muscles attached (the temporal fossa). These muscle attachment sites indicated that this creature, with its 3 metre long skull, had one of the strongest bite forces of the natural world.  In addition to this, these huge teeth were implanted deeply into its jaws and like with other raptorial sperm whales, the teeth interlocked with one another.  This was a whale that was perfectly poised for ripping apart large prey.

I heard on the grapevine that a site in South America has yielded 40 centimetre teeth... Images via Lambert et al. 2010

But one thing remains a mystery; the use of the spermaceti organ. In modern sperm whales, the skull looks like a satellite dish. It cradles the spermaceti organ, which is filled with a waxy substance that the modern sperm whale uses to control its buoyancy during deep dives. “Livyatan” also has this “satellite dish” shaped skull; is it possible that “Livyatan” used it for a similar purpose?

"Livyatan" (a) Modern Sperm whale (b) and Orca (c). Highlighted are their respective temporal fossa... Despite being a physeteroid, "Livyatan" was very "Orca-esque". Image via Lambert et al. 2010

It’s incredibly difficult to say. We do not have any first hand evidence of predation like we do with “Otodus megalodon”, (serrated gouges in the bones of small sized baleen whales match their serrated teeth). I have personally heard of anecdotal reports of “impact craters” in baleen whale ribs and vertebrae that infer a bite from “Livyatan”, but nothing has been formally published. Despite this, I doubt that “Livyatan” was a deep diver like its modern sperm whale cousins. Deep diving is an extreme adaptation, most likely in response to a changing environment. It’s possible that sperm whales only survived to the modern day by weathering out severe environmental fluctuations in the deepest parts of the ocean, where it was less affected. Perhaps “Livyatan” used its giant bulbous forehead as a battering ram, or was even capable of producing a noise so deafening that it could stun its prey. Modern sperm whales are capable of producing “clicks” of 230 decibels; at 195 decibels, human eardrums rupture. But one critical question remained: when did “Livyatan” die out?

The writer of this blog is currently creating a documentary series that looks at the biology of "Livyatan". These are the screen-shots of his doco...

In 2016, the youngest known evidence of macro-raptorial sperm whales was discovered at the critically important locality of Beaumaris, Victoria, Australia. Dating back to the earliest Pliocene (roughly 5.2 million years ago) a single, isolated tooth, at just over 30 centimetres in length, was found. It remains the youngest evidence of these giant killer sperm whales in the fossil record. Museums Victoria is on the cutting edge of cetacean palaeontology; watch this space over the next few years…

So what killed them off? After dominating the Middle – late Miocene marine ecosystems, it seems that the disappearance of the macro-raptorial sperm whales also roughly coincided with the early - middle Pliocene extinction of “Otodus megalodon”. These were two large predators that co-inhabited the same ecological niche. At more than 15 metres in length, they terrified oceans for millions of years. I wrote up a previous blog post “The Megalodon: Mega-deadly food obsession”, to understand how such a massive predator could die out: 

https://a-fools-experiment.blogspot.com/2019/02/the-megalodon-mega-deadly-food-obsession.html

Hint: it has something to do with geographical barriers hampering taxon dispersal and a lack of prey items...  

Why don't we find more "Livyatan" teeth in the fossil record compared to "O. megalodon"? Physeteroids only have one set of teeth their entire life. They continually add cementum to their tooth to accomodate their size. Sharks, like "O. Megalodon", would have gone through anywhere between 10,000 - 15,000 teeth in a given lifetime based on modern estimates of sharks. 40<10,000 per individual lifetime... Image via user Ghedoghedo on Wikipedia

Killer Sperm Whales are, in my opinion, one of the largest macro-predators the world has ever seen (rivalled only in size by the Megalodon). Over the next few years, more peer-reviewed papers will be released to the mainstream scientific audience that will allow us to understand the palaeo-biology and disappearance of this stem-physeteroid…

In the meantime, I’ll be searching for more evidence of these giants along the jagged southern coastline of Australia…   

References

Lambert, Olivier, et al. "The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru." Nature 466.7302 (2010): 105.

Bianucci, Giovanni, et al. "Distribution of fossil marine vertebrates in Cerro Colorado, the type locality of the giant raptorial sperm whale Livyatan melvillei (Miocene, Pisco Formation, Peru)." Journal of Maps 12.3 (2016): 543-557.

Fitzgerald, ERICH MG. "A review of the Tertiary fossil Cetacea (Mammalia) localities in Australia." Memoirs of Museum Victoria 61.2 (2004): 183-208.

GoL'Din, Pavel, Dmitry Startsev, and Tatiana Krakhmalnaya. "The anatomy of the Late Miocene baleen whale Cetotherium riabinini from Ukraine." Acta Palaeontologica Polonica 59.4 (2013): 795-815.

Pimiento, Catalina, and Christopher F. Clements. "When did Carcharocles megalodon become extinct? A new analysis of the fossil record." PLoS One 9.10 (2014): e111086.

Whitehead, Hal. "Sperm whale: Physeter macrocephalus." Encyclopedia of marine mammals. Academic Press, 2018. 919-925.

Fordyce, R. Ewan. "Cetacean evolution." Encyclopedia of marine mammals. Academic Press, 2018. 180-185.

Fitzgerald, Erich MG, Travis Park, and Trevor H. Worthy. "First giant bony-toothed bird (Pelagornithidae) from Australia." Journal of Vertebrate Paleontology 32.4 (2012): 971-974.