What Is Phiomicetus Anubis? Fearsome Ancient Whale With Four Legs Discovered

Scientists have discovered a fossil that once belonged to a previously unknown type of four-legged whale that lived tens of millions of years ago.

The researchers also found that the whale's mouth was better-designed for a "strong raptorial feeding style" than was usual for other types of early whale-like animals and that it would have been a fearsome predator.

The evolution of whales is thought to have proceeded at a rapid pace millions of years ago—so fast that over a period of 10 million years the ancestors of whales evolved from "deer-like" herbivores that lived on land into carnivorous marine animals, according to the researchers' study published in the Proceedings Of The Royal Society B.

The fossil that the team have investigated is thought to have come from a protocetid, a type of early whale from the Eocene era which started 56 million years ago and ended 33.9 million years ago.

The researchers have named the newly discovered extinct whale species Phiomicetus anubis. The first part of the name refers to the Fayum Depression in Egypt's Western Desert where the fossil was found, and the second part refers to Anubis, the ancient Egyptian god of the afterlife.

The fossil is 43 million years old. In a press release documenting the team's work, lead author Abdullah Gohar at Mansoura University in Egypt called it "a critical discovery for Egyptian and African paleontology."

The animal, estimated to have had a body length of about 10 feet and a body mass of about 1,320 lb, would likely have been a top predator in its community at the time, like the killer whale of today.

There is still much to be learned about early whale evolution in Africa and researchers hope that studying the region could uncover more about how early whales changed from animals that spent time both in and out of the water to animals that lived in the water all the time.

The fact that the early whale ancestors walked on four legs is nothing new. Indeed, scientists think that a four-legged goat-sized animal known as Pakicetus was one of the first cetaceans—the family of marine animals including dolphins and whales—ever to exist.

But it is the evolutionary pathway from these four-legged ancestors to the fully water-based animals we know today that intrigues researchers, according to an article on four-legged whales by the the U.K.'s National History Museum.

Other aspects of Phiomicetus anubis that set it apart from other protocetids include an elongated temporal fossae, or shallow depression on the side of the skull, and a difference in the placement of the pterygoid bones.

The study abstract concludes: "The discovery of Phiomicetus further augments our understanding of the biogeography and feeding ecology of early whales."

Phiomicetus anubis
An illustration of Phiomicetus anubis by Robert W. Boessenecker at UC Berkeley. The animal would have been a top predator, researchers think. Robert W. Boessenecker