When we think about prehistoric animals, we tend to think BIG.
That is because due to a bunch of different circumstances, many of these creatures grew much bigger than their modern-day counterparts. From insects to mammals to reptiles, they were big, big, big.
But despite the fact that giant sloths would've towered over polar bears and a sauropod would have made an elephant look like a housecat, the largest animal to have existed lives today.
That is the blue whale!
Though the blue whale is not longer than the longest known sauropods, it is much heavier and has more body mass than any dinosaur. (You can think of body mass as the amount of stuff that makes the animal.)
But now the blue whale's title is finally under threat. Meet Perucetus colossus, a prehistoric whale that experts say might be the most massive animal to have ever lived.
It makes sense that this blue whale challenger also comes from the sea.
Whales are only able to be so heavy because the water helps to support their weight. (This is why you can float horizontally in a swimming pool without touching the ground, while trying the same thing in midair would leave you landing with a thud!)
A sauropod trying to carry the blue whale's weight around would have broken its legs. That's not a good design for an animal!
According to researchers, P. colossus would've used the same principle to support its own baffling weight. But incredibly, it carried this weight around in a body that was even shorter than a blue whale's!
Putting it together
So where does P. colossus come from?
The fossils of this animal—which were 13 total bones—were found in a desert in Peru. (That's where the Perucetus part of its name comes from.)
Paleontologists were able to figure out that this was a new species of basilosaurid. These were the world's first fully aquatic cetaceans (whales). They are the ancestors of all of the world's porpoises, dolphins, and whales.
Basilosaurids were toothed whales that generally looked like a cross between a dolphin and a crocodile. These large animals lived around 43 to 33 million years ago. But the sheer size of these new bones left researchers puzzled. They were larger than what they had encountered before. And by comparing them with other fossils on record, and with modern bones, they also felt that these fossils weren't even from an adult.
This animal was likely still growing when it died!
What does it all mean?
As we've mentioned before, fossils are almost never complete. Working with them involves a lot of research and comparison with other species (both extinct and alive) to come up with the best estimation of what they were like when they were alive.
That is why the estimations of the size and mass of the P. colossus are so all over the map. Experts think a fully grown adult was anywhere between 85 and 340 tonnes. (The biggest blue whale known weighed 199 tonnes.) That's a huge difference, and enough of a reason to not hand Mr. Colossus the blue whale's crown just yet.
Still, the research offers a fascinating glimpse into the huge unknown possibilities of prehistoric life.
Watch a video summary of the research below!