Ancient Whales Walked on Four Legs, Moved Like Giant Otters, Scientists Say

Mindy Sparks
April 6, 2019

With its four strong limbs and a powerful tail, the odd animal looks more like an otter or beaver than a modern whale.

The fossil was found about 0.6 miles (one kilometer) inland from Peru's Pacific coast, at Playa Media Luna. The four-legged early whale, which could apparently move on land as well as in the sea, is the most complete fossil of its kind outside what is now India and Pakistan, where whales first began to evolve from dog-sized carnivorous mammals 50 million years ago, researchers say in a press release.

Peregocetus represents the most complete quadrupedal whale skeleton outside India and Pakistan, and the first known from the Pacific region and the Southern Hemisphere.

Its mandibles grazed the desert soil and during excavations, the researchers found the lower jaw, teeth, vertebrae, ribs, parts of front and back legs, and even the whale ancestor's long fingers that were likely webbed.

"It most likely spent most of its time in the water, especially for feeding, as it was certainly better at swimming than walking, but it may have moved back to land to rest, maybe to breed and for other social interactions, and possibly also to give birth", Lambert told Newsweek.

It belonged to an entirely new genus and species of whales.

These aquatically capable creatures initially spread out from Southern Asia, taking millions of years to spread around the world into the hippos and whales commonly known today. What's for sure now, is that this so-called "traveling whale that reached the Pacific" (Peregocetus pacificus) was adapted to both swimming and walking.

The research was published online this week in the journal Current Biology.


Although the bones are several million years old and broken into many pieces, they were nicely preserved and easy to spot in the sediment surrounding them, Lambert said.

This illustration shows what Peregocetus might have looked like.

A pair of Peregocetus hunt on the rocky coast of Peru.

"Those early animals are amphibious, but they are not very good swimmers", said Thewissen, who didn't work on the study.

"The moderately elongated snout bearing robust anterior teeth with markedly ornamented enamel and shearing molars suggests that this medium-size protocetid was capable of preying upon relatively large prey, for example, large bony fish, an interpretation further supported by the incipient apical dental wear", Lambert said in comments obtained by SWNS. Movement in the water would have been similar to otters, the researchers say. As whales' ancient ancestors became increasingly adapted to aquatic environments, they dispersed to North Africa and then to the Americas, eventually losing their hind legs and gaining flippers.

"The leg and foot anatomy is similar to that seen in older whales from Pakistan, so this discovery raises important questions about the routes early whales took to disperse around the globe as well as how effective they were moving through the water", Geisler said.

Scientists are intrigued about how ancient whales evolved from "small hoofed mammals to the blue whale we have today", as Travis Park from the Natural History Museum in London stated. Today, a giant otter-type creature would have to swim a long way to migrate, but at that time in the Earth's history, the distance between Africa and South America was two times shorter and the currents were strong.

Other reports by Iphone Fresh

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