Walking whales and underwater wolves. Halloween? No, just evolution.

Walking whales and underwater wolves. Halloween? No, just evolution.

At the dawn of time, when whales walked the Earth… they looked more like wolves than the whales we know and love today. Really.

About 50 million years ago in the Eocene Age, according to marine mammal expert Professor Tracey Rogers of UNSW, the Earth’s environment boasted high temperatures supporting rich rainforests and warm waters abundant with sea life. Around this time, a species of land mammal returned to the sea.

Fossils found in Pakistan are evidence of the Pakicetus, a wolf-like mammal that lived in rivers and the adjoining forests. The Pakicetus had small, sharp teeth, suggesting a carnivorous diet of fish. And whale ears – an interesting mix. The existence of whale ears, properly called ‘auditory bulla’, shows that the mammal was adapted to living underwater. Auditory bulla comprise a hollow, bony prominence in rounded form that is most suited to hearing underwater. Whales today still have them.

At 47 million years ago another marine mammal developed: the Ambulocetus. It had short legs and dense bones, resembling a crocodile more than a wolf. The back legs ended in huge feet, suitable for swimming fast rather than walking – think Olympic swimmer, but not as attractive.

37 million years ago saw the marine mammals adapting even further to a watery habitat with the advent of the Durodon, a 5 metre long tail-powered mammal whose front arms evolved into flippers. Likewise, the Durodon nostrils moved from the more usual location at the end of the snout to midway to the top of the head, an adaption that made it faster to surface for a breath of air. Really interesting is that the Durodon swam with a vertical up and down fin movement, just like today’s dolphins and whales.

Around this time there is also record of the first Baleen whale, although they did not yet have baleen plates. Rather, the Llanocetus, as it has been called, used lobed teeth, like a leopard seal.

During the fluctuations in temperature, as the Earth’s environment stabilised, the tectonic plates were active (still are, moving at up to 10 centimetres per year). At 34 million years, South America split from Antarctica. The thermal winds that this land division created further separated Antarctica from warmer climes, which saw mass extinctions. However, the phytoplankton thrived in cooler waters and with the nutrient-rich phytoplankton, which includes krill, came the whales.

That’s a short summary of this fascinating 5-minute video. Professor Rogers explains the whole process in greater detail, with the help of fossils, skeletons, animations and her incredible knowledge. Watching it helps understand the awe-inspiring process of evolution that gave us the beautiful humpback whale and consequently, why we need to protect them and their environment.

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