Basilosaurus. That name means "King Lizard". 18 meters of predatory whale. Four times the length of a Great White Shark, these whales weigh 60 tons.
— Allen, about Basilosaurus
in Big Blue Killer Whale

Basilosaurus ("King Lizard") was a large, primitive, predatory whale from the Eocene. Despite being a whale, its name was kept because it fit. Basilosaurus was the top predator in the Tethys ocean during its existence.



Basilosaurus lived in the Seas of the Late Eocene period from 36-30 million years ago. It was the top predator in the Eocene seas. They evolved from small fury tree dwelling creatures. The end of the Eocene had been brought to the brink of great climatic change. As the Oligocene began, Basilosaurus vanished, falling victim of the climatic shifts that ended the Eocene, changing the warm sea into a cold ocean and causing the Tethys Sea to disappear.


By far the largest predators in the Eocene seas, Basilosaurus were predatory whales that measured 18-20 meters long, well over four times the length of a Great White Shark, and weighed 60 tons. It's incredible to think, then, their ancestors were tiny, furry, shrew-like animals that lived in trees.


Basilosaurus Head

Because its name "Basilosaurus" means "King Lizard", when the fossils were first discovered in 1832, Basilosaurus were originally thought to have been giant marine reptiles, much like the Mosasaurus and Plesiosaurs of the Mesezoic Era. But instead, they were eventually found out to be a primitive species of whales.

According to an artist drawing of them in 1960, Paleontologists also once thought Basilosaurus were very reptilian just like sea serpents or even the Loch Ness Monster.

But their skulls are what were chilling. There are no whales with skulls like the skull of Basilosaurus in modern times, not even toothed whales. Great peg–like teeth at the front for seizing prey. Once inside the mouth, the prey was sliced up by the big teeth at the back, great big cusps at the front. They were for slicing through flesh.



Basilosaurus mating

During the mating season, Female Basilosaurus were eagerly pressured by several males, but it was the eldest and the biggest males that the females chose to mate with. Mating was not an easy task for such huge, free–floating animals. So Basilosaurus needed a little extra help.

As the successful male maneuvered into position, these whales called upon one small legacy of their distant lend ancestors. Basilosaurus retained two tiny back legs. These were useless for walking or even swimming, but they were used to lock their long narrow bodies together during mating.

Being far bigger, meaner whales then Dorudon, Basilosaurus ate those little tiddlers for breakfast, especially the young. And for Basilosaurus, hunting them is what it meant to be top of the food chain.