When Whales Walked the Land

Protocetus, a close relative of the new species

The Eocene, the second epoch of the Age of Mammals, was a time of many strange creatures. The mammals were well established by this point, but few of the modern groups of mammal we are familiar with had yet evolved, and those that had did not necessarily look the same as they do today. Take the whales, for example:

Today, there are two basic types of whale. The odontocetes, or toothed whales, are the largest group, and include the porpoises and dolphins, as well as several larger species, including the mighty sperm whale. The other group are the mysticetes, or baleen whales, which have no teeth, and are instead filter feeders. This latter group includes the right whales and, perhaps most famously, the blue whale, which, so far as we know, is the largest animal ever to have lived.

Both of these groups first appeared at the end of the Eocene, but in those days, they shared the seas with a third, older, type of whale, that would die out during the following, Oligocene, epoch. These were the archaeocetes, and they include the original whales from which all the others later evolved.