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Illustration of Basilosaurus by Pavel Riha
View of the Basilosaurus cetoides skeleton displayed at the Alabama Museum of Natural History.

Basilosaurus ("King Lizard") was a genus of cetacean (whale) that lived from 39 to 34 million years ago in the Eocene period. The species is the state fossil of Alabama, and examples of Basilosaurus fossils are on display at the McWane Science Center in downtown Birmingham and at the Alabama Museum of Natural History at the University of Alabama in Tuscaloosa.

Its fossilized remains were first discovered in the southern United States, and were initially believed to be some sort of reptilian sea monster, hence the suffix -"saurus". Fossils from at least two other species of this taxon have been found in Egypt and Pakistan. Basilosaurus averaged about 60 feet in length, and displayed an unparalleled degree of elongation compared with modern whales. Their very small vestigial hind limbs have also been a matter of interest for paleontologists.

Fossil finds

During the early 19th century, Basilosaurus cetoides fossils were so common in the South that they were regularly used as furniture. One vertebra was sent in to the American Philosophical Society by a Judge John Creagh of Clarke County, who was concerned that the unique finds were being destroyed by the locals. Anatomist Richard Harlan wrote to Creagh asking for additional artifacts and, with a collection of fossil bones speculated that the creature was an exceptionally large (150-foot) marine reptile, cousin of the plesiosaur and icthyosaur. He suggested the name "Basilosaurus" meaning "king reptile".

When the British anatomist Sir Richard Owen studied the spine, mandibular fragments, arms, and ribs (recently found) he proclaimed them to have instead been from a mammal. Owen proposed renaming the find to Zeuglodon cetoides ("whale-like yoke teeth"), which is now a junior synonym;. Though the latter is considered by many to be a more fitting name, the first-published name always takes precedent.

In 1845, Albert Koch heard stories of giant bones in Alabama, and came here to cobble together a full skeleton. He eventually created a huge 114-foot skeleton of a "sea serpent", which he displayed in New York City, and later Europe. It was eventually shown to have come from 5 different individuals, some of which were not Basilosaurus. The remains were eventually destroyed in the Great Chicago Fire.


The most notable physical feature of Basilosaurus is the great deal of elongation it possessed. It accomplished this through an unparalleled elongation of its vertebrae, and has been described as being the closest a whale ever came to a snake. It is also believed to have had unusual locomotion, compared with all other cetaceans; similarly sized thoracic, lumbar, sacral and causal vertebrae imply that Basilosaurus moved in an anguilliform (eel-like) fashion, only vertically. Even more oddly, paleontologist Philip Gingerich theorized that it may also have moved in a horizontal anguilliform fashion to some degree, something completely unknown in cetaceans. The skeletal anatomy of the tail suggests that a small fluke was probably present, which would have only aided vertical motion. Most reconstructions show a small, speculative dorsal fin similar to a rorqual whale's, but other reconstructions show a dorsal ridge.

The most famous part of the whale's anatomy are the 0.6 meter (2 foot) hind limbs, which clearly cannot aid locomotion on a 15-25 meter (50-85 foot) animal. Analysis has shown that the reduced limbs could only snap between two positions. They appear similar to the reduced legs used as copulatory guides on boas, and might have been used in the same manner.

The vertebrae of the whale appear to have been hollow, and it is likely that they were fluid filled as well. This would imply that Basilosaurus typically only functioned in two dimensions at the sea's surface, compared with the three dimensional habit of most other cetaceans. Judging from the relatively weak axial musculature and the thick bones in the limbs, Basilosaurus is not believed to have been capable of sustained swimming or deep diving. It is also believed that the primitive whale did not have any competency at terrestrial locomotion.

The head of Basilosaurus did not have room for a melon organ like modern day toothed whales, and the brain was smaller in comparison as well. It is believed that they did not have the social capabilities of modern whales, possibly as a result of that.

At one point of time it was believed that Basilosaurus had some sort of armor plating, but it was likely the misidentification of turtle shells. Some cryptozoologists believe that either Basilosaurus or an evolved relative is currently alive and responsible for sea serpent sightings, but its fossil record appears to end 37 million years ago, so there is no evidence to support that claim.

External links


  • Basilosaurus. (2007, July 8). In Wikipedia, The Free Encyclopedia. Retrieved 18:26, July 9, 2007, [1]
  • Perrin, William and Wursigm Bernd, and Thweisse, J. G. M. (2002) J.G.M. Encyclopedia of Marine Mammals. Academic Press
  • Thewissen, J. G. M., ed. (1998) The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacean. Plenum Press, New York and London ISBN 0-306-45853-5
  • Zimmer, Carl (1998) At the Water's Edge. Free Press