10 Terrifying Extinct Cetaceans

Pakicetus inachus
Paleontologists realized they had an ancient whale on their hands when they noticed this creature had developed the capability for underwater hearing. Photo courtesy Udo Schroter/Used under Creative Commons CC BY-SA 2.0 License

All is quiet at the shoreline, and water eddies around a few small rocks. But wait, are those rocks? Did they just blink? Suddenly a giant dog-rat with a snout like a steroidal wild boar darts out of the water, a fish clenched in its jaws. This, believe it or not, is an ancient whale.

Back in the 1980s, a team of paleontologists were combing through rock formations in Northern Pakistan, looking for fossils. One day, they came across the crest of a large, long skull. Unearthing it, they discovered that its brain cavity was relatively small compared to the size of the skull. It also had a developed tympanic bone for limited underwater hearing. These two features tipped them off that they had a 50-million-year-old whale on their hands. They named it Pakicetus inachus.

But unlike modern whales, P. inachus divided its time between land and sea, which might be part of the reason why it hadn't yet developed the sophisticated hearing mechanisms found in later species. Scarily, its eyes poked up and were positioned on the side of its scalp – which means it probably hunted from below like an alligator [source: Gingerich].