Ancient Seas #6

Liyvatan or Leviathan Melvelli

Artistic Rendering from Scary Nature's YouTube

Kingdom: Animalia

Class: Mammalia

Conservation Status: Extinct (EX)

Found: Peru

Era: Miocene

Lived: 11-12 million years ago

Diet: Smaller whales

Weight: 57 tonnes*

Size: 13.5 - 17.5m (44 - 57ft)*

Habitat: Unknown

*These are estimates, without living specimens or more remains it is nearly impossible to know.

The leviathan melvelli or Livyatan was a toothed whale which lived around 12 million years ago during the Miocene era. It is the largest known extinct whale, which grew up to 17.5m (57ft). This is still smaller than the Blue Whale which lives today but it would have ruled the seas all those years ago, with evidence of it being a fierce hunter. Its remains were found in Peru, an area which would have been under the sea at the time making it rife with marine fossils. Colossal teeth had been found in 2008, but it wasn't until 2010 when more of this whale was found that it was officially a new species. While it's teeth are distinctive and impressive, more was needed to do so confidently. A skull, to be precise.

The Livyatan has been classified as a hyper-predatory macroraptorial sperm whale. This means it shares genealogy with modern sperm whales, though is it theorised that they are distant cousins rather than direct descendants. It is entirely possible they evolved the spermaceti organ completely independently. But like their modern counterpart, they did indeed possess a spermaceti organ. It is a large sac in their head which contains an oily/waxy substance which was likely used for echo location and/or communication. These are theories held for modern sperm whales too. 

While they potentially looked a lot like sperm whales, they had a much more aggressive hunting style. It is believed they hunted like orcas (killer whales) - pursuing and tiring their prey on the surface until they drown from exhaustion. It is even possible they hunted alone, because of their impressive size. Due to the fact that only their skulls have been discovered and the close connections to two modern mammals all estimates of their shape, size and weight are scaled on both mammals, hence the variation in estimates.

Everything we know about the Livyatan has come from its robust, thick skull. This beast of a skull, measuring 3.5m (10ft).

Photo from Wikipedia

When I say the Livyatan was a toothed whale, I mean it was a toothed whale. The largest of them measured up to 35.5cm (14 in), the largest of any known animal, and were usually found towards the back of the jaw. These enamel-coated teeth were designed to hold and clamp down on struggling prey. They sheared past each other, meaning they would interlock and create little chance of escape for anything they preyed upon. These teeth were deeply embedded into the gums as well, so they would not work loose either. Modern toothed whales have much smaller teeth and hunt by sucking in boneless prey like squid. These beasts hunted smaller baleen whales and evolved so that they could! So they may have looked like sperm whales, they certainly didn't eat like them!

It is likely that the way they hunted would have had an impact on the Miocene ecosystem. They would have filled a similar predatory niche that orcas fill today - eating whales, sharks, seals. Their size was their own defence against predation, they were simply too big to be hunted. Their only threat was climate change (who else is tired of singing this song?). Much like other large predators of the time, with cooling waters killing off their food source they were unable to sustain themselves. 

Image from LifesBiggestQuestions YouTube

Fun Facts:

• Livyatan was likely to have shared waters and interacted with Megalodon.
• Its name leviathan melvelli is in honour of Herman Melville who wrote Moby Dick, a novel about a sperm whale.
• Some of its lower teeth developed a facet so they the jaw could actually close.
• Other theories of use for its spermaceti organ include: vocally stunning prey, combat, and as a buoyancy aid in deep waters.