The Walking Whale
How did a Creature Built for Land Become Master of the Ocean?

The Walking Whale
How did a Creature Built for Land Become Master of the Ocean?

Pakicetus is a genus of extinct terrestrial carnivorous mammal of the family Pakicetidae which was endemic to Pakistan from the Eocene.

Pakicetus existed for approximately 15.8 million years. Many paleontologists regard it as a close relative to the direct ancestors of modern day whales.

Fifty million years ago, a hungry land animal waded in shallow sea water. Four million years later, it lived permanently in the oceans and seas of planet earth.

How did a creature built for land become master of the ocean? 'Evolutions' follows the extraordinary evolution of a land animal into the modern whale.

Using CGI and fossil evidence we demonstrate nature's survival of the fittest in action. Evolutions illuminates unique and bizarre evolutionary journeys that have brought forth some of the world's most impressive animals.

We unearth a 50-million-year-old mystery mammal, discover the missing link between the velociraptor and modern day birds, and find out if a new bear species could be about to evolve before our very eyes.

The first fossils were uncovered in Pakistan, hence their name. The strata of western Pakistan where the fossils were found was then the coastal region of the Tethys Sea.

The first fossil found of the creature consisted of an incomplete skull with a skull cap and a broken mandible with some teeth.

It was thought to be from a mesonychid, but Gingerich and Russell recognized it as an early cetacean from characteristic features of the inner ear, found only in cetaceans: the large auditory bulla is formed from the ectotympanic bone only.

This suggests that it is a transitional species between extinct land mammals and modern cetaceans. It was restorated on the cover of Science as a semiaquatic, somewhat crocodilelike mammal, diving after fish.

Somewhat more complete skeletal remains were discovered in 2001, prompting the view that Pakicetus was primarily a land animal about the size of a wolf, and very similar in form to the related mesonychids. In 2001, J. G. M. Thewissen and colleagues wrote that "Pakicetids were terrestrial mammals, no more amphibious than a tapir."

However, in 2009 Thewissen et al argued that "the orbits ... of these cetaceans were located close together on top of the skull, as is common in aquatic animals that live in water but look at emerged objects. Just like Indohyus, limb bones of pakicetids are osteosclerotic, also suggestive of aquatic habitat" (since heavy bones provide ballast).