As a rule among modern whales, the big ones are friendly and feed on plankton and the smaller ones like killer whales are hunters, feeding mostly off fish. If Livyatan melvillei was still alive it would be an exception to this rule.
Livyatan melvillei grew to 17.5 meters long, a little smaller than a blue whale or sperm whale but definitely one of the big ones. It's skull measured up to 3 meters long and its teeth got up to 36 cm in length. These are the largest teeth that work as teeth of any known animal ever.
So what did it need such big teeth for? It used to hunt and kill other whales! Other than humans whales have not really had many predators in their history so that makes Livyatan melvillei part of a very small club. Sperm whales are also large hunters but their primary food source is large squids and not other whales.
Livyatan melvillei lived 12-13 million years ago and were found not far off the west coast of Peru.
Livyatan is a monotypic genus and its familial placement is uncertain. They are large toothed whales belonging to the superfamily Physeteroidea with sperm whales but for now they have not been designated a family.