Life on Earth began in the water, then it moved up on land. Water to land. Water to land.
It's one of the basic lessons about how life evolved on this planet. So much so, that it's informing how scientists look for life on other planets, too!
But just because that's the direction that life moves when it starts doesn't mean that it can't go back later on. Case in point: whales.
Today, these mammoth sea titans are some of the largest animals to have ever lived. But their ancestors were bear-like mammals that roamed the land. Eventually, these animals spent more and more of their time hunting prey in the water. And so they evolved.
Life returned to the sea!
An example of this transition-in-progress was recently discovered in Egypt. Named Phiomicetus anubis, this walking whale ancestor would have been a powerful predator that lived about 43 million years ago. And its name gives this beast a connection to something quite frightening ... the god of death!
A whale of a name
In ancient Egyptian mythology, Anubis was the god of death, or the afterworld. He was drawn as a man with the head of a jackal. Though he sounds pretty fearsome, he was actually viewed by the ancient Egyptians as a protector in the afterlife. But that jackal head still looks pretty ferocious. Kind of like Phiomicetus anubis!
The fossil that was found contains parts of the animal's jaw, teeth, skull, ribs, and vertebrae. Researchers were able to figure out that it had a long, narrow jaw that was powered by strong muscles and filled with large, sharp teeth. These would have been ideal features for catching slippery aquatic prey—fish or other smaller aquatic mammals.
It was also large. At around 3 metres (10 feet) long, it was about as long as a saltwater crocodile (though a bit bigger). It would've hunted a lot like a croc, too—walking around on land before heading to the water to grab its prey.
All in all, maybe not quite as scary as the mythical lord of the underworld. But still, not many animals would've been comfortable seeing this whale ancestor diving into its waters!