Basilosaurus

Basilosaurus is a genus of cetacean that lived from 40 to 34 million years ago during the end of the Eocene period. The first Basilosaurus fossils were found in Louisiana, USA, but another species was soon discovered preserved in large numbers in the Fayum deposits of Egypt.

A Basilosaurus cetoides fossil was discovered in the United States and was initially believed to be some sort of reptile, but it was later found to be a marine mammal. Richard Owen wanted to rename the creature differently, but by taxonomic rules, the creature's first name remained permanent. Fossils of Basilosaurus isis have been found in Egypt and Jordan.Zalmout I.S; Mustafa H.A. & Gingerich P.D. 2000. Priabonian Basilosaurus isis (Cetacea) from the Wadi Esh-Shallala Formation: first marine mammal from the Eocene of Jordan. Journal of Vertebrate Paleontology 20 (1): 201–204.  

Far from being a marine reptile, Basilosaurus is a stage in the evolution of whales. At 15–20 m (49–66 ft), Basilosaurus was one of the largest oceanic animals of all time. It went extinct during the Eocene extinction event. 
 References 

Category:Cetaceans