Discover The 70 Foot Predator Eel That Once Ate Whales

Written by Austin S.
Updated: June 15, 2022
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The dinosaur era was full of scary animals. These animals possessed enormous power and were very big. They roamed the earth, skies, and the seas. This 70-foot predator eel was a sea creature that ruled its oceans. This animal was the Basilosaurus.

A prehistoric whale that hunted and fed on other whales. Due to its large size, Basilosaurus outsized most marine animals of the time. This feature made it a king of the ocean. It is also reflected in its name. Basilosaurus in greek interpretation means King Lizard. This article will explore what the Basilosaurus looked like and how it lived. We will also discuss the circumstances around its extinction.

What is a Basilosaurus?

Basilosaurus was not like the current whales or dolphins in appearance. Its body structure was more of an eel than a whale. It had a long, thin body with a small snout lined with various-shaped teeth. On initial discovery, this body structure caused it to be mistaken for a sea reptile. 

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This confusion earned it the name Basilosaurus. Basilosaurus existed between 40 and 34 million years ago in the Late Eocene Period.

Irrespective of their vast size, these creatures’ brains were small. Research shows that they were not capable of echolocation. These animals also couldn’t engage in herd movement. 

The name identifies two species, which are Basilosaurus cetoides and Basilosaurus isis. The size of each Basilosaurus depends on its species. Their lack of herd movement indicates they existed and survived alone.  Some of the other species include:

  • Basilosaurus drazindai
  • Basilosaurus ‬harwoodi
  • Basilosaurus‭ ‬caucasicus
  • Basilosaurus‭ ‬paulsoni,
  • Basilosaurus‭ puschi
  • Basilosaurus‭ ‬vredensis
  • Basilosaurus‭ ‬wanklyni

How Big Was Basilosaurus?

Basilosaurus was sleek and eel-like for a prehistoric whale. Meaning it was long. This ancient whale measures between 65 to 70 feet long. The measurement is from the tip of its head to the end of its tail fin. The length applies to both species covered under the Basilosaurus name. Basilosaurus weighed between ten to fifteen tons. These characteristics describe Basilosaurus as larger than most creatures of its time.

Physical Attributes of Basilosaurus

Basilosaurus was an unusual-looking creature. Its body was long and slim, like that of an eel. It possessed a nose filled with teeth of various shapes. Many prominent cusps were on the teeth closer to the rear of the Basilosaurus’ snout. Basilosaurus had their blowhole on their snout. They could breathe at the surface by pushing their snout out. This feature was different from what most ancient whales had.

Most primitive whales had their blowholes at the tip of their snout. These primitive whales include whales like Pakicetus. Modern whales and dolphins have their blowhole located between or behind the eyes. Basilosaurus had hindlimbs on their body. The hindlimbs had functioning knees and toes. The ankle and the foot had many fused joints while others can move within limits.

Basilosaurus cetoides - total view - Smithsonian Museum of Natural History

Basilosaurus cetoides was shaped more like an eel than a modern whale.


What Basilosaurus Ate

Basilosaurus cetoides skeleton was all over the Mississippi region. This discovery was alongside a pile of digested fish bones. These remains showed that Basilosaurus ate fish. Basilosaurus may have preyed on other marine animals too. 

Basilosaurus used a method of delivering finishing blows to their prey’s head. They then proceed to tear their prey apart. Basilosaurus’ feeding and hunting patterns are like today’s Killer whales, Orcas.

Many specimens of other marine animals like the Dorudon display significant puncture wounds. There are speculations that some of these wounds may have been inflicted by the Basilosaurus. This discovery was made at the Eocene fossil sites in Egypt.

The teeth and jaws of Basilosaurus are that of a carnivore. Examination of the jaws and teeth of Basilosaurus reveals that it possessed a massive biting power. They discovered that Basilosaurus had a biting force of roughly 2,300 pounds. Their bite force is stronger than that of most animals today. To put things in perspective, gray wolves, lions, and bears all have biting forces of 406 pounds, 691 pounds, and 850 pounds respectively.

Basilosaurus could hunt larger prey and kill them with their terrifying bite force. Fish and sharks are some of the contents found in the stomachs of Basilosaurus cetoides. These whales were most likely predators that intimidated their prey due to their great size and presence of teeth. 

Basilosaurus had a scary set of teeth in the front. They had canine-shaped incisors and triangular molar-like teeth in the back. The flattened teeth had some wear facets. These extended wear facets show that the upper and lower teeth grind over each other. Basilosaurus is one of the rare fossil marine animals with preserved digestive content.

