Basilosaurus Fact Sheet

Common Name:

Basilosaurus cetoides

Scientific Name:

Whale-shaped king lizard

Wild Status:

Eocene Epoch, 30-40 MYA


North America, Egypt, Jordan


Countries in Africa and North America



Life Span:



60 feet long, 10 tons

Cool Facts:

  • For its time, Basilosaurus was the largest predator on the planet. The remains of bony fishes and sharks have been found within their stomachs. Wear patterns on the teeth indicate that Basilosaurus actually chewed its food to an extent. Holes found in the skulls of smaller Dorudon whales match up perfectly with Basilosaurus premolars, which suggests that it preyed on marine mammals as well.
  • It is estimated that Basilosaurus could bite down with nearly 4,000 pounds of force. This is the highest bite force recorded for a mammal and is proportionally more powerful than the bite of a crocodilian with a similarly-sized skull.
  • In 1845, a man named Albert Koch took the remains from several individual Basilosaurus and combined them to make a single gigantic specimen that he called Hydrachos and claimed to be a fossil sea serpent.


The name Basilosaurus means “king lizard” because when it was first discovered, it was believed to be a marine reptile of some sort. Closer examination of the teeth revealed mammalian roots and the distinctive yolk shape lead to the creation of the name Zeuglodon. Since the name Basilosaurus had already been published, Zeuglodon was considered a junior synonym and the old, misleading name stuck. Basilosaurus had a very different body plan than modern cetaceans. It had an elongated eel-like body that could undulate in a vertical angulliform unknown in extant whales. It is unlikely that Basilosaurus was capable of deep diving. Hind flippers were still present, although these were greatly reduced in size and may have been vestigial. Also unlike modern whales, Basilosaurus had differentiated teeth.

Taxonomic Breakdown:

Kingdom - Animalia Phylum - Chordata Class - Mammalia Order - Artiodactyla Family - Basilosauridae Genus - Basilosaurus Species - B. cetoides

Conservation & Helping:

Basilosaurus is currently extinct and lived from 30 to 40 million years ago.

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