A new stage in whale evolution discovered

The evolution of whales is one of the most fascinating stories in evolution because it goes in the opposite direction to the conventional story, of a land animal becoming a water-based one. The outlines of this have been pretty well established but now comes a report of the discovery of a new fossil of a large whale with four large legs that showed it to be capable of life on land and sea.

Photograph: A. Gennari/CellPress

The giant 42.6m-year-old fossil, discovered in marine sediments along the coast of Peru, appears to have been adapted for a semi-aquatic lifestyle. Its hoofed feet and the shape of its legs suggest it would have been capable of bearing the weight of its bulky four metre long body and walking on land. Other anatomical features, including a powerful tail and webbed feet similar to an otter suggest it was also a strong swimmer.

The latest specimen proves that early whales could swim for days or possibly weeks at a time while retaining their ability to rove around on land.

“Even though it could swim in the water [with] no problem, it still had little hooves on its fingers and toes,” said Park. “It’d be a lot more capable than seals at getting around on land.”

Its sharp teeth and long snout suggest the early whales may have eaten fish or crustaceans.

According to Lambert, it is likely that whales would initially have had to return to land for certain activities such as mating and giving birth to young. The first fully aquatic whales date to around 41m to 35m years ago, filling an ecological niche left vacant when the last marine reptiles – along with the dinosaurs – went extinct 66m years ago.

Note that this fossil was actually found in 2011 but the report released only today. It is common practice in archeology and paleontology for new fossil discoveries to be kept under very tight wraps while the painstaking task of completely excavating and analyzing goes on and they are ready to go public.

Here’s an animation of the evolution of whales.


  1. larpar says

    From the link and to add: “It has since been named Peregocetus pacificus, meaning “the travelling whale that reached the Pacific”.”
    I wonder what ‘kind’ the creationists would put it in?

  2. Mano Singham says

    Owlmirror @#5,

    I had been meaning to write a post about vanity license plates when I came across this interesting story about whales and forgot to change the URL. Thanks for pointing it out!

  3. Owlmirror says

    It has hoofed-webbed feet?
    How does that work?

    With the understanding that I am not a zoological anatomist, I think it means this: Cetaceans are artiodactyls, and like all artiodactyls, the tips of the digits on those ancestors (like Pakicetus and Peregocetus) that still had limbs and digits have a certain characteristic hooflike appearance. This can be seen in the closest land relative of Cetaceans, the hippopotamus — see the digits on the limbs of this fetal hippo. The skeleton in figure 1 of the paper doesn’t have all of the bones of the digits, but the tips that are there do seem to have that hooflike look, even if they are relatively small. Their limbs being webbed is inferred from their long phalanges, as visible in the same figure 1. They would not have stood on the tips of those hooflike toes while alive, but would probably have used the entire webbed flipper for support, much like a modern sea lion.

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