An extinct species of whale that existed 41 million years ago, when whale ancestors were just finishing their transition from land to sea, has been discovered by paleontologists in Egypt.

The species has been given the name "Tutcetus rayanensis" in honor of Tutankhamun, the young king of Egypt, and the Wadi El-Rayan Protected Area in Egypt's Fayoum Oasis, where the type specimen was discovered.

Tutcetus is the smallest species of basilosaurid whale that has been discovered so far, measuring an estimated 2.5 meters (eight feet) in length and weighing roughly 187 kilograms (410 pounds). Basilosaurids are the oldest known whales that lived only in the water.

It was a "remarkable discovery that documents one of the first phases of the transition to a fully aquatic lifestyle", team leader Hesham Sallam, of the American University in Cairo (AUC), said.

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Basilosaurids "developed fish-like characteristics, such as a streamlined body, a strong tail, flippers, and a tail fin, and had the last hind limbs visible enough to be recognized as 'legs', which were not used for walking but possibly for mating," Sallam said in an AUC statement. 

The Eocene fossil sites of Egypt's Western Desert have long been the world's most significant for comprehending the early evolution of whales and their transition to a fully aquatic existence, according to Erik Seiffert of the University of Southern California, a co-author of the team's findings published in the journal Communications Biology.

About 150 kilometers (90 miles) southwest of Cairo, in the Fayoum Oasis, is Wadi al-Hitan, the Valley of the Whales, a UNESCO World Heritage Site where thousands of fossilized remains of some of the earliest whale species have been discovered.

Fayoum, now an oasis in the Western Desert, was once submerged beneath a tropical sea between 56 and 34 million years ago.

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