When Whales Walked: Journeys in Deep Time

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Narrator

At the Museum of Natural History in Paris, one of the birthplaces of paleontology, they have been assembling the skeletons of prehistoric animals for over 200 years. They now have one of the few complete reconstructions of the extraordinary whale ancestor, Pakicetus. This is a quadrupedal animal with forelimbs and hind limbs. It means that this animal was definitely partly terrestrial. I am Christian de Muizon. I'm a paleontologist working at the Natural History Museum in Paris. And obviously it's quite a strange animal, very small, doesn't whale-looking at all. It more looks like a dog with a long snout. -

Narrator

Pakicetus is one of the strangest surprises of evolution. A whale ancestor that looks like a small wolf with webbed feet for swimming. The key thing about it is it has elongated finger and toe bones, so clearly it's already semi-aquatic. (upbeat music) -

Narrator

Pakicetus was a creature of the shoreline, hunting for fish and perhaps other small animals in the shallows. And we think that it was using its longer snout to probe for aquatic prey in the water, and so it was feeding in the water, while almost certainly going out on land to breed and have their young. -

Narrator

Once they adapted to life in the shallows, it took 10 million years for the descendants of Pakicetus to become fully aquatic. Why did it take so long? Because to live underwater, they had to change. It is one of the most remarkable stories of total physical transformation in the annals of evolution. (whale vocalizing) After Pakicetus, whales take about 10 to 12 million years to evolve into fully aquatic forms. And during that time, their hind limbs tend to get smaller, their skulls tend to get longer, and the nares, which is the hole in the skull where the nose is, moves up the skull. In addition, their forelimbs tend to turn into flippers, and they get more vertebrae in their back, which makes their bodies longer.