Basilosaurus Whale

The Basilosaurus Whale is Alabama's official state fossil, designated in 1984. Despite its name (Greek for "king lizard"), Basilosaurus cetoides was not a reptile but an early whale, a mammal fully adapted to ocean life. It is one of the largest animals known to have lived during the Eocene epoch.

Alabama is one of the best places in the world to find Basilosaurus fossils. The ancient shallow sea that covered the Gulf Coastal Plain during the Eocene left thick marine sediments across the southwestern part of the state, and Basilosaurus bones have turned up across several counties.

Basilosaurus cetoides had a long, eel-like body unlike any living whale today. At up to 60 feet from snout to tail, it was enormous, but much of that length came from stretched, elongated vertebrae that gave it a serpentine shape. It was a sleek ambush predator, not the barrel-chested bulk of a modern blue whale.

Its teeth tell the whole story of its diet. Basilosaurus had two types: cone-shaped front teeth for grabbing, and serrated rear teeth for slicing. Fossilized stomach contents from related specimens found in Egypt show fish bones and shark remains, confirming it hunted actively rather than filtering water.

Basilosaurus still had tiny vestigial hind limbs, about two feet long, left over from the land-dwelling ancestor it descended from. Those small legs had no role in swimming and could not support the animal on land. They are among the clearest fossil evidence that modern whales evolved from four-legged terrestrial mammals.

The story of Basilosaurus starts with a mistake. In 1834, American physician and naturalist Richard Harlan described bones found in Louisiana and named the creature Basilosaurus, convinced he had found a giant sea reptile. Two years later, British anatomist Richard Owen examined the same material and corrected the record: the teeth and bone structure matched a mammal, not a reptile. By the rules of scientific naming, Harlan's name stuck even after the classification changed.

Albert Koch made the story stranger in 1845, when he assembled a composite skeleton from multiple individuals, stretched it to over 100 feet, and exhibited it across the United States and Europe under the name "Hydrarchos," meaning water king. Scientists quickly identified the fraud, but the publicity cemented Basilosaurus in the public imagination.

Alabama designated Basilosaurus cetoides as its state fossil in 1984, the same year it adopted its state dinosaur. The choice reflected the state's exceptional Eocene marine fossil record: southwest Alabama contains some of the richest Basilosaurus deposits in North America.

Southwest Alabama sits on top of what was once a warm, shallow sea during the Eocene. As that sea receded, it left behind thick layers of marine sediment, now exposed as the Lisbon and Gosport formations, that have produced Basilosaurus bones across Choctaw, Washington, Clarke, and surrounding counties. These counties remain the core of Alabama's Basilosaurus fossil zone.

The Alabama Museum of Natural History at the University of Alabama in Tuscaloosa holds significant Basilosaurus specimens from the state. The McWane Science Center in Birmingham also displays Alabama fossil material, including marine vertebrates from the Eocene formations.