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 (name meaning "King Lizard") is a genus of large, prehistoric, predatory serpentine-like cetacean that originated during the Eocene period. Despite being a whale, its name was kept because it fit. This whale the top predator in the Tethys ocean during its existence and was one of the first in the line of giant cetaceans. It was 1518 meters in length, weighed 60 tons, and has a long slender body that was like that of a serpent.


Era & DiscoveryEdit

Basilosaurus lived in the Seas of the Late Eocene period from 3630 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.

For many decades Basilosaurus was the oldest-known fossilized cetacean (or whale). Its tiny back legs were seen as proof that the whales had once been land animals, but it was not until the discovery of 'walking whales', such as Ambulocetus, that there was proof of this. It is now known that the whales evolved from large, crocodile-like animals called mesonychians such as Andrewsarchus.

Physical AttributesEdit

By far the largest predators in the Eocene seas, Basilosaurus were large, carnivorous whales that were well over four times the length of a Great White Shark, measuring 5060 feet (1518 m) long and weighed up to 60 tons (120,000 lbs.). 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 Mosasaurs 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.

It also had a streamlined, serpentine body shape with was useful in making it a swift and deadly predator. Basilosaurus had small hind paddles which were useless for aiding in locomotion but were extremely important during copulation. It also had a long and strong fluke used to propel its weight and size through the water. Basilosaurus had light blue skin on its back and white skin on its underside. Because of this, Rebecca nicknamed Basilosaurus "the big blue killer whale".

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. It had a very large skull with strong jaws, which were lined with large teeth used to severely injure its victim. 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.

Behavior & TraitsEdit

Basilosaurus was a solitary animal and as such, it would have spent long periods of time on its own. Unlike most of the modern species of cetaceans, interaction between members of the same kind were often hostile and lethal. It lacked a 'melon', the organ that modern whales and dolphins use for echolocation and to 'sing' to one another. Even though Basilosaurus couldn't sing, the only time the males and female would interact was during courtship and mating. During these mating competitions, Female Basilosaurus were eagerly pressured by several males, but it was the largest and oldest male that would win the right to mate with the target female. Mating was not an easy task for such huge, free–floating animals. So Basilosaurus needed a little extra help.


Basilosaurus mating

As the successful male maneuvered into position, given their sinuous body shape, these whales called upon a relic of their distant land-living ancestors. Both a memento of its land-dwelling ancestors and a useful tool during copulation, Basilosaurus retained two, small hind flippers, or "back legs".

Due to their tiny size, they were useless as a means of walking or even steering while swimming. However, during mating, they were used to lock their long narrow bodies onto each other, guiding one another into the correct mating position during mating.

Like all whales, Basilosaurus was an air breather, but it had no blow-hole. Instead, it had to raise the tip of its nose out of the water to take a breath. Its ribcage was solid and not very flexible, which meant that its lung space was restricted; thus Basilosaurus could not stay under water for prolonged periods of time. Any attacks it made therefore had to be swift and accurate. With its high mammalian metabolism, Basilosaurus would have needed to eat often in order to keep its energy reserves high.

Basilosaurus lived in most of the warm seas around the world. It did not have the large insulating fat deposits of modern whales, so it could not have strayed into cooler waters. It was therefore restricted mainly to warmer waters, such as the ancient Tethys Sea that once ran between the African and European continents.

Easily being the largest predator of its time, Basilosaurus was a deadly predator and was capable of attacking large prey, including other whales, such as its smaller relative - Dorudon. When it came to food, Basilosaurus was not a fussy eater. Its favored prey Dorudon, but its diet also extended to fish, sharks, squid, turtles, and other marine mammals, such as primitive proboscideans like Moeritherium which lived in the shallow mangrove swamps as well as other types of marine animal could all fall prey to the keen eyesight of Basilosaurus. It would swim in pursuit of its victims, using its powerful serpentine tail to make brief but fast pursuits. Once its powerful jaws and sharp, serrated teeth clamped down on to an animal, there could be no escape.