Picture from Nature and C Letenneur/MNHN
The fossil of a massive sea monster which lived 12 million years ago has been unearthed in South America.
The 17-metre-long whale had huge teeth, and the people who found the remains reckon that it liked fighting other big sea creatures.
They've called the scary beast 'Leviathan', and think it would have caught dolphins, seals and other whales in its huge jaws to eat.
The skull and teeth were dug up in the country of Peru.
Here's Leviathan's huge jaw!
Scientist Dr Christian de Muizon said: "At the same time in the same waters was another monster, which was a giant shark about 15 metres long. It's possible that they might have fought each other."
No one is sure why Leviathan died out, although it could have been because of the changing environment.