Sensory Abilities the Basilosaurus Possessed

Basilosaurus receive and process sound through their skull. These waves reach their inner ears simultaneously. Basilosaurus was able to detect where sounds were coming from underwater. Land animals do not have this feature. It is why land animals can’t discern sound direction when underwater. 

Their lower jaw features a vast opening called the mandibular foramen. This opening has thin sides that contain a massive pad in contemporary toothed whales. Sound waves enter through the lower jaw’s pan bone. It then proceeded to the middle and inner ear of Basilosaurus.

The tympanic bulla was less attached to the skull. This reduced connections and the formation of sacs filled with air separated the inner ear from sound waves that pass through the bones. Sound waves first hit the left ear from the left side before the right side. Sounds coming from the right side reach the right ear before the left. Basilosaurus had a sound pad that received these sound waves.

Basilosaurus could discern the direction of incoming sound based on the time difference. This timing means the time between when the sound reaches each ear. The skull of Basilosaurus retained bony auditory canals. 

This feature suggests that it preserved a restricted external ear. It is a feature that is unlike contemporary cetaceans. The other hearing characteristics show that it was marine. Meaning any adaptations for hearing sound outside water was most likely vestigial.

Locations Where the Basilosaurus Lived

The Northern Atlantic Ocean is a well-known Basilosaurus habitat.  Other places include the Tethys Sea and Paratethys Sea. The fossil sites in the southeastern United States are evidence of their habitat. There have been such discoveries in England, Egypt, Jordan, and Pakistan

There has been no discovery of the Basilosaurus cetoides outside North America. The more minor and related Basilosaurus isis has turned up in Egypt. These discoveries suggest that Basilosaurus lived in oceans around the world.

How the Basilosaurus Navigated the Oceans

The primitive hindlimbs of Basilosaurus were ineffective for any movement on land. The hindlimbs were very short. The pelvis was also lacking any bone connections to the spinal column. This feature means that these joints and limbs cannot support any weight on land.

Muscle attachments on the bones of the hindlimbs were well-developed. This indicates that they were functional and not vestigial. It also suggests that they were likely used as claspers when mating. It’s also plausible that the hindlimbs served no use.

Basilosaurus possessed modest tail flukes based on the vertebrae’s proportions near the tail’s tip. These flukes may have been in early whales for which the tail is unknown.  The Basilosaurus is the earliest whale genus having evidence of flukes. The vertebrae of Basilosaurus are very elongated and they possessed a high degree of vertebral column flexibility.

Their flexibility, along with the presumed short flukes in Basilosaurus, suggests a whole body undulating movement when Basilosaurus swims. This phenomenon is unlike current cetaceans that use their tail for swimming. This type of mobility is “anguilliform,” or eel-like. However, unlike eels that use side-to-side movement, Basilosaurus’ engaged in an up and down movement.

When and How Did It Go Extinct?

Basilosaurus went extinct as far back as 34 million years ago. The cooling of Earth’s climate globally led to changes in ocean circulation. These changes caused the extinction of these animals, leaving their remains around the world for discovery.

Animals Similar to Basilosaurus

Dolphins – Dolphins are intelligent marine animals that look like Basilosaurus. Though they’re no match in size, Dolphins are one of the fastest swimmers in the ocean.

Dorudon – This is an extinct whale that existed in the Eocene era with Basilosaurus. They lived in oceans worldwide and were one of the favorite food for Basilosaurus.

Blue Whale – Blue whales are one of the largest animals in the world today. Unlike Basilosaurus, Blue whales feed on small fish and crustaceans.


The Basilosaurus is a large animal, especially for its environment and the time it reigned. It was a king of the sea. It is not the largest whale to have existed, but its tremendous bite force is one for horror tales. Their bite force, coupled with its size, describes an almost matchless sea monster of old.

The photo featured at the top of this post is ©

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About the Author

Growing up in rural New England on a small scale farm gave me a lifelong passion for animals. I love learning about new wild animal species, habitats, animal evolutions, dogs, cats, and more. I've always been surrounded by pets and believe the best dog and best cat products are important to keeping our animals happy and healthy. It's my mission to help you learn more about wild animals, and how to care for your pets better with carefully reviewed products.

FAQs (Frequently Asked Questions) 

Was Basilosaurus a lizard?

Basilosaurus was not a lizard. It was confused as a lizard due to the short limbs it had. Further examination reveals that the limbs were not for movement on land.

Was Basilosaurus prey to other whales?

Basilosaurus had no rival in the ocean. The significant threats they faced were old age and injury.

Is Basilosaurus the largest whale ever?

The largest whale award belongs to the Leviathan, a giant prehistoric whale that weighed up to 50 tons.

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