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What Is Basilosaurus?

Basilosaurus, known as the "king lizard," is found in the late Eocene, which is about 41.3 to 33.9 million years ago. It is the classification of predatory, big, and archaeocete whales, depicted in 1834 and known as the first prehistoric whale discovered by science. The "Saurus" in their name is because of the giant size of these reptiles. 

Later, scientists discovered it was an early marine mammal by studying its fossils. The very first fossil of type species B. cetoides was discovered in the United States. Later the species, B. isis was found in Jordon, Egypt, Morocco, Western Sahara, Tunisia, Pakistan, and other Southeastern US parts. It used to be the biggest predator used to prey on the water mammals like large fishes, sharks, and Dorudon. 

Nowadays, scientists tend to discover basilosaurus fossils to have a deep study on them. Here are some interesting facts about basilosaurus. 

  • Typically, prehistoric whales used to be large, but basilosaurus is around 65 feet long and had a sleek, eel-like structure. 
  • Back in the Eocene era, giant mammals, including basilosaurus, used to have small brains compared to their bodies. 
  • Before the 18th century, when basilosaurus was discovered, individuals often used their fossils to make furniture.
  • Basilosaurus fossils are the official state fossil of Alabama and Mississippi. 
  • The length and flexibility of basilosaurus are because their front flippers hold onto their elbow hinges.
  • Usually, the vertebrae of a modern whale are solid, but in basilosaurus, the vertebrae are filled with fluid and are hollow.
  • Despite its length, the basilosaurus was not the largest whale in history. There are more examples of giant whales like Leviathan.


There are three basilosaurus species, about 34-40 million years old. The length of a basilosaurus is approximately 56 feet (17 meters), moreover, you can find their skeletons in museums. If you want to buy basilosaurus teeth fossils you can refer to Fossil Age Minerals. 

The appearance of basilosaurus differs from that of other marine mammals. It has an extremely long, sleek, and slender body. Their teeth are of various shapes and sizes and are attached to a narrow snout. The body type is entirely different from whales. Therefore it was named "king lizard" because of its reptile-like structure. The blowhole in basilosaurus is usually placed far from the eye sockets, unlike other water mammals with the blowhole placed between or behind the eyes. There are numerous cusps in the teeth at the back of their mouth, mostly serration-like.

The mobility of basilosaurus is better as compared to other water mammals. There are external hindlimbs present that consist of functional toes and knees. Even tho with hindlimbs, basilosaurus could not move in terrestrial land. Because of the fluid-like vertebra and tiny hindlimbs, the movement of this mammal is limited to inside the water. However, despite the long structure, basilosaurus is not an extremely aggressive or dreadful mammal. They used to be passive and tolerated the survivors until they felt attacked.

History Of Basilosaurus

The very first and largest species of basilosaurus, B. cetoides is found in Alabama and Louisiana. The first discovered basilosaurus fossils were the teeth and vertebra, which were then examined by the scientists, and they found out that it was an ocean-living mammal. At first, individuals used to collect these fossils and make furniture for their homes until it was discovered by scientists and sent further for research. Moreover, during Wadi El Hitan in Egypt, there were many basilosaurus fossils were discovered which made it easy for scientists to study them deeply. Skeleton of huge fishes and Dorudon was also discovered in their stomach, which made it clear who their prey used to be. There were debates on whether it was a reptile or a marine animal. The structure portrayed it as a reptile. However, the anatomist Richard Owen then studied the fossils, and by their complex teeth structure, he figured this was not a normal reptile structure. It is an ocean mammal.


Cranium, or the bones that make the structure of the head, is quite complex in basilosaurus. The molars of the upper and lower portions and the premolars of the fourth and second portions are high-crowned and deeply rooted. The size of the brain is typically smaller than that of modern whales. Hence, it is said that the social capabilities are less of basilosaurus. Their skull is asymmetrical, which associates the high-frequency echolocation. There is a dense tympanic bulla present in the inner and middle ear. It helps them in hearing the directions of water inside the ocean. 

Movement And Spine

Found in 2015, the whole structure of basilosaurus consists of 70 vertebrae overlapping three skeletons with seven cervical, 20 lumbar, 18 thoracics, 25 caudal vertebrae, and 20 sacral. Because of this structure, the basilosaurus appeared to be buoyant. The movement of basilosaurus was usually two-dimensional at the sea surface. Their structure portrays that they only swam in a vertical motion. The fluid-filled vertebrae make its movements limited. 


The whales of 34-41 million years ago used to have traits of living on both land and water. With the evolution of their species, they became completely water mammals. The basilosaurus fossils were commonly found in the United States' southern parts. When the first basilosaurus skeleton was found in Egypt in 1990, it still has its feet and toes intact. The basilosaurus is stated as a strange mammal because of its structure and how it appears. From then, to now, water mammals have evolved in many ways. The structure and function of these mammals were different and slow from modern-day whales. Because of their fluid vertebrae, the movements were sow which did not allow them to swim deep in the ocean. However, modern whales are more flexible and prone to swim deeply without any hassle.


The records show that basilosaurus was distinct 33.9-35 million years ago. The time of their presence was from Eocene to the Oligocene extinction. At that time, many archaeocetes became extinct. The events that result in the extinction of these mammals are volcanic activities, climate change, meteor impacts, and factors disrupting ocean circulation. There were no descendants left of basilosaurus. They have distinct completely. Moreover, if you want to collect these fossils, you can get your hand on the basilosaurus fossils.


The first discovery of basilosaurus stated that it was a giant reptile. Because of its long eel-like structure and tiny head, early scientists thought it was a reptile and named it basilosaurus, which means the king lizard. But later, some scientists examined basilosaurus' teeth structure and found they were water mammals. Moreover, in ancient southern parts of the US, individuals often used their fossils to create firewood and other furniture-related home decor. Because a lot of structure and the whole skeleton was found in Wadi Al-Hitan in Egypt, it became the official fossil of Egypt. However, later it was discovered that the majority of basilosauus were used to be present in the United States. 

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If you are interested in studying the fossils or simply keeping them as a collection, Fossil Age Minerals is your one-stop solution. You can get your hands on our basilosaurus fossils . Visit us today to know more about our products.

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